1 //===- InlineSimple.cpp - Code to perform simple function inlining --------===//
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 bottom-up inlining of functions into callees.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #define DEBUG_TYPE "inline"
15 #include "llvm/Transforms/IPO.h"
16 #include "llvm/Analysis/CallGraph.h"
17 #include "llvm/Analysis/InlineCost.h"
18 #include "llvm/IR/CallSite.h"
19 #include "llvm/IR/CallingConv.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/Instructions.h"
22 #include "llvm/IR/IntrinsicInst.h"
23 #include "llvm/IR/Module.h"
24 #include "llvm/IR/Type.h"
25 #include "llvm/Transforms/IPO/InlinerPass.h"
26 
27 using namespace llvm;
28 
29 namespace {
30 
31 /// \brief Actual inliner pass implementation.
32 ///
33 /// The common implementation of the inlining logic is shared between this
34 /// inliner pass and the always inliner pass. The two passes use different cost
35 /// analyses to determine when to inline.
36 class SimpleInliner : public Inliner {
37   InlineCostAnalysis *ICA;
38 
39 public:
40   SimpleInliner() : Inliner(ID), ICA(0) {
41     initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
42   }
43 
44   SimpleInliner(int Threshold)
45       : Inliner(ID, Threshold, /*InsertLifetime*/ true), ICA(0) {
46     initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
47   }
48 
49   static char ID; // Pass identification, replacement for typeid
50 
51   InlineCost getInlineCost(CallSite CS) override {
52     return ICA->getInlineCost(CS, getInlineThreshold(CS));
53   }
54 
55   bool runOnSCC(CallGraphSCC &SCC) override;
56   void getAnalysisUsage(AnalysisUsage &AU) const override;
57 };
58 
59 static int computeThresholdFromOptLevels(unsigned OptLevel,
60                                          unsigned SizeOptLevel) {
61   if (OptLevel > 2)
62     return 275;
63   if (SizeOptLevel == 1) // -Os
64     return 75;
65   if (SizeOptLevel == 2) // -Oz
66     return 25;
67   return 225;
68 }
69 
70 } // end anonymous namespace
71 
72 char SimpleInliner::ID = 0;
73 INITIALIZE_PASS_BEGIN(SimpleInliner, "inline",
74                 "Function Integration/Inlining", false, false)
75 INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
76 INITIALIZE_PASS_DEPENDENCY(InlineCostAnalysis)
77 INITIALIZE_PASS_END(SimpleInliner, "inline",
78                 "Function Integration/Inlining", false, false)
79 
80 Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
81 
82 Pass *llvm::createFunctionInliningPass(int Threshold) {
83   return new SimpleInliner(Threshold);
84 }
85 
86 Pass *llvm::createFunctionInliningPass(unsigned OptLevel,
87                                        unsigned SizeOptLevel) {
88   return new SimpleInliner(
89       computeThresholdFromOptLevels(OptLevel, SizeOptLevel));
90 }
91 
92 bool SimpleInliner::runOnSCC(CallGraphSCC &SCC) {
93   ICA = &getAnalysis<InlineCostAnalysis>();
94   return Inliner::runOnSCC(SCC);
95 }
96 
97 void SimpleInliner::getAnalysisUsage(AnalysisUsage &AU) const {
98   AU.addRequired<InlineCostAnalysis>();
99   Inliner::getAnalysisUsage(AU);
100 }
101