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Diffstat (limited to 'third_party/abseil_cpp/absl/base/optimization.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/optimization.h | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/third_party/abseil_cpp/absl/base/optimization.h b/third_party/abseil_cpp/absl/base/optimization.h deleted file mode 100644 index 92bf9cd388..0000000000 --- a/third_party/abseil_cpp/absl/base/optimization.h +++ /dev/null @@ -1,241 +0,0 @@ -// -// 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 "absl/base/config.h" - -// ABSL_BLOCK_TAIL_CALL_OPTIMIZATION -// -// Instructs the compiler to avoid optimizing tail-call recursion. Use of 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. -// -// NOTE: this macro should be replaced with usage of `alignas()` using -// `std::hardware_constructive_interference_size` and/or -// `std::hardware_destructive_interference_size` when available within C++17. -// -// 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(x, 0)) -#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 than a condition is always true and that it can assume -// it to be true for optimization purposes. The call has undefined behavior if -// the condition is false. -// In !NDEBUG mode, the condition is checked with an assert(). -// NOTE: The expression must not have side effects, as it will only be evaluated -// in some compilation modes and not others. -// -// Example: -// -// int x = ...; -// ABSL_INTERNAL_ASSUME(x >= 0); -// // The compiler can optimize the division to a simple right shift using the -// // assumption specified above. -// int y = x / 16; -// -#if !defined(NDEBUG) -#define ABSL_INTERNAL_ASSUME(cond) assert(cond) -#elif ABSL_HAVE_BUILTIN(__builtin_assume) -#define ABSL_INTERNAL_ASSUME(cond) __builtin_assume(cond) -#elif defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_unreachable) -#define ABSL_INTERNAL_ASSUME(cond) \ - do { \ - if (!(cond)) __builtin_unreachable(); \ - } while (0) -#elif defined(_MSC_VER) -#define ABSL_INTERNAL_ASSUME(cond) __assume(cond) -#else -#define ABSL_INTERNAL_ASSUME(cond) \ - do { \ - static_cast<void>(false && (cond)); \ - } while (0) -#endif - -// ABSL_INTERNAL_UNIQUE_SMALL_NAME(cond) -// This macro forces small unique name on a static file level symbols like -// static local variables or static functions. This is intended to be used in -// macro definitions to optimize the cost of generated code. Do NOT use it on -// symbols exported from translation unit since it may casue a link time -// conflict. -// -// Example: -// -// #define MY_MACRO(txt) -// namespace { -// char VeryVeryLongVarName[] ABSL_INTERNAL_UNIQUE_SMALL_NAME() = txt; -// const char* VeryVeryLongFuncName() ABSL_INTERNAL_UNIQUE_SMALL_NAME(); -// const char* VeryVeryLongFuncName() { return txt; } -// } -// - -#if defined(__GNUC__) -#define ABSL_INTERNAL_UNIQUE_SMALL_NAME2(x) #x -#define ABSL_INTERNAL_UNIQUE_SMALL_NAME1(x) ABSL_INTERNAL_UNIQUE_SMALL_NAME2(x) -#define ABSL_INTERNAL_UNIQUE_SMALL_NAME() \ - asm(ABSL_INTERNAL_UNIQUE_SMALL_NAME1(.absl.__COUNTER__)) -#else -#define ABSL_INTERNAL_UNIQUE_SMALL_NAME() -#endif - -#endif // ABSL_BASE_OPTIMIZATION_H_ |