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Commit the removal of this file, which is now moved to lib/Analysis.

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llvm-svn: 83999
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Dan Gohman 2009-10-13 18:37:20 +00:00
parent 18cdd7ef1b
commit 81218aa90e
1 changed files with 0 additions and 337 deletions
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lib/Transforms/Utils/InlineCost.cpp
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@ -1,337 +0,0 @@
//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file 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"
#include "llvm/ADT/SmallPtrSet.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::RegionInfo::
CountCodeReductionForConstant(Value *V) {
unsigned Reduction = 0;
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
if (isa<BranchInst>(*UI))
Reduction += 40; // Eliminating a conditional branch is a big win
else if (SwitchInst *SI = dyn_cast<SwitchInst>(*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<CallInst>(*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<InvokeInst>(*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<Instruction>(**UI);
// We can't constant propagate instructions which have effects or
// read memory.
//
// FIXME: It would be nice to capture the fact that a load from a
// pointer-to-constant-global is actually a *really* good thing to zap.
// Unfortunately, we don't know the pointer that may get propagated here,
// so we can't make this decision.
if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
isa<AllocationInst>(Inst))
continue;
bool AllOperandsConstant = true;
for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
if (!isa<Constant>(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::RegionInfo::
CountCodeReductionForAlloca(Value *V) {
if (!isa<PointerType>(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<Instruction>(*UI);
if (isa<LoadInst>(I) || isa<StoreInst>(I))
Reduction += 10;
else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
// If the GEP has variable indices, we won't be able to do much with it.
if (!GEP->hasAllConstantIndices())
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;
}
/// analyzeBasicBlock - Fill in the current structure with information gleaned
/// from the specified block.
void InlineCostAnalyzer::RegionInfo::analyzeBasicBlock(const BasicBlock *BB) {
++NumBlocks;
for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
II != E; ++II) {
if (isa<PHINode>(II)) continue; // PHI nodes don't count.
// Special handling for calls.
if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
if (isa<DbgInfoIntrinsic>(II))
continue; // Debug intrinsics don't count as size.
CallSite CS = CallSite::get(const_cast<Instruction*>(&*II));
// If this function contains a call to setjmp or _setjmp, never inline
// it. This is a hack because we depend on the user marking their local
// variables as volatile if they are live across a setjmp call, and they
// probably won't do this in callers.
if (Function *F = CS.getCalledFunction())
if (F->isDeclaration() &&
(F->getName() == "setjmp" || F->getName() == "_setjmp")) {
NeverInline = true;
return;
}
// Calls often compile into many machine instructions. Bump up their
// cost to reflect this.
if (!isa<IntrinsicInst>(II))
NumInsts += InlineConstants::CallPenalty;
}
// These, too, are calls.
if (isa<MallocInst>(II) || isa<FreeInst>(II))
NumInsts += InlineConstants::CallPenalty;
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (!AI->isStaticAlloca())
this->usesDynamicAlloca = true;
}
if (isa<ExtractElementInst>(II) || isa<VectorType>(II->getType()))
++NumVectorInsts;
// Noop casts, including ptr <-> int, don't count.
if (const CastInst *CI = dyn_cast<CastInst>(II)) {
if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
isa<PtrToIntInst>(CI))
continue;
} else if (const GetElementPtrInst *GEPI =
dyn_cast<GetElementPtrInst>(II)) {
// If a GEP has all constant indices, it will probably be folded with
// a load/store.
if (GEPI->hasAllConstantIndices())
continue;
}
if (isa<ReturnInst>(II))
++NumRets;
++NumInsts;
}
}
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
void InlineCostAnalyzer::RegionInfo::analyzeFunction(Function *F) {
// Look at the size of the callee. Each basic block counts as 20 units, and
// each instruction counts as 5.
for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
analyzeBasicBlock(&*BB);
// A function with exactly one return has it removed during the inlining
// process (see InlineFunction), so don't count it.
// FIXME: This knowledge should really be encoded outside of RegionInfo.
if (NumRets==1)
--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.
//
InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
SmallPtrSet<const Function *, 16> &NeverInline) {
Instruction *TheCall = CS.getInstruction();
Function *Callee = CS.getCalledFunction();
Function *Caller = TheCall->getParent()->getParent();
// Don't inline functions which can be redefined at link-time to mean
// something else. Don't inline functions marked noinline.
if (Callee->mayBeOverridden() ||
Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee))
return llvm::InlineCost::getNever();
// 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->hasLocalLinkage() && Callee->hasOneUse())
InlineCost += InlineConstants::LastCallToStaticBonus;
// If this function uses the coldcc calling convention, prefer not to inline
// it.
if (Callee->getCallingConv() == CallingConv::Cold)
InlineCost += InlineConstants::ColdccPenalty;
// 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<InvokeInst>(TheCall)) {
if (isa<UnreachableInst>(II->getNormalDest()->begin()))
InlineCost += InlineConstants::NoreturnPenalty;
} else if (isa<UnreachableInst>(++BasicBlock::iterator(TheCall)))
InlineCost += InlineConstants::NoreturnPenalty;
// Get information about the callee...
RegionInfo &CalleeFI = CachedFunctionInfo[Callee];
// If we haven't calculated this information yet, do so now.
if (CalleeFI.NumBlocks == 0)
CalleeFI.analyzeFunction(Callee);
// If we should never inline this, return a huge cost.
if (CalleeFI.NeverInline)
return InlineCost::getNever();
// FIXME: It would be nice to kill off CalleeFI.NeverInline. Then we
// could move this up and avoid computing the RegionInfo for
// things we are going to just return always inline for. This
// requires handling setjmp somewhere else, however.
if (!Callee->isDeclaration() && Callee->hasFnAttr(Attribute::AlwaysInline))
return InlineCost::getAlways();
if (CalleeFI.usesDynamicAlloca) {
// Get infomation about the caller...
RegionInfo &CallerFI = CachedFunctionInfo[Caller];
// If we haven't calculated this information yet, do so now.
if (CallerFI.NumBlocks == 0)
CallerFI.analyzeFunction(Caller);
// Don't inline a callee with dynamic alloca into a caller without them.
// Functions containing dynamic alloca's are inefficient in various ways;
// don't create more inefficiency.
if (!CallerFI.usesDynamicAlloca)
return InlineCost::getNever();
}
// 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<Function>(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<AllocaInst>(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<Constant>(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.
// "size" here is the number of basic blocks, not instructions.
//
InlineCost += Caller->size()/15;
// Look at the size of the callee. Each instruction counts as 5.
InlineCost += CalleeFI.NumInsts*5;
return llvm::InlineCost::get(InlineCost);
}
// getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
// higher threshold to determine if the function call should be inlined.
float InlineCostAnalyzer::getInlineFudgeFactor(CallSite CS) {
Function *Callee = CS.getCalledFunction();
// Get information about the callee...
RegionInfo &CalleeFI = CachedFunctionInfo[Callee];
// If we haven't calculated this information yet, do so now.
if (CalleeFI.NumBlocks == 0)
CalleeFI.analyzeFunction(Callee);
float Factor = 1.0f;
// Single BB functions are often written to be inlined.
if (CalleeFI.NumBlocks == 1)
Factor += 0.5f;
// Be more aggressive if the function contains a good chunk (if it mades up
// at least 10% of the instructions) of vector instructions.
if (CalleeFI.NumVectorInsts > CalleeFI.NumInsts/2)
Factor += 2.0f;
else if (CalleeFI.NumVectorInsts > CalleeFI.NumInsts/10)
Factor += 1.5f;
return Factor;
}