Members/tobaru/cbc/CbC_llvm: docs/GarbageCollection.rst annotate

annotate docs/GarbageCollection.rst @ 20:a5b470e0d09d

set FastCC(Calling Convention) when the function is code segment and set GuaranteedTailCallOpt. but llvm still output not jmp but call...

author	Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date	Sun, 06 Oct 2013 18:16:15 +0900
parents	9ad51c7bc036
children

rev	line source
3 9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1 =====================================
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	2 Accurate Garbage Collection with LLVM
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	3 =====================================
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	4
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	5 .. contents::
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	6 :local:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	7
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	8 Introduction
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	9 ============
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	10
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	11 Garbage collection is a widely used technique that frees the programmer from
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	12 having to know the lifetimes of heap objects, making software easier to produce
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	13 and maintain. Many programming languages rely on garbage collection for
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	14 automatic memory management. There are two primary forms of garbage collection:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	15 conservative and accurate.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	16
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	17 Conservative garbage collection often does not require any special support from
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	18 either the language or the compiler: it can handle non-type-safe programming
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	19 languages (such as C/C++) and does not require any special information from the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	20 compiler. The `Boehm collector
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	21 <http://www.hpl.hp.com/personal/Hans_Boehm/gc/>`__ is an example of a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	22 state-of-the-art conservative collector.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	23
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	24 Accurate garbage collection requires the ability to identify all pointers in the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	25 program at run-time (which requires that the source-language be type-safe in
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	26 most cases). Identifying pointers at run-time requires compiler support to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	27 locate all places that hold live pointer variables at run-time, including the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	28 :ref:`processor stack and registers <gcroot>`.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	29
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	30 Conservative garbage collection is attractive because it does not require any
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	31 special compiler support, but it does have problems. In particular, because the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	32 conservative garbage collector cannot know that a particular word in the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	33 machine is a pointer, it cannot move live objects in the heap (preventing the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	34 use of compacting and generational GC algorithms) and it can occasionally suffer
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	35 from memory leaks due to integer values that happen to point to objects in the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	36 program. In addition, some aggressive compiler transformations can break
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	37 conservative garbage collectors (though these seem rare in practice).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	38
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	39 Accurate garbage collectors do not suffer from any of these problems, but they
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	40 can suffer from degraded scalar optimization of the program. In particular,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	41 because the runtime must be able to identify and update all pointers active in
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	42 the program, some optimizations are less effective. In practice, however, the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	43 locality and performance benefits of using aggressive garbage collection
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	44 techniques dominates any low-level losses.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	45
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	46 This document describes the mechanisms and interfaces provided by LLVM to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	47 support accurate garbage collection.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	48
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	49 Goals and non-goals
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	50 -------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	51
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	52 LLVM's intermediate representation provides :ref:`garbage collection intrinsics
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	53 <gc_intrinsics>` that offer support for a broad class of collector models. For
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	54 instance, the intrinsics permit:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	55
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	56 * semi-space collectors
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	57
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	58 * mark-sweep collectors
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	59
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	60 * generational collectors
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	61
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	62 * reference counting
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	63
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	64 * incremental collectors
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	65
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	66 * concurrent collectors
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	67
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	68 * cooperative collectors
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	69
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	70 We hope that the primitive support built into the LLVM IR is sufficient to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	71 support a broad class of garbage collected languages including Scheme, ML, Java,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	72 C#, Perl, Python, Lua, Ruby, other scripting languages, and more.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	73
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	74 However, LLVM does not itself provide a garbage collector --- this should be
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	75 part of your language's runtime library. LLVM provides a framework for compile
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	76 time :ref:`code generation plugins <plugin>`. The role of these plugins is to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	77 generate code and data structures which conforms to the binary interface
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	78 specified by the runtime library. This is similar to the relationship between
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	79 LLVM and DWARF debugging info, for example. The difference primarily lies in
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	80 the lack of an established standard in the domain of garbage collection --- thus
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	81 the plugins.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	82
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	83 The aspects of the binary interface with which LLVM's GC support is
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	84 concerned are:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	85
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	86 * Creation of GC-safe points within code where collection is allowed to execute
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	87 safely.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	88
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	89 * Computation of the stack map. For each safe point in the code, object
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	90 references within the stack frame must be identified so that the collector may
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	91 traverse and perhaps update them.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	92
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	93 * Write barriers when storing object references to the heap. These are commonly
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	94 used to optimize incremental scans in generational collectors.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	95
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	96 * Emission of read barriers when loading object references. These are useful
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	97 for interoperating with concurrent collectors.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	98
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	99 There are additional areas that LLVM does not directly address:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	100
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	101 * Registration of global roots with the runtime.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	102
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	103 * Registration of stack map entries with the runtime.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	104
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	105 * The functions used by the program to allocate memory, trigger a collection,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	106 etc.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	107
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	108 * Computation or compilation of type maps, or registration of them with the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	109 runtime. These are used to crawl the heap for object references.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	110
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	111 In general, LLVM's support for GC does not include features which can be
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	112 adequately addressed with other features of the IR and does not specify a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	113 particular binary interface. On the plus side, this means that you should be
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	114 able to integrate LLVM with an existing runtime. On the other hand, it leaves a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	115 lot of work for the developer of a novel language. However, it's easy to get
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	116 started quickly and scale up to a more sophisticated implementation as your
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	117 compiler matures.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	118
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	119 Getting started
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	120 ===============
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	121
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	122 Using a GC with LLVM implies many things, for example:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	123
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	124 * Write a runtime library or find an existing one which implements a GC heap.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	125
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	126 #. Implement a memory allocator.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	127
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	128 #. Design a binary interface for the stack map, used to identify references
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	129 within a stack frame on the machine stack.\*
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	130
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	131 #. Implement a stack crawler to discover functions on the call stack.\*
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	132
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	133 #. Implement a registry for global roots.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	134
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	135 #. Design a binary interface for type maps, used to identify references
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	136 within heap objects.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	137
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	138 #. Implement a collection routine bringing together all of the above.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	139
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	140 * Emit compatible code from your compiler.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	141
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	142 * Initialization in the main function.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	143
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	144 * Use the ``gc "..."`` attribute to enable GC code generation (or
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	145 ``F.setGC("...")``).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	146
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	147 * Use ``@llvm.gcroot`` to mark stack roots.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	148
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	149 * Use ``@llvm.gcread`` and/or ``@llvm.gcwrite`` to manipulate GC references,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	150 if necessary.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	151
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	152 * Allocate memory using the GC allocation routine provided by the runtime
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	153 library.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	154
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	155 * Generate type maps according to your runtime's binary interface.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	156
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	157 * Write a compiler plugin to interface LLVM with the runtime library.\*
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	158
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	159 * Lower ``@llvm.gcread`` and ``@llvm.gcwrite`` to appropriate code
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	160 sequences.\*
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	161
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	162 * Compile LLVM's stack map to the binary form expected by the runtime.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	163
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	164 * Load the plugin into the compiler. Use ``llc -load`` or link the plugin
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	165 statically with your language's compiler.\*
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	166
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	167 * Link program executables with the runtime.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	168
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	169 To help with several of these tasks (those indicated with a \*), LLVM includes a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	170 highly portable, built-in ShadowStack code generator. It is compiled into
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	171 ``llc`` and works even with the interpreter and C backends.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	172
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	173 In your compiler
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	174 ----------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	175
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	176 To turn the shadow stack on for your functions, first call:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	177
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	178 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	179
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	180 F.setGC("shadow-stack");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	181
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	182 for each function your compiler emits. Since the shadow stack is built into
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	183 LLVM, you do not need to load a plugin.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	184
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	185 Your compiler must also use ``@llvm.gcroot`` as documented. Don't forget to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	186 create a root for each intermediate value that is generated when evaluating an
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	187 expression. In ``h(f(), g())``, the result of ``f()`` could easily be collected
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	188 if evaluating ``g()`` triggers a collection.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	189
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	190 There's no need to use ``@llvm.gcread`` and ``@llvm.gcwrite`` over plain
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	191 ``load`` and ``store`` for now. You will need them when switching to a more
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	192 advanced GC.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	193
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	194 In your runtime
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	195 ---------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	196
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	197 The shadow stack doesn't imply a memory allocation algorithm. A semispace
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	198 collector or building atop ``malloc`` are great places to start, and can be
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	199 implemented with very little code.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	200
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	201 When it comes time to collect, however, your runtime needs to traverse the stack
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	202 roots, and for this it needs to integrate with the shadow stack. Luckily, doing
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	203 so is very simple. (This code is heavily commented to help you understand the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	204 data structure, but there are only 20 lines of meaningful code.)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	205
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	206 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	207
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	208 /// @brief The map for a single function's stack frame. One of these is
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	209 /// compiled as constant data into the executable for each function.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	210 ///
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	211 /// Storage of metadata values is elided if the %metadata parameter to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	212 /// @llvm.gcroot is null.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	213 struct FrameMap {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	214 int32_t NumRoots; //< Number of roots in stack frame.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	215 int32_t NumMeta; //< Number of metadata entries. May be < NumRoots.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	216 const void *Meta[0]; //< Metadata for each root.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	217 };
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	218
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	219 /// @brief A link in the dynamic shadow stack. One of these is embedded in
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	220 /// the stack frame of each function on the call stack.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	221 struct StackEntry {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	222 StackEntry *Next; //< Link to next stack entry (the caller's).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	223 const FrameMap *Map; //< Pointer to constant FrameMap.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	224 void *Roots[0]; //< Stack roots (in-place array).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	225 };
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	226
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	227 /// @brief The head of the singly-linked list of StackEntries. Functions push
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	228 /// and pop onto this in their prologue and epilogue.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	229 ///
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	230 /// Since there is only a global list, this technique is not threadsafe.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	231 StackEntry *llvm_gc_root_chain;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	232
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	233 /// @brief Calls Visitor(root, meta) for each GC root on the stack.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	234 /// root and meta are exactly the values passed to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	235 /// @llvm.gcroot.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	236 ///
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	237 /// Visitor could be a function to recursively mark live objects. Or it
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	238 /// might copy them to another heap or generation.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	239 ///
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	240 /// @param Visitor A function to invoke for every GC root on the stack.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	241 void visitGCRoots(void (Visitor)(void Root, const void Meta)) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	242 for (StackEntry *R = llvm_gc_root_chain; R; R = R->Next) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	243 unsigned i = 0;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	244
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	245 // For roots [0, NumMeta), the metadata pointer is in the FrameMap.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	246 for (unsigned e = R->Map->NumMeta; i != e; ++i)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	247 Visitor(&R->Roots[i], R->Map->Meta[i]);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	248
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	249 // For roots [NumMeta, NumRoots), the metadata pointer is null.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	250 for (unsigned e = R->Map->NumRoots; i != e; ++i)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	251 Visitor(&R->Roots[i], NULL);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	252 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	253 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	254
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	255 About the shadow stack
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	256 ----------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	257
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	258 Unlike many GC algorithms which rely on a cooperative code generator to compile
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	259 stack maps, this algorithm carefully maintains a linked list of stack roots
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	260 [:ref:`Henderson2002 <henderson02>`]. This so-called "shadow stack" mirrors the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	261 machine stack. Maintaining this data structure is slower than using a stack map
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	262 compiled into the executable as constant data, but has a significant portability
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	263 advantage because it requires no special support from the target code generator,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	264 and does not require tricky platform-specific code to crawl the machine stack.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	265
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	266 The tradeoff for this simplicity and portability is:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	267
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	268 * High overhead per function call.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	269
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	270 * Not thread-safe.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	271
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	272 Still, it's an easy way to get started. After your compiler and runtime are up
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	273 and running, writing a :ref:`plugin <plugin>` will allow you to take advantage
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	274 of :ref:`more advanced GC features <collector-algos>` of LLVM in order to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	275 improve performance.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	276
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	277 .. _gc_intrinsics:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	278
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	279 IR features
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	280 ===========
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	281
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	282 This section describes the garbage collection facilities provided by the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	283 :doc:`LLVM intermediate representation <LangRef>`. The exact behavior of these
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	284 IR features is specified by the binary interface implemented by a :ref:`code
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	285 generation plugin <plugin>`, not by this document.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	286
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	287 These facilities are limited to those strictly necessary; they are not intended
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	288 to be a complete interface to any garbage collector. A program will need to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	289 interface with the GC library using the facilities provided by that program.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	290
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	291 Specifying GC code generation: ``gc "..."``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	292 -------------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	293
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	294 .. code-block:: llvm
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	295
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	296 define ty @name(...) gc "name" { ...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	297
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	298 The ``gc`` function attribute is used to specify the desired GC style to the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	299 compiler. Its programmatic equivalent is the ``setGC`` method of ``Function``.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	300
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	301 Setting ``gc "name"`` on a function triggers a search for a matching code
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	302 generation plugin "name"; it is that plugin which defines the exact nature of
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	303 the code generated to support GC. If none is found, the compiler will raise an
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	304 error.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	305
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	306 Specifying the GC style on a per-function basis allows LLVM to link together
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	307 programs that use different garbage collection algorithms (or none at all).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	308
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	309 .. _gcroot:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	310
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	311 Identifying GC roots on the stack: ``llvm.gcroot``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	312 --------------------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	313
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	314 .. code-block:: llvm
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	315
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	316 void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	317
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	318 The ``llvm.gcroot`` intrinsic is used to inform LLVM that a stack variable
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	319 references an object on the heap and is to be tracked for garbage collection.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	320 The exact impact on generated code is specified by a :ref:`compiler plugin
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	321 <plugin>`. All calls to ``llvm.gcroot`` must reside inside the first basic
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	322 block.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	323
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	324 A compiler which uses mem2reg to raise imperative code using ``alloca`` into SSA
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	325 form need only add a call to ``@llvm.gcroot`` for those variables which a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	326 pointers into the GC heap.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	327
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	328 It is also important to mark intermediate values with ``llvm.gcroot``. For
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	329 example, consider ``h(f(), g())``. Beware leaking the result of ``f()`` in the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	330 case that ``g()`` triggers a collection. Note, that stack variables must be
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	331 initialized and marked with ``llvm.gcroot`` in function's prologue.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	332
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	333 The first argument must be a value referring to an alloca instruction or a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	334 bitcast of an alloca. The second contains a pointer to metadata that should be
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	335 associated with the pointer, and must be a constant or global value
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	336 address. If your target collector uses tags, use a null pointer for metadata.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	337
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	338 The ``%metadata`` argument can be used to avoid requiring heap objects to have
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	339 'isa' pointers or tag bits. [Appel89_, Goldberg91_, Tolmach94_] If specified,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	340 its value will be tracked along with the location of the pointer in the stack
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	341 frame.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	342
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	343 Consider the following fragment of Java code:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	344
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	345 .. code-block:: java
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	346
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	347 {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	348 Object X; // A null-initialized reference to an object
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	349 ...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	350 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	351
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	352 This block (which may be located in the middle of a function or in a loop nest),
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	353 could be compiled to this LLVM code:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	354
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	355 .. code-block:: llvm
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	356
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	357 Entry:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	358 ;; In the entry block for the function, allocate the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	359 ;; stack space for X, which is an LLVM pointer.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	360 %X = alloca %Object*
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	361
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	362 ;; Tell LLVM that the stack space is a stack root.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	363 ;; Java has type-tags on objects, so we pass null as metadata.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	364 %tmp = bitcast %Object %X to i8
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	365 call void @llvm.gcroot(i8** %tmp, i8* null)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	366 ...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	367
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	368 ;; "CodeBlock" is the block corresponding to the start
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	369 ;; of the scope above.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	370 CodeBlock:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	371 ;; Java null-initializes pointers.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	372 store %Object* null, %Object** %X
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	373
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	374 ...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	375
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	376 ;; As the pointer goes out of scope, store a null value into
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	377 ;; it, to indicate that the value is no longer live.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	378 store %Object* null, %Object** %X
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	379 ...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	380
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	381 Reading and writing references in the heap
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	382 ------------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	383
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	384 Some collectors need to be informed when the mutator (the program that needs
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	385 garbage collection) either reads a pointer from or writes a pointer to a field
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	386 of a heap object. The code fragments inserted at these points are called *read
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	387 barriers* and write barriers, respectively. The amount of code that needs to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	388 be executed is usually quite small and not on the critical path of any
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	389 computation, so the overall performance impact of the barrier is tolerable.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	390
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	391 Barriers often require access to the object pointer rather than the *derived
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	392 pointer* (which is a pointer to the field within the object). Accordingly,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	393 these intrinsics take both pointers as separate arguments for completeness. In
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	394 this snippet, ``%object`` is the object pointer, and ``%derived`` is the derived
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	395 pointer:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	396
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	397 .. code-block:: llvm
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	398
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	399 ;; An array type.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	400 %class.Array = type { %class.Object, i32, [0 x %class.Object*] }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	401 ...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	402
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	403 ;; Load the object pointer from a gcroot.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	404 %object = load %class.Array** %object_addr
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	405
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	406 ;; Compute the derived pointer.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	407 %derived = getelementptr %object, i32 0, i32 2, i32 %n
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	408
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	409 LLVM does not enforce this relationship between the object and derived pointer
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	410 (although a :ref:`plugin <plugin>` might). However, it would be an unusual
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	411 collector that violated it.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	412
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	413 The use of these intrinsics is naturally optional if the target GC does require
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	414 the corresponding barrier. Such a GC plugin will replace the intrinsic calls
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	415 with the corresponding ``load`` or ``store`` instruction if they are used.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	416
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	417 Write barrier: ``llvm.gcwrite``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	418 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	419
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	420 .. code-block:: llvm
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	421
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	422 void @llvm.gcwrite(i8* %value, i8* %object, i8** %derived)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	423
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	424 For write barriers, LLVM provides the ``llvm.gcwrite`` intrinsic function. It
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	425 has exactly the same semantics as a non-volatile ``store`` to the derived
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	426 pointer (the third argument). The exact code generated is specified by a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	427 compiler :ref:`plugin <plugin>`.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	428
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	429 Many important algorithms require write barriers, including generational and
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	430 concurrent collectors. Additionally, write barriers could be used to implement
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	431 reference counting.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	432
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	433 Read barrier: ``llvm.gcread``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	434 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	435
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	436 .. code-block:: llvm
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	437
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	438 i8* @llvm.gcread(i8* %object, i8** %derived)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	439
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	440 For read barriers, LLVM provides the ``llvm.gcread`` intrinsic function. It has
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	441 exactly the same semantics as a non-volatile ``load`` from the derived pointer
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	442 (the second argument). The exact code generated is specified by a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	443 :ref:`compiler plugin <plugin>`.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	444
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	445 Read barriers are needed by fewer algorithms than write barriers, and may have a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	446 greater performance impact since pointer reads are more frequent than writes.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	447
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	448 .. _plugin:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	449
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	450 Implementing a collector plugin
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	451 ===============================
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	452
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	453 User code specifies which GC code generation to use with the ``gc`` function
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	454 attribute or, equivalently, with the ``setGC`` method of ``Function``.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	455
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	456 To implement a GC plugin, it is necessary to subclass ``llvm::GCStrategy``,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	457 which can be accomplished in a few lines of boilerplate code. LLVM's
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	458 infrastructure provides access to several important algorithms. For an
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	459 uncontroversial collector, all that remains may be to compile LLVM's computed
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	460 stack map to assembly code (using the binary representation expected by the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	461 runtime library). This can be accomplished in about 100 lines of code.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	462
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	463 This is not the appropriate place to implement a garbage collected heap or a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	464 garbage collector itself. That code should exist in the language's runtime
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	465 library. The compiler plugin is responsible for generating code which conforms
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	466 to the binary interface defined by library, most essentially the :ref:`stack map
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	467 <stack-map>`.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	468
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	469 To subclass ``llvm::GCStrategy`` and register it with the compiler:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	470
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	471 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	472
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	473 // lib/MyGC/MyGC.cpp - Example LLVM GC plugin
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	474
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	475 #include "llvm/CodeGen/GCStrategy.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	476 #include "llvm/CodeGen/GCMetadata.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	477 #include "llvm/Support/Compiler.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	478
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	479 using namespace llvm;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	480
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	481 namespace {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	482 class LLVM_LIBRARY_VISIBILITY MyGC : public GCStrategy {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	483 public:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	484 MyGC() {}
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	485 };
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	486
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	487 GCRegistry::Add<MyGC>
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	488 X("mygc", "My bespoke garbage collector.");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	489 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	490
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	491 This boilerplate collector does nothing. More specifically:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	492
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	493 * ``llvm.gcread`` calls are replaced with the corresponding ``load``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	494 instruction.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	495
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	496 * ``llvm.gcwrite`` calls are replaced with the corresponding ``store``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	497 instruction.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	498
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	499 * No safe points are added to the code.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	500
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	501 * The stack map is not compiled into the executable.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	502
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	503 Using the LLVM makefiles (like the `sample project
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	504 <http://llvm.org/viewvc/llvm-project/llvm/trunk/projects/sample/>`__), this code
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	505 can be compiled as a plugin using a simple makefile:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	506
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	507 .. code-block:: make
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	508
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	509 # lib/MyGC/Makefile
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	510
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	511 LEVEL := ../..
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	512 LIBRARYNAME = MyGC
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	513 LOADABLE_MODULE = 1
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	514
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	515 include $(LEVEL)/Makefile.common
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	516
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	517 Once the plugin is compiled, code using it may be compiled using ``llc
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	518 -load=MyGC.so`` (though MyGC.so may have some other platform-specific
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	519 extension):
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	520
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	521 ::
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	522
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	523 $ cat sample.ll
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	524 define void @f() gc "mygc" {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	525 entry:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	526 ret void
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	527 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	528 $ llvm-as < sample.ll \| llc -load=MyGC.so
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	529
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	530 It is also possible to statically link the collector plugin into tools, such as
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	531 a language-specific compiler front-end.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	532
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	533 .. _collector-algos:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	534
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	535 Overview of available features
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	536 ------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	537
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	538 ``GCStrategy`` provides a range of features through which a plugin may do useful
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	539 work. Some of these are callbacks, some are algorithms that can be enabled,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	540 disabled, or customized. This matrix summarizes the supported (and planned)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	541 features and correlates them with the collection techniques which typically
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	542 require them.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	543
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	544 .. \|v\| unicode:: 0x2714
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	545 :trim:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	546
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	547 .. \|x\| unicode:: 0x2718
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	548 :trim:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	549
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	550 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	551 \| Algorithm \| Done \| Shadow \| refcount \| mark- \| copying \| incremental \| threaded \| concurrent \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	552 \| \| \| stack \| \| sweep \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	553 +============+======+========+==========+=======+=========+=============+==========+============+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	554 \| stack map \| \|v\| \| \| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	555 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	556 \| initialize \| \|v\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	557 \| roots \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	558 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	559 \| derived \| NO \| \| \| \| \| \| N\* \| N\* \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	560 \| pointers \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	561 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	562 \| **custom \| \|v\| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	563 \| lowering** \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	564 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	565 \| gcroot \| \|v\| \| \|x\| \| \|x\| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	566 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	567 \| gcwrite \| \|v\| \| \| \|x\| \| \| \| \|x\| \| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	568 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	569 \| gcread \| \|v\| \| \| \| \| \| \| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	570 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	571 \| **safe \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	572 \| points** \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	573 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	574 \| *in \| \|v\| \| \| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	575 \| calls* \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	576 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	577 \| *before \| \|v\| \| \| \| \| \| \| \|x\| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	578 \| calls* \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	579 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	580 \| for \| NO \| \| \| \| \| \| N* \| N \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	581 \| loops* \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	582 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	583 \| *before \| \|v\| \| \| \| \| \| \| \|x\| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	584 \| escape* \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	585 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	586 \| emit code \| NO \| \| \| \| \| \| N \| N \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	587 \| at safe \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	588 \| points \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	589 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	590 \| output \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	591 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	592 \| assembly \| \|v\| \| \| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \| \|x\| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	593 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	594 \| JIT \| NO \| \| \| ? \| ? \| ? \| ? \| ? \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	595 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	596 \| obj \| NO \| \| \| ? \| ? \| ? \| ? \| ? \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	597 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	598 \| live \| NO \| \| \| ? \| ? \| ? \| ? \| ? \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	599 \| analysis \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	600 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	601 \| register \| NO \| \| \| ? \| ? \| ? \| ? \| ? \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	602 \| map \| \| \| \| \| \| \| \| \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	603 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	604 \| \* Derived pointers only pose a hasard to copying collections. \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	605 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	606 \| ? denotes a feature which could be utilized if available. \|
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	607 +------------+------+--------+----------+-------+---------+-------------+----------+------------+
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	608
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	609 To be clear, the collection techniques above are defined as:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	610
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	611 Shadow Stack
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	612 The mutator carefully maintains a linked list of stack roots.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	613
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	614 Reference Counting
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	615 The mutator maintains a reference count for each object and frees an object
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	616 when its count falls to zero.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	617
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	618 Mark-Sweep
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	619 When the heap is exhausted, the collector marks reachable objects starting
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	620 from the roots, then deallocates unreachable objects in a sweep phase.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	621
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	622 Copying
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	623 As reachability analysis proceeds, the collector copies objects from one heap
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	624 area to another, compacting them in the process. Copying collectors enable
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	625 highly efficient "bump pointer" allocation and can improve locality of
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	626 reference.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	627
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	628 Incremental
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	629 (Including generational collectors.) Incremental collectors generally have all
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	630 the properties of a copying collector (regardless of whether the mature heap
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	631 is compacting), but bring the added complexity of requiring write barriers.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	632
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	633 Threaded
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	634 Denotes a multithreaded mutator; the collector must still stop the mutator
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	635 ("stop the world") before beginning reachability analysis. Stopping a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	636 multithreaded mutator is a complicated problem. It generally requires highly
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	637 platform specific code in the runtime, and the production of carefully
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	638 designed machine code at safe points.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	639
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	640 Concurrent
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	641 In this technique, the mutator and the collector run concurrently, with the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	642 goal of eliminating pause times. In a cooperative collector, the mutator
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	643 further aids with collection should a pause occur, allowing collection to take
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	644 advantage of multiprocessor hosts. The "stop the world" problem of threaded
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	645 collectors is generally still present to a limited extent. Sophisticated
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	646 marking algorithms are necessary. Read barriers may be necessary.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	647
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	648 As the matrix indicates, LLVM's garbage collection infrastructure is already
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	649 suitable for a wide variety of collectors, but does not currently extend to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	650 multithreaded programs. This will be added in the future as there is
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	651 interest.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	652
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	653 .. _stack-map:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	654
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	655 Computing stack maps
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	656 --------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	657
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	658 LLVM automatically computes a stack map. One of the most important features
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	659 of a ``GCStrategy`` is to compile this information into the executable in
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	660 the binary representation expected by the runtime library.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	661
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	662 The stack map consists of the location and identity of each GC root in the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	663 each function in the module. For each root:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	664
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	665 * ``RootNum``: The index of the root.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	666
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	667 * ``StackOffset``: The offset of the object relative to the frame pointer.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	668
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	669 * ``RootMetadata``: The value passed as the ``%metadata`` parameter to the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	670 ``@llvm.gcroot`` intrinsic.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	671
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	672 Also, for the function as a whole:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	673
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	674 * ``getFrameSize()``: The overall size of the function's initial stack frame,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	675 not accounting for any dynamic allocation.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	676
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	677 * ``roots_size()``: The count of roots in the function.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	678
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	679 To access the stack map, use ``GCFunctionMetadata::roots_begin()`` and
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	680 -``end()`` from the :ref:`GCMetadataPrinter <assembly>`:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	681
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	682 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	683
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	684 for (iterator I = begin(), E = end(); I != E; ++I) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	685 GCFunctionInfo FI = I;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	686 unsigned FrameSize = FI->getFrameSize();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	687 size_t RootCount = FI->roots_size();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	688
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	689 for (GCFunctionInfo::roots_iterator RI = FI->roots_begin(),
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	690 RE = FI->roots_end();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	691 RI != RE; ++RI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	692 int RootNum = RI->Num;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	693 int RootStackOffset = RI->StackOffset;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	694 Constant *RootMetadata = RI->Metadata;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	695 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	696 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	697
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	698 If the ``llvm.gcroot`` intrinsic is eliminated before code generation by a
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	699 custom lowering pass, LLVM will compute an empty stack map. This may be useful
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	700 for collector plugins which implement reference counting or a shadow stack.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	701
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	702 .. _init-roots:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	703
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	704 Initializing roots to null: ``InitRoots``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	705 -----------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	706
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	707 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	708
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	709 MyGC::MyGC() {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	710 InitRoots = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	711 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	712
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	713 When set, LLVM will automatically initialize each root to ``null`` upon entry to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	714 the function. This prevents the GC's sweep phase from visiting uninitialized
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	715 pointers, which will almost certainly cause it to crash. This initialization
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	716 occurs before custom lowering, so the two may be used together.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	717
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	718 Since LLVM does not yet compute liveness information, there is no means of
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	719 distinguishing an uninitialized stack root from an initialized one. Therefore,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	720 this feature should be used by all GC plugins. It is enabled by default.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	721
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	722 Custom lowering of intrinsics: ``CustomRoots``, ``CustomReadBarriers``, and ``CustomWriteBarriers``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	723 ---------------------------------------------------------------------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	724
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	725 For GCs which use barriers or unusual treatment of stack roots, these flags
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	726 allow the collector to perform arbitrary transformations of the LLVM IR:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	727
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	728 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	729
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	730 class MyGC : public GCStrategy {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	731 public:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	732 MyGC() {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	733 CustomRoots = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	734 CustomReadBarriers = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	735 CustomWriteBarriers = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	736 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	737
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	738 virtual bool initializeCustomLowering(Module &M);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	739 virtual bool performCustomLowering(Function &F);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	740 };
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	741
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	742 If any of these flags are set, then LLVM suppresses its default lowering for the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	743 corresponding intrinsics and instead calls ``performCustomLowering``.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	744
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	745 LLVM's default action for each intrinsic is as follows:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	746
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	747 * ``llvm.gcroot``: Leave it alone. The code generator must see it or the stack
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	748 map will not be computed.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	749
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	750 * ``llvm.gcread``: Substitute a ``load`` instruction.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	751
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	752 * ``llvm.gcwrite``: Substitute a ``store`` instruction.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	753
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	754 If ``CustomReadBarriers`` or ``CustomWriteBarriers`` are specified, then
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	755 ``performCustomLowering`` must eliminate the corresponding barriers.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	756
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	757 ``performCustomLowering`` must comply with the same restrictions as
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	758 :ref:`FunctionPass::runOnFunction <writing-an-llvm-pass-runOnFunction>`
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	759 Likewise, ``initializeCustomLowering`` has the same semantics as
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	760 :ref:`Pass::doInitialization(Module&)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	761 <writing-an-llvm-pass-doInitialization-mod>`
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	762
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	763 The following can be used as a template:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	764
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	765 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	766
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	767 #include "llvm/Module.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	768 #include "llvm/IntrinsicInst.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	769
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	770 bool MyGC::initializeCustomLowering(Module &M) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	771 return false;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	772 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	773
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	774 bool MyGC::performCustomLowering(Function &F) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	775 bool MadeChange = false;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	776
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	777 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	778 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; )
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	779 if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++))
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	780 if (Function *F = CI->getCalledFunction())
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	781 switch (F->getIntrinsicID()) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	782 case Intrinsic::gcwrite:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	783 // Handle llvm.gcwrite.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	784 CI->eraseFromParent();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	785 MadeChange = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	786 break;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	787 case Intrinsic::gcread:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	788 // Handle llvm.gcread.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	789 CI->eraseFromParent();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	790 MadeChange = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	791 break;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	792 case Intrinsic::gcroot:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	793 // Handle llvm.gcroot.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	794 CI->eraseFromParent();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	795 MadeChange = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	796 break;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	797 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	798
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	799 return MadeChange;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	800 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	801
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	802 .. _safe-points:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	803
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	804 Generating safe points: ``NeededSafePoints``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	805 --------------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	806
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	807 LLVM can compute four kinds of safe points:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	808
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	809 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	810
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	811 namespace GC {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	812 /// PointKind - The type of a collector-safe point.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	813 ///
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	814 enum PointKind {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	815 Loop, //< Instr is a loop (backwards branch).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	816 Return, //< Instr is a return instruction.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	817 PreCall, //< Instr is a call instruction.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	818 PostCall //< Instr is the return address of a call.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	819 };
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	820 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	821
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	822 A collector can request any combination of the four by setting the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	823 ``NeededSafePoints`` mask:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	824
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	825 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	826
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	827 MyGC::MyGC() {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	828 NeededSafePoints = 1 << GC::Loop
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	829 \| 1 << GC::Return
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	830 \| 1 << GC::PreCall
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	831 \| 1 << GC::PostCall;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	832 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	833
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	834 It can then use the following routines to access safe points.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	835
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	836 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	837
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	838 for (iterator I = begin(), E = end(); I != E; ++I) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	839 GCFunctionInfo MD = I;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	840 size_t PointCount = MD->size();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	841
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	842 for (GCFunctionInfo::iterator PI = MD->begin(),
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	843 PE = MD->end(); PI != PE; ++PI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	844 GC::PointKind PointKind = PI->Kind;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	845 unsigned PointNum = PI->Num;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	846 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	847 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	848
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	849 Almost every collector requires ``PostCall`` safe points, since these correspond
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	850 to the moments when the function is suspended during a call to a subroutine.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	851
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	852 Threaded programs generally require ``Loop`` safe points to guarantee that the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	853 application will reach a safe point within a bounded amount of time, even if it
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	854 is executing a long-running loop which contains no function calls.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	855
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	856 Threaded collectors may also require ``Return`` and ``PreCall`` safe points to
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	857 implement "stop the world" techniques using self-modifying code, where it is
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	858 important that the program not exit the function without reaching a safe point
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	859 (because only the topmost function has been patched).
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	860
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	861 .. _assembly:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	862
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	863 Emitting assembly code: ``GCMetadataPrinter``
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	864 ---------------------------------------------
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	865
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	866 LLVM allows a plugin to print arbitrary assembly code before and after the rest
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	867 of a module's assembly code. At the end of the module, the GC can compile the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	868 LLVM stack map into assembly code. (At the beginning, this information is not
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	869 yet computed.)
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	870
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	871 Since AsmWriter and CodeGen are separate components of LLVM, a separate abstract
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	872 base class and registry is provided for printing assembly code, the
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	873 ``GCMetadaPrinter`` and ``GCMetadataPrinterRegistry``. The AsmWriter will look
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	874 for such a subclass if the ``GCStrategy`` sets ``UsesMetadata``:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	875
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	876 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	877
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	878 MyGC::MyGC() {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	879 UsesMetadata = true;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	880 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	881
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	882 This separation allows JIT-only clients to be smaller.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	883
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	884 Note that LLVM does not currently have analogous APIs to support code generation
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	885 in the JIT, nor using the object writers.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	886
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	887 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	888
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	889 // lib/MyGC/MyGCPrinter.cpp - Example LLVM GC printer
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	890
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	891 #include "llvm/CodeGen/GCMetadataPrinter.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	892 #include "llvm/Support/Compiler.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	893
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	894 using namespace llvm;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	895
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	896 namespace {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	897 class LLVM_LIBRARY_VISIBILITY MyGCPrinter : public GCMetadataPrinter {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	898 public:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	899 virtual void beginAssembly(std::ostream &OS, AsmPrinter &AP,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	900 const TargetAsmInfo &TAI);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	901
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	902 virtual void finishAssembly(std::ostream &OS, AsmPrinter &AP,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	903 const TargetAsmInfo &TAI);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	904 };
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	905
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	906 GCMetadataPrinterRegistry::Add<MyGCPrinter>
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	907 X("mygc", "My bespoke garbage collector.");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	908 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	909
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	910 The collector should use ``AsmPrinter`` and ``TargetAsmInfo`` to print portable
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	911 assembly code to the ``std::ostream``. The collector itself contains the stack
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	912 map for the entire module, and may access the ``GCFunctionInfo`` using its own
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	913 ``begin()`` and ``end()`` methods. Here's a realistic example:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	914
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	915 .. code-block:: c++
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	916
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	917 #include "llvm/CodeGen/AsmPrinter.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	918 #include "llvm/Function.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	919 #include "llvm/Target/TargetMachine.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	920 #include "llvm/DataLayout.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	921 #include "llvm/Target/TargetAsmInfo.h"
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	922
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	923 void MyGCPrinter::beginAssembly(std::ostream &OS, AsmPrinter &AP,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	924 const TargetAsmInfo &TAI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	925 // Nothing to do.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	926 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	927
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	928 void MyGCPrinter::finishAssembly(std::ostream &OS, AsmPrinter &AP,
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	929 const TargetAsmInfo &TAI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	930 // Set up for emitting addresses.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	931 const char *AddressDirective;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	932 int AddressAlignLog;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	933 if (AP.TM.getDataLayout()->getPointerSize() == sizeof(int32_t)) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	934 AddressDirective = TAI.getData32bitsDirective();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	935 AddressAlignLog = 2;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	936 } else {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	937 AddressDirective = TAI.getData64bitsDirective();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	938 AddressAlignLog = 3;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	939 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	940
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	941 // Put this in the data section.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	942 AP.SwitchToDataSection(TAI.getDataSection());
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	943
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	944 // For each function...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	945 for (iterator FI = begin(), FE = end(); FI != FE; ++FI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	946 GCFunctionInfo &MD = **FI;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	947
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	948 // Emit this data structure:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	949 //
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	950 // struct {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	951 // int32_t PointCount;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	952 // struct {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	953 // void *SafePointAddress;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	954 // int32_t LiveCount;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	955 // int32_t LiveOffsets[LiveCount];
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	956 // } Points[PointCount];
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	957 // } __gcmap_<FUNCTIONNAME>;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	958
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	959 // Align to address width.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	960 AP.EmitAlignment(AddressAlignLog);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	961
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	962 // Emit the symbol by which the stack map entry can be found.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	963 std::string Symbol;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	964 Symbol += TAI.getGlobalPrefix();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	965 Symbol += "__gcmap_";
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	966 Symbol += MD.getFunction().getName();
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	967 if (const char *GlobalDirective = TAI.getGlobalDirective())
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	968 OS << GlobalDirective << Symbol << "\n";
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	969 OS << TAI.getGlobalPrefix() << Symbol << ":\n";
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	970
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	971 // Emit PointCount.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	972 AP.EmitInt32(MD.size());
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	973 AP.EOL("safe point count");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	974
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	975 // And each safe point...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	976 for (GCFunctionInfo::iterator PI = MD.begin(),
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	977 PE = MD.end(); PI != PE; ++PI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	978 // Align to address width.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	979 AP.EmitAlignment(AddressAlignLog);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	980
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	981 // Emit the address of the safe point.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	982 OS << AddressDirective
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	983 << TAI.getPrivateGlobalPrefix() << "label" << PI->Num;
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	984 AP.EOL("safe point address");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	985
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	986 // Emit the stack frame size.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	987 AP.EmitInt32(MD.getFrameSize());
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	988 AP.EOL("stack frame size");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	989
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	990 // Emit the number of live roots in the function.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	991 AP.EmitInt32(MD.live_size(PI));
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	992 AP.EOL("live root count");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	993
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	994 // And for each live root...
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	995 for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI),
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	996 LE = MD.live_end(PI);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	997 LI != LE; ++LI) {
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	998 // Print its offset within the stack frame.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	999 AP.EmitInt32(LI->StackOffset);
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1000 AP.EOL("stack offset");
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1001 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1002 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1003 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1004 }
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1005
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1006 References
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1007 ==========
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1008
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1009 .. _appel89:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1010
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1011 [Appel89] Runtime Tags Aren't Necessary. Andrew W. Appel. Lisp and Symbolic
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1012 Computation 19(7):703-705, July 1989.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1013
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1014 .. _goldberg91:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1015
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1016 [Goldberg91] Tag-free garbage collection for strongly typed programming
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1017 languages. Benjamin Goldberg. ACM SIGPLAN PLDI'91.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1018
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1019 .. _tolmach94:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1020
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1021 [Tolmach94] Tag-free garbage collection using explicit type parameters. Andrew
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1022 Tolmach. Proceedings of the 1994 ACM conference on LISP and functional
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1023 programming.
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1024
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1025 .. _henderson02:
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1026
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1027 [Henderson2002] `Accurate Garbage Collection in an Uncooperative Environment
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1028 <http://citeseer.ist.psu.edu/henderson02accurate.html>`__
9ad51c7bc036 1st commit. remove git dir and add all files. Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1029

Mercurial > hg > Members > tobaru > cbc > CbC_llvm

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