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author	Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date	Sun, 31 Jan 2016 17:34:49 +0900
parents	7d135dc70f03
children	1172e4bd9c6f

rev	line source
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1 ====================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	2 Writing an LLVM Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	3 ====================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	4
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	5 .. contents::
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	6 :local:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	7
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	8 Introduction --- What is a pass?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	9 ================================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	10
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	11 The LLVM Pass Framework is an important part of the LLVM system, because LLVM
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	12 passes are where most of the interesting parts of the compiler exist. Passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	13 perform the transformations and optimizations that make up the compiler, they
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	14 build the analysis results that are used by these transformations, and they
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	15 are, above all, a structuring technique for compiler code.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	16
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	17 All LLVM passes are subclasses of the `Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	18 <http://llvm.org/doxygen/classllvm_1_1Pass.html>`_ class, which implement
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	19 functionality by overriding virtual methods inherited from ``Pass``. Depending
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	20 on how your pass works, you should inherit from the :ref:`ModulePass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	21 <writing-an-llvm-pass-ModulePass>` , :ref:`CallGraphSCCPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	22 <writing-an-llvm-pass-CallGraphSCCPass>`, :ref:`FunctionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	23 <writing-an-llvm-pass-FunctionPass>` , or :ref:`LoopPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	24 <writing-an-llvm-pass-LoopPass>`, or :ref:`RegionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	25 <writing-an-llvm-pass-RegionPass>`, or :ref:`BasicBlockPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	26 <writing-an-llvm-pass-BasicBlockPass>` classes, which gives the system more
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	27 information about what your pass does, and how it can be combined with other
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	28 passes. One of the main features of the LLVM Pass Framework is that it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	29 schedules passes to run in an efficient way based on the constraints that your
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	30 pass meets (which are indicated by which class they derive from).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	31
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	32 We start by showing you how to construct a pass, everything from setting up the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	33 code, to compiling, loading, and executing it. After the basics are down, more
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	34 advanced features are discussed.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	35
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	36 Quick Start --- Writing hello world
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	37 ===================================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	38
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	39 Here we describe how to write the "hello world" of passes. The "Hello" pass is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	40 designed to simply print out the name of non-external functions that exist in
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	41 the program being compiled. It does not modify the program at all, it just
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	42 inspects it. The source code and files for this pass are available in the LLVM
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	43 source tree in the ``lib/Transforms/Hello`` directory.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	44
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	45 .. _writing-an-llvm-pass-makefile:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	46
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	47 Setting up the build environment
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	48 --------------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	49
95 afa8332a0e37 LLVM 3.8 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 83 diff changeset	50 First, configure and build LLVM. Next, you need to create a new directory
afa8332a0e37 LLVM 3.8 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 83 diff changeset	51 somewhere in the LLVM source base. For this example, we'll assume that you
afa8332a0e37 LLVM 3.8 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 83 diff changeset	52 made ``lib/Transforms/Hello``. Finally, you must set up a build script
afa8332a0e37 LLVM 3.8 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 83 diff changeset	53 (``Makefile``) that will compile the source code for the new pass. To do this,
afa8332a0e37 LLVM 3.8 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 83 diff changeset	54 copy the following into ``Makefile``:
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	55
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	56 .. code-block:: make
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	57
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	58 # Makefile for hello pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	59
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	60 # Path to top level of LLVM hierarchy
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	61 LEVEL = ../../..
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	62
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	63 # Name of the library to build
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	64 LIBRARYNAME = Hello
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	65
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	66 # Make the shared library become a loadable module so the tools can
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	67 # dlopen/dlsym on the resulting library.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	68 LOADABLE_MODULE = 1
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	69
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	70 # Include the makefile implementation stuff
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	71 include $(LEVEL)/Makefile.common
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	72
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	73 This makefile specifies that all of the ``.cpp`` files in the current directory
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	74 are to be compiled and linked together into a shared object
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	75 ``$(LEVEL)/Debug+Asserts/lib/Hello.so`` that can be dynamically loaded by the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	76 :program:`opt` or :program:`bugpoint` tools via their :option:`-load` options.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	77 If your operating system uses a suffix other than ``.so`` (such as Windows or Mac
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	78 OS X), the appropriate extension will be used.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	79
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	80 If you are used CMake to build LLVM, see :ref:`cmake-out-of-source-pass`.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	81
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	82 Now that we have the build scripts set up, we just need to write the code for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	83 the pass itself.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	84
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	85 .. _writing-an-llvm-pass-basiccode:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	86
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	87 Basic code required
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	88 -------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	89
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	90 Now that we have a way to compile our new pass, we just have to write it.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	91 Start out with:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	92
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	93 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	94
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	95 #include "llvm/Pass.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	96 #include "llvm/IR/Function.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	97 #include "llvm/Support/raw_ostream.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	98
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	99 Which are needed because we are writing a `Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	100 <http://llvm.org/doxygen/classllvm_1_1Pass.html>`_, we are operating on
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	101 `Function <http://llvm.org/doxygen/classllvm_1_1Function.html>`_\ s, and we will
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	102 be doing some printing.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	103
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	104 Next we have:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	105
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	106 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	107
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	108 using namespace llvm;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	109
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	110 ... which is required because the functions from the include files live in the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	111 llvm namespace.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	112
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	113 Next we have:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	114
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	115 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	116
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	117 namespace {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	118
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	119 ... which starts out an anonymous namespace. Anonymous namespaces are to C++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	120 what the "``static``" keyword is to C (at global scope). It makes the things
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	121 declared inside of the anonymous namespace visible only to the current file.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	122 If you're not familiar with them, consult a decent C++ book for more
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	123 information.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	124
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	125 Next, we declare our pass itself:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	126
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	127 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	128
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	129 struct Hello : public FunctionPass {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	130
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	131 This declares a "``Hello``" class that is a subclass of :ref:`FunctionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	132 <writing-an-llvm-pass-FunctionPass>`. The different builtin pass subclasses
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	133 are described in detail :ref:`later <writing-an-llvm-pass-pass-classes>`, but
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	134 for now, know that ``FunctionPass`` operates on a function at a time.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	135
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	136 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	137
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	138 static char ID;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	139 Hello() : FunctionPass(ID) {}
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	140
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	141 This declares pass identifier used by LLVM to identify pass. This allows LLVM
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	142 to avoid using expensive C++ runtime information.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	143
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	144 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	145
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	146 bool runOnFunction(Function &F) override {
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	147 errs() << "Hello: ";
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	148 errs().write_escaped(F.getName()) << "\n";
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	149 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	150 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	151 }; // end of struct Hello
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	152 } // end of anonymous namespace
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	153
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	154 We declare a :ref:`runOnFunction <writing-an-llvm-pass-runOnFunction>` method,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	155 which overrides an abstract virtual method inherited from :ref:`FunctionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	156 <writing-an-llvm-pass-FunctionPass>`. This is where we are supposed to do our
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	157 thing, so we just print out our message with the name of each function.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	158
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	159 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	160
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	161 char Hello::ID = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	162
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	163 We initialize pass ID here. LLVM uses ID's address to identify a pass, so
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	164 initialization value is not important.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	165
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	166 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	167
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	168 static RegisterPass<Hello> X("hello", "Hello World Pass",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	169 false /* Only looks at CFG */,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	170 false /* Analysis Pass */);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	171
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	172 Lastly, we :ref:`register our class <writing-an-llvm-pass-registration>`
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	173 ``Hello``, giving it a command line argument "``hello``", and a name "Hello
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	174 World Pass". The last two arguments describe its behavior: if a pass walks CFG
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	175 without modifying it then the third argument is set to ``true``; if a pass is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	176 an analysis pass, for example dominator tree pass, then ``true`` is supplied as
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	177 the fourth argument.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	178
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	179 As a whole, the ``.cpp`` file looks like:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	180
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	181 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	182
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	183 #include "llvm/Pass.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	184 #include "llvm/IR/Function.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	185 #include "llvm/Support/raw_ostream.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	186
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	187 using namespace llvm;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	188
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	189 namespace {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	190 struct Hello : public FunctionPass {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	191 static char ID;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	192 Hello() : FunctionPass(ID) {}
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	193
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	194 bool runOnFunction(Function &F) override {
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	195 errs() << "Hello: ";
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	196 errs().write_escaped(F.getName()) << '\n';
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	197 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	198 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	199 };
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	200 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	201
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	202 char Hello::ID = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	203 static RegisterPass<Hello> X("hello", "Hello World Pass", false, false);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	204
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	205 Now that it's all together, compile the file with a simple "``gmake``" command
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	206 from the top level of your build directory and you should get a new file
7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	207 "``Debug+Asserts/lib/Hello.so``". Note that everything in this file is
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	208 contained in an anonymous namespace --- this reflects the fact that passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	209 are self contained units that do not need external interfaces (although they
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	210 can have them) to be useful.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	211
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	212 Running a pass with ``opt``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	213 ---------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	214
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	215 Now that you have a brand new shiny shared object file, we can use the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	216 :program:`opt` command to run an LLVM program through your pass. Because you
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	217 registered your pass with ``RegisterPass``, you will be able to use the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	218 :program:`opt` tool to access it, once loaded.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	219
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	220 To test it, follow the example at the end of the :doc:`GettingStarted` to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	221 compile "Hello World" to LLVM. We can now run the bitcode file (hello.bc) for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	222 the program through our transformation like this (or course, any bitcode file
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	223 will work):
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	224
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	225 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	226
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	227 $ opt -load ../../Debug+Asserts/lib/Hello.so -hello < hello.bc > /dev/null
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	228 Hello: __main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	229 Hello: puts
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	230 Hello: main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	231
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	232 The :option:`-load` option specifies that :program:`opt` should load your pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	233 as a shared object, which makes "``-hello``" a valid command line argument
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	234 (which is one reason you need to :ref:`register your pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	235 <writing-an-llvm-pass-registration>`). Because the Hello pass does not modify
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	236 the program in any interesting way, we just throw away the result of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	237 :program:`opt` (sending it to ``/dev/null``).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	238
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	239 To see what happened to the other string you registered, try running
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	240 :program:`opt` with the :option:`-help` option:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	241
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	242 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	243
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	244 $ opt -load ../../Debug+Asserts/lib/Hello.so -help
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	245 OVERVIEW: llvm .bc -> .bc modular optimizer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	246
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	247 USAGE: opt [options] <input bitcode>
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	248
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	249 OPTIONS:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	250 Optimizations available:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	251 ...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	252 -globalopt - Global Variable Optimizer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	253 -globalsmodref-aa - Simple mod/ref analysis for globals
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	254 -gvn - Global Value Numbering
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	255 -hello - Hello World Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	256 -indvars - Induction Variable Simplification
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	257 -inline - Function Integration/Inlining
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	258 ...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	259
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	260 The pass name gets added as the information string for your pass, giving some
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	261 documentation to users of :program:`opt`. Now that you have a working pass,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	262 you would go ahead and make it do the cool transformations you want. Once you
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	263 get it all working and tested, it may become useful to find out how fast your
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	264 pass is. The :ref:`PassManager <writing-an-llvm-pass-passmanager>` provides a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	265 nice command line option (:option:`--time-passes`) that allows you to get
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	266 information about the execution time of your pass along with the other passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	267 you queue up. For example:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	268
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	269 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	270
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	271 $ opt -load ../../Debug+Asserts/lib/Hello.so -hello -time-passes < hello.bc > /dev/null
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	272 Hello: __main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	273 Hello: puts
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	274 Hello: main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	275 ===============================================================================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	276 ... Pass execution timing report ...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	277 ===============================================================================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	278 Total Execution Time: 0.02 seconds (0.0479059 wall clock)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	279
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	280 ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Pass Name ---
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	281 0.0100 (100.0%) 0.0000 ( 0.0%) 0.0100 ( 50.0%) 0.0402 ( 84.0%) Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	282 0.0000 ( 0.0%) 0.0100 (100.0%) 0.0100 ( 50.0%) 0.0031 ( 6.4%) Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	283 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0013 ( 2.7%) Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	284 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0033 ( 6.9%) Hello World Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	285 0.0100 (100.0%) 0.0100 (100.0%) 0.0200 (100.0%) 0.0479 (100.0%) TOTAL
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	286
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	287 As you can see, our implementation above is pretty fast. The additional
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	288 passes listed are automatically inserted by the :program:`opt` tool to verify
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	289 that the LLVM emitted by your pass is still valid and well formed LLVM, which
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	290 hasn't been broken somehow.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	291
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	292 Now that you have seen the basics of the mechanics behind passes, we can talk
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	293 about some more details of how they work and how to use them.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	294
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	295 .. _writing-an-llvm-pass-pass-classes:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	296
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	297 Pass classes and requirements
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	298 =============================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	299
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	300 One of the first things that you should do when designing a new pass is to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	301 decide what class you should subclass for your pass. The :ref:`Hello World
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	302 <writing-an-llvm-pass-basiccode>` example uses the :ref:`FunctionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	303 <writing-an-llvm-pass-FunctionPass>` class for its implementation, but we did
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	304 not discuss why or when this should occur. Here we talk about the classes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	305 available, from the most general to the most specific.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	306
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	307 When choosing a superclass for your ``Pass``, you should choose the **most
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	308 specific** class possible, while still being able to meet the requirements
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	309 listed. This gives the LLVM Pass Infrastructure information necessary to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	310 optimize how passes are run, so that the resultant compiler isn't unnecessarily
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	311 slow.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	312
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	313 The ``ImmutablePass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	314 ---------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	315
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	316 The most plain and boring type of pass is the "`ImmutablePass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	317 <http://llvm.org/doxygen/classllvm_1_1ImmutablePass.html>`_" class. This pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	318 type is used for passes that do not have to be run, do not change state, and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	319 never need to be updated. This is not a normal type of transformation or
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	320 analysis, but can provide information about the current compiler configuration.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	321
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	322 Although this pass class is very infrequently used, it is important for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	323 providing information about the current target machine being compiled for, and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	324 other static information that can affect the various transformations.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	325
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	326 ``ImmutablePass``\ es never invalidate other transformations, are never
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	327 invalidated, and are never "run".
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	328
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	329 .. _writing-an-llvm-pass-ModulePass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	330
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	331 The ``ModulePass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	332 ------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	333
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	334 The `ModulePass <http://llvm.org/doxygen/classllvm_1_1ModulePass.html>`_ class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	335 is the most general of all superclasses that you can use. Deriving from
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	336 ``ModulePass`` indicates that your pass uses the entire program as a unit,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	337 referring to function bodies in no predictable order, or adding and removing
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	338 functions. Because nothing is known about the behavior of ``ModulePass``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	339 subclasses, no optimization can be done for their execution.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	340
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	341 A module pass can use function level passes (e.g. dominators) using the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	342 ``getAnalysis`` interface ``getAnalysis<DominatorTree>(llvm::Function *)`` to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	343 provide the function to retrieve analysis result for, if the function pass does
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	344 not require any module or immutable passes. Note that this can only be done
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	345 for functions for which the analysis ran, e.g. in the case of dominators you
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	346 should only ask for the ``DominatorTree`` for function definitions, not
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	347 declarations.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	348
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	349 To write a correct ``ModulePass`` subclass, derive from ``ModulePass`` and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	350 overload the ``runOnModule`` method with the following signature:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	351
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	352 The ``runOnModule`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	353 ^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	354
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	355 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	356
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	357 virtual bool runOnModule(Module &M) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	358
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	359 The ``runOnModule`` method performs the interesting work of the pass. It
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	360 should return ``true`` if the module was modified by the transformation and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	361 ``false`` otherwise.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	362
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	363 .. _writing-an-llvm-pass-CallGraphSCCPass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	364
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	365 The ``CallGraphSCCPass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	366 ------------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	367
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	368 The `CallGraphSCCPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	369 <http://llvm.org/doxygen/classllvm_1_1CallGraphSCCPass.html>`_ is used by
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	370 passes that need to traverse the program bottom-up on the call graph (callees
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	371 before callers). Deriving from ``CallGraphSCCPass`` provides some mechanics
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	372 for building and traversing the ``CallGraph``, but also allows the system to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	373 optimize execution of ``CallGraphSCCPass``\ es. If your pass meets the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	374 requirements outlined below, and doesn't meet the requirements of a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	375 :ref:`FunctionPass <writing-an-llvm-pass-FunctionPass>` or :ref:`BasicBlockPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	376 <writing-an-llvm-pass-BasicBlockPass>`, you should derive from
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	377 ``CallGraphSCCPass``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	378
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	379 ``TODO``: explain briefly what SCC, Tarjan's algo, and B-U mean.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	380
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	381 To be explicit, CallGraphSCCPass subclasses are:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	382
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	383 #. ... not allowed to inspect or modify any ``Function``\ s other than those
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	384 in the current SCC and the direct callers and direct callees of the SCC.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	385 #. ... required to preserve the current ``CallGraph`` object, updating it to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	386 reflect any changes made to the program.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	387 #. ... not allowed to add or remove SCC's from the current Module, though
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	388 they may change the contents of an SCC.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	389 #. ... allowed to add or remove global variables from the current Module.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	390 #. ... allowed to maintain state across invocations of :ref:`runOnSCC
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	391 <writing-an-llvm-pass-runOnSCC>` (including global data).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	392
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	393 Implementing a ``CallGraphSCCPass`` is slightly tricky in some cases because it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	394 has to handle SCCs with more than one node in it. All of the virtual methods
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	395 described below should return ``true`` if they modified the program, or
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	396 ``false`` if they didn't.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	397
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	398 The ``doInitialization(CallGraph &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	399 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	400
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	401 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	402
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	403 virtual bool doInitialization(CallGraph &CG);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	404
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	405 The ``doInitialization`` method is allowed to do most of the things that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	406 ``CallGraphSCCPass``\ es are not allowed to do. They can add and remove
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	407 functions, get pointers to functions, etc. The ``doInitialization`` method is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	408 designed to do simple initialization type of stuff that does not depend on the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	409 SCCs being processed. The ``doInitialization`` method call is not scheduled to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	410 overlap with any other pass executions (thus it should be very fast).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	411
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	412 .. _writing-an-llvm-pass-runOnSCC:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	413
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	414 The ``runOnSCC`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	415 ^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	416
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	417 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	418
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	419 virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	420
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	421 The ``runOnSCC`` method performs the interesting work of the pass, and should
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	422 return ``true`` if the module was modified by the transformation, ``false``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	423 otherwise.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	424
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	425 The ``doFinalization(CallGraph &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	426 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	427
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	428 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	429
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	430 virtual bool doFinalization(CallGraph &CG);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	431
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	432 The ``doFinalization`` method is an infrequently used method that is called
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	433 when the pass framework has finished calling :ref:`runOnSCC
60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	434 <writing-an-llvm-pass-runOnSCC>` for every SCC in the program being compiled.
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	435
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	436 .. _writing-an-llvm-pass-FunctionPass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	437
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	438 The ``FunctionPass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	439 --------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	440
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	441 In contrast to ``ModulePass`` subclasses, `FunctionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	442 <http://llvm.org/doxygen/classllvm_1_1Pass.html>`_ subclasses do have a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	443 predictable, local behavior that can be expected by the system. All
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	444 ``FunctionPass`` execute on each function in the program independent of all of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	445 the other functions in the program. ``FunctionPass``\ es do not require that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	446 they are executed in a particular order, and ``FunctionPass``\ es do not modify
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	447 external functions.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	448
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	449 To be explicit, ``FunctionPass`` subclasses are not allowed to:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	450
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	451 #. Inspect or modify a ``Function`` other than the one currently being processed.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	452 #. Add or remove ``Function``\ s from the current ``Module``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	453 #. Add or remove global variables from the current ``Module``.
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	454 #. Maintain state across invocations of :ref:`runOnFunction
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	455 <writing-an-llvm-pass-runOnFunction>` (including global data).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	456
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	457 Implementing a ``FunctionPass`` is usually straightforward (See the :ref:`Hello
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	458 World <writing-an-llvm-pass-basiccode>` pass for example).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	459 ``FunctionPass``\ es may overload three virtual methods to do their work. All
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	460 of these methods should return ``true`` if they modified the program, or
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	461 ``false`` if they didn't.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	462
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	463 .. _writing-an-llvm-pass-doInitialization-mod:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	464
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	465 The ``doInitialization(Module &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	466 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	467
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	468 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	469
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	470 virtual bool doInitialization(Module &M);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	471
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	472 The ``doInitialization`` method is allowed to do most of the things that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	473 ``FunctionPass``\ es are not allowed to do. They can add and remove functions,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	474 get pointers to functions, etc. The ``doInitialization`` method is designed to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	475 do simple initialization type of stuff that does not depend on the functions
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	476 being processed. The ``doInitialization`` method call is not scheduled to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	477 overlap with any other pass executions (thus it should be very fast).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	478
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	479 A good example of how this method should be used is the `LowerAllocations
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	480 <http://llvm.org/doxygen/LowerAllocations_8cpp-source.html>`_ pass. This pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	481 converts ``malloc`` and ``free`` instructions into platform dependent
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	482 ``malloc()`` and ``free()`` function calls. It uses the ``doInitialization``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	483 method to get a reference to the ``malloc`` and ``free`` functions that it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	484 needs, adding prototypes to the module if necessary.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	485
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	486 .. _writing-an-llvm-pass-runOnFunction:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	487
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	488 The ``runOnFunction`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	489 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	490
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	491 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	492
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	493 virtual bool runOnFunction(Function &F) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	494
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	495 The ``runOnFunction`` method must be implemented by your subclass to do the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	496 transformation or analysis work of your pass. As usual, a ``true`` value
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	497 should be returned if the function is modified.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	498
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	499 .. _writing-an-llvm-pass-doFinalization-mod:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	500
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	501 The ``doFinalization(Module &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	502 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	503
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	504 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	505
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	506 virtual bool doFinalization(Module &M);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	507
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	508 The ``doFinalization`` method is an infrequently used method that is called
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	509 when the pass framework has finished calling :ref:`runOnFunction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	510 <writing-an-llvm-pass-runOnFunction>` for every function in the program being
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	511 compiled.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	512
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	513 .. _writing-an-llvm-pass-LoopPass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	514
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	515 The ``LoopPass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	516 ----------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	517
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	518 All ``LoopPass`` execute on each loop in the function independent of all of the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	519 other loops in the function. ``LoopPass`` processes loops in loop nest order
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	520 such that outer most loop is processed last.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	521
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	522 ``LoopPass`` subclasses are allowed to update loop nest using ``LPPassManager``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	523 interface. Implementing a loop pass is usually straightforward.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	524 ``LoopPass``\ es may overload three virtual methods to do their work. All
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	525 these methods should return ``true`` if they modified the program, or ``false``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	526 if they didn't.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	527
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	528 The ``doInitialization(Loop *, LPPassManager &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	529 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	530
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	531 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	532
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	533 virtual bool doInitialization(Loop *, LPPassManager &LPM);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	534
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	535 The ``doInitialization`` method is designed to do simple initialization type of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	536 stuff that does not depend on the functions being processed. The
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	537 ``doInitialization`` method call is not scheduled to overlap with any other
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	538 pass executions (thus it should be very fast). ``LPPassManager`` interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	539 should be used to access ``Function`` or ``Module`` level analysis information.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	540
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	541 .. _writing-an-llvm-pass-runOnLoop:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	542
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	543 The ``runOnLoop`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	544 ^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	545
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	546 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	547
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	548 virtual bool runOnLoop(Loop *, LPPassManager &LPM) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	549
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	550 The ``runOnLoop`` method must be implemented by your subclass to do the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	551 transformation or analysis work of your pass. As usual, a ``true`` value
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	552 should be returned if the function is modified. ``LPPassManager`` interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	553 should be used to update loop nest.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	554
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	555 The ``doFinalization()`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	556 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	557
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	558 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	559
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	560 virtual bool doFinalization();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	561
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	562 The ``doFinalization`` method is an infrequently used method that is called
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	563 when the pass framework has finished calling :ref:`runOnLoop
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	564 <writing-an-llvm-pass-runOnLoop>` for every loop in the program being compiled.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	565
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	566 .. _writing-an-llvm-pass-RegionPass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	567
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	568 The ``RegionPass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	569 ------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	570
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	571 ``RegionPass`` is similar to :ref:`LoopPass <writing-an-llvm-pass-LoopPass>`,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	572 but executes on each single entry single exit region in the function.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	573 ``RegionPass`` processes regions in nested order such that the outer most
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	574 region is processed last.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	575
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	576 ``RegionPass`` subclasses are allowed to update the region tree by using the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	577 ``RGPassManager`` interface. You may overload three virtual methods of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	578 ``RegionPass`` to implement your own region pass. All these methods should
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	579 return ``true`` if they modified the program, or ``false`` if they did not.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	580
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	581 The ``doInitialization(Region *, RGPassManager &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	582 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	583
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	584 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	585
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	586 virtual bool doInitialization(Region *, RGPassManager &RGM);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	587
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	588 The ``doInitialization`` method is designed to do simple initialization type of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	589 stuff that does not depend on the functions being processed. The
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	590 ``doInitialization`` method call is not scheduled to overlap with any other
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	591 pass executions (thus it should be very fast). ``RPPassManager`` interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	592 should be used to access ``Function`` or ``Module`` level analysis information.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	593
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	594 .. _writing-an-llvm-pass-runOnRegion:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	595
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	596 The ``runOnRegion`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	597 ^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	598
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	599 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	600
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	601 virtual bool runOnRegion(Region *, RGPassManager &RGM) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	602
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	603 The ``runOnRegion`` method must be implemented by your subclass to do the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	604 transformation or analysis work of your pass. As usual, a true value should be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	605 returned if the region is modified. ``RGPassManager`` interface should be used to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	606 update region tree.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	607
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	608 The ``doFinalization()`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	609 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	610
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	611 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	612
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	613 virtual bool doFinalization();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	614
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	615 The ``doFinalization`` method is an infrequently used method that is called
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	616 when the pass framework has finished calling :ref:`runOnRegion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	617 <writing-an-llvm-pass-runOnRegion>` for every region in the program being
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	618 compiled.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	619
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	620 .. _writing-an-llvm-pass-BasicBlockPass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	621
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	622 The ``BasicBlockPass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	623 ----------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	624
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	625 ``BasicBlockPass``\ es are just like :ref:`FunctionPass's
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	626 <writing-an-llvm-pass-FunctionPass>` , except that they must limit their scope
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	627 of inspection and modification to a single basic block at a time. As such,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	628 they are not allowed to do any of the following:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	629
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	630 #. Modify or inspect any basic blocks outside of the current one.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	631 #. Maintain state across invocations of :ref:`runOnBasicBlock
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	632 <writing-an-llvm-pass-runOnBasicBlock>`.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	633 #. Modify the control flow graph (by altering terminator instructions)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	634 #. Any of the things forbidden for :ref:`FunctionPasses
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	635 <writing-an-llvm-pass-FunctionPass>`.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	636
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	637 ``BasicBlockPass``\ es are useful for traditional local and "peephole"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	638 optimizations. They may override the same :ref:`doInitialization(Module &)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	639 <writing-an-llvm-pass-doInitialization-mod>` and :ref:`doFinalization(Module &)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	640 <writing-an-llvm-pass-doFinalization-mod>` methods that :ref:`FunctionPass's
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	641 <writing-an-llvm-pass-FunctionPass>` have, but also have the following virtual
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	642 methods that may also be implemented:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	643
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	644 The ``doInitialization(Function &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	645 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	646
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	647 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	648
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	649 virtual bool doInitialization(Function &F);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	650
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	651 The ``doInitialization`` method is allowed to do most of the things that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	652 ``BasicBlockPass``\ es are not allowed to do, but that ``FunctionPass``\ es
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	653 can. The ``doInitialization`` method is designed to do simple initialization
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	654 that does not depend on the ``BasicBlock``\ s being processed. The
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	655 ``doInitialization`` method call is not scheduled to overlap with any other
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	656 pass executions (thus it should be very fast).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	657
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	658 .. _writing-an-llvm-pass-runOnBasicBlock:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	659
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	660 The ``runOnBasicBlock`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	661 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	662
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	663 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	664
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	665 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	666
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	667 Override this function to do the work of the ``BasicBlockPass``. This function
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	668 is not allowed to inspect or modify basic blocks other than the parameter, and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	669 are not allowed to modify the CFG. A ``true`` value must be returned if the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	670 basic block is modified.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	671
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	672 The ``doFinalization(Function &)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	673 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	674
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	675 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	676
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	677 virtual bool doFinalization(Function &F);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	678
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	679 The ``doFinalization`` method is an infrequently used method that is called
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	680 when the pass framework has finished calling :ref:`runOnBasicBlock
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	681 <writing-an-llvm-pass-runOnBasicBlock>` for every ``BasicBlock`` in the program
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	682 being compiled. This can be used to perform per-function finalization.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	683
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	684 The ``MachineFunctionPass`` class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	685 ---------------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	686
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	687 A ``MachineFunctionPass`` is a part of the LLVM code generator that executes on
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	688 the machine-dependent representation of each LLVM function in the program.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	689
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	690 Code generator passes are registered and initialized specially by
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	691 ``TargetMachine::addPassesToEmitFile`` and similar routines, so they cannot
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	692 generally be run from the :program:`opt` or :program:`bugpoint` commands.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	693
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	694 A ``MachineFunctionPass`` is also a ``FunctionPass``, so all the restrictions
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	695 that apply to a ``FunctionPass`` also apply to it. ``MachineFunctionPass``\ es
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	696 also have additional restrictions. In particular, ``MachineFunctionPass``\ es
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	697 are not allowed to do any of the following:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	698
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	699 #. Modify or create any LLVM IR ``Instruction``\ s, ``BasicBlock``\ s,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	700 ``Argument``\ s, ``Function``\ s, ``GlobalVariable``\ s,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	701 ``GlobalAlias``\ es, or ``Module``\ s.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	702 #. Modify a ``MachineFunction`` other than the one currently being processed.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	703 #. Maintain state across invocations of :ref:`runOnMachineFunction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	704 <writing-an-llvm-pass-runOnMachineFunction>` (including global data).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	705
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	706 .. _writing-an-llvm-pass-runOnMachineFunction:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	707
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	708 The ``runOnMachineFunction(MachineFunction &MF)`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	709 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	710
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	711 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	712
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	713 virtual bool runOnMachineFunction(MachineFunction &MF) = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	714
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	715 ``runOnMachineFunction`` can be considered the main entry point of a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	716 ``MachineFunctionPass``; that is, you should override this method to do the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	717 work of your ``MachineFunctionPass``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	718
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	719 The ``runOnMachineFunction`` method is called on every ``MachineFunction`` in a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	720 ``Module``, so that the ``MachineFunctionPass`` may perform optimizations on
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	721 the machine-dependent representation of the function. If you want to get at
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	722 the LLVM ``Function`` for the ``MachineFunction`` you're working on, use
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	723 ``MachineFunction``'s ``getFunction()`` accessor method --- but remember, you
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	724 may not modify the LLVM ``Function`` or its contents from a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	725 ``MachineFunctionPass``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	726
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	727 .. _writing-an-llvm-pass-registration:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	728
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	729 Pass registration
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	730 -----------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	731
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	732 In the :ref:`Hello World <writing-an-llvm-pass-basiccode>` example pass we
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	733 illustrated how pass registration works, and discussed some of the reasons that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	734 it is used and what it does. Here we discuss how and why passes are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	735 registered.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	736
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	737 As we saw above, passes are registered with the ``RegisterPass`` template. The
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	738 template parameter is the name of the pass that is to be used on the command
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	739 line to specify that the pass should be added to a program (for example, with
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	740 :program:`opt` or :program:`bugpoint`). The first argument is the name of the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	741 pass, which is to be used for the :option:`-help` output of programs, as well
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	742 as for debug output generated by the :option:`--debug-pass` option.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	743
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	744 If you want your pass to be easily dumpable, you should implement the virtual
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	745 print method:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	746
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	747 The ``print`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	748 ^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	749
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	750 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	751
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	752 virtual void print(llvm::raw_ostream &O, const Module *M) const;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	753
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	754 The ``print`` method must be implemented by "analyses" in order to print a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	755 human readable version of the analysis results. This is useful for debugging
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	756 an analysis itself, as well as for other people to figure out how an analysis
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	757 works. Use the opt ``-analyze`` argument to invoke this method.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	758
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	759 The ``llvm::raw_ostream`` parameter specifies the stream to write the results
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	760 on, and the ``Module`` parameter gives a pointer to the top level module of the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	761 program that has been analyzed. Note however that this pointer may be ``NULL``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	762 in certain circumstances (such as calling the ``Pass::dump()`` from a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	763 debugger), so it should only be used to enhance debug output, it should not be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	764 depended on.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	765
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	766 .. _writing-an-llvm-pass-interaction:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	767
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	768 Specifying interactions between passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	769 --------------------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	770
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	771 One of the main responsibilities of the ``PassManager`` is to make sure that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	772 passes interact with each other correctly. Because ``PassManager`` tries to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	773 :ref:`optimize the execution of passes <writing-an-llvm-pass-passmanager>` it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	774 must know how the passes interact with each other and what dependencies exist
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	775 between the various passes. To track this, each pass can declare the set of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	776 passes that are required to be executed before the current pass, and the passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	777 which are invalidated by the current pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	778
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	779 Typically this functionality is used to require that analysis results are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	780 computed before your pass is run. Running arbitrary transformation passes can
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	781 invalidate the computed analysis results, which is what the invalidation set
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	782 specifies. If a pass does not implement the :ref:`getAnalysisUsage
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	783 <writing-an-llvm-pass-getAnalysisUsage>` method, it defaults to not having any
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	784 prerequisite passes, and invalidating all other passes.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	785
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	786 .. _writing-an-llvm-pass-getAnalysisUsage:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	787
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	788 The ``getAnalysisUsage`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	789 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	790
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	791 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	792
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	793 virtual void getAnalysisUsage(AnalysisUsage &Info) const;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	794
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	795 By implementing the ``getAnalysisUsage`` method, the required and invalidated
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	796 sets may be specified for your transformation. The implementation should fill
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	797 in the `AnalysisUsage
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	798 <http://llvm.org/doxygen/classllvm_1_1AnalysisUsage.html>`_ object with
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	799 information about which passes are required and not invalidated. To do this, a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	800 pass may call any of the following methods on the ``AnalysisUsage`` object:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	801
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	802 The ``AnalysisUsage::addRequired<>`` and ``AnalysisUsage::addRequiredTransitive<>`` methods
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	803 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	804
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	805 If your pass requires a previous pass to be executed (an analysis for example),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	806 it can use one of these methods to arrange for it to be run before your pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	807 LLVM has many different types of analyses and passes that can be required,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	808 spanning the range from ``DominatorSet`` to ``BreakCriticalEdges``. Requiring
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	809 ``BreakCriticalEdges``, for example, guarantees that there will be no critical
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	810 edges in the CFG when your pass has been run.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	811
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	812 Some analyses chain to other analyses to do their job. For example, an
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	813 `AliasAnalysis <AliasAnalysis>` implementation is required to :ref:`chain
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	814 <aliasanalysis-chaining>` to other alias analysis passes. In cases where
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	815 analyses chain, the ``addRequiredTransitive`` method should be used instead of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	816 the ``addRequired`` method. This informs the ``PassManager`` that the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	817 transitively required pass should be alive as long as the requiring pass is.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	818
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	819 The ``AnalysisUsage::addPreserved<>`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	820 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	821
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	822 One of the jobs of the ``PassManager`` is to optimize how and when analyses are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	823 run. In particular, it attempts to avoid recomputing data unless it needs to.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	824 For this reason, passes are allowed to declare that they preserve (i.e., they
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	825 don't invalidate) an existing analysis if it's available. For example, a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	826 simple constant folding pass would not modify the CFG, so it can't possibly
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	827 affect the results of dominator analysis. By default, all passes are assumed
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	828 to invalidate all others.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	829
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	830 The ``AnalysisUsage`` class provides several methods which are useful in
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	831 certain circumstances that are related to ``addPreserved``. In particular, the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	832 ``setPreservesAll`` method can be called to indicate that the pass does not
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	833 modify the LLVM program at all (which is true for analyses), and the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	834 ``setPreservesCFG`` method can be used by transformations that change
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	835 instructions in the program but do not modify the CFG or terminator
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	836 instructions (note that this property is implicitly set for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	837 :ref:`BasicBlockPass <writing-an-llvm-pass-BasicBlockPass>`\ es).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	838
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	839 ``addPreserved`` is particularly useful for transformations like
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	840 ``BreakCriticalEdges``. This pass knows how to update a small set of loop and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	841 dominator related analyses if they exist, so it can preserve them, despite the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	842 fact that it hacks on the CFG.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	843
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	844 Example implementations of ``getAnalysisUsage``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	845 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	846
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	847 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	848
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	849 // This example modifies the program, but does not modify the CFG
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	850 void LICM::getAnalysisUsage(AnalysisUsage &AU) const {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	851 AU.setPreservesCFG();
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	852 AU.addRequired<LoopInfoWrapperPass>();
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	853 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	854
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	855 .. _writing-an-llvm-pass-getAnalysis:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	856
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	857 The ``getAnalysis<>`` and ``getAnalysisIfAvailable<>`` methods
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	858 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	859
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	860 The ``Pass::getAnalysis<>`` method is automatically inherited by your class,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	861 providing you with access to the passes that you declared that you required
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	862 with the :ref:`getAnalysisUsage <writing-an-llvm-pass-getAnalysisUsage>`
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	863 method. It takes a single template argument that specifies which pass class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	864 you want, and returns a reference to that pass. For example:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	865
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	866 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	867
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	868 bool LICM::runOnFunction(Function &F) {
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	869 LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	870 //...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	871 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	872
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	873 This method call returns a reference to the pass desired. You may get a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	874 runtime assertion failure if you attempt to get an analysis that you did not
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	875 declare as required in your :ref:`getAnalysisUsage
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	876 <writing-an-llvm-pass-getAnalysisUsage>` implementation. This method can be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	877 called by your ``run*`` method implementation, or by any other local method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	878 invoked by your ``run*`` method.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	879
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	880 A module level pass can use function level analysis info using this interface.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	881 For example:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	882
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	883 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	884
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	885 bool ModuleLevelPass::runOnModule(Module &M) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	886 //...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	887 DominatorTree &DT = getAnalysis<DominatorTree>(Func);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	888 //...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	889 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	890
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	891 In above example, ``runOnFunction`` for ``DominatorTree`` is called by pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	892 manager before returning a reference to the desired pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	893
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	894 If your pass is capable of updating analyses if they exist (e.g.,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	895 ``BreakCriticalEdges``, as described above), you can use the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	896 ``getAnalysisIfAvailable`` method, which returns a pointer to the analysis if
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	897 it is active. For example:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	898
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	899 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	900
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	901 if (DominatorSet *DS = getAnalysisIfAvailable<DominatorSet>()) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	902 // A DominatorSet is active. This code will update it.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	903 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	904
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	905 Implementing Analysis Groups
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	906 ----------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	907
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	908 Now that we understand the basics of how passes are defined, how they are used,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	909 and how they are required from other passes, it's time to get a little bit
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	910 fancier. All of the pass relationships that we have seen so far are very
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	911 simple: one pass depends on one other specific pass to be run before it can
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	912 run. For many applications, this is great, for others, more flexibility is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	913 required.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	914
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	915 In particular, some analyses are defined such that there is a single simple
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	916 interface to the analysis results, but multiple ways of calculating them.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	917 Consider alias analysis for example. The most trivial alias analysis returns
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	918 "may alias" for any alias query. The most sophisticated analysis a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	919 flow-sensitive, context-sensitive interprocedural analysis that can take a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	920 significant amount of time to execute (and obviously, there is a lot of room
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	921 between these two extremes for other implementations). To cleanly support
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	922 situations like this, the LLVM Pass Infrastructure supports the notion of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	923 Analysis Groups.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	924
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	925 Analysis Group Concepts
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	926 ^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	927
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	928 An Analysis Group is a single simple interface that may be implemented by
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	929 multiple different passes. Analysis Groups can be given human readable names
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	930 just like passes, but unlike passes, they need not derive from the ``Pass``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	931 class. An analysis group may have one or more implementations, one of which is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	932 the "default" implementation.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	933
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	934 Analysis groups are used by client passes just like other passes are: the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	935 ``AnalysisUsage::addRequired()`` and ``Pass::getAnalysis()`` methods. In order
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	936 to resolve this requirement, the :ref:`PassManager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	937 <writing-an-llvm-pass-passmanager>` scans the available passes to see if any
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	938 implementations of the analysis group are available. If none is available, the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	939 default implementation is created for the pass to use. All standard rules for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	940 :ref:`interaction between passes <writing-an-llvm-pass-interaction>` still
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	941 apply.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	942
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	943 Although :ref:`Pass Registration <writing-an-llvm-pass-registration>` is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	944 optional for normal passes, all analysis group implementations must be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	945 registered, and must use the :ref:`INITIALIZE_AG_PASS
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	946 <writing-an-llvm-pass-RegisterAnalysisGroup>` template to join the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	947 implementation pool. Also, a default implementation of the interface must
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	948 be registered with :ref:`RegisterAnalysisGroup
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	949 <writing-an-llvm-pass-RegisterAnalysisGroup>`.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	950
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	951 As a concrete example of an Analysis Group in action, consider the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	952 `AliasAnalysis <http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html>`_
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	953 analysis group. The default implementation of the alias analysis interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	954 (the `basicaa <http://llvm.org/doxygen/structBasicAliasAnalysis.html>`_ pass)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	955 just does a few simple checks that don't require significant analysis to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	956 compute (such as: two different globals can never alias each other, etc).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	957 Passes that use the `AliasAnalysis
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	958 <http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html>`_ interface (for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	959 example the `gcse <http://llvm.org/doxygen/structGCSE.html>`_ pass), do not
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	960 care which implementation of alias analysis is actually provided, they just use
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	961 the designated interface.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	962
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	963 From the user's perspective, commands work just like normal. Issuing the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	964 command ``opt -gcse ...`` will cause the ``basicaa`` class to be instantiated
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	965 and added to the pass sequence. Issuing the command ``opt -somefancyaa -gcse
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	966 ...`` will cause the ``gcse`` pass to use the ``somefancyaa`` alias analysis
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	967 (which doesn't actually exist, it's just a hypothetical example) instead.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	968
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	969 .. _writing-an-llvm-pass-RegisterAnalysisGroup:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	970
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	971 Using ``RegisterAnalysisGroup``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	972 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	973
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	974 The ``RegisterAnalysisGroup`` template is used to register the analysis group
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	975 itself, while the ``INITIALIZE_AG_PASS`` is used to add pass implementations to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	976 the analysis group. First, an analysis group should be registered, with a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	977 human readable name provided for it. Unlike registration of passes, there is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	978 no command line argument to be specified for the Analysis Group Interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	979 itself, because it is "abstract":
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	980
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	981 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	982
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	983 static RegisterAnalysisGroup<AliasAnalysis> A("Alias Analysis");
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	984
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	985 Once the analysis is registered, passes can declare that they are valid
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	986 implementations of the interface by using the following code:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	987
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	988 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	989
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	990 namespace {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	991 // Declare that we implement the AliasAnalysis interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	992 INITIALIZE_AG_PASS(FancyAA, AliasAnalysis , "somefancyaa",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	993 "A more complex alias analysis implementation",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	994 false, // Is CFG Only?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	995 true, // Is Analysis?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	996 false); // Is default Analysis Group implementation?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	997 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	998
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	999 This just shows a class ``FancyAA`` that uses the ``INITIALIZE_AG_PASS`` macro
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1000 both to register and to "join" the `AliasAnalysis
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1001 <http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html>`_ analysis group.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1002 Every implementation of an analysis group should join using this macro.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1003
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1004 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1005
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1006 namespace {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1007 // Declare that we implement the AliasAnalysis interface
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1008 INITIALIZE_AG_PASS(BasicAA, AliasAnalysis, "basicaa",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1009 "Basic Alias Analysis (default AA impl)",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1010 false, // Is CFG Only?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1011 true, // Is Analysis?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1012 true); // Is default Analysis Group implementation?
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1013 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1014
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1015 Here we show how the default implementation is specified (using the final
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1016 argument to the ``INITIALIZE_AG_PASS`` template). There must be exactly one
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1017 default implementation available at all times for an Analysis Group to be used.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1018 Only default implementation can derive from ``ImmutablePass``. Here we declare
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1019 that the `BasicAliasAnalysis
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1020 <http://llvm.org/doxygen/structBasicAliasAnalysis.html>`_ pass is the default
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1021 implementation for the interface.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1022
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1023 Pass Statistics
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1024 ===============
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1025
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1026 The `Statistic <http://llvm.org/doxygen/Statistic_8h-source.html>`_ class is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1027 designed to be an easy way to expose various success metrics from passes.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1028 These statistics are printed at the end of a run, when the :option:`-stats`
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1029 command line option is enabled on the command line. See the :ref:`Statistics
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1030 section <Statistic>` in the Programmer's Manual for details.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1031
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1032 .. _writing-an-llvm-pass-passmanager:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1033
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1034 What PassManager does
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1035 ---------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1036
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1037 The `PassManager <http://llvm.org/doxygen/PassManager_8h-source.html>`_ `class
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1038 <http://llvm.org/doxygen/classllvm_1_1PassManager.html>`_ takes a list of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1039 passes, ensures their :ref:`prerequisites <writing-an-llvm-pass-interaction>`
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1040 are set up correctly, and then schedules passes to run efficiently. All of the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1041 LLVM tools that run passes use the PassManager for execution of these passes.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1042
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1043 The PassManager does two main things to try to reduce the execution time of a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1044 series of passes:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1045
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1046 #. Share analysis results. The ``PassManager`` attempts to avoid
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1047 recomputing analysis results as much as possible. This means keeping track
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1048 of which analyses are available already, which analyses get invalidated, and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1049 which analyses are needed to be run for a pass. An important part of work
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1050 is that the ``PassManager`` tracks the exact lifetime of all analysis
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1051 results, allowing it to :ref:`free memory
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1052 <writing-an-llvm-pass-releaseMemory>` allocated to holding analysis results
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1053 as soon as they are no longer needed.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1054
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1055 #. Pipeline the execution of passes on the program. The ``PassManager``
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1056 attempts to get better cache and memory usage behavior out of a series of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1057 passes by pipelining the passes together. This means that, given a series
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1058 of consecutive :ref:`FunctionPass <writing-an-llvm-pass-FunctionPass>`, it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1059 will execute all of the :ref:`FunctionPass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1060 <writing-an-llvm-pass-FunctionPass>` on the first function, then all of the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1061 :ref:`FunctionPasses <writing-an-llvm-pass-FunctionPass>` on the second
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1062 function, etc... until the entire program has been run through the passes.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1063
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1064 This improves the cache behavior of the compiler, because it is only
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1065 touching the LLVM program representation for a single function at a time,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1066 instead of traversing the entire program. It reduces the memory consumption
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1067 of compiler, because, for example, only one `DominatorSet
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1068 <http://llvm.org/doxygen/classllvm_1_1DominatorSet.html>`_ needs to be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1069 calculated at a time. This also makes it possible to implement some
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1070 :ref:`interesting enhancements <writing-an-llvm-pass-SMP>` in the future.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1071
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1072 The effectiveness of the ``PassManager`` is influenced directly by how much
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1073 information it has about the behaviors of the passes it is scheduling. For
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1074 example, the "preserved" set is intentionally conservative in the face of an
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1075 unimplemented :ref:`getAnalysisUsage <writing-an-llvm-pass-getAnalysisUsage>`
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1076 method. Not implementing when it should be implemented will have the effect of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1077 not allowing any analysis results to live across the execution of your pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1078
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1079 The ``PassManager`` class exposes a ``--debug-pass`` command line options that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1080 is useful for debugging pass execution, seeing how things work, and diagnosing
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1081 when you should be preserving more analyses than you currently are. (To get
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1082 information about all of the variants of the ``--debug-pass`` option, just type
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1083 "``opt -help-hidden``").
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1084
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1085 By using the --debug-pass=Structure option, for example, we can see how our
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1086 :ref:`Hello World <writing-an-llvm-pass-basiccode>` pass interacts with other
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1087 passes. Lets try it out with the gcse and licm passes:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1088
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1089 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1090
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	1091 $ opt -load ../../Debug+Asserts/lib/Hello.so -gcse -licm --debug-pass=Structure < hello.bc > /dev/null
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1092 Module Pass Manager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1093 Function Pass Manager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1094 Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1095 Immediate Dominators Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1096 Global Common Subexpression Elimination
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1097 -- Immediate Dominators Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1098 -- Global Common Subexpression Elimination
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1099 Natural Loop Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1100 Loop Invariant Code Motion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1101 -- Natural Loop Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1102 -- Loop Invariant Code Motion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1103 Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1104 -- Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1105 -- Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1106 Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1107 --Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1108
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1109 This output shows us when passes are constructed and when the analysis results
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1110 are known to be dead (prefixed with "``--``"). Here we see that GCSE uses
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1111 dominator and immediate dominator information to do its job. The LICM pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1112 uses natural loop information, which uses dominator sets, but not immediate
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1113 dominators. Because immediate dominators are no longer useful after the GCSE
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1114 pass, it is immediately destroyed. The dominator sets are then reused to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1115 compute natural loop information, which is then used by the LICM pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1116
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1117 After the LICM pass, the module verifier runs (which is automatically added by
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1118 the :program:`opt` tool), which uses the dominator set to check that the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1119 resultant LLVM code is well formed. After it finishes, the dominator set
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1120 information is destroyed, after being computed once, and shared by three
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1121 passes.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1122
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1123 Lets see how this changes when we run the :ref:`Hello World
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1124 <writing-an-llvm-pass-basiccode>` pass in between the two passes:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1125
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1126 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1127
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	1128 $ opt -load ../../Debug+Asserts/lib/Hello.so -gcse -hello -licm --debug-pass=Structure < hello.bc > /dev/null
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1129 Module Pass Manager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1130 Function Pass Manager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1131 Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1132 Immediate Dominators Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1133 Global Common Subexpression Elimination
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1134 -- Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1135 -- Immediate Dominators Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1136 -- Global Common Subexpression Elimination
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1137 Hello World Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1138 -- Hello World Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1139 Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1140 Natural Loop Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1141 Loop Invariant Code Motion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1142 -- Natural Loop Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1143 -- Loop Invariant Code Motion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1144 Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1145 -- Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1146 -- Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1147 Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1148 --Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1149 Hello: __main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1150 Hello: puts
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1151 Hello: main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1152
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1153 Here we see that the :ref:`Hello World <writing-an-llvm-pass-basiccode>` pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1154 has killed the Dominator Set pass, even though it doesn't modify the code at
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1155 all! To fix this, we need to add the following :ref:`getAnalysisUsage
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1156 <writing-an-llvm-pass-getAnalysisUsage>` method to our pass:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1157
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1158 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1159
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1160 // We don't modify the program, so we preserve all analyses
83 60c9769439b8 LLVM 3.7 Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> parents: 77 diff changeset	1161 void getAnalysisUsage(AnalysisUsage &AU) const override {
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1162 AU.setPreservesAll();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1163 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1164
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1165 Now when we run our pass, we get this output:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1166
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1167 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1168
100 7d135dc70f03 LLVM 3.9 Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp> parents: 95 diff changeset	1169 $ opt -load ../../Debug+Asserts/lib/Hello.so -gcse -hello -licm --debug-pass=Structure < hello.bc > /dev/null
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1170 Pass Arguments: -gcse -hello -licm
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1171 Module Pass Manager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1172 Function Pass Manager
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1173 Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1174 Immediate Dominators Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1175 Global Common Subexpression Elimination
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1176 -- Immediate Dominators Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1177 -- Global Common Subexpression Elimination
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1178 Hello World Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1179 -- Hello World Pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1180 Natural Loop Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1181 Loop Invariant Code Motion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1182 -- Loop Invariant Code Motion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1183 -- Natural Loop Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1184 Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1185 -- Dominator Set Construction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1186 -- Module Verifier
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1187 Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1188 --Bitcode Writer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1189 Hello: __main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1190 Hello: puts
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1191 Hello: main
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1192
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1193 Which shows that we don't accidentally invalidate dominator information
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1194 anymore, and therefore do not have to compute it twice.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1195
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1196 .. _writing-an-llvm-pass-releaseMemory:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1197
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1198 The ``releaseMemory`` method
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1199 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1200
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1201 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1202
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1203 virtual void releaseMemory();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1204
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1205 The ``PassManager`` automatically determines when to compute analysis results,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1206 and how long to keep them around for. Because the lifetime of the pass object
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1207 itself is effectively the entire duration of the compilation process, we need
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1208 some way to free analysis results when they are no longer useful. The
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1209 ``releaseMemory`` virtual method is the way to do this.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1210
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1211 If you are writing an analysis or any other pass that retains a significant
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1212 amount of state (for use by another pass which "requires" your pass and uses
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1213 the :ref:`getAnalysis <writing-an-llvm-pass-getAnalysis>` method) you should
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1214 implement ``releaseMemory`` to, well, release the memory allocated to maintain
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1215 this internal state. This method is called after the ``run*`` method for the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1216 class, before the next call of ``run*`` in your pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1217
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1218 Registering dynamically loaded passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1219 =====================================
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1220
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1221 Size matters when constructing production quality tools using LLVM, both for
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1222 the purposes of distribution, and for regulating the resident code size when
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1223 running on the target system. Therefore, it becomes desirable to selectively
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1224 use some passes, while omitting others and maintain the flexibility to change
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1225 configurations later on. You want to be able to do all this, and, provide
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1226 feedback to the user. This is where pass registration comes into play.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1227
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1228 The fundamental mechanisms for pass registration are the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1229 ``MachinePassRegistry`` class and subclasses of ``MachinePassRegistryNode``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1230
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1231 An instance of ``MachinePassRegistry`` is used to maintain a list of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1232 ``MachinePassRegistryNode`` objects. This instance maintains the list and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1233 communicates additions and deletions to the command line interface.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1234
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1235 An instance of ``MachinePassRegistryNode`` subclass is used to maintain
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1236 information provided about a particular pass. This information includes the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1237 command line name, the command help string and the address of the function used
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1238 to create an instance of the pass. A global static constructor of one of these
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1239 instances registers with a corresponding ``MachinePassRegistry``, the static
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1240 destructor unregisters. Thus a pass that is statically linked in the tool
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1241 will be registered at start up. A dynamically loaded pass will register on
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1242 load and unregister at unload.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1243
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1244 Using existing registries
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1245 -------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1246
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1247 There are predefined registries to track instruction scheduling
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1248 (``RegisterScheduler``) and register allocation (``RegisterRegAlloc``) machine
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1249 passes. Here we will describe how to register a register allocator machine
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1250 pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1251
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1252 Implement your register allocator machine pass. In your register allocator
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1253 ``.cpp`` file add the following include:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1254
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1255 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1256
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1257 #include "llvm/CodeGen/RegAllocRegistry.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1258
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1259 Also in your register allocator ``.cpp`` file, define a creator function in the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1260 form:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1261
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1262 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1263
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1264 FunctionPass *createMyRegisterAllocator() {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1265 return new MyRegisterAllocator();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1266 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1267
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1268 Note that the signature of this function should match the type of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1269 ``RegisterRegAlloc::FunctionPassCtor``. In the same file add the "installing"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1270 declaration, in the form:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1271
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1272 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1273
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1274 static RegisterRegAlloc myRegAlloc("myregalloc",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1275 "my register allocator help string",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1276 createMyRegisterAllocator);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1277
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1278 Note the two spaces prior to the help string produces a tidy result on the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1279 :option:`-help` query.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1280
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1281 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1282
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1283 $ llc -help
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1284 ...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1285 -regalloc - Register allocator to use (default=linearscan)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1286 =linearscan - linear scan register allocator
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1287 =local - local register allocator
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1288 =simple - simple register allocator
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1289 =myregalloc - my register allocator help string
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1290 ...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1291
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1292 And that's it. The user is now free to use ``-regalloc=myregalloc`` as an
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1293 option. Registering instruction schedulers is similar except use the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1294 ``RegisterScheduler`` class. Note that the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1295 ``RegisterScheduler::FunctionPassCtor`` is significantly different from
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1296 ``RegisterRegAlloc::FunctionPassCtor``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1297
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1298 To force the load/linking of your register allocator into the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1299 :program:`llc`/:program:`lli` tools, add your creator function's global
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1300 declaration to ``Passes.h`` and add a "pseudo" call line to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1301 ``llvm/Codegen/LinkAllCodegenComponents.h``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1302
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1303 Creating new registries
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1304 -----------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1305
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1306 The easiest way to get started is to clone one of the existing registries; we
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1307 recommend ``llvm/CodeGen/RegAllocRegistry.h``. The key things to modify are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1308 the class name and the ``FunctionPassCtor`` type.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1309
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1310 Then you need to declare the registry. Example: if your pass registry is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1311 ``RegisterMyPasses`` then define:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1312
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1313 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1314
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1315 MachinePassRegistry RegisterMyPasses::Registry;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1316
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1317 And finally, declare the command line option for your passes. Example:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1318
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1319 .. code-block:: c++
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1320
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1321 cl::opt<RegisterMyPasses::FunctionPassCtor, false,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1322 RegisterPassParser<RegisterMyPasses> >
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1323 MyPassOpt("mypass",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1324 cl::init(&createDefaultMyPass),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1325 cl::desc("my pass option help"));
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1326
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1327 Here the command option is "``mypass``", with ``createDefaultMyPass`` as the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1328 default creator.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1329
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1330 Using GDB with dynamically loaded passes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1331 ----------------------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1332
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1333 Unfortunately, using GDB with dynamically loaded passes is not as easy as it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1334 should be. First of all, you can't set a breakpoint in a shared object that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1335 has not been loaded yet, and second of all there are problems with inlined
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1336 functions in shared objects. Here are some suggestions to debugging your pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1337 with GDB.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1338
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1339 For sake of discussion, I'm going to assume that you are debugging a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1340 transformation invoked by :program:`opt`, although nothing described here
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1341 depends on that.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1342
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1343 Setting a breakpoint in your pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1344 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1345
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1346 First thing you do is start gdb on the opt process:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1347
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1348 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1349
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1350 $ gdb opt
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1351 GNU gdb 5.0
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1352 Copyright 2000 Free Software Foundation, Inc.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1353 GDB is free software, covered by the GNU General Public License, and you are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1354 welcome to change it and/or distribute copies of it under certain conditions.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1355 Type "show copying" to see the conditions.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1356 There is absolutely no warranty for GDB. Type "show warranty" for details.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1357 This GDB was configured as "sparc-sun-solaris2.6"...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1358 (gdb)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1359
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1360 Note that :program:`opt` has a lot of debugging information in it, so it takes
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1361 time to load. Be patient. Since we cannot set a breakpoint in our pass yet
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1362 (the shared object isn't loaded until runtime), we must execute the process,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1363 and have it stop before it invokes our pass, but after it has loaded the shared
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1364 object. The most foolproof way of doing this is to set a breakpoint in
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1365 ``PassManager::run`` and then run the process with the arguments you want:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1366
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1367 .. code-block:: console
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1368
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1369 $ (gdb) break llvm::PassManager::run
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1370 Breakpoint 1 at 0x2413bc: file Pass.cpp, line 70.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1371 (gdb) run test.bc -load $(LLVMTOP)/llvm/Debug+Asserts/lib/[libname].so -[passoption]
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1372 Starting program: opt test.bc -load $(LLVMTOP)/llvm/Debug+Asserts/lib/[libname].so -[passoption]
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1373 Breakpoint 1, PassManager::run (this=0xffbef174, M=@0x70b298) at Pass.cpp:70
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1374 70 bool PassManager::run(Module &M) { return PM->run(M); }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1375 (gdb)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1376
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1377 Once the :program:`opt` stops in the ``PassManager::run`` method you are now
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1378 free to set breakpoints in your pass so that you can trace through execution or
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1379 do other standard debugging stuff.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1380
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1381 Miscellaneous Problems
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1382 ^^^^^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1383
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1384 Once you have the basics down, there are a couple of problems that GDB has,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1385 some with solutions, some without.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1386
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1387 * Inline functions have bogus stack information. In general, GDB does a pretty
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1388 good job getting stack traces and stepping through inline functions. When a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1389 pass is dynamically loaded however, it somehow completely loses this
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1390 capability. The only solution I know of is to de-inline a function (move it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1391 from the body of a class to a ``.cpp`` file).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1392
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1393 * Restarting the program breaks breakpoints. After following the information
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1394 above, you have succeeded in getting some breakpoints planted in your pass.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1395 Nex thing you know, you restart the program (i.e., you type "``run``" again),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1396 and you start getting errors about breakpoints being unsettable. The only
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1397 way I have found to "fix" this problem is to delete the breakpoints that are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1398 already set in your pass, run the program, and re-set the breakpoints once
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1399 execution stops in ``PassManager::run``.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1400
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1401 Hopefully these tips will help with common case debugging situations. If you'd
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1402 like to contribute some tips of your own, just contact `Chris
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1403 <mailto:sabre@nondot.org>`_.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1404
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1405 Future extensions planned
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1406 -------------------------
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1407
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1408 Although the LLVM Pass Infrastructure is very capable as it stands, and does
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1409 some nifty stuff, there are things we'd like to add in the future. Here is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1410 where we are going:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1411
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1412 .. _writing-an-llvm-pass-SMP:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1413
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1414 Multithreaded LLVM
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1415 ^^^^^^^^^^^^^^^^^^
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1416
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1417 Multiple CPU machines are becoming more common and compilation can never be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1418 fast enough: obviously we should allow for a multithreaded compiler. Because
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1419 of the semantics defined for passes above (specifically they cannot maintain
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1420 state across invocations of their ``run*`` methods), a nice clean way to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1421 implement a multithreaded compiler would be for the ``PassManager`` class to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1422 create multiple instances of each pass object, and allow the separate instances
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1423 to be hacking on different parts of the program at the same time.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1424
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1425 This implementation would prevent each of the passes from having to implement
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1426 multithreaded constructs, requiring only the LLVM core to have locking in a few
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1427 places (for global resources). Although this is a simple extension, we simply
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1428 haven't had time (or multiprocessor machines, thus a reason) to implement this.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1429 Despite that, we have kept the LLVM passes SMP ready, and you should too.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1430

Mercurial > hg > Members > tobaru > cbc > CbC_llvm

annotate docs/WritingAnLLVMPass.rst @ 107:a03ddd01be7e