Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/CodeGen/MachineBranchProbabilityInfo.h
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//=- MachineBranchProbabilityInfo.h - Branch Probability 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 pass is used to evaluate branch probabilties on machine basic blocks.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H
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#define LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/BranchProbability.h"
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#include <climits>
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#include <numeric>
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namespace llvm {
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class MachineBranchProbabilityInfo : public ImmutablePass {
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  virtual void anchor();
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  // Default weight value. Used when we don't have information about the edge.
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  // TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
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  // the successors have a weight yet. But it doesn't make sense when providing
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  // weight to an edge that may have siblings with non-zero weights. This can
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  // be handled various ways, but it's probably fine for an edge with unknown
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  // weight to just "inherit" the non-zero weight of an adjacent successor.
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  static const uint32_t DEFAULT_WEIGHT = 16;
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public:
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  static char ID;
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  MachineBranchProbabilityInfo() : ImmutablePass(ID) {
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    PassRegistry &Registry = *PassRegistry::getPassRegistry();
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    initializeMachineBranchProbabilityInfoPass(Registry);
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  }
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  void getAnalysisUsage(AnalysisUsage &AU) const override {
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    AU.setPreservesAll();
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  }
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  // Return edge probability.
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  BranchProbability getEdgeProbability(const MachineBasicBlock *Src,
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                                       const MachineBasicBlock *Dst) const;
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  // Same as above, but using a const_succ_iterator from Src. This is faster
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  // when the iterator is already available.
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  BranchProbability
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  getEdgeProbability(const MachineBasicBlock *Src,
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                     MachineBasicBlock::const_succ_iterator Dst) const;
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  // A 'Hot' edge is an edge which probability is >= 80%.
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  bool isEdgeHot(const MachineBasicBlock *Src,
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                 const MachineBasicBlock *Dst) const;
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  // Return a hot successor for the block BB or null if there isn't one.
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  // NB: This routine's complexity is linear on the number of successors.
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  MachineBasicBlock *getHotSucc(MachineBasicBlock *MBB) const;
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  // Print value between 0 (0% probability) and 1 (100% probability),
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  // however the value is never equal to 0, and can be 1 only iff SRC block
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  // has only one successor.
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  raw_ostream &printEdgeProbability(raw_ostream &OS,
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                                    const MachineBasicBlock *Src,
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                                    const MachineBasicBlock *Dst) const;
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};
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}
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#endif