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comparison lib/Transforms/IPO/InlineAlways.cpp @ 0:95c75e76d11b LLVM3.4

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LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
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children e4204d083e25
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-1:000000000000 0:95c75e76d11b
1 //===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements a custom inliner that handles only functions that
11 // are marked as "always inline".
12 //
13 //===----------------------------------------------------------------------===//
14
15 #define DEBUG_TYPE "inline"
16 #include "llvm/Transforms/IPO.h"
17 #include "llvm/ADT/SmallPtrSet.h"
18 #include "llvm/Analysis/CallGraph.h"
19 #include "llvm/Analysis/InlineCost.h"
20 #include "llvm/IR/CallingConv.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/IntrinsicInst.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/IR/Type.h"
26 #include "llvm/Support/CallSite.h"
27 #include "llvm/Transforms/IPO/InlinerPass.h"
28
29 using namespace llvm;
30
31 namespace {
32
33 /// \brief Inliner pass which only handles "always inline" functions.
34 class AlwaysInliner : public Inliner {
35 InlineCostAnalysis *ICA;
36
37 public:
38 // Use extremely low threshold.
39 AlwaysInliner() : Inliner(ID, -2000000000, /*InsertLifetime*/ true), ICA(0) {
40 initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
41 }
42
43 AlwaysInliner(bool InsertLifetime)
44 : Inliner(ID, -2000000000, InsertLifetime), ICA(0) {
45 initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
46 }
47
48 static char ID; // Pass identification, replacement for typeid
49
50 virtual InlineCost getInlineCost(CallSite CS);
51
52 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
53 virtual bool runOnSCC(CallGraphSCC &SCC);
54
55 using llvm::Pass::doFinalization;
56 virtual bool doFinalization(CallGraph &CG) {
57 return removeDeadFunctions(CG, /*AlwaysInlineOnly=*/ true);
58 }
59 };
60
61 }
62
63 char AlwaysInliner::ID = 0;
64 INITIALIZE_PASS_BEGIN(AlwaysInliner, "always-inline",
65 "Inliner for always_inline functions", false, false)
66 INITIALIZE_PASS_DEPENDENCY(CallGraph)
67 INITIALIZE_PASS_DEPENDENCY(InlineCostAnalysis)
68 INITIALIZE_PASS_END(AlwaysInliner, "always-inline",
69 "Inliner for always_inline functions", false, false)
70
71 Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
72
73 Pass *llvm::createAlwaysInlinerPass(bool InsertLifetime) {
74 return new AlwaysInliner(InsertLifetime);
75 }
76
77 /// \brief Get the inline cost for the always-inliner.
78 ///
79 /// The always inliner *only* handles functions which are marked with the
80 /// attribute to force inlining. As such, it is dramatically simpler and avoids
81 /// using the powerful (but expensive) inline cost analysis. Instead it uses
82 /// a very simple and boring direct walk of the instructions looking for
83 /// impossible-to-inline constructs.
84 ///
85 /// Note, it would be possible to go to some lengths to cache the information
86 /// computed here, but as we only expect to do this for relatively few and
87 /// small functions which have the explicit attribute to force inlining, it is
88 /// likely not worth it in practice.
89 InlineCost AlwaysInliner::getInlineCost(CallSite CS) {
90 Function *Callee = CS.getCalledFunction();
91
92 // Only inline direct calls to functions with always-inline attributes
93 // that are viable for inlining. FIXME: We shouldn't even get here for
94 // declarations.
95 if (Callee && !Callee->isDeclaration() &&
96 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
97 Attribute::AlwaysInline) &&
98 ICA->isInlineViable(*Callee))
99 return InlineCost::getAlways();
100
101 return InlineCost::getNever();
102 }
103
104 bool AlwaysInliner::runOnSCC(CallGraphSCC &SCC) {
105 ICA = &getAnalysis<InlineCostAnalysis>();
106 return Inliner::runOnSCC(SCC);
107 }
108
109 void AlwaysInliner::getAnalysisUsage(AnalysisUsage &AU) const {
110 AU.addRequired<InlineCostAnalysis>();
111 Inliner::getAnalysisUsage(AU);
112 }