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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 #define DEBUG_TYPE "inline"
     15 #include "llvm/CallingConv.h"
     16 #include "llvm/Instructions.h"
     17 #include "llvm/IntrinsicInst.h"
     18 #include "llvm/Module.h"
     19 #include "llvm/Type.h"
     20 #include "llvm/Analysis/CallGraph.h"
     21 #include "llvm/Analysis/InlineCost.h"
     22 #include "llvm/Support/CallSite.h"
     23 #include "llvm/Transforms/IPO.h"
     24 #include "llvm/Transforms/IPO/InlinerPass.h"
     25 #include "llvm/ADT/SmallPtrSet.h"
     26 
     27 using namespace llvm;
     28 
     29 namespace {
     30 
     31   class SimpleInliner : public Inliner {
     32     // Functions that are never inlined
     33     SmallPtrSet<const Function*, 16> NeverInline;
     34     InlineCostAnalyzer CA;
     35   public:
     36     SimpleInliner() : Inliner(ID) {
     37       initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
     38     }
     39     SimpleInliner(int Threshold) : Inliner(ID, Threshold) {
     40       initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
     41     }
     42     static char ID; // Pass identification, replacement for typeid
     43     InlineCost getInlineCost(CallSite CS) {
     44       return CA.getInlineCost(CS, NeverInline);
     45     }
     46     float getInlineFudgeFactor(CallSite CS) {
     47       return CA.getInlineFudgeFactor(CS);
     48     }
     49     void resetCachedCostInfo(Function *Caller) {
     50       CA.resetCachedCostInfo(Caller);
     51     }
     52     void growCachedCostInfo(Function* Caller, Function* Callee) {
     53       CA.growCachedCostInfo(Caller, Callee);
     54     }
     55     virtual bool doInitialization(CallGraph &CG);
     56     void releaseMemory() {
     57       CA.clear();
     58     }
     59   };
     60 }
     61 
     62 char SimpleInliner::ID = 0;
     63 INITIALIZE_PASS_BEGIN(SimpleInliner, "inline",
     64                 "Function Integration/Inlining", false, false)
     65 INITIALIZE_AG_DEPENDENCY(CallGraph)
     66 INITIALIZE_PASS_END(SimpleInliner, "inline",
     67                 "Function Integration/Inlining", false, false)
     68 
     69 Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
     70 
     71 Pass *llvm::createFunctionInliningPass(int Threshold) {
     72   return new SimpleInliner(Threshold);
     73 }
     74 
     75 // doInitialization - Initializes the vector of functions that have been
     76 // annotated with the noinline attribute.
     77 bool SimpleInliner::doInitialization(CallGraph &CG) {
     78 
     79   Module &M = CG.getModule();
     80 
     81   for (Module::iterator I = M.begin(), E = M.end();
     82        I != E; ++I)
     83     if (!I->isDeclaration() && I->hasFnAttr(Attribute::NoInline))
     84       NeverInline.insert(I);
     85 
     86   // Get llvm.noinline
     87   GlobalVariable *GV = M.getNamedGlobal("llvm.noinline");
     88 
     89   if (GV == 0)
     90     return false;
     91 
     92   // Don't crash on invalid code
     93   if (!GV->hasDefinitiveInitializer())
     94     return false;
     95 
     96   const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
     97 
     98   if (InitList == 0)
     99     return false;
    100 
    101   // Iterate over each element and add to the NeverInline set
    102   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
    103 
    104     // Get Source
    105     const Constant *Elt = InitList->getOperand(i);
    106 
    107     if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(Elt))
    108       if (CE->getOpcode() == Instruction::BitCast)
    109         Elt = CE->getOperand(0);
    110 
    111     // Insert into set of functions to never inline
    112     if (const Function *F = dyn_cast<Function>(Elt))
    113       NeverInline.insert(F);
    114   }
    115 
    116   return false;
    117 }
    118 
    119