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      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 #include "llvm/Transforms/IPO.h"
     15 #include "llvm/Analysis/AssumptionCache.h"
     16 #include "llvm/Analysis/CallGraph.h"
     17 #include "llvm/Analysis/InlineCost.h"
     18 #include "llvm/Analysis/TargetLibraryInfo.h"
     19 #include "llvm/IR/CallSite.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/Transforms/IPO/InlinerPass.h"
     27 
     28 using namespace llvm;
     29 
     30 #define DEBUG_TYPE "inline"
     31 
     32 namespace {
     33 
     34 /// \brief Actual inliner pass implementation.
     35 ///
     36 /// The common implementation of the inlining logic is shared between this
     37 /// inliner pass and the always inliner pass. The two passes use different cost
     38 /// analyses to determine when to inline.
     39 class SimpleInliner : public Inliner {
     40   InlineCostAnalysis *ICA;
     41 
     42 public:
     43   SimpleInliner() : Inliner(ID), ICA(nullptr) {
     44     initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
     45   }
     46 
     47   SimpleInliner(int Threshold)
     48       : Inliner(ID, Threshold, /*InsertLifetime*/ true), ICA(nullptr) {
     49     initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
     50   }
     51 
     52   static char ID; // Pass identification, replacement for typeid
     53 
     54   InlineCost getInlineCost(CallSite CS) override {
     55     return ICA->getInlineCost(CS, getInlineThreshold(CS));
     56   }
     57 
     58   bool runOnSCC(CallGraphSCC &SCC) override;
     59   void getAnalysisUsage(AnalysisUsage &AU) const override;
     60 };
     61 
     62 static int computeThresholdFromOptLevels(unsigned OptLevel,
     63                                          unsigned SizeOptLevel) {
     64   if (OptLevel > 2)
     65     return 275;
     66   if (SizeOptLevel == 1) // -Os
     67     return 75;
     68   if (SizeOptLevel == 2) // -Oz
     69     return 25;
     70   return 225;
     71 }
     72 
     73 } // end anonymous namespace
     74 
     75 char SimpleInliner::ID = 0;
     76 INITIALIZE_PASS_BEGIN(SimpleInliner, "inline",
     77                 "Function Integration/Inlining", false, false)
     78 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
     79 INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
     80 INITIALIZE_PASS_DEPENDENCY(InlineCostAnalysis)
     81 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
     82 INITIALIZE_PASS_END(SimpleInliner, "inline",
     83                 "Function Integration/Inlining", false, false)
     84 
     85 Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
     86 
     87 Pass *llvm::createFunctionInliningPass(int Threshold) {
     88   return new SimpleInliner(Threshold);
     89 }
     90 
     91 Pass *llvm::createFunctionInliningPass(unsigned OptLevel,
     92                                        unsigned SizeOptLevel) {
     93   return new SimpleInliner(
     94       computeThresholdFromOptLevels(OptLevel, SizeOptLevel));
     95 }
     96 
     97 bool SimpleInliner::runOnSCC(CallGraphSCC &SCC) {
     98   ICA = &getAnalysis<InlineCostAnalysis>();
     99   return Inliner::runOnSCC(SCC);
    100 }
    101 
    102 void SimpleInliner::getAnalysisUsage(AnalysisUsage &AU) const {
    103   AU.addRequired<InlineCostAnalysis>();
    104   Inliner::getAnalysisUsage(AU);
    105 }
    106