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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
//===--- BranchProbabilityInfo.h - Branch Probability Analysis --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass is used to evaluate branch probabilties.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
#define LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/BranchProbability.h"
namespace llvm {
class LoopInfo;
class raw_ostream;
class BranchProbabilityInfo : public FunctionPass {
public:
static char ID;
BranchProbabilityInfo() : FunctionPass(ID) {
initializeBranchProbabilityInfoPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const;
bool runOnFunction(Function &F);
void print(raw_ostream &OS, const Module *M = 0) const;
// Returned value is between 1 and UINT32_MAX. Look at
// BranchProbabilityInfo.cpp for details.
uint32_t getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst) const;
// Look at BranchProbabilityInfo.cpp for details. Use it with caution!
void setEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst,
uint32_t Weight);
// A 'Hot' edge is an edge which probability is >= 80%.
bool isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const;
// Return a hot successor for the block BB or null if there isn't one.
BasicBlock *getHotSucc(BasicBlock *BB) const;
// Return a probability as a fraction between 0 (0% probability) and
// 1 (100% probability), however the value is never equal to 0, and can be 1
// only iff SRC block has only one successor.
BranchProbability getEdgeProbability(const BasicBlock *Src,
const BasicBlock *Dst) const;
// Print value between 0 (0% probability) and 1 (100% probability),
// however the value is never equal to 0, and can be 1 only iff SRC block
// has only one successor.
raw_ostream &printEdgeProbability(raw_ostream &OS, const BasicBlock *Src,
const BasicBlock *Dst) const;
private:
typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
// Default weight value. Used when we don't have information about the edge.
// TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
// the successors have a weight yet. But it doesn't make sense when providing
// weight to an edge that may have siblings with non-zero weights. This can
// be handled various ways, but it's probably fine for an edge with unknown
// weight to just "inherit" the non-zero weight of an adjacent successor.
static const uint32_t DEFAULT_WEIGHT = 16;
DenseMap<Edge, uint32_t> Weights;
/// \brief Handle to the LoopInfo analysis.
LoopInfo *LI;
/// \brief Track the last function we run over for printing.
Function *LastF;
/// \brief Get sum of the block successors' weights.
uint32_t getSumForBlock(const BasicBlock *BB) const;
bool calcMetadataWeights(BasicBlock *BB);
bool calcReturnHeuristics(BasicBlock *BB);
bool calcPointerHeuristics(BasicBlock *BB);
bool calcLoopBranchHeuristics(BasicBlock *BB);
bool calcZeroHeuristics(BasicBlock *BB);
bool calcFloatingPointHeuristics(BasicBlock *BB);
};
}
#endif
|
