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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232998 91177308-0d34-0410-b5e6-96231b3b80d8
188 lines
6.3 KiB
C++
188 lines
6.3 KiB
C++
//===- CodeMetrics.cpp - Code cost measurements ---------------------------===//
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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 code cost measurement utilities.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/CodeMetrics.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#define DEBUG_TYPE "code-metrics"
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using namespace llvm;
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static void completeEphemeralValues(SmallVector<const Value *, 16> &WorkSet,
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SmallPtrSetImpl<const Value*> &EphValues) {
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SmallPtrSet<const Value *, 32> Visited;
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// Make sure that all of the items in WorkSet are in our EphValues set.
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EphValues.insert(WorkSet.begin(), WorkSet.end());
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// Note: We don't speculate PHIs here, so we'll miss instruction chains kept
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// alive only by ephemeral values.
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while (!WorkSet.empty()) {
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const Value *V = WorkSet.front();
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WorkSet.erase(WorkSet.begin());
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if (!Visited.insert(V).second)
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continue;
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// If all uses of this value are ephemeral, then so is this value.
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bool FoundNEUse = false;
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for (const User *I : V->users())
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if (!EphValues.count(I)) {
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FoundNEUse = true;
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break;
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}
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if (FoundNEUse)
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continue;
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EphValues.insert(V);
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DEBUG(dbgs() << "Ephemeral Value: " << *V << "\n");
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if (const User *U = dyn_cast<User>(V))
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for (const Value *J : U->operands()) {
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if (isSafeToSpeculativelyExecute(J))
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WorkSet.push_back(J);
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}
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}
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}
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// Find all ephemeral values.
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void CodeMetrics::collectEphemeralValues(
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const Loop *L, AssumptionCache *AC,
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SmallPtrSetImpl<const Value *> &EphValues) {
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SmallVector<const Value *, 16> WorkSet;
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for (auto &AssumeVH : AC->assumptions()) {
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if (!AssumeVH)
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continue;
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Instruction *I = cast<Instruction>(AssumeVH);
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// Filter out call sites outside of the loop so we don't to a function's
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// worth of work for each of its loops (and, in the common case, ephemeral
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// values in the loop are likely due to @llvm.assume calls in the loop).
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if (!L->contains(I->getParent()))
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continue;
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WorkSet.push_back(I);
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}
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completeEphemeralValues(WorkSet, EphValues);
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}
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void CodeMetrics::collectEphemeralValues(
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const Function *F, AssumptionCache *AC,
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SmallPtrSetImpl<const Value *> &EphValues) {
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SmallVector<const Value *, 16> WorkSet;
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for (auto &AssumeVH : AC->assumptions()) {
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if (!AssumeVH)
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continue;
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Instruction *I = cast<Instruction>(AssumeVH);
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assert(I->getParent()->getParent() == F &&
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"Found assumption for the wrong function!");
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WorkSet.push_back(I);
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}
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completeEphemeralValues(WorkSet, EphValues);
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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 TargetTransformInfo &TTI,
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SmallPtrSetImpl<const Value*> &EphValues) {
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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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// Skip ephemeral values.
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if (EphValues.count(II))
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continue;
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// Special handling for calls.
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if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
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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 (!CS.isNoInline() && 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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if (TTI.isLoweredToCall(F))
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++NumCalls;
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} else {
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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 CallInst *CI = dyn_cast<CallInst>(II))
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if (CI->cannotDuplicate())
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notDuplicatable = true;
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if (const InvokeInst *InvI = dyn_cast<InvokeInst>(II))
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if (InvI->cannotDuplicate())
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notDuplicatable = true;
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NumInsts += TTI.getUserCost(&*II);
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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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// FIXME: This logic isn't really right; we can safely inline functions
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// with indirectbr's as long as no other function or global references the
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// blockaddress of a block within the current function. And as a QOI issue,
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// if someone is using a blockaddress without an indirectbr, and that
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// reference somehow ends up in another function or global, we probably
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// don't want to inline this function.
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notDuplicatable |= isa<IndirectBrInst>(BB->getTerminator());
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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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