Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/CodeGen/MachineBranchProbabilityInfo.cpp
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//===- MachineBranchProbabilityInfo.cpp - Machine Branch Probability Info -===//
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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 analysis uses probability info stored in Machine Basic Blocks.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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INITIALIZE_PASS_BEGIN(MachineBranchProbabilityInfo, "machine-branch-prob",
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                      "Machine Branch Probability Analysis", false, true)
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INITIALIZE_PASS_END(MachineBranchProbabilityInfo, "machine-branch-prob",
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                    "Machine Branch Probability Analysis", false, true)
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cl::opt<unsigned>
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    StaticLikelyProb("static-likely-prob",
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                     cl::desc("branch probability threshold in percentage"
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                              "to be considered very likely"),
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                     cl::init(80), cl::Hidden);
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cl::opt<unsigned> ProfileLikelyProb(
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    "profile-likely-prob",
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    cl::desc("branch probability threshold in percentage to be considered"
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             " very likely when profile is available"),
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    cl::init(51), cl::Hidden);
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char MachineBranchProbabilityInfo::ID = 0;
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void MachineBranchProbabilityInfo::anchor() {}
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BranchProbability MachineBranchProbabilityInfo::getEdgeProbability(
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    const MachineBasicBlock *Src,
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23.6M
    MachineBasicBlock::const_succ_iterator Dst) const {
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23.6M
  return Src->getSuccProbability(Dst);
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}
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BranchProbability MachineBranchProbabilityInfo::getEdgeProbability(
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10.0M
    const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
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10.0M
  // This is a linear search. Try to use the const_succ_iterator version when
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  // possible.
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10.0M
  return getEdgeProbability(Src, find(Src->successors(), Dst));
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10.0M
}
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bool MachineBranchProbabilityInfo::isEdgeHot(
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    const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
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  BranchProbability HotProb(StaticLikelyProb, 100);
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  return getEdgeProbability(Src, Dst) > HotProb;
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}
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MachineBasicBlock *
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MachineBranchProbabilityInfo::getHotSucc(MachineBasicBlock *MBB) const {
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  auto MaxProb = BranchProbability::getZero();
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  MachineBasicBlock *MaxSucc = nullptr;
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  for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
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       E = MBB->succ_end(); I != E; ++I) {
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    auto Prob = getEdgeProbability(MBB, I);
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    if (Prob > MaxProb) {
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      MaxProb = Prob;
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      MaxSucc = *I;
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    }
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  }
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  BranchProbability HotProb(StaticLikelyProb, 100);
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  if (getEdgeProbability(MBB, MaxSucc) >= HotProb)
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    return MaxSucc;
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  return nullptr;
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}
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raw_ostream &MachineBranchProbabilityInfo::printEdgeProbability(
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    raw_ostream &OS, const MachineBasicBlock *Src,
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    const MachineBasicBlock *Dst) const {
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  const BranchProbability Prob = getEdgeProbability(Src, Dst);
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  OS << "edge " << printMBBReference(*Src) << " -> " << printMBBReference(*Dst)
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     << " probability is " << Prob
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     << (isEdgeHot(Src, Dst) ? " [HOT edge]\n" : "\n");
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  return OS;
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}