From 1bae23e32ba1f1af7c7d1488a69a351ec96dc98d Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Wed, 16 Dec 2020 11:07:40 -0800 Subject: Export of internal Abseil changes -- dab5caab05d89d03066ef92584660688595a3aaf by Mark Barolak : Add absl::Status and absl::StatusOr to absl/README.md Import of https://github.com/abseil/abseil-cpp/pull/863 PiperOrigin-RevId: 347857368 -- 1ca3c7a96417cd6e6d62f4dc36fd5ddaa61cfa20 by Chris Kennelly : Leverage integer power-of-2 functions and bit counting library in Abseil. PiperOrigin-RevId: 347816486 -- e5cbe05879fd65dce7875e2e0105331a1615d89b by Chris Kennelly : Mitigate narrowing warning on MSVC. If sizeof(x) <= sizeof(uint32_t), no truncation occurs when casting to uint32_t, but the compiler cannot always determine this. PiperOrigin-RevId: 347696526 -- 079dff64cb175d282d9e22dfb4a522199ffdae2e by Benjamin Barenblat : Avoid libgcc -NaN narrowing bug When testing -NaN parsing, avoid narrowing -NaN from double to float. This avoids a bug in libgcc (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98251). PiperOrigin-RevId: 347654751 -- 2e78a7634865aeef6765e1f447e96cf8d9985059 by Chris Kennelly : Mark popcount helpers as inline. These are conditionally constexpr, so we need to add inline to cover the non-constexpr builds to avoid ODR violations. PiperOrigin-RevId: 347620138 -- 437fbb363aea1654179f102dcdd607ec33c1af1e by Chris Kennelly : Use explicit narrowing cast. This is never invoked in practice, but compilers with -Wimplicit-int-conversion may trigger when sizeof(T) > sizeof(uint16_t) prior to determining this never runs. PiperOrigin-RevId: 347609857 GitOrigin-RevId: dab5caab05d89d03066ef92584660688595a3aaf Change-Id: I6296ddffe7ec646f8ce121138f21e1e85a2cff4b --- absl/base/internal/bits.h | 219 ---------------------------------------- absl/base/internal/bits_test.cc | 97 ------------------ 2 files changed, 316 deletions(-) delete mode 100644 absl/base/internal/bits.h delete mode 100644 absl/base/internal/bits_test.cc (limited to 'absl/base/internal') diff --git a/absl/base/internal/bits.h b/absl/base/internal/bits.h deleted file mode 100644 index 81648e2c..00000000 --- a/absl/base/internal/bits.h +++ /dev/null @@ -1,219 +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 - -#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 -#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, static_cast(n >> 32))) { - return 31 - result; - } - if (_BitScanReverse(&result, static_cast(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(n) == 0) { - _BitScanForward(&result, static_cast(n >> 32)); - return result + 32; - } - _BitScanForward(&result, static_cast(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_ diff --git a/absl/base/internal/bits_test.cc b/absl/base/internal/bits_test.cc deleted file mode 100644 index 7855fa62..00000000 --- a/absl/base/internal/bits_test.cc +++ /dev/null @@ -1,97 +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. - -#include "absl/base/internal/bits.h" - -#include "gtest/gtest.h" - -namespace { - -int CLZ64(uint64_t n) { - int fast = absl::base_internal::CountLeadingZeros64(n); - int slow = absl::base_internal::CountLeadingZeros64Slow(n); - EXPECT_EQ(fast, slow) << n; - return fast; -} - -TEST(BitsTest, CountLeadingZeros64) { - EXPECT_EQ(64, CLZ64(uint64_t{})); - EXPECT_EQ(0, CLZ64(~uint64_t{})); - - for (int index = 0; index < 64; index++) { - uint64_t x = static_cast(1) << index; - const auto cnt = 63 - index; - ASSERT_EQ(cnt, CLZ64(x)) << index; - ASSERT_EQ(cnt, CLZ64(x + x - 1)) << index; - } -} - -int CLZ32(uint32_t n) { - int fast = absl::base_internal::CountLeadingZeros32(n); - int slow = absl::base_internal::CountLeadingZeros32Slow(n); - EXPECT_EQ(fast, slow) << n; - return fast; -} - -TEST(BitsTest, CountLeadingZeros32) { - EXPECT_EQ(32, CLZ32(uint32_t{})); - EXPECT_EQ(0, CLZ32(~uint32_t{})); - - for (int index = 0; index < 32; index++) { - uint32_t x = static_cast(1) << index; - const auto cnt = 31 - index; - ASSERT_EQ(cnt, CLZ32(x)) << index; - ASSERT_EQ(cnt, CLZ32(x + x - 1)) << index; - ASSERT_EQ(CLZ64(x), CLZ32(x) + 32); - } -} - -int CTZ64(uint64_t n) { - int fast = absl::base_internal::CountTrailingZerosNonZero64(n); - int slow = absl::base_internal::CountTrailingZerosNonZero64Slow(n); - EXPECT_EQ(fast, slow) << n; - return fast; -} - -TEST(BitsTest, CountTrailingZerosNonZero64) { - EXPECT_EQ(0, CTZ64(~uint64_t{})); - - for (int index = 0; index < 64; index++) { - uint64_t x = static_cast(1) << index; - const auto cnt = index; - ASSERT_EQ(cnt, CTZ64(x)) << index; - ASSERT_EQ(cnt, CTZ64(~(x - 1))) << index; - } -} - -int CTZ32(uint32_t n) { - int fast = absl::base_internal::CountTrailingZerosNonZero32(n); - int slow = absl::base_internal::CountTrailingZerosNonZero32Slow(n); - EXPECT_EQ(fast, slow) << n; - return fast; -} - -TEST(BitsTest, CountTrailingZerosNonZero32) { - EXPECT_EQ(0, CTZ32(~uint32_t{})); - - for (int index = 0; index < 32; index++) { - uint32_t x = static_cast(1) << index; - const auto cnt = index; - ASSERT_EQ(cnt, CTZ32(x)) << index; - ASSERT_EQ(cnt, CTZ32(~(x - 1))) << index; - } -} - - -} // namespace -- cgit v1.2.3