LLVM  15.0.0git
MachineBranchProbabilityInfo.cpp
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1 //===- MachineBranchProbabilityInfo.cpp - Machine Branch Probability Info -===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This analysis uses probability info stored in Machine Basic Blocks.
10 //
11 //===----------------------------------------------------------------------===//
12 
15 #include "llvm/InitializePasses.h"
18 
19 using namespace llvm;
20 
22  "Machine Branch Probability Analysis", false, true)
24  "Machine Branch Probability Analysis", false, true)
25 
26 namespace llvm {
28  StaticLikelyProb("static-likely-prob",
29  cl::desc("branch probability threshold in percentage"
30  "to be considered very likely"),
31  cl::init(80), cl::Hidden);
32 
34  "profile-likely-prob",
35  cl::desc("branch probability threshold in percentage to be considered"
36  " very likely when profile is available"),
37  cl::init(51), cl::Hidden);
38 } // namespace llvm
39 
41 
43  : ImmutablePass(ID) {
46 }
47 
48 void MachineBranchProbabilityInfo::anchor() {}
49 
51  const MachineBasicBlock *Src,
53  return Src->getSuccProbability(Dst);
54 }
55 
57  const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
58  // This is a linear search. Try to use the const_succ_iterator version when
59  // possible.
60  return getEdgeProbability(Src, find(Src->successors(), Dst));
61 }
62 
64  const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
65  BranchProbability HotProb(StaticLikelyProb, 100);
66  return getEdgeProbability(Src, Dst) > HotProb;
67 }
68 
70  raw_ostream &OS, const MachineBasicBlock *Src,
71  const MachineBasicBlock *Dst) const {
72 
73  const BranchProbability Prob = getEdgeProbability(Src, Dst);
74  OS << "edge " << printMBBReference(*Src) << " -> " << printMBBReference(*Dst)
75  << " probability is " << Prob
76  << (isEdgeHot(Src, Dst) ? " [HOT edge]\n" : "\n");
77 
78  return OS;
79 }
llvm::MachineBranchProbabilityInfo::MachineBranchProbabilityInfo
MachineBranchProbabilityInfo()
Definition: MachineBranchProbabilityInfo.cpp:42
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:17
llvm::ImmutablePass
ImmutablePass class - This class is used to provide information that does not need to be run.
Definition: Pass.h:279
llvm::printMBBReference
Printable printMBBReference(const MachineBasicBlock &MBB)
Prints a machine basic block reference.
Definition: MachineBasicBlock.cpp:116
llvm::MachineBranchProbabilityInfo::ID
static char ID
Definition: MachineBranchProbabilityInfo.h:34
MachineBasicBlock.h
llvm::cl::Hidden
@ Hidden
Definition: CommandLine.h:139
true
basic Basic Alias true
Definition: BasicAliasAnalysis.cpp:1886
llvm::initializeMachineBranchProbabilityInfoPass
void initializeMachineBranchProbabilityInfoPass(PassRegistry &)
CommandLine.h
llvm::MachineBranchProbabilityInfo::printEdgeProbability
raw_ostream & printEdgeProbability(raw_ostream &OS, const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const
Definition: MachineBranchProbabilityInfo.cpp:69
llvm::PassRegistry::getPassRegistry
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Definition: PassRegistry.cpp:31
llvm::MachineBranchProbabilityInfo
Definition: MachineBranchProbabilityInfo.h:22
false
Definition: StackSlotColoring.cpp:141
llvm::PassRegistry
PassRegistry - This class manages the registration and intitialization of the pass subsystem as appli...
Definition: PassRegistry.h:38
llvm::StaticLikelyProb
cl::opt< unsigned > StaticLikelyProb
llvm::raw_ostream
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:54
llvm::ProfileLikelyProb
cl::opt< unsigned > ProfileLikelyProb
llvm::CallingConv::ID
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
Definition: CallingConv.h:24
llvm::MachineBasicBlock
Definition: MachineBasicBlock.h:94
INITIALIZE_PASS_END
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:58
llvm::cl::opt
Definition: CommandLine.h:1392
prob
machine branch prob
Definition: MachineBranchProbabilityInfo.cpp:23
llvm::find
auto find(R &&Range, const T &Val)
Provide wrappers to std::find which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1637
llvm::cl::init
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:432
MachineBranchProbabilityInfo.h
llvm::MachineBranchProbabilityInfo::getEdgeProbability
BranchProbability getEdgeProbability(const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const
Definition: MachineBranchProbabilityInfo.cpp:56
llvm::BranchProbability
Definition: BranchProbability.h:30
llvm::MCID::Branch
@ Branch
Definition: MCInstrDesc.h:158
llvm::Registry
A global registry used in conjunction with static constructors to make pluggable components (like tar...
Definition: Registry.h:44
Machine
COFF::MachineTypes Machine
Definition: COFFYAML.cpp:369
llvm::MachineBasicBlock::const_succ_iterator
std::vector< MachineBasicBlock * >::const_iterator const_succ_iterator
Definition: MachineBasicBlock.h:317
llvm::cl::desc
Definition: CommandLine.h:405
raw_ostream.h
INITIALIZE_PASS_BEGIN
INITIALIZE_PASS_BEGIN(MachineBranchProbabilityInfo, "machine-branch-prob", "Machine Branch Probability Analysis", false, true) INITIALIZE_PASS_END(MachineBranchProbabilityInfo
InitializePasses.h
llvm::MachineBranchProbabilityInfo::isEdgeHot
bool isEdgeHot(const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const
Definition: MachineBranchProbabilityInfo.cpp:63