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68dc5fad79
llvm::format compiles down to snprintf which has no defined rounding for floating point arguments, and MSVC has implemented it differently from what the BSD libcs and glibc do. Try to emulate the glibc rounding behavior to avoid changing tests. While there simplify code a bit and move trivial methods inline. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248665 91177308-0d34-0410-b5e6-96231b3b80d8
99 lines
2.9 KiB
C++
99 lines
2.9 KiB
C++
//===-------------- lib/Support/BranchProbability.cpp -----------*- 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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// This file implements Branch Probability class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/BranchProbability.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/raw_ostream.h"
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#include <cassert>
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using namespace llvm;
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const uint32_t BranchProbability::D;
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raw_ostream &BranchProbability::print(raw_ostream &OS) const {
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// Get a percentage rounded to two decimal digits. This avoids
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// implementation-defined rounding inside printf.
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double Percent = rint(((double)N / D) * 100.0 * 100.0) / 100.0;
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OS << format("0x%08" PRIx32 " / 0x%08" PRIx32 " = %.2f%%", N, D, Percent);
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return OS;
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}
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void BranchProbability::dump() const { print(dbgs()) << '\n'; }
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BranchProbability::BranchProbability(uint32_t Numerator, uint32_t Denominator) {
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assert(Denominator > 0 && "Denominator cannot be 0!");
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assert(Numerator <= Denominator && "Probability cannot be bigger than 1!");
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if (Denominator == D)
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N = Numerator;
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else {
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uint64_t Prob64 =
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(Numerator * static_cast<uint64_t>(D) + Denominator / 2) / Denominator;
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N = static_cast<uint32_t>(Prob64);
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}
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}
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// If ConstD is not zero, then replace D by ConstD so that division and modulo
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// operations by D can be optimized, in case this function is not inlined by the
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// compiler.
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template <uint32_t ConstD>
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static uint64_t scale(uint64_t Num, uint32_t N, uint32_t D) {
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if (ConstD > 0)
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D = ConstD;
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assert(D && "divide by 0");
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// Fast path for multiplying by 1.0.
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if (!Num || D == N)
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return Num;
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// Split Num into upper and lower parts to multiply, then recombine.
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uint64_t ProductHigh = (Num >> 32) * N;
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uint64_t ProductLow = (Num & UINT32_MAX) * N;
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// Split into 32-bit digits.
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uint32_t Upper32 = ProductHigh >> 32;
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uint32_t Lower32 = ProductLow & UINT32_MAX;
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uint32_t Mid32Partial = ProductHigh & UINT32_MAX;
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uint32_t Mid32 = Mid32Partial + (ProductLow >> 32);
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// Carry.
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Upper32 += Mid32 < Mid32Partial;
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// Check for overflow.
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if (Upper32 >= D)
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return UINT64_MAX;
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uint64_t Rem = (uint64_t(Upper32) << 32) | Mid32;
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uint64_t UpperQ = Rem / D;
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// Check for overflow.
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if (UpperQ > UINT32_MAX)
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return UINT64_MAX;
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Rem = ((Rem % D) << 32) | Lower32;
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uint64_t LowerQ = Rem / D;
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uint64_t Q = (UpperQ << 32) + LowerQ;
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// Check for overflow.
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return Q < LowerQ ? UINT64_MAX : Q;
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}
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uint64_t BranchProbability::scale(uint64_t Num) const {
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return ::scale<D>(Num, N, D);
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}
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uint64_t BranchProbability::scaleByInverse(uint64_t Num) const {
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return ::scale<0>(Num, D, N);
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}
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