Coverage Report

Created: 2019-02-20 07:29

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/Analysis/LazyBlockFrequencyInfo.h
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//===- LazyBlockFrequencyInfo.h - Lazy Block Frequency Analysis -*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This is an alternative analysis pass to BlockFrequencyInfoWrapperPass.  The
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// difference is that with this pass the block frequencies are not computed when
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// the analysis pass is executed but rather when the BFI result is explicitly
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// requested by the analysis client.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LAZYBLOCKFREQUENCYINFO_H
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#define LLVM_ANALYSIS_LAZYBLOCKFREQUENCYINFO_H
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#include "llvm/Analysis/BlockFrequencyInfo.h"
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#include "llvm/Analysis/LazyBranchProbabilityInfo.h"
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#include "llvm/Pass.h"
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namespace llvm {
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class AnalysisUsage;
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class BranchProbabilityInfo;
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class Function;
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class LoopInfo;
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/// Wraps a BFI to allow lazy computation of the block frequencies.
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///
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/// A pass that only conditionally uses BFI can uncondtionally require the
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/// analysis without paying for the overhead if BFI doesn't end up being used.
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template <typename FunctionT, typename BranchProbabilityInfoPassT,
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          typename LoopInfoT, typename BlockFrequencyInfoT>
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class LazyBlockFrequencyInfo {
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public:
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  LazyBlockFrequencyInfo()
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      : Calculated(false), F(nullptr), BPIPass(nullptr), LI(nullptr) {}
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  /// Set up the per-function input.
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  void setAnalysis(const FunctionT *F, BranchProbabilityInfoPassT *BPIPass,
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                   const LoopInfoT *LI) {
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    this->F = F;
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    this->BPIPass = BPIPass;
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    this->LI = LI;
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  }
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  /// Retrieve the BFI with the block frequencies computed.
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  BlockFrequencyInfoT &getCalculated() {
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    if (!Calculated) {
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      assert(F && BPIPass && LI && "call setAnalysis");
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      BFI.calculate(
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          *F, BPIPassTrait<BranchProbabilityInfoPassT>::getBPI(BPIPass), *LI);
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      Calculated = true;
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    }
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    return BFI;
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  }
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  const BlockFrequencyInfoT &getCalculated() const {
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    return const_cast<LazyBlockFrequencyInfo *>(this)->getCalculated();
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  }
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  void releaseMemory() {
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    BFI.releaseMemory();
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    Calculated = false;
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    setAnalysis(nullptr, nullptr, nullptr);
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  }
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private:
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  BlockFrequencyInfoT BFI;
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  bool Calculated;
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  const FunctionT *F;
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  BranchProbabilityInfoPassT *BPIPass;
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  const LoopInfoT *LI;
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};
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/// This is an alternative analysis pass to
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/// BlockFrequencyInfoWrapperPass.  The difference is that with this pass the
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/// block frequencies are not computed when the analysis pass is executed but
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/// rather when the BFI result is explicitly requested by the analysis client.
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///
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/// There are some additional requirements for any client pass that wants to use
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/// the analysis:
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///
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/// 1. The pass needs to initialize dependent passes with:
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///
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///   INITIALIZE_PASS_DEPENDENCY(LazyBFIPass)
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///
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/// 2. Similarly, getAnalysisUsage should call:
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///
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///   LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AU)
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///
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/// 3. The computed BFI should be requested with
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///    getAnalysis<LazyBlockFrequencyInfoPass>().getBFI() before either LoopInfo
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///    or BPI could be invalidated for example by changing the CFG.
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///
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/// Note that it is expected that we wouldn't need this functionality for the
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/// new PM since with the new PM, analyses are executed on demand.
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class LazyBlockFrequencyInfoPass : public FunctionPass {
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private:
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  LazyBlockFrequencyInfo<Function, LazyBranchProbabilityInfoPass, LoopInfo,
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                         BlockFrequencyInfo>
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      LBFI;
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public:
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  static char ID;
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  LazyBlockFrequencyInfoPass();
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  /// Compute and return the block frequencies.
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  BlockFrequencyInfo &getBFI() { return LBFI.getCalculated(); }
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  /// Compute and return the block frequencies.
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  const BlockFrequencyInfo &getBFI() const { return LBFI.getCalculated(); }
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  void getAnalysisUsage(AnalysisUsage &AU) const override;
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  /// Helper for client passes to set up the analysis usage on behalf of this
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  /// pass.
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  static void getLazyBFIAnalysisUsage(AnalysisUsage &AU);
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  bool runOnFunction(Function &F) override;
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  void releaseMemory() override;
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  void print(raw_ostream &OS, const Module *M) const override;
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};
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/// Helper for client passes to initialize dependent passes for LBFI.
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void initializeLazyBFIPassPass(PassRegistry &Registry);
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}
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#endif