0b57cec536
This uses the new layout of the upstream repository, which was recently migrated to GitHub, and converted into a "monorepo". That is, most of the earlier separate sub-projects with their own branches and tags were consolidated into one top-level directory, and are now branched and tagged together. Updating the vendor area to match this layout is next.
92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
//===- MachineBranchProbabilityInfo.cpp - Machine Branch Probability Info -===//
|
|
//
|
|
// 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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This analysis uses probability info stored in Machine Basic Blocks.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
|
|
#include "llvm/CodeGen/MachineBasicBlock.h"
|
|
#include "llvm/IR/Instructions.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
|
|
using namespace llvm;
|
|
|
|
INITIALIZE_PASS_BEGIN(MachineBranchProbabilityInfo, "machine-branch-prob",
|
|
"Machine Branch Probability Analysis", false, true)
|
|
INITIALIZE_PASS_END(MachineBranchProbabilityInfo, "machine-branch-prob",
|
|
"Machine Branch Probability Analysis", false, true)
|
|
|
|
cl::opt<unsigned>
|
|
StaticLikelyProb("static-likely-prob",
|
|
cl::desc("branch probability threshold in percentage"
|
|
"to be considered very likely"),
|
|
cl::init(80), cl::Hidden);
|
|
|
|
cl::opt<unsigned> ProfileLikelyProb(
|
|
"profile-likely-prob",
|
|
cl::desc("branch probability threshold in percentage to be considered"
|
|
" very likely when profile is available"),
|
|
cl::init(51), cl::Hidden);
|
|
|
|
char MachineBranchProbabilityInfo::ID = 0;
|
|
|
|
void MachineBranchProbabilityInfo::anchor() {}
|
|
|
|
BranchProbability MachineBranchProbabilityInfo::getEdgeProbability(
|
|
const MachineBasicBlock *Src,
|
|
MachineBasicBlock::const_succ_iterator Dst) const {
|
|
return Src->getSuccProbability(Dst);
|
|
}
|
|
|
|
BranchProbability MachineBranchProbabilityInfo::getEdgeProbability(
|
|
const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
|
|
// This is a linear search. Try to use the const_succ_iterator version when
|
|
// possible.
|
|
return getEdgeProbability(Src, find(Src->successors(), Dst));
|
|
}
|
|
|
|
bool MachineBranchProbabilityInfo::isEdgeHot(
|
|
const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
|
|
BranchProbability HotProb(StaticLikelyProb, 100);
|
|
return getEdgeProbability(Src, Dst) > HotProb;
|
|
}
|
|
|
|
MachineBasicBlock *
|
|
MachineBranchProbabilityInfo::getHotSucc(MachineBasicBlock *MBB) const {
|
|
auto MaxProb = BranchProbability::getZero();
|
|
MachineBasicBlock *MaxSucc = nullptr;
|
|
for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
|
|
E = MBB->succ_end(); I != E; ++I) {
|
|
auto Prob = getEdgeProbability(MBB, I);
|
|
if (Prob > MaxProb) {
|
|
MaxProb = Prob;
|
|
MaxSucc = *I;
|
|
}
|
|
}
|
|
|
|
BranchProbability HotProb(StaticLikelyProb, 100);
|
|
if (getEdgeProbability(MBB, MaxSucc) >= HotProb)
|
|
return MaxSucc;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
raw_ostream &MachineBranchProbabilityInfo::printEdgeProbability(
|
|
raw_ostream &OS, const MachineBasicBlock *Src,
|
|
const MachineBasicBlock *Dst) const {
|
|
|
|
const BranchProbability Prob = getEdgeProbability(Src, Dst);
|
|
OS << "edge " << printMBBReference(*Src) << " -> " << printMBBReference(*Dst)
|
|
<< " probability is " << Prob
|
|
<< (isEdgeHot(Src, Dst) ? " [HOT edge]\n" : "\n");
|
|
|
|
return OS;
|
|
}
|