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345 lines
11 KiB
C++
345 lines
11 KiB
C++
//===- ProfileVerifierPass.cpp - LLVM Pass to estimate profile info -------===//
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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 a pass that checks profiling information for
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// plausibility.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "profile-verifier"
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#include "llvm/Instructions.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/ProfileInfo.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/InstIterator.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Support/Debug.h"
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#include <set>
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using namespace llvm;
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static cl::opt<bool,false>
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ProfileVerifierDisableAssertions("profile-verifier-noassert",
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cl::desc("Disable assertions"));
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namespace {
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class ProfileVerifierPass : public FunctionPass {
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struct DetailedBlockInfo {
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const BasicBlock *BB;
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double BBWeight;
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double inWeight;
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int inCount;
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double outWeight;
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int outCount;
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};
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ProfileInfo *PI;
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std::set<const BasicBlock*> BBisVisited;
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std::set<const Function*> FisVisited;
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bool DisableAssertions;
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// When debugging is enabled, the verifier prints a whole slew of debug
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// information, otherwise its just the assert. These are all the helper
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// functions.
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bool PrintedDebugTree;
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std::set<const BasicBlock*> BBisPrinted;
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void debugEntry(DetailedBlockInfo*);
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void printDebugInfo(const BasicBlock *BB);
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public:
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static char ID; // Class identification, replacement for typeinfo
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explicit ProfileVerifierPass () : FunctionPass(&ID) {
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DisableAssertions = ProfileVerifierDisableAssertions;
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}
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explicit ProfileVerifierPass (bool da) : FunctionPass(&ID),
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DisableAssertions(da) {
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}
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void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequired<ProfileInfo>();
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}
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const char *getPassName() const {
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return "Profiling information verifier";
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}
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/// run - Verify the profile information.
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bool runOnFunction(Function &F);
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void recurseBasicBlock(const BasicBlock*);
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bool exitReachable(const Function*);
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double ReadOrAssert(ProfileInfo::Edge);
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void CheckValue(bool, const char*, DetailedBlockInfo*);
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};
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} // End of anonymous namespace
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char ProfileVerifierPass::ID = 0;
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static RegisterPass<ProfileVerifierPass>
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X("profile-verifier", "Verify profiling information", false, true);
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namespace llvm {
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FunctionPass *createProfileVerifierPass() {
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return new ProfileVerifierPass(ProfileVerifierDisableAssertions);
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}
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}
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void ProfileVerifierPass::printDebugInfo(const BasicBlock *BB) {
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if (BBisPrinted.find(BB) != BBisPrinted.end()) return;
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double BBWeight = PI->getExecutionCount(BB);
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if (BBWeight == ProfileInfo::MissingValue) { BBWeight = 0; }
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double inWeight = 0;
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int inCount = 0;
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std::set<const BasicBlock*> ProcessedPreds;
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for ( pred_const_iterator bbi = pred_begin(BB), bbe = pred_end(BB);
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bbi != bbe; ++bbi ) {
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if (ProcessedPreds.insert(*bbi).second) {
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ProfileInfo::Edge E = PI->getEdge(*bbi,BB);
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double EdgeWeight = PI->getEdgeWeight(E);
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if (EdgeWeight == ProfileInfo::MissingValue) { EdgeWeight = 0; }
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errs() << "calculated in-edge " << E << ": " << EdgeWeight << "\n";
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inWeight += EdgeWeight;
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inCount++;
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}
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}
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double outWeight = 0;
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int outCount = 0;
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std::set<const BasicBlock*> ProcessedSuccs;
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for ( succ_const_iterator bbi = succ_begin(BB), bbe = succ_end(BB);
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bbi != bbe; ++bbi ) {
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if (ProcessedSuccs.insert(*bbi).second) {
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ProfileInfo::Edge E = PI->getEdge(BB,*bbi);
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double EdgeWeight = PI->getEdgeWeight(E);
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if (EdgeWeight == ProfileInfo::MissingValue) { EdgeWeight = 0; }
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errs() << "calculated out-edge " << E << ": " << EdgeWeight << "\n";
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outWeight += EdgeWeight;
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outCount++;
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}
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}
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errs()<<"Block "<<BB->getNameStr()<<" in "<<BB->getParent()->getNameStr()
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<<",BBWeight="<<BBWeight<<",inWeight="<<inWeight<<",inCount="<<inCount
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<<",outWeight="<<outWeight<<",outCount"<<outCount<<"\n";
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// mark as visited and recurse into subnodes
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BBisPrinted.insert(BB);
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for ( succ_const_iterator bbi = succ_begin(BB), bbe = succ_end(BB);
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bbi != bbe; ++bbi ) {
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printDebugInfo(*bbi);
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}
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}
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void ProfileVerifierPass::debugEntry (DetailedBlockInfo *DI) {
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errs() << "TROUBLE: Block " << DI->BB->getNameStr() << " in "
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<< DI->BB->getParent()->getNameStr() << ":";
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errs() << "BBWeight=" << DI->BBWeight << ",";
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errs() << "inWeight=" << DI->inWeight << ",";
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errs() << "inCount=" << DI->inCount << ",";
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errs() << "outWeight=" << DI->outWeight << ",";
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errs() << "outCount=" << DI->outCount << "\n";
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if (!PrintedDebugTree) {
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PrintedDebugTree = true;
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printDebugInfo(&(DI->BB->getParent()->getEntryBlock()));
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}
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}
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// This compares A and B but considering maybe small differences.
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static bool Equals(double A, double B) {
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double maxRelativeError = 0.0000001;
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if (A == B)
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return true;
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double relativeError;
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if (fabs(B) > fabs(A))
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relativeError = fabs((A - B) / B);
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else
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relativeError = fabs((A - B) / A);
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if (relativeError <= maxRelativeError) return true;
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return false;
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}
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// This checks if the function "exit" is reachable from an given function
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// via calls, this is necessary to check if a profile is valid despite the
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// counts not fitting exactly.
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bool ProfileVerifierPass::exitReachable(const Function *F) {
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if (!F) return false;
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if (FisVisited.count(F)) return false;
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Function *Exit = F->getParent()->getFunction("exit");
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if (Exit == F) {
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return true;
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}
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FisVisited.insert(F);
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bool exits = false;
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for (const_inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
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if (const CallInst *CI = dyn_cast<CallInst>(&*I)) {
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exits |= exitReachable(CI->getCalledFunction());
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if (exits) break;
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}
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}
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return exits;
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}
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#define ASSERTMESSAGE(M) \
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errs() << (M) << "\n"; \
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if (!DisableAssertions) assert(0 && (M));
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double ProfileVerifierPass::ReadOrAssert(ProfileInfo::Edge E) {
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double EdgeWeight = PI->getEdgeWeight(E);
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if (EdgeWeight == ProfileInfo::MissingValue) {
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errs() << "Edge " << E << " in Function "
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<< ProfileInfo::getFunction(E)->getNameStr() << ": ";
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ASSERTMESSAGE("ASSERT:Edge has missing value");
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return 0;
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} else {
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return EdgeWeight;
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}
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}
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void ProfileVerifierPass::CheckValue(bool Error, const char *Message,
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DetailedBlockInfo *DI) {
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if (Error) {
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DEBUG(debugEntry(DI));
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errs() << "Block " << DI->BB->getNameStr() << " in Function "
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<< DI->BB->getParent()->getNameStr() << ": ";
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ASSERTMESSAGE(Message);
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}
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return;
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}
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// This calculates the Information for a block and then recurses into the
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// successors.
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void ProfileVerifierPass::recurseBasicBlock(const BasicBlock *BB) {
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// Break the recursion by remembering all visited blocks.
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if (BBisVisited.find(BB) != BBisVisited.end()) return;
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// Use a data structure to store all the information, this can then be handed
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// to debug printers.
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DetailedBlockInfo DI;
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DI.BB = BB;
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DI.outCount = DI.inCount = 0;
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DI.inWeight = DI.outWeight = 0.0;
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// Read predecessors.
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std::set<const BasicBlock*> ProcessedPreds;
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pred_const_iterator bpi = pred_begin(BB), bpe = pred_end(BB);
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// If there are none, check for (0,BB) edge.
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if (bpi == bpe) {
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DI.inWeight += ReadOrAssert(PI->getEdge(0,BB));
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DI.inCount++;
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}
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for (;bpi != bpe; ++bpi) {
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if (ProcessedPreds.insert(*bpi).second) {
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DI.inWeight += ReadOrAssert(PI->getEdge(*bpi,BB));
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DI.inCount++;
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}
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}
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// Read successors.
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std::set<const BasicBlock*> ProcessedSuccs;
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succ_const_iterator bbi = succ_begin(BB), bbe = succ_end(BB);
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// If there is an (0,BB) edge, consider it too. (This is done not only when
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// there are no successors, but every time; not every function contains
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// return blocks with no successors (think loop latch as return block)).
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double w = PI->getEdgeWeight(PI->getEdge(BB,0));
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if (w != ProfileInfo::MissingValue) {
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DI.outWeight += w;
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DI.outCount++;
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}
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for (;bbi != bbe; ++bbi) {
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if (ProcessedSuccs.insert(*bbi).second) {
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DI.outWeight += ReadOrAssert(PI->getEdge(BB,*bbi));
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DI.outCount++;
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}
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}
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// Read block weight.
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DI.BBWeight = PI->getExecutionCount(BB);
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CheckValue(DI.BBWeight == ProfileInfo::MissingValue,
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"ASSERT:BasicBlock has missing value", &DI);
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// Check if this block is a setjmp target.
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bool isSetJmpTarget = false;
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if (DI.outWeight > DI.inWeight) {
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for (BasicBlock::const_iterator i = BB->begin(), ie = BB->end();
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i != ie; ++i) {
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if (const CallInst *CI = dyn_cast<CallInst>(&*i)) {
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Function *F = CI->getCalledFunction();
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if (F && (F->getNameStr() == "_setjmp")) {
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isSetJmpTarget = true; break;
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}
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}
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}
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}
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// Check if this block is eventually reaching exit.
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bool isExitReachable = false;
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if (DI.inWeight > DI.outWeight) {
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for (BasicBlock::const_iterator i = BB->begin(), ie = BB->end();
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i != ie; ++i) {
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if (const CallInst *CI = dyn_cast<CallInst>(&*i)) {
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FisVisited.clear();
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isExitReachable |= exitReachable(CI->getCalledFunction());
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if (isExitReachable) break;
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}
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}
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}
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if (DI.inCount > 0 && DI.outCount == 0) {
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// If this is a block with no successors.
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if (!isSetJmpTarget) {
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CheckValue(!Equals(DI.inWeight,DI.BBWeight),
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"ASSERT:inWeight and BBWeight do not match", &DI);
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}
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} else if (DI.inCount == 0 && DI.outCount > 0) {
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// If this is a block with no predecessors.
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if (!isExitReachable)
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CheckValue(!Equals(DI.BBWeight,DI.outWeight),
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"ASSERT:BBWeight and outWeight do not match", &DI);
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} else {
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// If this block has successors and predecessors.
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if (DI.inWeight > DI.outWeight && !isExitReachable)
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CheckValue(!Equals(DI.inWeight,DI.outWeight),
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"ASSERT:inWeight and outWeight do not match", &DI);
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if (DI.inWeight < DI.outWeight && !isSetJmpTarget)
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CheckValue(!Equals(DI.inWeight,DI.outWeight),
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"ASSERT:inWeight and outWeight do not match", &DI);
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}
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// Mark this block as visited, rescurse into successors.
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BBisVisited.insert(BB);
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for ( succ_const_iterator bbi = succ_begin(BB), bbe = succ_end(BB);
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bbi != bbe; ++bbi ) {
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recurseBasicBlock(*bbi);
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}
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}
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bool ProfileVerifierPass::runOnFunction(Function &F) {
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PI = &getAnalysis<ProfileInfo>();
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// Prepare global variables.
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PrintedDebugTree = false;
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BBisVisited.clear();
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// Fetch entry block and recurse into it.
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const BasicBlock *entry = &F.getEntryBlock();
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recurseBasicBlock(entry);
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if (!DisableAssertions)
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assert((PI->getExecutionCount(&F)==PI->getExecutionCount(entry)) &&
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"Function count and entry block count do not match");
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return false;
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}
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