mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-11-04 05:17:07 +00:00
bc1430a0a0
This trades one 64 bit div for one 64 bit mul and some arithmetic. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143106 91177308-0d34-0410-b5e6-96231b3b80d8
131 lines
3.0 KiB
C++
131 lines
3.0 KiB
C++
//====--------------- lib/Support/BlockFrequency.cpp -----------*- C++ -*-====//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements Block Frequency class.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Support/BranchProbability.h"
|
|
#include "llvm/Support/BlockFrequency.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include <cassert>
|
|
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
|
|
/// mult96bit - Multiply FREQ by N and store result in W array.
|
|
void mult96bit(uint64_t freq, uint32_t N, uint64_t W[2]) {
|
|
uint64_t u0 = freq & UINT32_MAX;
|
|
uint64_t u1 = freq >> 32;
|
|
|
|
// Represent 96-bit value as w[2]:w[1]:w[0];
|
|
uint32_t w[3] = { 0, 0, 0 };
|
|
|
|
uint64_t t = u0 * N;
|
|
uint64_t k = t >> 32;
|
|
w[0] = t;
|
|
t = u1 * N + k;
|
|
w[1] = t;
|
|
w[2] = t >> 32;
|
|
|
|
// W[1] - higher bits.
|
|
// W[0] - lower bits.
|
|
W[0] = w[0] + ((uint64_t) w[1] << 32);
|
|
W[1] = w[2];
|
|
}
|
|
|
|
|
|
/// div96bit - Divide 96-bit value stored in W array by D. Return 64-bit frequency.
|
|
uint64_t div96bit(uint64_t W[2], uint32_t D) {
|
|
uint64_t y = W[0];
|
|
uint64_t x = W[1];
|
|
int i;
|
|
|
|
for (i = 1; i <= 64 && x; ++i) {
|
|
uint32_t t = (int)x >> 31;
|
|
x = (x << 1) | (y >> 63);
|
|
y = y << 1;
|
|
if ((x | t) >= D) {
|
|
x -= D;
|
|
++y;
|
|
}
|
|
}
|
|
|
|
return y << (64 - i + 1);
|
|
}
|
|
|
|
}
|
|
|
|
|
|
BlockFrequency &BlockFrequency::operator*=(const BranchProbability &Prob) {
|
|
uint32_t n = Prob.getNumerator();
|
|
uint32_t d = Prob.getDenominator();
|
|
|
|
assert(n <= d && "Probability must be less or equal to 1.");
|
|
|
|
// Calculate Frequency * n.
|
|
uint64_t mulLo = (Frequency & UINT32_MAX) * n;
|
|
uint64_t mulHi = (Frequency >> 32) * n;
|
|
uint64_t mulRes = (mulHi << 32) + mulLo;
|
|
|
|
// If there was overflow use 96-bit operations.
|
|
if (mulHi > UINT32_MAX || mulRes < mulLo) {
|
|
// 96-bit value represented as W[1]:W[0].
|
|
uint64_t W[2];
|
|
|
|
// Probability is less or equal to 1 which means that results must fit
|
|
// 64-bit.
|
|
mult96bit(Frequency, n, W);
|
|
Frequency = div96bit(W, d);
|
|
return *this;
|
|
}
|
|
|
|
Frequency = mulRes / d;
|
|
return *this;
|
|
}
|
|
|
|
const BlockFrequency
|
|
BlockFrequency::operator*(const BranchProbability &Prob) const {
|
|
BlockFrequency Freq(Frequency);
|
|
Freq *= Prob;
|
|
return Freq;
|
|
}
|
|
|
|
BlockFrequency &BlockFrequency::operator+=(const 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;
|
|
}
|
|
|
|
const BlockFrequency
|
|
BlockFrequency::operator+(const BlockFrequency &Prob) const {
|
|
BlockFrequency Freq(Frequency);
|
|
Freq += Prob;
|
|
return Freq;
|
|
}
|
|
|
|
void BlockFrequency::print(raw_ostream &OS) const {
|
|
OS << Frequency;
|
|
}
|
|
|
|
namespace llvm {
|
|
|
|
raw_ostream &operator<<(raw_ostream &OS, const BlockFrequency &Freq) {
|
|
Freq.print(OS);
|
|
return OS;
|
|
}
|
|
|
|
}
|