[llvm-commits] [llvm] r83999 - /llvm/trunk/lib/Transforms/Utils/InlineCost.cpp
Dan Gohman
gohman at apple.com
Tue Oct 13 11:37:21 PDT 2009
Author: djg
Date: Tue Oct 13 13:37:20 2009
New Revision: 83999
URL: http://llvm.org/viewvc/llvm-project?rev=83999&view=rev
Log:
Commit the removal of this file, which is now moved to lib/Analysis.
Removed:
llvm/trunk/lib/Transforms/Utils/InlineCost.cpp
Removed: llvm/trunk/lib/Transforms/Utils/InlineCost.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/InlineCost.cpp?rev=83998&view=auto
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/InlineCost.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/InlineCost.cpp (removed)
@@ -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;
-}
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