67 lines
1.9 KiB
C++
67 lines
1.9 KiB
C++
//===-- MathExtras.cpp - Implement the MathExtras header --------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the MathExtras.h header
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/MathExtras.h"
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#ifdef _MSC_VER
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#include <limits>
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#else
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#include <cmath>
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#endif
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namespace llvm {
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#if defined(_MSC_VER)
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// Visual Studio defines the HUGE_VAL class of macros using purposeful
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// constant arithmetic overflow, which it then warns on when encountered.
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const float huge_valf = std::numeric_limits<float>::infinity();
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#else
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const float huge_valf = HUGE_VALF;
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#endif
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/// Returns the number of digits in the given integer.
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int NumDigitsBase10(uint64_t X) {
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static constexpr struct ConstexprData {
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uint8_t AtLeast[65] = {};
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uint64_t Boundaries[20] = {};
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static constexpr int NumDigitsConstexpr(uint64_t N) {
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int res = 1;
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while (N >= 10) {
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res++;
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N /= 10;
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}
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return res;
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}
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constexpr ConstexprData() {
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uint64_t Val = ~0ull;
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for (uint64_t i = 0; i <= 64; i++) {
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uint64_t Digits = NumDigitsConstexpr(Val) - 1;
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AtLeast[i] = Digits;
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Val >>= 1;
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}
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// Special case because X=0 should return 1 and not 0
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Boundaries[0] = 0;
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Val = 10;
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for (uint64_t i = 1; i < 20; i++) {
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Boundaries[i] = Val;
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Val *= 10;
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}
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}
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} Data;
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uint64_t Base2 = X ? countl_zero(X) : 64;
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uint64_t Digits = Data.AtLeast[Base2];
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return Digits + (X >= Data.Boundaries[Digits]);
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}
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} // namespace llvm
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