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author | anastasy888 <anastasy888@yandex-team.ru> | 2022-02-10 16:45:54 +0300 |
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committer | Daniil Cherednik <dcherednik@yandex-team.ru> | 2022-02-10 16:45:54 +0300 |
commit | 49f765d71da452ea93138a25559dfa68dd76c7f3 (patch) | |
tree | 1016041feb637349e401dcc0fa85217dd2c2c639 /contrib/restricted/abseil-cpp/absl/base/optimization.h | |
parent | 7353a3fdea9c67c256980c00a2b3b67f09b23a27 (diff) | |
download | ydb-49f765d71da452ea93138a25559dfa68dd76c7f3.tar.gz |
Restoring authorship annotation for <anastasy888@yandex-team.ru>. Commit 1 of 2.
Diffstat (limited to 'contrib/restricted/abseil-cpp/absl/base/optimization.h')
-rw-r--r-- | contrib/restricted/abseil-cpp/absl/base/optimization.h | 350 |
1 files changed, 175 insertions, 175 deletions
diff --git a/contrib/restricted/abseil-cpp/absl/base/optimization.h b/contrib/restricted/abseil-cpp/absl/base/optimization.h index d090be1286..fe6bcab3f6 100644 --- a/contrib/restricted/abseil-cpp/absl/base/optimization.h +++ b/contrib/restricted/abseil-cpp/absl/base/optimization.h @@ -1,186 +1,186 @@ -// -// Copyright 2017 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. -// -// ----------------------------------------------------------------------------- -// File: optimization.h -// ----------------------------------------------------------------------------- -// -// This header file defines portable macros for performance optimization. - -#ifndef ABSL_BASE_OPTIMIZATION_H_ -#define ABSL_BASE_OPTIMIZATION_H_ - +// +// Copyright 2017 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. +// +// ----------------------------------------------------------------------------- +// File: optimization.h +// ----------------------------------------------------------------------------- +// +// This header file defines portable macros for performance optimization. + +#ifndef ABSL_BASE_OPTIMIZATION_H_ +#define ABSL_BASE_OPTIMIZATION_H_ + #include <assert.h> -#include "absl/base/config.h" - -// ABSL_BLOCK_TAIL_CALL_OPTIMIZATION -// +#include "absl/base/config.h" + +// ABSL_BLOCK_TAIL_CALL_OPTIMIZATION +// // Instructs the compiler to avoid optimizing tail-call recursion. This macro is // useful when you wish to preserve the existing function order within a stack // trace for logging, debugging, or profiling purposes. -// -// Example: -// -// int f() { -// int result = g(); -// ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); -// return result; -// } -#if defined(__pnacl__) -#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() if (volatile int x = 0) { (void)x; } -#elif defined(__clang__) -// Clang will not tail call given inline volatile assembly. -#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() __asm__ __volatile__("") -#elif defined(__GNUC__) -// GCC will not tail call given inline volatile assembly. -#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() __asm__ __volatile__("") -#elif defined(_MSC_VER) -#include <intrin.h> -// The __nop() intrinsic blocks the optimisation. -#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() __nop() -#else -#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() if (volatile int x = 0) { (void)x; } -#endif - -// ABSL_CACHELINE_SIZE -// -// Explicitly defines the size of the L1 cache for purposes of alignment. -// Setting the cacheline size allows you to specify that certain objects be -// aligned on a cacheline boundary with `ABSL_CACHELINE_ALIGNED` declarations. -// (See below.) -// -// NOTE: this macro should be replaced with the following C++17 features, when -// those are generally available: -// -// * `std::hardware_constructive_interference_size` -// * `std::hardware_destructive_interference_size` -// -// See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0154r1.html -// for more information. -#if defined(__GNUC__) -// Cache line alignment -#if defined(__i386__) || defined(__x86_64__) -#define ABSL_CACHELINE_SIZE 64 -#elif defined(__powerpc64__) -#define ABSL_CACHELINE_SIZE 128 -#elif defined(__aarch64__) -// We would need to read special register ctr_el0 to find out L1 dcache size. -// This value is a good estimate based on a real aarch64 machine. -#define ABSL_CACHELINE_SIZE 64 -#elif defined(__arm__) -// Cache line sizes for ARM: These values are not strictly correct since -// cache line sizes depend on implementations, not architectures. There -// are even implementations with cache line sizes configurable at boot -// time. -#if defined(__ARM_ARCH_5T__) -#define ABSL_CACHELINE_SIZE 32 -#elif defined(__ARM_ARCH_7A__) -#define ABSL_CACHELINE_SIZE 64 -#endif -#endif - -#ifndef ABSL_CACHELINE_SIZE -// A reasonable default guess. Note that overestimates tend to waste more -// space, while underestimates tend to waste more time. -#define ABSL_CACHELINE_SIZE 64 -#endif - -// ABSL_CACHELINE_ALIGNED -// -// Indicates that the declared object be cache aligned using -// `ABSL_CACHELINE_SIZE` (see above). Cacheline aligning objects allows you to -// load a set of related objects in the L1 cache for performance improvements. -// Cacheline aligning objects properly allows constructive memory sharing and -// prevents destructive (or "false") memory sharing. -// +// +// Example: +// +// int f() { +// int result = g(); +// ABSL_BLOCK_TAIL_CALL_OPTIMIZATION(); +// return result; +// } +#if defined(__pnacl__) +#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() if (volatile int x = 0) { (void)x; } +#elif defined(__clang__) +// Clang will not tail call given inline volatile assembly. +#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() __asm__ __volatile__("") +#elif defined(__GNUC__) +// GCC will not tail call given inline volatile assembly. +#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() __asm__ __volatile__("") +#elif defined(_MSC_VER) +#include <intrin.h> +// The __nop() intrinsic blocks the optimisation. +#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() __nop() +#else +#define ABSL_BLOCK_TAIL_CALL_OPTIMIZATION() if (volatile int x = 0) { (void)x; } +#endif + +// ABSL_CACHELINE_SIZE +// +// Explicitly defines the size of the L1 cache for purposes of alignment. +// Setting the cacheline size allows you to specify that certain objects be +// aligned on a cacheline boundary with `ABSL_CACHELINE_ALIGNED` declarations. +// (See below.) +// +// NOTE: this macro should be replaced with the following C++17 features, when +// those are generally available: +// +// * `std::hardware_constructive_interference_size` +// * `std::hardware_destructive_interference_size` +// +// See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0154r1.html +// for more information. +#if defined(__GNUC__) +// Cache line alignment +#if defined(__i386__) || defined(__x86_64__) +#define ABSL_CACHELINE_SIZE 64 +#elif defined(__powerpc64__) +#define ABSL_CACHELINE_SIZE 128 +#elif defined(__aarch64__) +// We would need to read special register ctr_el0 to find out L1 dcache size. +// This value is a good estimate based on a real aarch64 machine. +#define ABSL_CACHELINE_SIZE 64 +#elif defined(__arm__) +// Cache line sizes for ARM: These values are not strictly correct since +// cache line sizes depend on implementations, not architectures. There +// are even implementations with cache line sizes configurable at boot +// time. +#if defined(__ARM_ARCH_5T__) +#define ABSL_CACHELINE_SIZE 32 +#elif defined(__ARM_ARCH_7A__) +#define ABSL_CACHELINE_SIZE 64 +#endif +#endif + +#ifndef ABSL_CACHELINE_SIZE +// A reasonable default guess. Note that overestimates tend to waste more +// space, while underestimates tend to waste more time. +#define ABSL_CACHELINE_SIZE 64 +#endif + +// ABSL_CACHELINE_ALIGNED +// +// Indicates that the declared object be cache aligned using +// `ABSL_CACHELINE_SIZE` (see above). Cacheline aligning objects allows you to +// load a set of related objects in the L1 cache for performance improvements. +// Cacheline aligning objects properly allows constructive memory sharing and +// prevents destructive (or "false") memory sharing. +// // NOTE: callers should replace uses of this macro with `alignas()` using -// `std::hardware_constructive_interference_size` and/or +// `std::hardware_constructive_interference_size` and/or // `std::hardware_destructive_interference_size` when C++17 becomes available to // them. -// -// See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0154r1.html -// for more information. -// -// On some compilers, `ABSL_CACHELINE_ALIGNED` expands to an `__attribute__` -// or `__declspec` attribute. For compilers where this is not known to work, -// the macro expands to nothing. -// -// No further guarantees are made here. The result of applying the macro -// to variables and types is always implementation-defined. -// -// WARNING: It is easy to use this attribute incorrectly, even to the point -// of causing bugs that are difficult to diagnose, crash, etc. It does not -// of itself guarantee that objects are aligned to a cache line. -// -// NOTE: Some compilers are picky about the locations of annotations such as -// this attribute, so prefer to put it at the beginning of your declaration. -// For example, -// -// ABSL_CACHELINE_ALIGNED static Foo* foo = ... -// -// class ABSL_CACHELINE_ALIGNED Bar { ... -// -// Recommendations: -// -// 1) Consult compiler documentation; this comment is not kept in sync as -// toolchains evolve. -// 2) Verify your use has the intended effect. This often requires inspecting -// the generated machine code. -// 3) Prefer applying this attribute to individual variables. Avoid -// applying it to types. This tends to localize the effect. -#define ABSL_CACHELINE_ALIGNED __attribute__((aligned(ABSL_CACHELINE_SIZE))) -#elif defined(_MSC_VER) -#define ABSL_CACHELINE_SIZE 64 -#define ABSL_CACHELINE_ALIGNED __declspec(align(ABSL_CACHELINE_SIZE)) -#else -#define ABSL_CACHELINE_SIZE 64 -#define ABSL_CACHELINE_ALIGNED -#endif - -// ABSL_PREDICT_TRUE, ABSL_PREDICT_FALSE -// -// Enables the compiler to prioritize compilation using static analysis for -// likely paths within a boolean branch. -// -// Example: -// -// if (ABSL_PREDICT_TRUE(expression)) { -// return result; // Faster if more likely -// } else { -// return 0; -// } -// -// Compilers can use the information that a certain branch is not likely to be -// taken (for instance, a CHECK failure) to optimize for the common case in -// the absence of better information (ie. compiling gcc with `-fprofile-arcs`). -// -// Recommendation: Modern CPUs dynamically predict branch execution paths, -// typically with accuracy greater than 97%. As a result, annotating every -// branch in a codebase is likely counterproductive; however, annotating -// specific branches that are both hot and consistently mispredicted is likely -// to yield performance improvements. -#if ABSL_HAVE_BUILTIN(__builtin_expect) || \ - (defined(__GNUC__) && !defined(__clang__)) +// +// See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0154r1.html +// for more information. +// +// On some compilers, `ABSL_CACHELINE_ALIGNED` expands to an `__attribute__` +// or `__declspec` attribute. For compilers where this is not known to work, +// the macro expands to nothing. +// +// No further guarantees are made here. The result of applying the macro +// to variables and types is always implementation-defined. +// +// WARNING: It is easy to use this attribute incorrectly, even to the point +// of causing bugs that are difficult to diagnose, crash, etc. It does not +// of itself guarantee that objects are aligned to a cache line. +// +// NOTE: Some compilers are picky about the locations of annotations such as +// this attribute, so prefer to put it at the beginning of your declaration. +// For example, +// +// ABSL_CACHELINE_ALIGNED static Foo* foo = ... +// +// class ABSL_CACHELINE_ALIGNED Bar { ... +// +// Recommendations: +// +// 1) Consult compiler documentation; this comment is not kept in sync as +// toolchains evolve. +// 2) Verify your use has the intended effect. This often requires inspecting +// the generated machine code. +// 3) Prefer applying this attribute to individual variables. Avoid +// applying it to types. This tends to localize the effect. +#define ABSL_CACHELINE_ALIGNED __attribute__((aligned(ABSL_CACHELINE_SIZE))) +#elif defined(_MSC_VER) +#define ABSL_CACHELINE_SIZE 64 +#define ABSL_CACHELINE_ALIGNED __declspec(align(ABSL_CACHELINE_SIZE)) +#else +#define ABSL_CACHELINE_SIZE 64 +#define ABSL_CACHELINE_ALIGNED +#endif + +// ABSL_PREDICT_TRUE, ABSL_PREDICT_FALSE +// +// Enables the compiler to prioritize compilation using static analysis for +// likely paths within a boolean branch. +// +// Example: +// +// if (ABSL_PREDICT_TRUE(expression)) { +// return result; // Faster if more likely +// } else { +// return 0; +// } +// +// Compilers can use the information that a certain branch is not likely to be +// taken (for instance, a CHECK failure) to optimize for the common case in +// the absence of better information (ie. compiling gcc with `-fprofile-arcs`). +// +// Recommendation: Modern CPUs dynamically predict branch execution paths, +// typically with accuracy greater than 97%. As a result, annotating every +// branch in a codebase is likely counterproductive; however, annotating +// specific branches that are both hot and consistently mispredicted is likely +// to yield performance improvements. +#if ABSL_HAVE_BUILTIN(__builtin_expect) || \ + (defined(__GNUC__) && !defined(__clang__)) #define ABSL_PREDICT_FALSE(x) (__builtin_expect(false || (x), false)) -#define ABSL_PREDICT_TRUE(x) (__builtin_expect(false || (x), true)) -#else -#define ABSL_PREDICT_FALSE(x) (x) -#define ABSL_PREDICT_TRUE(x) (x) -#endif - +#define ABSL_PREDICT_TRUE(x) (__builtin_expect(false || (x), true)) +#else +#define ABSL_PREDICT_FALSE(x) (x) +#define ABSL_PREDICT_TRUE(x) (x) +#endif + // ABSL_INTERNAL_ASSUME(cond) // Informs the compiler that a condition is always true and that it can assume // it to be true for optimization purposes. The call has undefined behavior if @@ -241,4 +241,4 @@ #define ABSL_INTERNAL_UNIQUE_SMALL_NAME() #endif -#endif // ABSL_BASE_OPTIMIZATION_H_ +#endif // ABSL_BASE_OPTIMIZATION_H_ |