diff --git a/include/llvm/Transforms/Utils/BasicInliner.h b/include/llvm/Transforms/Utils/BasicInliner.h new file mode 100644 index 00000000000..311047ccddf --- /dev/null +++ b/include/llvm/Transforms/Utils/BasicInliner.h @@ -0,0 +1,55 @@ +//===- BasicInliner.h - Basic function level inliner ------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file was developed by Devang Patel and is distributed under +// the University of Illinois Open Source License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines a simple function based inliner that does not use +// call graph information. +// +//===----------------------------------------------------------------------===// + +#ifndef BASICINLINER_H +#define BASICINLINER_H + +#include "llvm/Transforms/Utils/InlineCost.h" + +namespace llvm { + + class Function; + class TargetData; + class BasicInlinerImpl; + + /// BasicInliner - BasicInliner provides function level inlining interface. + /// Clients provide list of functions which are inline without using + /// module level call graph information. Note that the BasicInliner is + /// free to delete a function if it is inlined into all call sites. + class BasicInliner { + public: + + BasicInliner(TargetData *T = NULL); + ~BasicInliner(); + + /// addFunction - Add function into the list of functions to process. + /// All functions must be inserted using this interface before invoking + /// inlineFunctions(). + void addFunction(Function *F); + + /// neverInlineFunction - Sometimes a function is never to be inlined + /// because of one or other reason. + void neverInlineFunction(Function *F); + + /// inlineFuctions - Walk all call sites in all functions supplied by + /// client. Inline as many call sites as possible. Delete completely + /// inlined functions. + void inlineFunctions(); + + private: + BasicInlinerImpl *Impl; + }; +} + +#endif diff --git a/include/llvm/Transforms/Utils/InlineCost.h b/include/llvm/Transforms/Utils/InlineCost.h new file mode 100644 index 00000000000..c54b98af523 --- /dev/null +++ b/include/llvm/Transforms/Utils/InlineCost.h @@ -0,0 +1,80 @@ +//===- InlineCost.cpp - Cost analysis for inliner ---------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file was developed by the LLVM research group and is distributed under +// the University of Illinois Open Source License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements bottom-up inlining of functions into callees. +// +//===----------------------------------------------------------------------===// + +#ifndef INLINECOST_H +#define INLINECOST_H + +#include +#include +#include + +namespace llvm { + + class Value; + class Function; + class CallSite; + + /// InlineCostAnalyzer - Cost analyzer used by inliner. + class InlineCostAnalyzer { + struct ArgInfo { + public: + unsigned ConstantWeight; + unsigned AllocaWeight; + + ArgInfo(unsigned CWeight, unsigned AWeight) + : ConstantWeight(CWeight), AllocaWeight(AWeight) {} + }; + + // FunctionInfo - For each function, calculate the size of it in blocks and + // instructions. + struct FunctionInfo { + // NumInsts, NumBlocks - Keep track of how large each function is, which is + // used to estimate the code size cost of inlining it. + unsigned NumInsts, NumBlocks; + + // ArgumentWeights - Each formal argument of the function is inspected to + // see if it is used in any contexts where making it a constant or alloca + // would reduce the code size. If so, we add some value to the argument + // entry here. + std::vector ArgumentWeights; + + FunctionInfo() : NumInsts(0), NumBlocks(0) {} + + /// analyzeFunction - Fill in the current structure with information gleaned + /// from the specified function. + void analyzeFunction(Function *F); + + // CountCodeReductionForConstant - Figure out an approximation for how many + // instructions will be constant folded if the specified value is constant. + // + unsigned CountCodeReductionForConstant(Value *V); + + // CountCodeReductionForAlloca - Figure out an approximation of how much smaller + // the function will be if it is inlined into a context where an argument + // becomes an alloca. + // + unsigned CountCodeReductionForAlloca(Value *V); + }; + + std::mapCachedFunctionInfo; + + public: + + // getInlineCost - The heuristic used to determine if we should inline the + // function call or not. + // + int getInlineCost(CallSite CS, std::set &NeverInline); + }; +} + +#endif diff --git a/lib/Transforms/IPO/InlineSimple.cpp b/lib/Transforms/IPO/InlineSimple.cpp index 2157dcd2fec..eea28a745c5 100644 --- a/lib/Transforms/IPO/InlineSimple.cpp +++ b/lib/Transforms/IPO/InlineSimple.cpp @@ -22,46 +22,22 @@ #include "llvm/Support/Compiler.h" #include "llvm/Transforms/IPO.h" #include "llvm/Transforms/IPO/InlinerPass.h" +#include "llvm/Transforms/Utils/InlineCost.h" #include using namespace llvm; namespace { - struct VISIBILITY_HIDDEN ArgInfo { - unsigned ConstantWeight; - unsigned AllocaWeight; - - ArgInfo(unsigned CWeight, unsigned AWeight) - : ConstantWeight(CWeight), AllocaWeight(AWeight) {} - }; - - // FunctionInfo - For each function, calculate the size of it in blocks and - // instructions. - struct VISIBILITY_HIDDEN FunctionInfo { - // NumInsts, NumBlocks - Keep track of how large each function is, which is - // used to estimate the code size cost of inlining it. - unsigned NumInsts, NumBlocks; - - // ArgumentWeights - Each formal argument of the function is inspected to - // see if it is used in any contexts where making it a constant or alloca - // would reduce the code size. If so, we add some value to the argument - // entry here. - std::vector ArgumentWeights; - - FunctionInfo() : NumInsts(0), NumBlocks(0) {} - - /// analyzeFunction - Fill in the current structure with information gleaned - /// from the specified function. - void analyzeFunction(Function *F); - }; class VISIBILITY_HIDDEN SimpleInliner : public Inliner { - std::map CachedFunctionInfo; std::set NeverInline; // Functions that are never inlined + InlineCostAnalyzer CA; public: SimpleInliner() : Inliner(&ID) {} static char ID; // Pass identification, replacement for typeid - int getInlineCost(CallSite CS); + int getInlineCost(CallSite CS) { + return CA.getInlineCost(CS, NeverInline); + } virtual bool doInitialization(CallGraph &CG); }; char SimpleInliner::ID = 0; @@ -70,223 +46,6 @@ namespace { Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); } -// CountCodeReductionForConstant - Figure out an approximation for how many -// instructions will be constant folded if the specified value is constant. -// -static unsigned CountCodeReductionForConstant(Value *V) { - unsigned Reduction = 0; - for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) - if (isa(*UI)) - Reduction += 40; // Eliminating a conditional branch is a big win - else if (SwitchInst *SI = dyn_cast(*UI)) - // Eliminating a switch is a big win, proportional to the number of edges - // deleted. - Reduction += (SI->getNumSuccessors()-1) * 40; - else if (CallInst *CI = dyn_cast(*UI)) { - // Turning an indirect call into a direct call is a BIG win - Reduction += CI->getCalledValue() == V ? 500 : 0; - } else if (InvokeInst *II = dyn_cast(*UI)) { - // Turning an indirect call into a direct call is a BIG win - Reduction += II->getCalledValue() == V ? 500 : 0; - } else { - // Figure out if this instruction will be removed due to simple constant - // propagation. - Instruction &Inst = cast(**UI); - bool AllOperandsConstant = true; - for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) - if (!isa(Inst.getOperand(i)) && Inst.getOperand(i) != V) { - AllOperandsConstant = false; - break; - } - - if (AllOperandsConstant) { - // We will get to remove this instruction... - Reduction += 7; - - // And any other instructions that use it which become constants - // themselves. - Reduction += CountCodeReductionForConstant(&Inst); - } - } - - return Reduction; -} - -// CountCodeReductionForAlloca - Figure out an approximation of how much smaller -// the function will be if it is inlined into a context where an argument -// becomes an alloca. -// -static unsigned CountCodeReductionForAlloca(Value *V) { - if (!isa(V->getType())) return 0; // Not a pointer - unsigned Reduction = 0; - for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){ - Instruction *I = cast(*UI); - if (isa(I) || isa(I)) - Reduction += 10; - else if (GetElementPtrInst *GEP = dyn_cast(I)) { - // If the GEP has variable indices, we won't be able to do much with it. - for (Instruction::op_iterator I = GEP->op_begin()+1, E = GEP->op_end(); - I != E; ++I) - if (!isa(*I)) return 0; - Reduction += CountCodeReductionForAlloca(GEP)+15; - } else { - // If there is some other strange instruction, we're not going to be able - // to do much if we inline this. - return 0; - } - } - - return Reduction; -} - -/// analyzeFunction - Fill in the current structure with information gleaned -/// from the specified function. -void FunctionInfo::analyzeFunction(Function *F) { - unsigned NumInsts = 0, NumBlocks = 0; - - // Look at the size of the callee. Each basic block counts as 20 units, and - // each instruction counts as 10. - for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { - for (BasicBlock::const_iterator II = BB->begin(), E = BB->end(); - II != E; ++II) { - if (isa(II)) continue; // Debug intrinsics don't count. - - // Noop casts, including ptr <-> int, don't count. - if (const CastInst *CI = dyn_cast(II)) { - if (CI->isLosslessCast() || isa(CI) || - isa(CI)) - continue; - } else if (const GetElementPtrInst *GEPI = - dyn_cast(II)) { - // If a GEP has all constant indices, it will probably be folded with - // a load/store. - bool AllConstant = true; - for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i) - if (!isa(GEPI->getOperand(i))) { - AllConstant = false; - break; - } - if (AllConstant) continue; - } - - ++NumInsts; - } - - ++NumBlocks; - } - - this->NumBlocks = NumBlocks; - this->NumInsts = NumInsts; - - // Check out all of the arguments to the function, figuring out how much - // code can be eliminated if one of the arguments is a constant. - for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) - ArgumentWeights.push_back(ArgInfo(CountCodeReductionForConstant(I), - CountCodeReductionForAlloca(I))); -} - - -// getInlineCost - The heuristic used to determine if we should inline the -// function call or not. -// -int SimpleInliner::getInlineCost(CallSite CS) { - Instruction *TheCall = CS.getInstruction(); - Function *Callee = CS.getCalledFunction(); - const Function *Caller = TheCall->getParent()->getParent(); - - // Don't inline a directly recursive call. - if (Caller == Callee || - // Don't inline functions which can be redefined at link-time to mean - // something else. link-once linkage is ok though. - Callee->hasWeakLinkage() || - - // Don't inline functions marked noinline. - NeverInline.count(Callee)) - return 2000000000; - - // InlineCost - This value measures how good of an inline candidate this call - // site is to inline. A lower inline cost make is more likely for the call to - // be inlined. This value may go negative. - // - int InlineCost = 0; - - // If there is only one call of the function, and it has internal linkage, - // make it almost guaranteed to be inlined. - // - if (Callee->hasInternalLinkage() && Callee->hasOneUse()) - InlineCost -= 30000; - - // If this function uses the coldcc calling convention, prefer not to inline - // it. - if (Callee->getCallingConv() == CallingConv::Cold) - InlineCost += 2000; - - // If the instruction after the call, or if the normal destination of the - // invoke is an unreachable instruction, the function is noreturn. As such, - // there is little point in inlining this. - if (InvokeInst *II = dyn_cast(TheCall)) { - if (isa(II->getNormalDest()->begin())) - InlineCost += 10000; - } else if (isa(++BasicBlock::iterator(TheCall))) - InlineCost += 10000; - - // Get information about the callee... - FunctionInfo &CalleeFI = CachedFunctionInfo[Callee]; - - // If we haven't calculated this information yet, do so now. - if (CalleeFI.NumBlocks == 0) - CalleeFI.analyzeFunction(Callee); - - // Add to the inline quality for properties that make the call valuable to - // inline. This includes factors that indicate that the result of inlining - // the function will be optimizable. Currently this just looks at arguments - // passed into the function. - // - unsigned ArgNo = 0; - for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); - I != E; ++I, ++ArgNo) { - // Each argument passed in has a cost at both the caller and the callee - // sides. This favors functions that take many arguments over functions - // that take few arguments. - InlineCost -= 20; - - // If this is a function being passed in, it is very likely that we will be - // able to turn an indirect function call into a direct function call. - if (isa(I)) - InlineCost -= 100; - - // If an alloca is passed in, inlining this function is likely to allow - // significant future optimization possibilities (like scalar promotion, and - // scalarization), so encourage the inlining of the function. - // - else if (isa(I)) { - if (ArgNo < CalleeFI.ArgumentWeights.size()) - InlineCost -= CalleeFI.ArgumentWeights[ArgNo].AllocaWeight; - - // If this is a constant being passed into the function, use the argument - // weights calculated for the callee to determine how much will be folded - // away with this information. - } else if (isa(I)) { - if (ArgNo < CalleeFI.ArgumentWeights.size()) - InlineCost -= CalleeFI.ArgumentWeights[ArgNo].ConstantWeight; - } - } - - // Now that we have considered all of the factors that make the call site more - // likely to be inlined, look at factors that make us not want to inline it. - - // Don't inline into something too big, which would make it bigger. Here, we - // count each basic block as a single unit. - // - InlineCost += Caller->size()/20; - - - // Look at the size of the callee. Each basic block counts as 20 units, and - // each instruction counts as 5. - InlineCost += CalleeFI.NumInsts*5 + CalleeFI.NumBlocks*20; - return InlineCost; -} - // doInitialization - Initializes the vector of functions that have been // annotated with the noinline attribute. bool SimpleInliner::doInitialization(CallGraph &CG) { @@ -321,3 +80,4 @@ bool SimpleInliner::doInitialization(CallGraph &CG) { return false; } + diff --git a/lib/Transforms/Utils/BasicInliner.cpp b/lib/Transforms/Utils/BasicInliner.cpp new file mode 100644 index 00000000000..871b1a504a3 --- /dev/null +++ b/lib/Transforms/Utils/BasicInliner.cpp @@ -0,0 +1,171 @@ +//===- BasicInliner.cpp - Basic function level inliner --------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file was developed by Devang Patel and is distributed under +// the University of Illinois Open Source License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines a simple function based inliner that does not use +// call graph information. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "basicinliner" + +#include "llvm/Module.h" +#include "llvm/Function.h" +#include "llvm/Transforms/Utils/BasicInliner.h" +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/Support/CallSite.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/ADT/SmallPtrSet.h" +#include +#include + +using namespace llvm; + +namespace { + cl::opt + BasicInlineThreshold("inline-threshold", cl::Hidden, cl::init(200), + cl::desc("Control the amount of basic inlining to perform (default = 200)")); +} + +namespace llvm { + + /// BasicInlinerImpl - BasicInliner implemantation class. This hides + /// container info, used by basic inliner, from public interface. + struct VISIBILITY_HIDDEN BasicInlinerImpl { + + BasicInlinerImpl(const BasicInlinerImpl&); // DO NOT IMPLEMENT + void operator=(const BasicInlinerImpl&); // DO NO IMPLEMENT + public: + BasicInlinerImpl(TargetData *T) : TD(T) {} + + /// addFunction - Add function into the list of functions to process. + /// All functions must be inserted using this interface before invoking + /// inlineFunctions(). + void addFunction(Function *F) { + Functions.push_back(F); + } + + /// neverInlineFunction - Sometimes a function is never to be inlined + /// because of one or other reason. + void neverInlineFunction(Function *F) { + NeverInline.insert(F); + } + + /// inlineFuctions - Walk all call sites in all functions supplied by + /// client. Inline as many call sites as possible. Delete completely + /// inlined functions. + void inlineFunctions(); + + private: + TargetData *TD; + std::vector Functions; + std::set NeverInline; + SmallPtrSet DeadFunctions; + InlineCostAnalyzer CA; + }; + +/// inlineFuctions - Walk all call sites in all functions supplied by +/// client. Inline as many call sites as possible. Delete completely +/// inlined functions. +void BasicInlinerImpl::inlineFunctions() { + + // Scan through and identify all call sites ahead of time so that we only + // inline call sites in the original functions, not call sites that result + // from inlining other functions. + std::vector CallSites; + + for (std::vector::iterator FI = Functions.begin(), + FE = Functions.end(); FI != FE; ++FI) { + Function *F = *FI; + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) + for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) { + CallSite CS = CallSite::get(I); + if (CS.getInstruction() && CS.getCalledFunction() + && !CS.getCalledFunction()->isDeclaration()) + CallSites.push_back(CS); + } + } + + DOUT << ": " << CallSites.size() << " call sites.\n"; + + // Inline call sites. + bool Changed = false; + do { + Changed = false; + for (unsigned index = 0; index != CallSites.size() && !CallSites.empty(); ++index) { + CallSite CS = CallSites[index]; + if (Function *Callee = CS.getCalledFunction()) { + + // Eliminate calls taht are never inlinable. + if (Callee->isDeclaration() || + CS.getInstruction()->getParent()->getParent() == Callee) { + CallSites.erase(CallSites.begin() + index); + --index; + continue; + } + int InlineCost = CA.getInlineCost(CS, NeverInline); + if (InlineCost >= (int) BasicInlineThreshold) { + DOUT << " NOT Inlining: cost = " << InlineCost + << ", call: " << *CS.getInstruction(); + continue; + } + + DOUT << " Inlining: cost=" << InlineCost + <<", call: " << *CS.getInstruction(); + + // Inline + if (InlineFunction(CS, NULL, TD)) { + if (Callee->use_empty() && Callee->hasInternalLinkage()) + DeadFunctions.insert(Callee); + Changed = true; + CallSites.erase(CallSites.begin() + index); + --index; + } + } + } + } while (Changed); + + // Remove completely inlined functions from module. + for(SmallPtrSet::iterator I = DeadFunctions.begin(), + E = DeadFunctions.end(); I != E; ++I) { + Function *D = *I; + Module *M = D->getParent(); + M->getFunctionList().remove(D); + } +} + +BasicInliner::BasicInliner(TargetData *TD) { + Impl = new BasicInlinerImpl(TD); +} + +BasicInliner::~BasicInliner() { + delete Impl; +} + +/// addFunction - Add function into the list of functions to process. +/// All functions must be inserted using this interface before invoking +/// inlineFunctions(). +void BasicInliner::addFunction(Function *F) { + Impl->addFunction(F); +} + +/// neverInlineFunction - Sometimes a function is never to be inlined because +/// of one or other reason. +void BasicInliner::neverInlineFunction(Function *F) { + Impl->neverInlineFunction(F); +} + +/// inlineFuctions - Walk all call sites in all functions supplied by +/// client. Inline as many call sites as possible. Delete completely +/// inlined functions. +void BasicInliner::inlineFunctions() { + Impl->inlineFunctions(); +} + +} diff --git a/lib/Transforms/Utils/InlineCost.cpp b/lib/Transforms/Utils/InlineCost.cpp new file mode 100644 index 00000000000..8b34427ac67 --- /dev/null +++ b/lib/Transforms/Utils/InlineCost.cpp @@ -0,0 +1,241 @@ +//===- InlineCoast.cpp - Cost analysis for inliner ------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file was developed by the LLVM research group and is distributed under +// the University of Illinois Open Source License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements inline cost analysis. +// +//===----------------------------------------------------------------------===// + + +#include "llvm/Transforms/Utils/InlineCost.h" +#include "llvm/Support/CallSite.h" +#include "llvm/CallingConv.h" +#include "llvm/IntrinsicInst.h" + +using namespace llvm; + +// CountCodeReductionForConstant - Figure out an approximation for how many +// instructions will be constant folded if the specified value is constant. +// +unsigned InlineCostAnalyzer::FunctionInfo:: + CountCodeReductionForConstant(Value *V) { + unsigned Reduction = 0; + for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI) + if (isa(*UI)) + Reduction += 40; // Eliminating a conditional branch is a big win + else if (SwitchInst *SI = dyn_cast(*UI)) + // Eliminating a switch is a big win, proportional to the number of edges + // deleted. + Reduction += (SI->getNumSuccessors()-1) * 40; + else if (CallInst *CI = dyn_cast(*UI)) { + // Turning an indirect call into a direct call is a BIG win + Reduction += CI->getCalledValue() == V ? 500 : 0; + } else if (InvokeInst *II = dyn_cast(*UI)) { + // Turning an indirect call into a direct call is a BIG win + Reduction += II->getCalledValue() == V ? 500 : 0; + } else { + // Figure out if this instruction will be removed due to simple constant + // propagation. + Instruction &Inst = cast(**UI); + bool AllOperandsConstant = true; + for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) + if (!isa(Inst.getOperand(i)) && Inst.getOperand(i) != V) { + AllOperandsConstant = false; + break; + } + + if (AllOperandsConstant) { + // We will get to remove this instruction... + Reduction += 7; + + // And any other instructions that use it which become constants + // themselves. + Reduction += CountCodeReductionForConstant(&Inst); + } + } + + return Reduction; +} + +// CountCodeReductionForAlloca - Figure out an approximation of how much smaller +// the function will be if it is inlined into a context where an argument +// becomes an alloca. +// +unsigned InlineCostAnalyzer::FunctionInfo:: + CountCodeReductionForAlloca(Value *V) { + if (!isa(V->getType())) return 0; // Not a pointer + unsigned Reduction = 0; + for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){ + Instruction *I = cast(*UI); + if (isa(I) || isa(I)) + Reduction += 10; + else if (GetElementPtrInst *GEP = dyn_cast(I)) { + // If the GEP has variable indices, we won't be able to do much with it. + for (Instruction::op_iterator I = GEP->op_begin()+1, E = GEP->op_end(); + I != E; ++I) + if (!isa(*I)) return 0; + Reduction += CountCodeReductionForAlloca(GEP)+15; + } else { + // If there is some other strange instruction, we're not going to be able + // to do much if we inline this. + return 0; + } + } + + return Reduction; +} + +/// analyzeFunction - Fill in the current structure with information gleaned +/// from the specified function. +void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) { + unsigned NumInsts = 0, NumBlocks = 0; + + // Look at the size of the callee. Each basic block counts as 20 units, and + // each instruction counts as 10. + for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { + for (BasicBlock::const_iterator II = BB->begin(), E = BB->end(); + II != E; ++II) { + if (isa(II)) continue; // Debug intrinsics don't count. + + // Noop casts, including ptr <-> int, don't count. + if (const CastInst *CI = dyn_cast(II)) { + if (CI->isLosslessCast() || isa(CI) || + isa(CI)) + continue; + } else if (const GetElementPtrInst *GEPI = + dyn_cast(II)) { + // If a GEP has all constant indices, it will probably be folded with + // a load/store. + bool AllConstant = true; + for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i) + if (!isa(GEPI->getOperand(i))) { + AllConstant = false; + break; + } + if (AllConstant) continue; + } + + ++NumInsts; + } + + ++NumBlocks; + } + + this->NumBlocks = NumBlocks; + this->NumInsts = NumInsts; + + // Check out all of the arguments to the function, figuring out how much + // code can be eliminated if one of the arguments is a constant. + for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) + ArgumentWeights.push_back(ArgInfo(CountCodeReductionForConstant(I), + CountCodeReductionForAlloca(I))); +} + + + +// getInlineCost - The heuristic used to determine if we should inline the +// function call or not. +// +int InlineCostAnalyzer::getInlineCost(CallSite CS, std::set &NeverInline) { + Instruction *TheCall = CS.getInstruction(); + Function *Callee = CS.getCalledFunction(); + const Function *Caller = TheCall->getParent()->getParent(); + + // Don't inline a directly recursive call. + if (Caller == Callee || + // Don't inline functions which can be redefined at link-time to mean + // something else. link-once linkage is ok though. + Callee->hasWeakLinkage() || + + // Don't inline functions marked noinline. + NeverInline.count(Callee)) + return 2000000000; + + // InlineCost - This value measures how good of an inline candidate this call + // site is to inline. A lower inline cost make is more likely for the call to + // be inlined. This value may go negative. + // + int InlineCost = 0; + + // If there is only one call of the function, and it has internal linkage, + // make it almost guaranteed to be inlined. + // + if (Callee->hasInternalLinkage() && Callee->hasOneUse()) + InlineCost -= 30000; + + // If this function uses the coldcc calling convention, prefer not to inline + // it. + if (Callee->getCallingConv() == CallingConv::Cold) + InlineCost += 2000; + + // If the instruction after the call, or if the normal destination of the + // invoke is an unreachable instruction, the function is noreturn. As such, + // there is little point in inlining this. + if (InvokeInst *II = dyn_cast(TheCall)) { + if (isa(II->getNormalDest()->begin())) + InlineCost += 10000; + } else if (isa(++BasicBlock::iterator(TheCall))) + InlineCost += 10000; + + // Get information about the callee... + FunctionInfo &CalleeFI = CachedFunctionInfo[Callee]; + + // If we haven't calculated this information yet, do so now. + if (CalleeFI.NumBlocks == 0) + CalleeFI.analyzeFunction(Callee); + + // Add to the inline quality for properties that make the call valuable to + // inline. This includes factors that indicate that the result of inlining + // the function will be optimizable. Currently this just looks at arguments + // passed into the function. + // + unsigned ArgNo = 0; + for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); + I != E; ++I, ++ArgNo) { + // Each argument passed in has a cost at both the caller and the callee + // sides. This favors functions that take many arguments over functions + // that take few arguments. + InlineCost -= 20; + + // If this is a function being passed in, it is very likely that we will be + // able to turn an indirect function call into a direct function call. + if (isa(I)) + InlineCost -= 100; + + // If an alloca is passed in, inlining this function is likely to allow + // significant future optimization possibilities (like scalar promotion, and + // scalarization), so encourage the inlining of the function. + // + else if (isa(I)) { + if (ArgNo < CalleeFI.ArgumentWeights.size()) + InlineCost -= CalleeFI.ArgumentWeights[ArgNo].AllocaWeight; + + // If this is a constant being passed into the function, use the argument + // weights calculated for the callee to determine how much will be folded + // away with this information. + } else if (isa(I)) { + if (ArgNo < CalleeFI.ArgumentWeights.size()) + InlineCost -= CalleeFI.ArgumentWeights[ArgNo].ConstantWeight; + } + } + + // Now that we have considered all of the factors that make the call site more + // likely to be inlined, look at factors that make us not want to inline it. + + // Don't inline into something too big, which would make it bigger. Here, we + // count each basic block as a single unit. + // + InlineCost += Caller->size()/20; + + + // Look at the size of the callee. Each basic block counts as 20 units, and + // each instruction counts as 5. + InlineCost += CalleeFI.NumInsts*5 + CalleeFI.NumBlocks*20; + return InlineCost; +} +