1 //====--------------- lib/Support/BlockFrequency.cpp -----------*- C++ -*-====//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements Block Frequency class.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Support/BranchProbability.h"
15 #include "llvm/Support/BlockFrequency.h"
16 #include "llvm/Support/raw_ostream.h"
23 /// mult96bit - Multiply FREQ by N and store result in W array.
24 void mult96bit(uint64_t freq, uint32_t N, uint64_t W[2]) {
25 uint64_t u0 = freq & UINT32_MAX;
26 uint64_t u1 = freq >> 32;
28 // Represent 96-bit value as w[2]:w[1]:w[0];
29 uint32_t w[3] = { 0, 0, 0 };
38 // W[1] - higher bits.
40 W[0] = w[0] + ((uint64_t) w[1] << 32);
45 /// div96bit - Divide 96-bit value stored in W array by D. Return 64-bit frequency.
46 uint64_t div96bit(uint64_t W[2], uint32_t D) {
50 for (int i = 1; i <= 64; ++i) {
51 uint32_t t = (int)x >> 31;
52 x = (x << 1) | (y >> 63);
66 BlockFrequency &BlockFrequency::operator*=(const BranchProbability &Prob) {
67 uint32_t n = Prob.getNumerator();
68 uint32_t d = Prob.getDenominator();
70 assert(n <= d && "Probability must be less or equal to 1.");
72 // If we can overflow use 96-bit operations.
73 if (n > 0 && Frequency > UINT64_MAX / n) {
74 // 96-bit value represented as W[1]:W[0].
77 // Probability is less or equal to 1 which means that results must fit
79 mult96bit(Frequency, n, W);
80 Frequency = div96bit(W, d);
90 BlockFrequency::operator*(const BranchProbability &Prob) const {
91 BlockFrequency Freq(Frequency);
96 BlockFrequency &BlockFrequency::operator+=(const BlockFrequency &Freq) {
97 uint64_t Before = Freq.Frequency;
98 Frequency += Freq.Frequency;
100 // If overflow, set frequency to the maximum value.
101 if (Frequency < Before)
102 Frequency = UINT64_MAX;
108 BlockFrequency::operator+(const BlockFrequency &Prob) const {
109 BlockFrequency Freq(Frequency);
114 void BlockFrequency::print(raw_ostream &OS) const {
120 raw_ostream &operator<<(raw_ostream &OS, const BlockFrequency &Freq) {