| //===- 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/Analysis/InlineCost.h" |
| #include "llvm/Support/CallSite.h" |
| #include "llvm/CallingConv.h" |
| #include "llvm/IntrinsicInst.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| |
| using namespace llvm; |
| |
| /// callIsSmall - If a call is likely to lower to a single target instruction, |
| /// or is otherwise deemed small return true. |
| /// TODO: Perhaps calls like memcpy, strcpy, etc? |
| bool llvm::callIsSmall(const Function *F) { |
| if (!F) return false; |
| |
| if (F->hasLocalLinkage()) return false; |
| |
| if (!F->hasName()) return false; |
| |
| StringRef Name = F->getName(); |
| |
| // These will all likely lower to a single selection DAG node. |
| if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" || |
| Name == "fabs" || Name == "fabsf" || Name == "fabsl" || |
| Name == "sin" || Name == "sinf" || Name == "sinl" || |
| Name == "cos" || Name == "cosf" || Name == "cosl" || |
| Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl" ) |
| return true; |
| |
| // These are all likely to be optimized into something smaller. |
| if (Name == "pow" || Name == "powf" || Name == "powl" || |
| Name == "exp2" || Name == "exp2l" || Name == "exp2f" || |
| Name == "floor" || Name == "floorf" || Name == "ceil" || |
| Name == "round" || Name == "ffs" || Name == "ffsl" || |
| Name == "abs" || Name == "labs" || Name == "llabs") |
| return true; |
| |
| return false; |
| } |
| |
| /// analyzeBasicBlock - Fill in the current structure with information gleaned |
| /// from the specified block. |
| void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB, |
| const TargetData *TD) { |
| ++NumBlocks; |
| unsigned NumInstsBeforeThisBB = NumInsts; |
| 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. |
| |
| ImmutableCallSite CS(cast<Instruction>(II)); |
| |
| if (const Function *F = CS.getCalledFunction()) { |
| // If a function is both internal and has a single use, then it is |
| // extremely likely to get inlined in the future (it was probably |
| // exposed by an interleaved devirtualization pass). |
| if (F->hasInternalLinkage() && F->hasOneUse()) |
| ++NumInlineCandidates; |
| |
| // If this call is to function itself, then the function is recursive. |
| // Inlining it into other functions is a bad idea, because this is |
| // basically just a form of loop peeling, and our metrics aren't useful |
| // for that case. |
| if (F == BB->getParent()) |
| isRecursive = true; |
| } |
| |
| if (!isa<IntrinsicInst>(II) && !callIsSmall(CS.getCalledFunction())) { |
| // Each argument to a call takes on average one instruction to set up. |
| NumInsts += CS.arg_size(); |
| |
| // We don't want inline asm to count as a call - that would prevent loop |
| // unrolling. The argument setup cost is still real, though. |
| if (!isa<InlineAsm>(CS.getCalledValue())) |
| ++NumCalls; |
| } |
| } |
| |
| if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) { |
| if (!AI->isStaticAlloca()) |
| this->usesDynamicAlloca = true; |
| } |
| |
| if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy()) |
| ++NumVectorInsts; |
| |
| if (const CastInst *CI = dyn_cast<CastInst>(II)) { |
| // Noop casts, including ptr <-> int, don't count. |
| if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) || |
| isa<PtrToIntInst>(CI)) |
| continue; |
| // trunc to a native type is free (assuming the target has compare and |
| // shift-right of the same width). |
| if (isa<TruncInst>(CI) && TD && |
| TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType()))) |
| continue; |
| // Result of a cmp instruction is often extended (to be used by other |
| // cmp instructions, logical or return instructions). These are usually |
| // nop on most sane targets. |
| if (isa<CmpInst>(CI->getOperand(0))) |
| 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; |
| } |
| |
| ++NumInsts; |
| } |
| |
| if (isa<ReturnInst>(BB->getTerminator())) |
| ++NumRets; |
| |
| // We never want to inline functions that contain an indirectbr. This is |
| // incorrect because all the blockaddress's (in static global initializers |
| // for example) would be referring to the original function, and this indirect |
| // jump would jump from the inlined copy of the function into the original |
| // function which is extremely undefined behavior. |
| if (isa<IndirectBrInst>(BB->getTerminator())) |
| containsIndirectBr = true; |
| |
| // Remember NumInsts for this BB. |
| NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB; |
| } |
| |
| // CountCodeReductionForConstant - Figure out an approximation for how many |
| // instructions will be constant folded if the specified value is constant. |
| // |
| unsigned CodeMetrics::CountCodeReductionForConstant(Value *V) { |
| unsigned Reduction = 0; |
| for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){ |
| User *U = *UI; |
| if (isa<BranchInst>(U) || isa<SwitchInst>(U)) { |
| // We will be able to eliminate all but one of the successors. |
| const TerminatorInst &TI = cast<TerminatorInst>(*U); |
| const unsigned NumSucc = TI.getNumSuccessors(); |
| unsigned Instrs = 0; |
| for (unsigned I = 0; I != NumSucc; ++I) |
| Instrs += NumBBInsts[TI.getSuccessor(I)]; |
| // We don't know which blocks will be eliminated, so use the average size. |
| Reduction += InlineConstants::InstrCost*Instrs*(NumSucc-1)/NumSucc; |
| } else { |
| // Figure out if this instruction will be removed due to simple constant |
| // propagation. |
| Instruction &Inst = cast<Instruction>(*U); |
| |
| // 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<AllocaInst>(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 += InlineConstants::InstrCost; |
| |
| // 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 CodeMetrics::CountCodeReductionForAlloca(Value *V) { |
| if (!V->getType()->isPointerTy()) 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 += InlineConstants::InstrCost; |
| 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); |
| } else if (BitCastInst *BCI = dyn_cast<BitCastInst>(I)) { |
| // Track pointer through bitcasts. |
| Reduction += CountCodeReductionForAlloca(BCI); |
| } 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 CodeMetrics::analyzeFunction(Function *F, const TargetData *TD) { |
| // 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 (F->callsFunctionThatReturnsTwice()) |
| callsSetJmp = true; |
| |
| // Look at the size of the callee. |
| for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) |
| analyzeBasicBlock(&*BB, TD); |
| } |
| |
| /// analyzeFunction - Fill in the current structure with information gleaned |
| /// from the specified function. |
| void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F, |
| const TargetData *TD) { |
| Metrics.analyzeFunction(F, TD); |
| |
| // 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 FunctionInfo. |
| if (Metrics.NumRets==1) |
| --Metrics.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. |
| ArgumentWeights.reserve(F->arg_size()); |
| for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I) |
| ArgumentWeights.push_back(ArgInfo(Metrics.CountCodeReductionForConstant(I), |
| Metrics.CountCodeReductionForAlloca(I))); |
| } |
| |
| /// NeverInline - returns true if the function should never be inlined into |
| /// any caller |
| bool InlineCostAnalyzer::FunctionInfo::NeverInline() { |
| return (Metrics.callsSetJmp || Metrics.isRecursive || |
| Metrics.containsIndirectBr); |
| } |
| // getSpecializationBonus - The heuristic used to determine the per-call |
| // performance boost for using a specialization of Callee with argument |
| // specializedArgNo replaced by a constant. |
| int InlineCostAnalyzer::getSpecializationBonus(Function *Callee, |
| SmallVectorImpl<unsigned> &SpecializedArgNos) |
| { |
| if (Callee->mayBeOverridden()) |
| return 0; |
| |
| int Bonus = 0; |
| // If this function uses the coldcc calling convention, prefer not to |
| // specialize it. |
| if (Callee->getCallingConv() == CallingConv::Cold) |
| Bonus -= InlineConstants::ColdccPenalty; |
| |
| // Get information about the callee. |
| FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CalleeFI->Metrics.NumBlocks == 0) |
| CalleeFI->analyzeFunction(Callee, TD); |
| |
| unsigned ArgNo = 0; |
| unsigned i = 0; |
| for (Function::arg_iterator I = Callee->arg_begin(), E = Callee->arg_end(); |
| I != E; ++I, ++ArgNo) |
| if (ArgNo == SpecializedArgNos[i]) { |
| ++i; |
| Bonus += CountBonusForConstant(I); |
| } |
| |
| // Calls usually take a long time, so they make the specialization gain |
| // smaller. |
| Bonus -= CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty; |
| |
| return Bonus; |
| } |
| |
| // ConstantFunctionBonus - Figure out how much of a bonus we can get for |
| // possibly devirtualizing a function. We'll subtract the size of the function |
| // we may wish to inline from the indirect call bonus providing a limit on |
| // growth. Leave an upper limit of 0 for the bonus - we don't want to penalize |
| // inlining because we decide we don't want to give a bonus for |
| // devirtualizing. |
| int InlineCostAnalyzer::ConstantFunctionBonus(CallSite CS, Constant *C) { |
| |
| // This could just be NULL. |
| if (!C) return 0; |
| |
| Function *F = dyn_cast<Function>(C); |
| if (!F) return 0; |
| |
| int Bonus = InlineConstants::IndirectCallBonus + getInlineSize(CS, F); |
| return (Bonus > 0) ? 0 : Bonus; |
| } |
| |
| // CountBonusForConstant - Figure out an approximation for how much per-call |
| // performance boost we can expect if the specified value is constant. |
| int InlineCostAnalyzer::CountBonusForConstant(Value *V, Constant *C) { |
| unsigned Bonus = 0; |
| for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){ |
| User *U = *UI; |
| if (CallInst *CI = dyn_cast<CallInst>(U)) { |
| // Turning an indirect call into a direct call is a BIG win |
| if (CI->getCalledValue() == V) |
| Bonus += ConstantFunctionBonus(CallSite(CI), C); |
| } else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) { |
| // Turning an indirect call into a direct call is a BIG win |
| if (II->getCalledValue() == V) |
| Bonus += ConstantFunctionBonus(CallSite(II), C); |
| } |
| // FIXME: Eliminating conditional branches and switches should |
| // also yield a per-call performance boost. |
| else { |
| // Figure out the bonuses that wll accrue due to simple constant |
| // propagation. |
| Instruction &Inst = cast<Instruction>(*U); |
| |
| // 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<AllocaInst>(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) |
| Bonus += CountBonusForConstant(&Inst); |
| } |
| } |
| |
| return Bonus; |
| } |
| |
| int InlineCostAnalyzer::getInlineSize(CallSite CS, Function *Callee) { |
| // Get information about the callee. |
| FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CalleeFI->Metrics.NumBlocks == 0) |
| CalleeFI->analyzeFunction(Callee, TD); |
| |
| // 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; |
| |
| // Compute any size reductions we can expect due to arguments being passed into |
| // the function. |
| // |
| unsigned ArgNo = 0; |
| CallSite::arg_iterator I = CS.arg_begin(); |
| for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end(); |
| FI != FE; ++I, ++FI, ++ArgNo) { |
| |
| // 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. |
| // |
| if (isa<AllocaInst>(I)) |
| 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)) |
| InlineCost -= CalleeFI->ArgumentWeights[ArgNo].ConstantWeight; |
| } |
| |
| // Each argument passed in has a cost at both the caller and the callee |
| // sides. Measurements show that each argument costs about the same as an |
| // instruction. |
| InlineCost -= (CS.arg_size() * InlineConstants::InstrCost); |
| |
| // 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. |
| |
| // Calls usually take a long time, so they make the inlining gain smaller. |
| InlineCost += CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty; |
| |
| // Look at the size of the callee. Each instruction counts as 5. |
| InlineCost += CalleeFI->Metrics.NumInsts*InlineConstants::InstrCost; |
| |
| return InlineCost; |
| } |
| |
| int InlineCostAnalyzer::getInlineBonuses(CallSite CS, Function *Callee) { |
| // Get information about the callee. |
| FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CalleeFI->Metrics.NumBlocks == 0) |
| CalleeFI->analyzeFunction(Callee, TD); |
| |
| bool isDirectCall = CS.getCalledFunction() == Callee; |
| Instruction *TheCall = CS.getInstruction(); |
| int Bonus = 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() && isDirectCall) |
| Bonus += InlineConstants::LastCallToStaticBonus; |
| |
| // 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())) |
| Bonus += InlineConstants::NoreturnPenalty; |
| } else if (isa<UnreachableInst>(++BasicBlock::iterator(TheCall))) |
| Bonus += InlineConstants::NoreturnPenalty; |
| |
| // If this function uses the coldcc calling convention, prefer not to inline |
| // it. |
| if (Callee->getCallingConv() == CallingConv::Cold) |
| Bonus += InlineConstants::ColdccPenalty; |
| |
| // 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. |
| // |
| CallSite::arg_iterator I = CS.arg_begin(); |
| for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end(); |
| FI != FE; ++I, ++FI) |
| // Compute any constant bonus due to inlining we want to give here. |
| if (isa<Constant>(I)) |
| Bonus += CountBonusForConstant(FI, cast<Constant>(I)); |
| |
| return Bonus; |
| } |
| |
| // 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) { |
| return getInlineCost(CS, CS.getCalledFunction(), NeverInline); |
| } |
| |
| InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS, |
| Function *Callee, |
| SmallPtrSet<const Function*, 16> &NeverInline) { |
| Instruction *TheCall = CS.getInstruction(); |
| 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 or call sites |
| // marked noinline. |
| if (Callee->mayBeOverridden() || |
| Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee) || |
| CS.isNoInline()) |
| return llvm::InlineCost::getNever(); |
| |
| // Get information about the callee. |
| FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CalleeFI->Metrics.NumBlocks == 0) |
| CalleeFI->analyzeFunction(Callee, TD); |
| |
| // 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 FunctionInfo 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->Metrics.usesDynamicAlloca) { |
| // Get information about the caller. |
| FunctionInfo &CallerFI = CachedFunctionInfo[Caller]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CallerFI.Metrics.NumBlocks == 0) { |
| CallerFI.analyzeFunction(Caller, TD); |
| |
| // Recompute the CalleeFI pointer, getting Caller could have invalidated |
| // it. |
| CalleeFI = &CachedFunctionInfo[Callee]; |
| } |
| |
| // 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.Metrics.usesDynamicAlloca) |
| return 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 due to the fact that bonuses |
| // are negative numbers. |
| // |
| int InlineCost = getInlineSize(CS, Callee) + getInlineBonuses(CS, Callee); |
| return llvm::InlineCost::get(InlineCost); |
| } |
| |
| // getSpecializationCost - The heuristic used to determine the code-size |
| // impact of creating a specialized version of Callee with argument |
| // SpecializedArgNo replaced by a constant. |
| InlineCost InlineCostAnalyzer::getSpecializationCost(Function *Callee, |
| SmallVectorImpl<unsigned> &SpecializedArgNos) |
| { |
| // Don't specialize functions which can be redefined at link-time to mean |
| // something else. |
| if (Callee->mayBeOverridden()) |
| return llvm::InlineCost::getNever(); |
| |
| // Get information about the callee. |
| FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CalleeFI->Metrics.NumBlocks == 0) |
| CalleeFI->analyzeFunction(Callee, TD); |
| |
| int Cost = 0; |
| |
| // Look at the original size of the callee. Each instruction counts as 5. |
| Cost += CalleeFI->Metrics.NumInsts * InlineConstants::InstrCost; |
| |
| // Offset that with the amount of code that can be constant-folded |
| // away with the given arguments replaced by constants. |
| for (SmallVectorImpl<unsigned>::iterator an = SpecializedArgNos.begin(), |
| ae = SpecializedArgNos.end(); an != ae; ++an) |
| Cost -= CalleeFI->ArgumentWeights[*an].ConstantWeight; |
| |
| return llvm::InlineCost::get(Cost); |
| } |
| |
| // 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. |
| FunctionInfo &CalleeFI = CachedFunctionInfo[Callee]; |
| |
| // If we haven't calculated this information yet, do so now. |
| if (CalleeFI.Metrics.NumBlocks == 0) |
| CalleeFI.analyzeFunction(Callee, TD); |
| |
| float Factor = 1.0f; |
| // Single BB functions are often written to be inlined. |
| if (CalleeFI.Metrics.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.Metrics.NumVectorInsts > CalleeFI.Metrics.NumInsts/2) |
| Factor += 2.0f; |
| else if (CalleeFI.Metrics.NumVectorInsts > CalleeFI.Metrics.NumInsts/10) |
| Factor += 1.5f; |
| return Factor; |
| } |
| |
| /// growCachedCostInfo - update the cached cost info for Caller after Callee has |
| /// been inlined. |
| void |
| InlineCostAnalyzer::growCachedCostInfo(Function *Caller, Function *Callee) { |
| CodeMetrics &CallerMetrics = CachedFunctionInfo[Caller].Metrics; |
| |
| // For small functions we prefer to recalculate the cost for better accuracy. |
| if (CallerMetrics.NumBlocks < 10 && CallerMetrics.NumInsts < 1000) { |
| resetCachedCostInfo(Caller); |
| return; |
| } |
| |
| // For large functions, we can save a lot of computation time by skipping |
| // recalculations. |
| if (CallerMetrics.NumCalls > 0) |
| --CallerMetrics.NumCalls; |
| |
| if (Callee == 0) return; |
| |
| CodeMetrics &CalleeMetrics = CachedFunctionInfo[Callee].Metrics; |
| |
| // If we don't have metrics for the callee, don't recalculate them just to |
| // update an approximation in the caller. Instead, just recalculate the |
| // caller info from scratch. |
| if (CalleeMetrics.NumBlocks == 0) { |
| resetCachedCostInfo(Caller); |
| return; |
| } |
| |
| // Since CalleeMetrics were already calculated, we know that the CallerMetrics |
| // reference isn't invalidated: both were in the DenseMap. |
| CallerMetrics.usesDynamicAlloca |= CalleeMetrics.usesDynamicAlloca; |
| |
| // FIXME: If any of these three are true for the callee, the callee was |
| // not inlined into the caller, so I think they're redundant here. |
| CallerMetrics.callsSetJmp |= CalleeMetrics.callsSetJmp; |
| CallerMetrics.isRecursive |= CalleeMetrics.isRecursive; |
| CallerMetrics.containsIndirectBr |= CalleeMetrics.containsIndirectBr; |
| |
| CallerMetrics.NumInsts += CalleeMetrics.NumInsts; |
| CallerMetrics.NumBlocks += CalleeMetrics.NumBlocks; |
| CallerMetrics.NumCalls += CalleeMetrics.NumCalls; |
| CallerMetrics.NumVectorInsts += CalleeMetrics.NumVectorInsts; |
| CallerMetrics.NumRets += CalleeMetrics.NumRets; |
| |
| // analyzeBasicBlock counts each function argument as an inst. |
| if (CallerMetrics.NumInsts >= Callee->arg_size()) |
| CallerMetrics.NumInsts -= Callee->arg_size(); |
| else |
| CallerMetrics.NumInsts = 0; |
| |
| // We are not updating the argument weights. We have already determined that |
| // Caller is a fairly large function, so we accept the loss of precision. |
| } |
| |
| /// clear - empty the cache of inline costs |
| void InlineCostAnalyzer::clear() { |
| CachedFunctionInfo.clear(); |
| } |