diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/bits.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/internal/bits.h | 218 |
1 files changed, 0 insertions, 218 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/bits.h b/third_party/abseil_cpp/absl/base/internal/bits.h deleted file mode 100644 index 14c51d8b30..0000000000 --- a/third_party/abseil_cpp/absl/base/internal/bits.h +++ /dev/null @@ -1,218 +0,0 @@ -// Copyright 2018 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#ifndef ABSL_BASE_INTERNAL_BITS_H_ -#define ABSL_BASE_INTERNAL_BITS_H_ - -// This file contains bitwise ops which are implementation details of various -// absl libraries. - -#include <cstdint> - -#include "absl/base/config.h" - -// Clang on Windows has __builtin_clzll; otherwise we need to use the -// windows intrinsic functions. -#if defined(_MSC_VER) && !defined(__clang__) -#include <intrin.h> -#if defined(_M_X64) -#pragma intrinsic(_BitScanReverse64) -#pragma intrinsic(_BitScanForward64) -#endif -#pragma intrinsic(_BitScanReverse) -#pragma intrinsic(_BitScanForward) -#endif - -#include "absl/base/attributes.h" - -#if defined(_MSC_VER) && !defined(__clang__) -// We can achieve something similar to attribute((always_inline)) with MSVC by -// using the __forceinline keyword, however this is not perfect. MSVC is -// much less aggressive about inlining, and even with the __forceinline keyword. -#define ABSL_BASE_INTERNAL_FORCEINLINE __forceinline -#else -// Use default attribute inline. -#define ABSL_BASE_INTERNAL_FORCEINLINE inline ABSL_ATTRIBUTE_ALWAYS_INLINE -#endif - - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace base_internal { - -ABSL_BASE_INTERNAL_FORCEINLINE int CountLeadingZeros64Slow(uint64_t n) { - int zeroes = 60; - if (n >> 32) { - zeroes -= 32; - n >>= 32; - } - if (n >> 16) { - zeroes -= 16; - n >>= 16; - } - if (n >> 8) { - zeroes -= 8; - n >>= 8; - } - if (n >> 4) { - zeroes -= 4; - n >>= 4; - } - return "\4\3\2\2\1\1\1\1\0\0\0\0\0\0\0"[n] + zeroes; -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountLeadingZeros64(uint64_t n) { -#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_X64) - // MSVC does not have __buitin_clzll. Use _BitScanReverse64. - unsigned long result = 0; // NOLINT(runtime/int) - if (_BitScanReverse64(&result, n)) { - return 63 - result; - } - return 64; -#elif defined(_MSC_VER) && !defined(__clang__) - // MSVC does not have __buitin_clzll. Compose two calls to _BitScanReverse - unsigned long result = 0; // NOLINT(runtime/int) - if ((n >> 32) && _BitScanReverse(&result, n >> 32)) { - return 31 - result; - } - if (_BitScanReverse(&result, n)) { - return 63 - result; - } - return 64; -#elif defined(__GNUC__) || defined(__clang__) - // Use __builtin_clzll, which uses the following instructions: - // x86: bsr - // ARM64: clz - // PPC: cntlzd - static_assert(sizeof(unsigned long long) == sizeof(n), // NOLINT(runtime/int) - "__builtin_clzll does not take 64-bit arg"); - - // Handle 0 as a special case because __builtin_clzll(0) is undefined. - if (n == 0) { - return 64; - } - return __builtin_clzll(n); -#else - return CountLeadingZeros64Slow(n); -#endif -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountLeadingZeros32Slow(uint64_t n) { - int zeroes = 28; - if (n >> 16) { - zeroes -= 16; - n >>= 16; - } - if (n >> 8) { - zeroes -= 8; - n >>= 8; - } - if (n >> 4) { - zeroes -= 4; - n >>= 4; - } - return "\4\3\2\2\1\1\1\1\0\0\0\0\0\0\0"[n] + zeroes; -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountLeadingZeros32(uint32_t n) { -#if defined(_MSC_VER) && !defined(__clang__) - unsigned long result = 0; // NOLINT(runtime/int) - if (_BitScanReverse(&result, n)) { - return 31 - result; - } - return 32; -#elif defined(__GNUC__) || defined(__clang__) - // Use __builtin_clz, which uses the following instructions: - // x86: bsr - // ARM64: clz - // PPC: cntlzd - static_assert(sizeof(int) == sizeof(n), - "__builtin_clz does not take 32-bit arg"); - - // Handle 0 as a special case because __builtin_clz(0) is undefined. - if (n == 0) { - return 32; - } - return __builtin_clz(n); -#else - return CountLeadingZeros32Slow(n); -#endif -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountTrailingZerosNonZero64Slow(uint64_t n) { - int c = 63; - n &= ~n + 1; - if (n & 0x00000000FFFFFFFF) c -= 32; - if (n & 0x0000FFFF0000FFFF) c -= 16; - if (n & 0x00FF00FF00FF00FF) c -= 8; - if (n & 0x0F0F0F0F0F0F0F0F) c -= 4; - if (n & 0x3333333333333333) c -= 2; - if (n & 0x5555555555555555) c -= 1; - return c; -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountTrailingZerosNonZero64(uint64_t n) { -#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_X64) - unsigned long result = 0; // NOLINT(runtime/int) - _BitScanForward64(&result, n); - return result; -#elif defined(_MSC_VER) && !defined(__clang__) - unsigned long result = 0; // NOLINT(runtime/int) - if (static_cast<uint32_t>(n) == 0) { - _BitScanForward(&result, n >> 32); - return result + 32; - } - _BitScanForward(&result, n); - return result; -#elif defined(__GNUC__) || defined(__clang__) - static_assert(sizeof(unsigned long long) == sizeof(n), // NOLINT(runtime/int) - "__builtin_ctzll does not take 64-bit arg"); - return __builtin_ctzll(n); -#else - return CountTrailingZerosNonZero64Slow(n); -#endif -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountTrailingZerosNonZero32Slow(uint32_t n) { - int c = 31; - n &= ~n + 1; - if (n & 0x0000FFFF) c -= 16; - if (n & 0x00FF00FF) c -= 8; - if (n & 0x0F0F0F0F) c -= 4; - if (n & 0x33333333) c -= 2; - if (n & 0x55555555) c -= 1; - return c; -} - -ABSL_BASE_INTERNAL_FORCEINLINE int CountTrailingZerosNonZero32(uint32_t n) { -#if defined(_MSC_VER) && !defined(__clang__) - unsigned long result = 0; // NOLINT(runtime/int) - _BitScanForward(&result, n); - return result; -#elif defined(__GNUC__) || defined(__clang__) - static_assert(sizeof(int) == sizeof(n), - "__builtin_ctz does not take 32-bit arg"); - return __builtin_ctz(n); -#else - return CountTrailingZerosNonZero32Slow(n); -#endif -} - -#undef ABSL_BASE_INTERNAL_FORCEINLINE - -} // namespace base_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_BASE_INTERNAL_BITS_H_ |