|  | //===- 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/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 <cassert> | 
|  | #include <optional> | 
|  | #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."))); | 
|  |  | 
|  | namespace llvm { | 
|  | 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 | 
|  |  | 
|  | 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; | 
|  | } | 
|  |  | 
|  | std::optional<uint64_t> | 
|  | BlockFrequencyInfo::getBlockProfileCount(const BasicBlock *BB, | 
|  | bool AllowSynthetic) const { | 
|  | if (!BFI) | 
|  | return std::nullopt; | 
|  |  | 
|  | return BFI->getBlockProfileCount(*getFunction(), BB, AllowSynthetic); | 
|  | } | 
|  |  | 
|  | std::optional<uint64_t> | 
|  | BlockFrequencyInfo::getProfileCountFromFreq(uint64_t Freq) const { | 
|  | if (!BFI) | 
|  | return std::nullopt; | 
|  | 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(); | 
|  | } |