| // Copyright 2017 The Dawn 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 |
| // |
| // http://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 SRC_DAWN_COMMON_COMPILER_H_ |
| #define SRC_DAWN_COMMON_COMPILER_H_ |
| |
| // Defines macros for compiler-specific functionality |
| // - DAWN_COMPILER_IS(CLANG|GCC|MSVC): Compiler detection |
| // - DAWN_BUILTIN_UNREACHABLE(): Hints the compiler that a code path is unreachable |
| // - DAWN_(UN)?LIKELY(EXPR): Where available, hints the compiler that the expression will be true |
| // (resp. false) to help it generate code that leads to better branch prediction. |
| // - DAWN_UNUSED(EXPR): Prevents unused variable/expression warnings on EXPR. |
| // - DAWN_UNUSED_FUNC(FUNC): Prevents unused function warnings on FUNC. |
| // - DAWN_DECLARE_UNUSED: Prevents unused function warnings a subsequent declaration. |
| // Both DAWN_UNUSED_FUNC and DAWN_DECLARE_UNUSED may be necessary, e.g. to suppress clang's |
| // unneeded-internal-declaration warning. |
| |
| // Clang and GCC, check for __clang__ too to catch clang-cl masquarading as MSVC |
| #if defined(__GNUC__) || defined(__clang__) |
| #if defined(__clang__) |
| #define DAWN_COMPILER_IS_CLANG 1 |
| #else |
| #define DAWN_COMPILER_IS_GCC 1 |
| #endif |
| |
| #define DAWN_BUILTIN_UNREACHABLE() __builtin_unreachable() |
| #define DAWN_LIKELY(x) __builtin_expect(!!(x), 1) |
| #define DAWN_UNLIKELY(x) __builtin_expect(!!(x), 0) |
| |
| #if !defined(__has_cpp_attribute) |
| #define __has_cpp_attribute(name) 0 |
| #endif |
| |
| #define DAWN_DECLARE_UNUSED __attribute__((unused)) |
| #if defined(NDEBUG) |
| #define DAWN_FORCE_INLINE inline __attribute__((always_inline)) |
| #endif |
| #define DAWN_NOINLINE __attribute__((noinline)) |
| |
| // MSVC |
| #elif defined(_MSC_VER) |
| #define DAWN_COMPILER_IS_MSVC 1 |
| |
| #define DAWN_BUILTIN_UNREACHABLE() __assume(false) |
| |
| #define DAWN_DECLARE_UNUSED |
| #if defined(NDEBUG) |
| #define DAWN_FORCE_INLINE __forceinline |
| #endif |
| #define DAWN_NOINLINE __declspec(noinline) |
| |
| #else |
| #error "Unsupported compiler" |
| #endif |
| |
| // This section defines other compiler macros to 0 to avoid undefined macro usage error. |
| #if !defined(DAWN_COMPILER_IS_CLANG) |
| #define DAWN_COMPILER_IS_CLANG 0 |
| #endif |
| #if !defined(DAWN_COMPILER_IS_GCC) |
| #define DAWN_COMPILER_IS_GCC 0 |
| #endif |
| #if !defined(DAWN_COMPILER_IS_MSVC) |
| #define DAWN_COMPILER_IS_MSVC 0 |
| #endif |
| |
| // Use #if DAWN_COMPILER_IS(XXX) for compiler specific code. |
| // Do not use #ifdef or the naked macro DAWN_COMPILER_IS_XXX. |
| // This can help avoid common mistakes like not including "Compiler.h" and falling into unwanted |
| // code block as usage of undefined macro "function" will be blocked by the compiler. |
| #define DAWN_COMPILER_IS(X) (1 == DAWN_COMPILER_IS_##X) |
| |
| // It seems that (void) EXPR works on all compilers to silence the unused variable warning. |
| #define DAWN_UNUSED(EXPR) (void)EXPR |
| // Likewise using static asserting on sizeof(&FUNC) seems to make it tagged as used |
| #define DAWN_UNUSED_FUNC(FUNC) static_assert(sizeof(&FUNC) == sizeof(void (*)())) |
| |
| // Add noop replacements for macros for features that aren't supported by the compiler. |
| #if !defined(DAWN_LIKELY) |
| #define DAWN_LIKELY(X) X |
| #endif |
| #if !defined(DAWN_UNLIKELY) |
| #define DAWN_UNLIKELY(X) X |
| #endif |
| #if !defined(DAWN_FORCE_INLINE) |
| #define DAWN_FORCE_INLINE inline |
| #endif |
| #if !defined(DAWN_NOINLINE) |
| #define DAWN_NOINLINE |
| #endif |
| |
| #endif // SRC_DAWN_COMMON_COMPILER_H_ |