| //===- BlockFrequencyInfo.cpp - Block Frequency Analysis ------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Loops should be simplified before this analysis. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/BlockFrequencyInfo.h" |
| #include "llvm/ADT/APInt.h" |
| #include "llvm/ADT/None.h" |
| #include "llvm/ADT/iterator.h" |
| #include "llvm/Analysis/BlockFrequencyInfoImpl.h" |
| #include "llvm/Analysis/BranchProbabilityInfo.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/IR/CFG.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/PassManager.h" |
| #include "llvm/InitializePasses.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/GraphWriter.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <algorithm> |
| #include <cassert> |
| #include <string> |
| |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "block-freq" |
| |
| static cl::opt<GVDAGType> ViewBlockFreqPropagationDAG( |
| "view-block-freq-propagation-dags", cl::Hidden, |
| cl::desc("Pop up a window to show a dag displaying how block " |
| "frequencies propagation through the CFG."), |
| cl::values(clEnumValN(GVDT_None, "none", "do not display graphs."), |
| clEnumValN(GVDT_Fraction, "fraction", |
| "display a graph using the " |
| "fractional block frequency representation."), |
| clEnumValN(GVDT_Integer, "integer", |
| "display a graph using the raw " |
| "integer fractional block frequency representation."), |
| clEnumValN(GVDT_Count, "count", "display a graph using the real " |
| "profile count if available."))); |
| |
| cl::opt<std::string> |
| ViewBlockFreqFuncName("view-bfi-func-name", cl::Hidden, |
| cl::desc("The option to specify " |
| "the name of the function " |
| "whose CFG will be displayed.")); |
| |
| cl::opt<unsigned> |
| ViewHotFreqPercent("view-hot-freq-percent", cl::init(10), cl::Hidden, |
| cl::desc("An integer in percent used to specify " |
| "the hot blocks/edges to be displayed " |
| "in red: a block or edge whose frequency " |
| "is no less than the max frequency of the " |
| "function multiplied by this percent.")); |
| |
| // Command line option to turn on CFG dot or text dump after profile annotation. |
| cl::opt<PGOViewCountsType> PGOViewCounts( |
| "pgo-view-counts", cl::Hidden, |
| cl::desc("A boolean option to show CFG dag or text with " |
| "block profile counts and branch probabilities " |
| "right after PGO profile annotation step. The " |
| "profile counts are computed using branch " |
| "probabilities from the runtime profile data and " |
| "block frequency propagation algorithm. To view " |
| "the raw counts from the profile, use option " |
| "-pgo-view-raw-counts instead. To limit graph " |
| "display to only one function, use filtering option " |
| "-view-bfi-func-name."), |
| cl::values(clEnumValN(PGOVCT_None, "none", "do not show."), |
| clEnumValN(PGOVCT_Graph, "graph", "show a graph."), |
| clEnumValN(PGOVCT_Text, "text", "show in text."))); |
| |
| static cl::opt<bool> PrintBlockFreq( |
| "print-bfi", cl::init(false), cl::Hidden, |
| cl::desc("Print the block frequency info.")); |
| |
| cl::opt<std::string> PrintBlockFreqFuncName( |
| "print-bfi-func-name", cl::Hidden, |
| cl::desc("The option to specify the name of the function " |
| "whose block frequency info is printed.")); |
| |
| namespace llvm { |
| |
| static GVDAGType getGVDT() { |
| if (PGOViewCounts == PGOVCT_Graph) |
| return GVDT_Count; |
| return ViewBlockFreqPropagationDAG; |
| } |
| |
| template <> |
| struct GraphTraits<BlockFrequencyInfo *> { |
| using NodeRef = const BasicBlock *; |
| using ChildIteratorType = const_succ_iterator; |
| using nodes_iterator = pointer_iterator<Function::const_iterator>; |
| |
| static NodeRef getEntryNode(const BlockFrequencyInfo *G) { |
| return &G->getFunction()->front(); |
| } |
| |
| static ChildIteratorType child_begin(const NodeRef N) { |
| return succ_begin(N); |
| } |
| |
| static ChildIteratorType child_end(const NodeRef N) { return succ_end(N); } |
| |
| static nodes_iterator nodes_begin(const BlockFrequencyInfo *G) { |
| return nodes_iterator(G->getFunction()->begin()); |
| } |
| |
| static nodes_iterator nodes_end(const BlockFrequencyInfo *G) { |
| return nodes_iterator(G->getFunction()->end()); |
| } |
| }; |
| |
| using BFIDOTGTraitsBase = |
| BFIDOTGraphTraitsBase<BlockFrequencyInfo, BranchProbabilityInfo>; |
| |
| template <> |
| struct DOTGraphTraits<BlockFrequencyInfo *> : public BFIDOTGTraitsBase { |
| explicit DOTGraphTraits(bool isSimple = false) |
| : BFIDOTGTraitsBase(isSimple) {} |
| |
| std::string getNodeLabel(const BasicBlock *Node, |
| const BlockFrequencyInfo *Graph) { |
| |
| return BFIDOTGTraitsBase::getNodeLabel(Node, Graph, getGVDT()); |
| } |
| |
| std::string getNodeAttributes(const BasicBlock *Node, |
| const BlockFrequencyInfo *Graph) { |
| return BFIDOTGTraitsBase::getNodeAttributes(Node, Graph, |
| ViewHotFreqPercent); |
| } |
| |
| std::string getEdgeAttributes(const BasicBlock *Node, EdgeIter EI, |
| const BlockFrequencyInfo *BFI) { |
| return BFIDOTGTraitsBase::getEdgeAttributes(Node, EI, BFI, BFI->getBPI(), |
| ViewHotFreqPercent); |
| } |
| }; |
| |
| } // end namespace llvm |
| |
| BlockFrequencyInfo::BlockFrequencyInfo() = default; |
| |
| BlockFrequencyInfo::BlockFrequencyInfo(const Function &F, |
| const BranchProbabilityInfo &BPI, |
| const LoopInfo &LI) { |
| calculate(F, BPI, LI); |
| } |
| |
| BlockFrequencyInfo::BlockFrequencyInfo(BlockFrequencyInfo &&Arg) |
| : BFI(std::move(Arg.BFI)) {} |
| |
| BlockFrequencyInfo &BlockFrequencyInfo::operator=(BlockFrequencyInfo &&RHS) { |
| releaseMemory(); |
| BFI = std::move(RHS.BFI); |
| return *this; |
| } |
| |
| // Explicitly define the default constructor otherwise it would be implicitly |
| // defined at the first ODR-use which is the BFI member in the |
| // LazyBlockFrequencyInfo header. The dtor needs the BlockFrequencyInfoImpl |
| // template instantiated which is not available in the header. |
| BlockFrequencyInfo::~BlockFrequencyInfo() = default; |
| |
| bool BlockFrequencyInfo::invalidate(Function &F, const PreservedAnalyses &PA, |
| FunctionAnalysisManager::Invalidator &) { |
| // Check whether the analysis, all analyses on functions, or the function's |
| // CFG have been preserved. |
| auto PAC = PA.getChecker<BlockFrequencyAnalysis>(); |
| return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() || |
| PAC.preservedSet<CFGAnalyses>()); |
| } |
| |
| void BlockFrequencyInfo::calculate(const Function &F, |
| const BranchProbabilityInfo &BPI, |
| const LoopInfo &LI) { |
| if (!BFI) |
| BFI.reset(new ImplType); |
| BFI->calculate(F, BPI, LI); |
| if (ViewBlockFreqPropagationDAG != GVDT_None && |
| (ViewBlockFreqFuncName.empty() || |
| F.getName().equals(ViewBlockFreqFuncName))) { |
| view(); |
| } |
| if (PrintBlockFreq && |
| (PrintBlockFreqFuncName.empty() || |
| F.getName().equals(PrintBlockFreqFuncName))) { |
| print(dbgs()); |
| } |
| } |
| |
| BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const { |
| return BFI ? BFI->getBlockFreq(BB) : 0; |
| } |
| |
| Optional<uint64_t> |
| BlockFrequencyInfo::getBlockProfileCount(const BasicBlock *BB, |
| bool AllowSynthetic) const { |
| if (!BFI) |
| return None; |
| |
| return BFI->getBlockProfileCount(*getFunction(), BB, AllowSynthetic); |
| } |
| |
| Optional<uint64_t> |
| BlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const { |
| if (!BFI) |
| return None; |
| return BFI->getProfileCountFromFreq(*getFunction(), Freq); |
| } |
| |
| bool BlockFrequencyInfo::isIrrLoopHeader(const BasicBlock *BB) { |
| assert(BFI && "Expected analysis to be available"); |
| return BFI->isIrrLoopHeader(BB); |
| } |
| |
| void BlockFrequencyInfo::setBlockFreq(const BasicBlock *BB, uint64_t Freq) { |
| assert(BFI && "Expected analysis to be available"); |
| BFI->setBlockFreq(BB, Freq); |
| } |
| |
| void BlockFrequencyInfo::setBlockFreqAndScale( |
| const BasicBlock *ReferenceBB, uint64_t Freq, |
| SmallPtrSetImpl<BasicBlock *> &BlocksToScale) { |
| assert(BFI && "Expected analysis to be available"); |
| // Use 128 bits APInt to avoid overflow. |
| APInt NewFreq(128, Freq); |
| APInt OldFreq(128, BFI->getBlockFreq(ReferenceBB).getFrequency()); |
| APInt BBFreq(128, 0); |
| for (auto *BB : BlocksToScale) { |
| BBFreq = BFI->getBlockFreq(BB).getFrequency(); |
| // Multiply first by NewFreq and then divide by OldFreq |
| // to minimize loss of precision. |
| BBFreq *= NewFreq; |
| // udiv is an expensive operation in the general case. If this ends up being |
| // a hot spot, one of the options proposed in |
| // https://reviews.llvm.org/D28535#650071 could be used to avoid this. |
| BBFreq = BBFreq.udiv(OldFreq); |
| BFI->setBlockFreq(BB, BBFreq.getLimitedValue()); |
| } |
| BFI->setBlockFreq(ReferenceBB, Freq); |
| } |
| |
| /// Pop up a ghostview window with the current block frequency propagation |
| /// rendered using dot. |
| void BlockFrequencyInfo::view(StringRef title) const { |
| ViewGraph(const_cast<BlockFrequencyInfo *>(this), title); |
| } |
| |
| const Function *BlockFrequencyInfo::getFunction() const { |
| return BFI ? BFI->getFunction() : nullptr; |
| } |
| |
| const BranchProbabilityInfo *BlockFrequencyInfo::getBPI() const { |
| return BFI ? &BFI->getBPI() : nullptr; |
| } |
| |
| raw_ostream &BlockFrequencyInfo:: |
| printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const { |
| return BFI ? BFI->printBlockFreq(OS, Freq) : OS; |
| } |
| |
| raw_ostream & |
| BlockFrequencyInfo::printBlockFreq(raw_ostream &OS, |
| const BasicBlock *BB) const { |
| return BFI ? BFI->printBlockFreq(OS, BB) : OS; |
| } |
| |
| uint64_t BlockFrequencyInfo::getEntryFreq() const { |
| return BFI ? BFI->getEntryFreq() : 0; |
| } |
| |
| void BlockFrequencyInfo::releaseMemory() { BFI.reset(); } |
| |
| void BlockFrequencyInfo::print(raw_ostream &OS) const { |
| if (BFI) |
| BFI->print(OS); |
| } |
| |
| void BlockFrequencyInfo::verifyMatch(BlockFrequencyInfo &Other) const { |
| if (BFI) |
| BFI->verifyMatch(*Other.BFI); |
| } |
| |
| INITIALIZE_PASS_BEGIN(BlockFrequencyInfoWrapperPass, "block-freq", |
| "Block Frequency Analysis", true, true) |
| INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass) |
| INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) |
| INITIALIZE_PASS_END(BlockFrequencyInfoWrapperPass, "block-freq", |
| "Block Frequency Analysis", true, true) |
| |
| char BlockFrequencyInfoWrapperPass::ID = 0; |
| |
| BlockFrequencyInfoWrapperPass::BlockFrequencyInfoWrapperPass() |
| : FunctionPass(ID) { |
| initializeBlockFrequencyInfoWrapperPassPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| BlockFrequencyInfoWrapperPass::~BlockFrequencyInfoWrapperPass() = default; |
| |
| void BlockFrequencyInfoWrapperPass::print(raw_ostream &OS, |
| const Module *) const { |
| BFI.print(OS); |
| } |
| |
| void BlockFrequencyInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequired<BranchProbabilityInfoWrapperPass>(); |
| AU.addRequired<LoopInfoWrapperPass>(); |
| AU.setPreservesAll(); |
| } |
| |
| void BlockFrequencyInfoWrapperPass::releaseMemory() { BFI.releaseMemory(); } |
| |
| bool BlockFrequencyInfoWrapperPass::runOnFunction(Function &F) { |
| BranchProbabilityInfo &BPI = |
| getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI(); |
| LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); |
| BFI.calculate(F, BPI, LI); |
| return false; |
| } |
| |
| AnalysisKey BlockFrequencyAnalysis::Key; |
| BlockFrequencyInfo BlockFrequencyAnalysis::run(Function &F, |
| FunctionAnalysisManager &AM) { |
| BlockFrequencyInfo BFI; |
| BFI.calculate(F, AM.getResult<BranchProbabilityAnalysis>(F), |
| AM.getResult<LoopAnalysis>(F)); |
| return BFI; |
| } |
| |
| PreservedAnalyses |
| BlockFrequencyPrinterPass::run(Function &F, FunctionAnalysisManager &AM) { |
| OS << "Printing analysis results of BFI for function " |
| << "'" << F.getName() << "':" |
| << "\n"; |
| AM.getResult<BlockFrequencyAnalysis>(F).print(OS); |
| return PreservedAnalyses::all(); |
| } |