1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
//===- 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/InitializePasses.h"
#include "llvm/Support/CommandLine.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)
namespace llvm {
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);
} // namespace llvm
char MachineBranchProbabilityInfo::ID = 0;
MachineBranchProbabilityInfo::MachineBranchProbabilityInfo()
: ImmutablePass(ID) {
PassRegistry &Registry = *PassRegistry::getPassRegistry();
initializeMachineBranchProbabilityInfoPass(Registry);
}
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;
}
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;
}
|
