251 lines
8.8 KiB
C
251 lines
8.8 KiB
C
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
#ifndef BASE_COMPILER_SPECIFIC_H_
|
|
#define BASE_COMPILER_SPECIFIC_H_
|
|
|
|
#include "build/build_config.h"
|
|
|
|
#if defined(COMPILER_MSVC) && !defined(__clang__)
|
|
#error "Only clang-cl is supported on Windows, see https://crbug.com/988071"
|
|
#endif
|
|
|
|
// Annotate a variable indicating it's ok if the variable is not used.
|
|
// (Typically used to silence a compiler warning when the assignment
|
|
// is important for some other reason.)
|
|
// Use like:
|
|
// int x = ...;
|
|
// ALLOW_UNUSED_LOCAL(x);
|
|
#define ALLOW_UNUSED_LOCAL(x) (void)x
|
|
|
|
// Annotate a typedef or function indicating it's ok if it's not used.
|
|
// Use like:
|
|
// typedef Foo Bar ALLOW_UNUSED_TYPE;
|
|
#if defined(COMPILER_GCC) || defined(__clang__)
|
|
#define ALLOW_UNUSED_TYPE __attribute__((unused))
|
|
#else
|
|
#define ALLOW_UNUSED_TYPE
|
|
#endif
|
|
|
|
// Annotate a function indicating it should not be inlined.
|
|
// Use like:
|
|
// NOINLINE void DoStuff() { ... }
|
|
#if defined(COMPILER_GCC)
|
|
#define NOINLINE __attribute__((noinline))
|
|
#elif defined(COMPILER_MSVC)
|
|
#define NOINLINE __declspec(noinline)
|
|
#else
|
|
#define NOINLINE
|
|
#endif
|
|
|
|
#if defined(COMPILER_GCC) && defined(NDEBUG)
|
|
#define ALWAYS_INLINE inline __attribute__((__always_inline__))
|
|
#elif defined(COMPILER_MSVC) && defined(NDEBUG)
|
|
#define ALWAYS_INLINE __forceinline
|
|
#else
|
|
#define ALWAYS_INLINE inline
|
|
#endif
|
|
|
|
// Specify memory alignment for structs, classes, etc.
|
|
// Use like:
|
|
// class ALIGNAS(16) MyClass { ... }
|
|
// ALIGNAS(16) int array[4];
|
|
//
|
|
// In most places you can use the C++11 keyword "alignas", which is preferred.
|
|
//
|
|
// But compilers have trouble mixing __attribute__((...)) syntax with
|
|
// alignas(...) syntax.
|
|
//
|
|
// Doesn't work in clang or gcc:
|
|
// struct alignas(16) __attribute__((packed)) S { char c; };
|
|
// Works in clang but not gcc:
|
|
// struct __attribute__((packed)) alignas(16) S2 { char c; };
|
|
// Works in clang and gcc:
|
|
// struct alignas(16) S3 { char c; } __attribute__((packed));
|
|
//
|
|
// There are also some attributes that must be specified *before* a class
|
|
// definition: visibility (used for exporting functions/classes) is one of
|
|
// these attributes. This means that it is not possible to use alignas() with a
|
|
// class that is marked as exported.
|
|
#if defined(COMPILER_MSVC)
|
|
#define ALIGNAS(byte_alignment) __declspec(align(byte_alignment))
|
|
#elif defined(COMPILER_GCC)
|
|
#define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
|
|
#endif
|
|
|
|
// Annotate a function indicating the caller must examine the return value.
|
|
// Use like:
|
|
// int foo() WARN_UNUSED_RESULT;
|
|
// To explicitly ignore a result, see |ignore_result()| in base/macros.h.
|
|
#undef WARN_UNUSED_RESULT
|
|
#if defined(COMPILER_GCC) || defined(__clang__)
|
|
#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
|
|
#else
|
|
#define WARN_UNUSED_RESULT
|
|
#endif
|
|
|
|
// Tell the compiler a function is using a printf-style format string.
|
|
// |format_param| is the one-based index of the format string parameter;
|
|
// |dots_param| is the one-based index of the "..." parameter.
|
|
// For v*printf functions (which take a va_list), pass 0 for dots_param.
|
|
// (This is undocumented but matches what the system C headers do.)
|
|
// For member functions, the implicit this parameter counts as index 1.
|
|
#if defined(COMPILER_GCC) || defined(__clang__)
|
|
#define PRINTF_FORMAT(format_param, dots_param) \
|
|
__attribute__((format(printf, format_param, dots_param)))
|
|
#else
|
|
#define PRINTF_FORMAT(format_param, dots_param)
|
|
#endif
|
|
|
|
// WPRINTF_FORMAT is the same, but for wide format strings.
|
|
// This doesn't appear to yet be implemented in any compiler.
|
|
// See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 .
|
|
#define WPRINTF_FORMAT(format_param, dots_param)
|
|
// If available, it would look like:
|
|
// __attribute__((format(wprintf, format_param, dots_param)))
|
|
|
|
// Sanitizers annotations.
|
|
#if defined(__has_attribute)
|
|
#if __has_attribute(no_sanitize)
|
|
#define NO_SANITIZE(what) __attribute__((no_sanitize(what)))
|
|
#endif
|
|
#endif
|
|
#if !defined(NO_SANITIZE)
|
|
#define NO_SANITIZE(what)
|
|
#endif
|
|
|
|
// MemorySanitizer annotations.
|
|
#if defined(MEMORY_SANITIZER) && !defined(OS_NACL)
|
|
#include <sanitizer/msan_interface.h>
|
|
|
|
// Mark a memory region fully initialized.
|
|
// Use this to annotate code that deliberately reads uninitialized data, for
|
|
// example a GC scavenging root set pointers from the stack.
|
|
#define MSAN_UNPOISON(p, size) __msan_unpoison(p, size)
|
|
|
|
// Check a memory region for initializedness, as if it was being used here.
|
|
// If any bits are uninitialized, crash with an MSan report.
|
|
// Use this to sanitize data which MSan won't be able to track, e.g. before
|
|
// passing data to another process via shared memory.
|
|
#define MSAN_CHECK_MEM_IS_INITIALIZED(p, size) \
|
|
__msan_check_mem_is_initialized(p, size)
|
|
#else // MEMORY_SANITIZER
|
|
#define MSAN_UNPOISON(p, size)
|
|
#define MSAN_CHECK_MEM_IS_INITIALIZED(p, size)
|
|
#endif // MEMORY_SANITIZER
|
|
|
|
// DISABLE_CFI_PERF -- Disable Control Flow Integrity for perf reasons.
|
|
#if !defined(DISABLE_CFI_PERF)
|
|
#if defined(__clang__) && defined(OFFICIAL_BUILD)
|
|
#define DISABLE_CFI_PERF __attribute__((no_sanitize("cfi")))
|
|
#else
|
|
#define DISABLE_CFI_PERF
|
|
#endif
|
|
#endif
|
|
|
|
// Macro useful for writing cross-platform function pointers.
|
|
#if !defined(CDECL)
|
|
#if defined(OS_WIN)
|
|
#define CDECL __cdecl
|
|
#else // defined(OS_WIN)
|
|
#define CDECL
|
|
#endif // defined(OS_WIN)
|
|
#endif // !defined(CDECL)
|
|
|
|
// Macro for hinting that an expression is likely to be false.
|
|
#if !defined(UNLIKELY)
|
|
#if defined(COMPILER_GCC) || defined(__clang__)
|
|
#define UNLIKELY(x) __builtin_expect(!!(x), 0)
|
|
#else
|
|
#define UNLIKELY(x) (x)
|
|
#endif // defined(COMPILER_GCC)
|
|
#endif // !defined(UNLIKELY)
|
|
|
|
#if !defined(LIKELY)
|
|
#if defined(COMPILER_GCC) || defined(__clang__)
|
|
#define LIKELY(x) __builtin_expect(!!(x), 1)
|
|
#else
|
|
#define LIKELY(x) (x)
|
|
#endif // defined(COMPILER_GCC)
|
|
#endif // !defined(LIKELY)
|
|
|
|
// Compiler feature-detection.
|
|
// clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension
|
|
#if defined(__has_feature)
|
|
#define HAS_FEATURE(FEATURE) __has_feature(FEATURE)
|
|
#else
|
|
#define HAS_FEATURE(FEATURE) 0
|
|
#endif
|
|
|
|
// Macro for telling -Wimplicit-fallthrough that a fallthrough is intentional.
|
|
#if defined(__clang__)
|
|
#define FALLTHROUGH [[clang::fallthrough]]
|
|
#else
|
|
#define FALLTHROUGH
|
|
#endif
|
|
|
|
#if defined(COMPILER_GCC)
|
|
#define PRETTY_FUNCTION __PRETTY_FUNCTION__
|
|
#elif defined(COMPILER_MSVC)
|
|
#define PRETTY_FUNCTION __FUNCSIG__
|
|
#else
|
|
// See https://en.cppreference.com/w/c/language/function_definition#func
|
|
#define PRETTY_FUNCTION __func__
|
|
#endif
|
|
|
|
#if !defined(CPU_ARM_NEON)
|
|
#if defined(__arm__)
|
|
#if !defined(__ARMEB__) && !defined(__ARM_EABI__) && !defined(__EABI__) && \
|
|
!defined(__VFP_FP__) && !defined(_WIN32_WCE) && !defined(ANDROID)
|
|
#error Chromium does not support middle endian architecture
|
|
#endif
|
|
#if defined(__ARM_NEON__)
|
|
#define CPU_ARM_NEON 1
|
|
#endif
|
|
#endif // defined(__arm__)
|
|
#endif // !defined(CPU_ARM_NEON)
|
|
|
|
#if !defined(HAVE_MIPS_MSA_INTRINSICS)
|
|
#if defined(__mips_msa) && defined(__mips_isa_rev) && (__mips_isa_rev >= 5)
|
|
#define HAVE_MIPS_MSA_INTRINSICS 1
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(__clang__) && __has_attribute(uninitialized)
|
|
// Attribute "uninitialized" disables -ftrivial-auto-var-init=pattern for
|
|
// the specified variable.
|
|
// Library-wide alternative is
|
|
// 'configs -= [ "//build/config/compiler:default_init_stack_vars" ]' in .gn
|
|
// file.
|
|
//
|
|
// See "init_stack_vars" in build/config/compiler/BUILD.gn and
|
|
// http://crbug.com/977230
|
|
// "init_stack_vars" is enabled for non-official builds and we hope to enable it
|
|
// in official build in 2020 as well. The flag writes fixed pattern into
|
|
// uninitialized parts of all local variables. In rare cases such initialization
|
|
// is undesirable and attribute can be used:
|
|
// 1. Degraded performance
|
|
// In most cases compiler is able to remove additional stores. E.g. if memory is
|
|
// never accessed or properly initialized later. Preserved stores mostly will
|
|
// not affect program performance. However if compiler failed on some
|
|
// performance critical code we can get a visible regression in a benchmark.
|
|
// 2. memset, memcpy calls
|
|
// Compiler may replaces some memory writes with memset or memcpy calls. This is
|
|
// not -ftrivial-auto-var-init specific, but it can happen more likely with the
|
|
// flag. It can be a problem if code is not linked with C run-time library.
|
|
//
|
|
// Note: The flag is security risk mitigation feature. So in future the
|
|
// attribute uses should be avoided when possible. However to enable this
|
|
// mitigation on the most of the code we need to be less strict now and minimize
|
|
// number of exceptions later. So if in doubt feel free to use attribute, but
|
|
// please document the problem for someone who is going to cleanup it later.
|
|
// E.g. platform, bot, benchmark or test name in patch description or next to
|
|
// the attribute.
|
|
#define STACK_UNINITIALIZED __attribute__((uninitialized))
|
|
#else
|
|
#define STACK_UNINITIALIZED
|
|
#endif
|
|
|
|
#endif // BASE_COMPILER_SPECIFIC_H_
|