| //===-------- BlockFrequency.h - Block Frequency Wrapper --------*- C++ -*-===// |
| // |
| // 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 file implements Block Frequency class. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_SUPPORT_BLOCKFREQUENCY_H |
| #define LLVM_SUPPORT_BLOCKFREQUENCY_H |
| |
| #include <cassert> |
| #include <cstdint> |
| #include <optional> |
| |
| namespace llvm { |
| |
| class BranchProbability; |
| |
| // This class represents Block Frequency as a 64-bit value. |
| class BlockFrequency { |
| uint64_t Frequency; |
| |
| public: |
| BlockFrequency() : Frequency(0) {} |
| explicit BlockFrequency(uint64_t Freq) : Frequency(Freq) {} |
| |
| /// Returns the maximum possible frequency, the saturation value. |
| static BlockFrequency max() { return BlockFrequency(UINT64_MAX); } |
| |
| /// Returns the frequency as a fixpoint number scaled by the entry |
| /// frequency. |
| uint64_t getFrequency() const { return Frequency; } |
| |
| /// Multiplies with a branch probability. The computation will never |
| /// overflow. |
| BlockFrequency &operator*=(BranchProbability Prob); |
| BlockFrequency operator*(BranchProbability Prob) const; |
| |
| /// Divide by a non-zero branch probability using saturating |
| /// arithmetic. |
| BlockFrequency &operator/=(BranchProbability Prob); |
| BlockFrequency operator/(BranchProbability Prob) const; |
| |
| /// Adds another block frequency using saturating arithmetic. |
| BlockFrequency &operator+=(BlockFrequency Freq) { |
| uint64_t Before = Freq.Frequency; |
| Frequency += Freq.Frequency; |
| |
| // If overflow, set frequency to the maximum value. |
| if (Frequency < Before) |
| Frequency = UINT64_MAX; |
| |
| return *this; |
| } |
| BlockFrequency operator+(BlockFrequency Freq) const { |
| BlockFrequency NewFreq(Frequency); |
| NewFreq += Freq; |
| return NewFreq; |
| } |
| |
| /// Subtracts another block frequency using saturating arithmetic. |
| BlockFrequency &operator-=(BlockFrequency Freq) { |
| // If underflow, set frequency to 0. |
| if (Frequency <= Freq.Frequency) |
| Frequency = 0; |
| else |
| Frequency -= Freq.Frequency; |
| return *this; |
| } |
| BlockFrequency operator-(BlockFrequency Freq) const { |
| BlockFrequency NewFreq(Frequency); |
| NewFreq -= Freq; |
| return NewFreq; |
| } |
| |
| /// Multiplies frequency with `Factor`. Returns `nullopt` in case of overflow. |
| std::optional<BlockFrequency> mul(uint64_t Factor) const; |
| |
| /// Shift block frequency to the right by count digits saturating to 1. |
| BlockFrequency &operator>>=(const unsigned count) { |
| // Frequency can never be 0 by design. |
| assert(Frequency != 0); |
| |
| // Shift right by count. |
| Frequency >>= count; |
| |
| // Saturate to 1 if we are 0. |
| Frequency |= Frequency == 0; |
| return *this; |
| } |
| |
| bool operator<(BlockFrequency RHS) const { |
| return Frequency < RHS.Frequency; |
| } |
| |
| bool operator<=(BlockFrequency RHS) const { |
| return Frequency <= RHS.Frequency; |
| } |
| |
| bool operator>(BlockFrequency RHS) const { |
| return Frequency > RHS.Frequency; |
| } |
| |
| bool operator>=(BlockFrequency RHS) const { |
| return Frequency >= RHS.Frequency; |
| } |
| |
| bool operator==(BlockFrequency RHS) const { |
| return Frequency == RHS.Frequency; |
| } |
| |
| bool operator!=(BlockFrequency RHS) const { |
| return Frequency != RHS.Frequency; |
| } |
| }; |
| |
| } // namespace llvm |
| |
| #endif |