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