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//===--- 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/Support/BranchProbability.h"
#include "llvm/Analysis/LoopInfo.h"
namespace llvm {
class raw_ostream;
class BranchProbabilityInfo : public FunctionPass {
// Default weight value. Used when we don't have information about the edge.
static const uint32_t DEFAULT_WEIGHT = 16;
typedef std::pair<BasicBlock *, BasicBlock *> Edge;
DenseMap<Edge, uint32_t> Weights;
// Get sum of the block successors' weights.
uint32_t getSumForBlock(BasicBlock *BB) const;
public:
static char ID;
BranchProbabilityInfo() : FunctionPass(ID) {
initializeBranchProbabilityInfoPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<LoopInfo>();
AU.setPreservesAll();
}
bool runOnFunction(Function &F);
// Returned value is between 1 and UINT32_MAX. Look at
// BranchProbabilityInfo.cpp for details.
uint32_t getEdgeWeight(BasicBlock *Src, BasicBlock *Dst) const;
// Look at BranchProbabilityInfo.cpp for details. Use it with caution!
void setEdgeWeight(BasicBlock *Src, BasicBlock *Dst, uint32_t Weight);
// A 'Hot' edge is an edge which probability is >= 80%.
bool isEdgeHot(BasicBlock *Src, 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(BasicBlock *Src, 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, BasicBlock *Src,
BasicBlock *Dst) const;
};
}
#endif
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