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90 lines
2.5 KiB
C++
90 lines
2.5 KiB
C++
//===- BranchProbability.h - Branch Probability Wrapper ---------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Definition of BranchProbability shared by IR and Machine Instructions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_BRANCHPROBABILITY_H
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#define LLVM_SUPPORT_BRANCHPROBABILITY_H
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#include "llvm/Support/DataTypes.h"
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#include <cassert>
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namespace llvm {
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class raw_ostream;
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// This class represents Branch Probability as a non-negative fraction.
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class BranchProbability {
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// Numerator
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uint32_t N;
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// Denominator
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uint32_t D;
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public:
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BranchProbability(uint32_t n, uint32_t d) : N(n), D(d) {
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assert(d > 0 && "Denominator cannot be 0!");
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assert(n <= d && "Probability cannot be bigger than 1!");
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}
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static BranchProbability getZero() { return BranchProbability(0, 1); }
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static BranchProbability getOne() { return BranchProbability(1, 1); }
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uint32_t getNumerator() const { return N; }
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uint32_t getDenominator() const { return D; }
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// Return (1 - Probability).
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BranchProbability getCompl() const {
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return BranchProbability(D - N, D);
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}
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raw_ostream &print(raw_ostream &OS) const;
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void dump() const;
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/// \brief Scale a large integer.
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///
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/// Scales \c Num. Guarantees full precision. Returns the floor of the
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/// result.
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///
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/// \return \c Num times \c this.
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uint64_t scale(uint64_t Num) const;
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/// \brief Scale a large integer by the inverse.
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///
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/// Scales \c Num by the inverse of \c this. Guarantees full precision.
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/// Returns the floor of the result.
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///
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/// \return \c Num divided by \c this.
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uint64_t scaleByInverse(uint64_t Num) const;
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bool operator==(BranchProbability RHS) const {
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return (uint64_t)N * RHS.D == (uint64_t)D * RHS.N;
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}
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bool operator!=(BranchProbability RHS) const {
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return !(*this == RHS);
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}
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bool operator<(BranchProbability RHS) const {
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return (uint64_t)N * RHS.D < (uint64_t)D * RHS.N;
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}
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bool operator>(BranchProbability RHS) const { return RHS < *this; }
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bool operator<=(BranchProbability RHS) const { return !(RHS < *this); }
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bool operator>=(BranchProbability RHS) const { return !(*this < RHS); }
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};
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inline raw_ostream &operator<<(raw_ostream &OS, const BranchProbability &Prob) {
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return Prob.print(OS);
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}
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}
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#endif
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