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We want heuristics to be based on accurate data, but more importantly we don't want llvm to behave randomly. A benign trunc inserted by an upstream pass should not cause a wild swings in optimization level. See PR11034. It's a general problem with threshold-based heuristics, but we can make it less bad. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140919 91177308-0d34-0410-b5e6-96231b3b80d8
656 lines
25 KiB
C++
656 lines
25 KiB
C++
//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements inline cost analysis.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/CallingConv.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/ADT/SmallPtrSet.h"
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using namespace llvm;
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/// callIsSmall - If a call is likely to lower to a single target instruction,
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/// or is otherwise deemed small return true.
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/// TODO: Perhaps calls like memcpy, strcpy, etc?
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bool llvm::callIsSmall(const Function *F) {
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if (!F) return false;
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if (F->hasLocalLinkage()) return false;
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if (!F->hasName()) return false;
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StringRef Name = F->getName();
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// These will all likely lower to a single selection DAG node.
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if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" ||
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Name == "fabs" || Name == "fabsf" || Name == "fabsl" ||
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Name == "sin" || Name == "sinf" || Name == "sinl" ||
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Name == "cos" || Name == "cosf" || Name == "cosl" ||
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Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl" )
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return true;
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// These are all likely to be optimized into something smaller.
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if (Name == "pow" || Name == "powf" || Name == "powl" ||
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Name == "exp2" || Name == "exp2l" || Name == "exp2f" ||
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Name == "floor" || Name == "floorf" || Name == "ceil" ||
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Name == "round" || Name == "ffs" || Name == "ffsl" ||
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Name == "abs" || Name == "labs" || Name == "llabs")
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return true;
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return false;
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}
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/// analyzeBasicBlock - Fill in the current structure with information gleaned
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/// from the specified block.
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void CodeMetrics::analyzeBasicBlock(const BasicBlock *BB,
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const TargetData *TD) {
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++NumBlocks;
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unsigned NumInstsBeforeThisBB = NumInsts;
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for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
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II != E; ++II) {
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if (isa<PHINode>(II)) continue; // PHI nodes don't count.
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// Special handling for calls.
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if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
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if (isa<DbgInfoIntrinsic>(II))
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continue; // Debug intrinsics don't count as size.
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ImmutableCallSite CS(cast<Instruction>(II));
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if (const Function *F = CS.getCalledFunction()) {
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// If a function is both internal and has a single use, then it is
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// extremely likely to get inlined in the future (it was probably
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// exposed by an interleaved devirtualization pass).
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if (F->hasInternalLinkage() && F->hasOneUse())
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++NumInlineCandidates;
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// If this call is to function itself, then the function is recursive.
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// Inlining it into other functions is a bad idea, because this is
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// basically just a form of loop peeling, and our metrics aren't useful
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// for that case.
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if (F == BB->getParent())
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isRecursive = true;
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}
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if (!isa<IntrinsicInst>(II) && !callIsSmall(CS.getCalledFunction())) {
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// Each argument to a call takes on average one instruction to set up.
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NumInsts += CS.arg_size();
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// We don't want inline asm to count as a call - that would prevent loop
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// unrolling. The argument setup cost is still real, though.
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if (!isa<InlineAsm>(CS.getCalledValue()))
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++NumCalls;
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}
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}
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if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
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if (!AI->isStaticAlloca())
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this->usesDynamicAlloca = true;
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}
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if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy())
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++NumVectorInsts;
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if (const CastInst *CI = dyn_cast<CastInst>(II)) {
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// Noop casts, including ptr <-> int, don't count.
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if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
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isa<PtrToIntInst>(CI))
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continue;
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// trunc to a native type is free (assuming the target has compare and
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// shift-right of the same width).
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if (isa<TruncInst>(CI) && TD &&
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TD->isLegalInteger(TD->getTypeSizeInBits(CI->getType())))
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continue;
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// Result of a cmp instruction is often extended (to be used by other
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// cmp instructions, logical or return instructions). These are usually
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// nop on most sane targets.
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if (isa<CmpInst>(CI->getOperand(0)))
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continue;
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} else if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(II)){
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// If a GEP has all constant indices, it will probably be folded with
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// a load/store.
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if (GEPI->hasAllConstantIndices())
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continue;
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}
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++NumInsts;
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}
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if (isa<ReturnInst>(BB->getTerminator()))
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++NumRets;
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// We never want to inline functions that contain an indirectbr. This is
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// incorrect because all the blockaddress's (in static global initializers
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// for example) would be referring to the original function, and this indirect
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// jump would jump from the inlined copy of the function into the original
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// function which is extremely undefined behavior.
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if (isa<IndirectBrInst>(BB->getTerminator()))
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containsIndirectBr = true;
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// Remember NumInsts for this BB.
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NumBBInsts[BB] = NumInsts - NumInstsBeforeThisBB;
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}
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// CountCodeReductionForConstant - Figure out an approximation for how many
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// instructions will be constant folded if the specified value is constant.
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//
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unsigned CodeMetrics::CountCodeReductionForConstant(Value *V) {
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unsigned Reduction = 0;
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for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
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User *U = *UI;
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if (isa<BranchInst>(U) || isa<SwitchInst>(U)) {
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// We will be able to eliminate all but one of the successors.
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const TerminatorInst &TI = cast<TerminatorInst>(*U);
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const unsigned NumSucc = TI.getNumSuccessors();
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unsigned Instrs = 0;
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for (unsigned I = 0; I != NumSucc; ++I)
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Instrs += NumBBInsts[TI.getSuccessor(I)];
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// We don't know which blocks will be eliminated, so use the average size.
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Reduction += InlineConstants::InstrCost*Instrs*(NumSucc-1)/NumSucc;
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} else {
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// Figure out if this instruction will be removed due to simple constant
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// propagation.
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Instruction &Inst = cast<Instruction>(*U);
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// We can't constant propagate instructions which have effects or
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// read memory.
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//
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// FIXME: It would be nice to capture the fact that a load from a
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// pointer-to-constant-global is actually a *really* good thing to zap.
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// Unfortunately, we don't know the pointer that may get propagated here,
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// so we can't make this decision.
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if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
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isa<AllocaInst>(Inst))
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continue;
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bool AllOperandsConstant = true;
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for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
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if (!isa<Constant>(Inst.getOperand(i)) && Inst.getOperand(i) != V) {
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AllOperandsConstant = false;
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break;
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}
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if (AllOperandsConstant) {
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// We will get to remove this instruction...
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Reduction += InlineConstants::InstrCost;
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// And any other instructions that use it which become constants
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// themselves.
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Reduction += CountCodeReductionForConstant(&Inst);
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}
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}
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}
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return Reduction;
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}
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// CountCodeReductionForAlloca - Figure out an approximation of how much smaller
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// the function will be if it is inlined into a context where an argument
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// becomes an alloca.
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//
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unsigned CodeMetrics::CountCodeReductionForAlloca(Value *V) {
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if (!V->getType()->isPointerTy()) return 0; // Not a pointer
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unsigned Reduction = 0;
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for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
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Instruction *I = cast<Instruction>(*UI);
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if (isa<LoadInst>(I) || isa<StoreInst>(I))
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Reduction += InlineConstants::InstrCost;
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else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
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// If the GEP has variable indices, we won't be able to do much with it.
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if (GEP->hasAllConstantIndices())
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Reduction += CountCodeReductionForAlloca(GEP);
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} else if (BitCastInst *BCI = dyn_cast<BitCastInst>(I)) {
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// Track pointer through bitcasts.
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Reduction += CountCodeReductionForAlloca(BCI);
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} else {
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// If there is some other strange instruction, we're not going to be able
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// to do much if we inline this.
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return 0;
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}
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}
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return Reduction;
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}
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/// analyzeFunction - Fill in the current structure with information gleaned
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/// from the specified function.
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void CodeMetrics::analyzeFunction(Function *F, const TargetData *TD) {
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// If this function contains a call to setjmp or _setjmp, never inline
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// it. This is a hack because we depend on the user marking their local
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// variables as volatile if they are live across a setjmp call, and they
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// probably won't do this in callers.
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if (F->callsFunctionThatReturnsTwice())
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callsSetJmp = true;
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// Look at the size of the callee.
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for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
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analyzeBasicBlock(&*BB, TD);
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}
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/// analyzeFunction - Fill in the current structure with information gleaned
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/// from the specified function.
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void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F,
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const TargetData *TD) {
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Metrics.analyzeFunction(F, TD);
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// A function with exactly one return has it removed during the inlining
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// process (see InlineFunction), so don't count it.
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// FIXME: This knowledge should really be encoded outside of FunctionInfo.
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if (Metrics.NumRets==1)
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--Metrics.NumInsts;
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// Check out all of the arguments to the function, figuring out how much
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// code can be eliminated if one of the arguments is a constant.
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ArgumentWeights.reserve(F->arg_size());
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for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I)
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ArgumentWeights.push_back(ArgInfo(Metrics.CountCodeReductionForConstant(I),
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Metrics.CountCodeReductionForAlloca(I)));
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}
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/// NeverInline - returns true if the function should never be inlined into
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/// any caller
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bool InlineCostAnalyzer::FunctionInfo::NeverInline() {
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return (Metrics.callsSetJmp || Metrics.isRecursive ||
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Metrics.containsIndirectBr);
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}
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// getSpecializationBonus - The heuristic used to determine the per-call
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// performance boost for using a specialization of Callee with argument
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// specializedArgNo replaced by a constant.
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int InlineCostAnalyzer::getSpecializationBonus(Function *Callee,
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SmallVectorImpl<unsigned> &SpecializedArgNos)
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{
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if (Callee->mayBeOverridden())
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return 0;
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int Bonus = 0;
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// If this function uses the coldcc calling convention, prefer not to
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// specialize it.
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if (Callee->getCallingConv() == CallingConv::Cold)
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Bonus -= InlineConstants::ColdccPenalty;
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// Get information about the callee.
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FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
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// If we haven't calculated this information yet, do so now.
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if (CalleeFI->Metrics.NumBlocks == 0)
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CalleeFI->analyzeFunction(Callee, TD);
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unsigned ArgNo = 0;
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unsigned i = 0;
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for (Function::arg_iterator I = Callee->arg_begin(), E = Callee->arg_end();
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I != E; ++I, ++ArgNo)
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if (ArgNo == SpecializedArgNos[i]) {
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++i;
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Bonus += CountBonusForConstant(I);
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}
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// Calls usually take a long time, so they make the specialization gain
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// smaller.
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Bonus -= CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty;
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return Bonus;
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}
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// ConstantFunctionBonus - Figure out how much of a bonus we can get for
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// possibly devirtualizing a function. We'll subtract the size of the function
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// we may wish to inline from the indirect call bonus providing a limit on
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// growth. Leave an upper limit of 0 for the bonus - we don't want to penalize
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// inlining because we decide we don't want to give a bonus for
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// devirtualizing.
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int InlineCostAnalyzer::ConstantFunctionBonus(CallSite CS, Constant *C) {
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// This could just be NULL.
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if (!C) return 0;
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Function *F = dyn_cast<Function>(C);
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if (!F) return 0;
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int Bonus = InlineConstants::IndirectCallBonus + getInlineSize(CS, F);
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return (Bonus > 0) ? 0 : Bonus;
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}
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// CountBonusForConstant - Figure out an approximation for how much per-call
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// performance boost we can expect if the specified value is constant.
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int InlineCostAnalyzer::CountBonusForConstant(Value *V, Constant *C) {
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unsigned Bonus = 0;
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for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
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User *U = *UI;
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if (CallInst *CI = dyn_cast<CallInst>(U)) {
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// Turning an indirect call into a direct call is a BIG win
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if (CI->getCalledValue() == V)
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Bonus += ConstantFunctionBonus(CallSite(CI), C);
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} else if (InvokeInst *II = dyn_cast<InvokeInst>(U)) {
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// Turning an indirect call into a direct call is a BIG win
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if (II->getCalledValue() == V)
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Bonus += ConstantFunctionBonus(CallSite(II), C);
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}
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// FIXME: Eliminating conditional branches and switches should
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// also yield a per-call performance boost.
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else {
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// Figure out the bonuses that wll accrue due to simple constant
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// propagation.
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Instruction &Inst = cast<Instruction>(*U);
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// We can't constant propagate instructions which have effects or
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// read memory.
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//
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// FIXME: It would be nice to capture the fact that a load from a
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// pointer-to-constant-global is actually a *really* good thing to zap.
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// Unfortunately, we don't know the pointer that may get propagated here,
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// so we can't make this decision.
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if (Inst.mayReadFromMemory() || Inst.mayHaveSideEffects() ||
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isa<AllocaInst>(Inst))
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continue;
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bool AllOperandsConstant = true;
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for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
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if (!isa<Constant>(Inst.getOperand(i)) && Inst.getOperand(i) != V) {
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AllOperandsConstant = false;
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break;
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}
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if (AllOperandsConstant)
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Bonus += CountBonusForConstant(&Inst);
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}
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}
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return Bonus;
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}
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int InlineCostAnalyzer::getInlineSize(CallSite CS, Function *Callee) {
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// Get information about the callee.
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FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
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// If we haven't calculated this information yet, do so now.
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if (CalleeFI->Metrics.NumBlocks == 0)
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CalleeFI->analyzeFunction(Callee, TD);
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// InlineCost - This value measures how good of an inline candidate this call
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// site is to inline. A lower inline cost make is more likely for the call to
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// be inlined. This value may go negative.
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//
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int InlineCost = 0;
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// Compute any size reductions we can expect due to arguments being passed into
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// the function.
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//
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unsigned ArgNo = 0;
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CallSite::arg_iterator I = CS.arg_begin();
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for (Function::arg_iterator FI = Callee->arg_begin(), FE = Callee->arg_end();
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FI != FE; ++I, ++FI, ++ArgNo) {
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// If an alloca is passed in, inlining this function is likely to allow
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// significant future optimization possibilities (like scalar promotion, and
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// scalarization), so encourage the inlining of the function.
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//
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if (isa<AllocaInst>(I))
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InlineCost -= CalleeFI->ArgumentWeights[ArgNo].AllocaWeight;
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// If this is a constant being passed into the function, use the argument
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// weights calculated for the callee to determine how much will be folded
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// away with this information.
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else if (isa<Constant>(I))
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InlineCost -= CalleeFI->ArgumentWeights[ArgNo].ConstantWeight;
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}
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// Each argument passed in has a cost at both the caller and the callee
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// sides. Measurements show that each argument costs about the same as an
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// instruction.
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InlineCost -= (CS.arg_size() * InlineConstants::InstrCost);
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// Now that we have considered all of the factors that make the call site more
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// likely to be inlined, look at factors that make us not want to inline it.
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// Calls usually take a long time, so they make the inlining gain smaller.
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InlineCost += CalleeFI->Metrics.NumCalls * InlineConstants::CallPenalty;
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// Look at the size of the callee. Each instruction counts as 5.
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InlineCost += CalleeFI->Metrics.NumInsts*InlineConstants::InstrCost;
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return InlineCost;
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}
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int InlineCostAnalyzer::getInlineBonuses(CallSite CS, Function *Callee) {
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// Get information about the callee.
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FunctionInfo *CalleeFI = &CachedFunctionInfo[Callee];
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// If we haven't calculated this information yet, do so now.
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if (CalleeFI->Metrics.NumBlocks == 0)
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CalleeFI->analyzeFunction(Callee, TD);
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bool isDirectCall = CS.getCalledFunction() == Callee;
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Instruction *TheCall = CS.getInstruction();
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int Bonus = 0;
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// If there is only one call of the function, and it has internal linkage,
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// make it almost guaranteed to be inlined.
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//
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if (Callee->hasLocalLinkage() && Callee->hasOneUse() && isDirectCall)
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Bonus += InlineConstants::LastCallToStaticBonus;
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// If the instruction after the call, or if the normal destination of the
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// invoke is an unreachable instruction, the function is noreturn. As such,
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// there is little point in inlining this.
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if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
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if (isa<UnreachableInst>(II->getNormalDest()->begin()))
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Bonus += InlineConstants::NoreturnPenalty;
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} else if (isa<UnreachableInst>(++BasicBlock::iterator(TheCall)))
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Bonus += InlineConstants::NoreturnPenalty;
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// If this function uses the coldcc calling convention, prefer not to inline
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// it.
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if (Callee->getCallingConv() == CallingConv::Cold)
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Bonus += InlineConstants::ColdccPenalty;
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// Add to the inline quality for properties that make the call valuable to
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// inline. This includes factors that indicate that the result of inlining
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// the function will be optimizable. Currently this just looks at arguments
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|
// 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();
|
|
}
|