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/*
* Copyright 2019 The libgav1 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 LIBGAV1_SRC_UTILS_COMPILER_ATTRIBUTES_H_
#define LIBGAV1_SRC_UTILS_COMPILER_ATTRIBUTES_H_
// A collection of compiler attribute checks and defines to control for
// compatibility across toolchains.
//------------------------------------------------------------------------------
// Language version, attribute and feature helpers.
// Detect c++17 support. Visual Studio sets __cplusplus to 199711L by default
// unless compiled with /Zc:__cplusplus, use the value controlled by /std
// instead.
// https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus
#if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
#define LIBGAV1_CXX17 1
#else
#define LIBGAV1_CXX17 0
#endif
#if defined(__has_attribute)
#define LIBGAV1_HAS_ATTRIBUTE __has_attribute
#else
#define LIBGAV1_HAS_ATTRIBUTE(x) 0
#endif
#if defined(__has_feature)
#define LIBGAV1_HAS_FEATURE __has_feature
#else
#define LIBGAV1_HAS_FEATURE(x) 0
#endif
//------------------------------------------------------------------------------
// Sanitizer attributes.
#if LIBGAV1_HAS_FEATURE(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
#define LIBGAV1_ASAN 1
#else
#define LIBGAV1_ASAN 0
#endif
#if LIBGAV1_HAS_FEATURE(memory_sanitizer)
#define LIBGAV1_MSAN 1
#else
#define LIBGAV1_MSAN 0
#endif
#if LIBGAV1_HAS_FEATURE(thread_sanitizer) || defined(__SANITIZE_THREAD__)
#define LIBGAV1_TSAN 1
#else
#define LIBGAV1_TSAN 0
#endif
//------------------------------------------------------------------------------
// AddressSanitizer support.
// Define the macros for AddressSanitizer manual memory poisoning. See
// https://github.com/google/sanitizers/wiki/AddressSanitizerManualPoisoning.
#if LIBGAV1_ASAN
#include <sanitizer/asan_interface.h>
#else
#define ASAN_POISON_MEMORY_REGION(addr, size) \
(static_cast<void>(addr), static_cast<void>(size))
#define ASAN_UNPOISON_MEMORY_REGION(addr, size) \
(static_cast<void>(addr), static_cast<void>(size))
#endif
//------------------------------------------------------------------------------
// Function attributes.
// GCC: https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
// Clang: https://clang.llvm.org/docs/AttributeReference.html
#if defined(__GNUC__)
#define LIBGAV1_ALWAYS_INLINE __attribute__((always_inline)) inline
#elif defined(_MSC_VER)
#define LIBGAV1_ALWAYS_INLINE __forceinline
#else
#define LIBGAV1_ALWAYS_INLINE inline
#endif
// LIBGAV1_MUST_USE_RESULT
//
// Tells the compiler to warn about unused results.
//
// When annotating a function, it must appear as the first part of the
// declaration or definition. The compiler will warn if the return value from
// such a function is unused:
//
// LIBGAV1_MUST_USE_RESULT Sprocket* AllocateSprocket();
// AllocateSprocket(); // Triggers a warning.
//
// When annotating a class, it is equivalent to annotating every function which
// returns an instance.
//
// class LIBGAV1_MUST_USE_RESULT Sprocket {};
// Sprocket(); // Triggers a warning.
//
// Sprocket MakeSprocket();
// MakeSprocket(); // Triggers a warning.
//
// Note that references and pointers are not instances:
//
// Sprocket* SprocketPointer();
// SprocketPointer(); // Does *not* trigger a warning.
//
// LIBGAV1_MUST_USE_RESULT allows using cast-to-void to suppress the unused
// result warning. For that, warn_unused_result is used only for clang but not
// for gcc. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425
#if LIBGAV1_HAS_ATTRIBUTE(nodiscard)
#define LIBGAV1_MUST_USE_RESULT [[nodiscard]]
#elif defined(__clang__) && LIBGAV1_HAS_ATTRIBUTE(warn_unused_result)
#define LIBGAV1_MUST_USE_RESULT __attribute__((warn_unused_result))
#else
#define LIBGAV1_MUST_USE_RESULT
#endif
// LIBGAV1_PRINTF_ATTRIBUTE
//
// Tells the compiler to perform `printf` format string checking if the
// compiler supports it; see the 'format' attribute in
// <https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>.
//
// Note: As the GCC manual states, "[s]ince non-static C++ methods
// have an implicit 'this' argument, the arguments of such methods
// should be counted from two, not one."
#if LIBGAV1_HAS_ATTRIBUTE(format) || (defined(__GNUC__) && !defined(__clang__))
#define LIBGAV1_PRINTF_ATTRIBUTE(string_index, first_to_check) \
__attribute__((__format__(__printf__, string_index, first_to_check)))
#else
#define LIBGAV1_PRINTF_ATTRIBUTE(string_index, first_to_check)
#endif
//------------------------------------------------------------------------------
// Thread annotations.
// LIBGAV1_GUARDED_BY()
//
// Documents if a shared field or global variable needs to be protected by a
// mutex. LIBGAV1_GUARDED_BY() allows the user to specify a particular mutex
// that should be held when accessing the annotated variable.
//
// Although this annotation cannot be applied to local variables, a local
// variable and its associated mutex can often be combined into a small class
// or struct, thereby allowing the annotation.
//
// Example:
//
// class Foo {
// Mutex mu_;
// int p1_ LIBGAV1_GUARDED_BY(mu_);
// ...
// };
// TODO(b/133245043): this can be reenabled after a local MutexLock
// implementation is added with proper thread annotations.
#if 0 // LIBGAV1_HAS_ATTRIBUTE(guarded_by)
#define LIBGAV1_GUARDED_BY(x) __attribute__((guarded_by(x)))
#else
#define LIBGAV1_GUARDED_BY(x)
#endif
//------------------------------------------------------------------------------
#undef LIBGAV1_HAS_ATTRIBUTE
#undef LIBGAV1_HAS_FEATURE
#endif // LIBGAV1_SRC_UTILS_COMPILER_ATTRIBUTES_H_
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