1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_COMPILER_SPECIFIC_H_
6#define BASE_COMPILER_SPECIFIC_H_
7
8#include "build/build_config.h"
9
10#if defined(ANDROID)
11// Prefer Android's libbase definitions to our own.
12#include <android-base/macros.h>
13#endif  // defined(ANDROID)
14
15#if defined(COMPILER_MSVC)
16
17// For _Printf_format_string_.
18#include <sal.h>
19
20// Macros for suppressing and disabling warnings on MSVC.
21//
22// Warning numbers are enumerated at:
23// http://msdn.microsoft.com/en-us/library/8x5x43k7(VS.80).aspx
24//
25// The warning pragma:
26// http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx
27//
28// Using __pragma instead of #pragma inside macros:
29// http://msdn.microsoft.com/en-us/library/d9x1s805.aspx
30
31// MSVC_SUPPRESS_WARNING disables warning |n| for the remainder of the line and
32// for the next line of the source file.
33#define MSVC_SUPPRESS_WARNING(n) __pragma(warning(suppress:n))
34
35// MSVC_PUSH_DISABLE_WARNING pushes |n| onto a stack of warnings to be disabled.
36// The warning remains disabled until popped by MSVC_POP_WARNING.
37#define MSVC_PUSH_DISABLE_WARNING(n) __pragma(warning(push)) \
38                                     __pragma(warning(disable:n))
39
40// MSVC_PUSH_WARNING_LEVEL pushes |n| as the global warning level.  The level
41// remains in effect until popped by MSVC_POP_WARNING().  Use 0 to disable all
42// warnings.
43#define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n))
44
45// Pop effects of innermost MSVC_PUSH_* macro.
46#define MSVC_POP_WARNING() __pragma(warning(pop))
47
48#define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off))
49#define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on))
50
51// Allows exporting a class that inherits from a non-exported base class.
52// This uses suppress instead of push/pop because the delimiter after the
53// declaration (either "," or "{") has to be placed before the pop macro.
54//
55// Example usage:
56// class EXPORT_API Foo : NON_EXPORTED_BASE(public Bar) {
57//
58// MSVC Compiler warning C4275:
59// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
60// Note that this is intended to be used only when no access to the base class'
61// static data is done through derived classes or inline methods. For more info,
62// see http://msdn.microsoft.com/en-us/library/3tdb471s(VS.80).aspx
63#define NON_EXPORTED_BASE(code) MSVC_SUPPRESS_WARNING(4275) \
64                                code
65
66#else  // Not MSVC
67
68#define _Printf_format_string_
69#define MSVC_SUPPRESS_WARNING(n)
70#define MSVC_PUSH_DISABLE_WARNING(n)
71#define MSVC_PUSH_WARNING_LEVEL(n)
72#define MSVC_POP_WARNING()
73#define MSVC_DISABLE_OPTIMIZE()
74#define MSVC_ENABLE_OPTIMIZE()
75#define NON_EXPORTED_BASE(code) code
76
77#endif  // COMPILER_MSVC
78
79
80// Annotate a variable indicating it's ok if the variable is not used.
81// (Typically used to silence a compiler warning when the assignment
82// is important for some other reason.)
83// Use like:
84//   int x = ...;
85//   ALLOW_UNUSED_LOCAL(x);
86#define ALLOW_UNUSED_LOCAL(x) false ? (void)x : (void)0
87
88// Annotate a typedef or function indicating it's ok if it's not used.
89// Use like:
90//   typedef Foo Bar ALLOW_UNUSED_TYPE;
91#if defined(COMPILER_GCC) || defined(__clang__)
92#define ALLOW_UNUSED_TYPE __attribute__((unused))
93#else
94#define ALLOW_UNUSED_TYPE
95#endif
96
97// Annotate a function indicating it should not be inlined.
98// Use like:
99//   NOINLINE void DoStuff() { ... }
100#if defined(COMPILER_GCC)
101#define NOINLINE __attribute__((noinline))
102#elif defined(COMPILER_MSVC)
103#define NOINLINE __declspec(noinline)
104#else
105#define NOINLINE
106#endif
107
108#if COMPILER_GCC && defined(NDEBUG)
109#define ALWAYS_INLINE inline __attribute__((__always_inline__))
110#elif COMPILER_MSVC && defined(NDEBUG)
111#define ALWAYS_INLINE __forceinline
112#else
113#define ALWAYS_INLINE inline
114#endif
115
116// Specify memory alignment for structs, classes, etc.
117// Use like:
118//   class ALIGNAS(16) MyClass { ... }
119//   ALIGNAS(16) int array[4];
120#if defined(COMPILER_MSVC)
121#define ALIGNAS(byte_alignment) __declspec(align(byte_alignment))
122#elif defined(COMPILER_GCC)
123#define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
124#endif
125
126// Return the byte alignment of the given type (available at compile time).
127// Use like:
128//   ALIGNOF(int32_t)  // this would be 4
129#if defined(COMPILER_MSVC)
130#define ALIGNOF(type) __alignof(type)
131#elif defined(COMPILER_GCC)
132#define ALIGNOF(type) __alignof__(type)
133#endif
134
135// Annotate a function indicating the caller must examine the return value.
136// Use like:
137//   int foo() WARN_UNUSED_RESULT;
138// To explicitly ignore a result, see |ignore_result()| in base/macros.h.
139#undef WARN_UNUSED_RESULT
140#if defined(COMPILER_GCC) || defined(__clang__)
141#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
142#else
143#define WARN_UNUSED_RESULT
144#endif
145
146// Tell the compiler a function is using a printf-style format string.
147// |format_param| is the one-based index of the format string parameter;
148// |dots_param| is the one-based index of the "..." parameter.
149// For v*printf functions (which take a va_list), pass 0 for dots_param.
150// (This is undocumented but matches what the system C headers do.)
151#if defined(COMPILER_GCC)
152#define PRINTF_FORMAT(format_param, dots_param) \
153    __attribute__((format(printf, format_param, dots_param)))
154#else
155#define PRINTF_FORMAT(format_param, dots_param)
156#endif
157
158// WPRINTF_FORMAT is the same, but for wide format strings.
159// This doesn't appear to yet be implemented in any compiler.
160// See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 .
161#define WPRINTF_FORMAT(format_param, dots_param)
162// If available, it would look like:
163//   __attribute__((format(wprintf, format_param, dots_param)))
164
165// Sanitizers annotations.
166#if defined(__has_attribute)
167#if __has_attribute(no_sanitize)
168#define NO_SANITIZE(what) __attribute__((no_sanitize(what)))
169#endif
170#endif
171#if !defined(NO_SANITIZE)
172#define NO_SANITIZE(what)
173#endif
174
175// MemorySanitizer annotations.
176#if defined(MEMORY_SANITIZER) && !defined(OS_NACL)
177#include <sanitizer/msan_interface.h>
178
179// Mark a memory region fully initialized.
180// Use this to annotate code that deliberately reads uninitialized data, for
181// example a GC scavenging root set pointers from the stack.
182#define MSAN_UNPOISON(p, size)  __msan_unpoison(p, size)
183
184// Check a memory region for initializedness, as if it was being used here.
185// If any bits are uninitialized, crash with an MSan report.
186// Use this to sanitize data which MSan won't be able to track, e.g. before
187// passing data to another process via shared memory.
188#define MSAN_CHECK_MEM_IS_INITIALIZED(p, size) \
189    __msan_check_mem_is_initialized(p, size)
190#else  // MEMORY_SANITIZER
191#define MSAN_UNPOISON(p, size)
192#define MSAN_CHECK_MEM_IS_INITIALIZED(p, size)
193#endif  // MEMORY_SANITIZER
194
195// DISABLE_CFI_PERF -- Disable Control Flow Integrity for perf reasons.
196#if !defined(DISABLE_CFI_PERF)
197#if defined(__clang__) && defined(OFFICIAL_BUILD)
198#define DISABLE_CFI_PERF __attribute__((no_sanitize("cfi")))
199#else
200#define DISABLE_CFI_PERF
201#endif
202#endif
203
204// Macro useful for writing cross-platform function pointers.
205#if !defined(CDECL)
206#if defined(OS_WIN)
207#define CDECL __cdecl
208#else  // defined(OS_WIN)
209#define CDECL
210#endif  // defined(OS_WIN)
211#endif  // !defined(CDECL)
212
213// Macro for hinting that an expression is likely to be false.
214#if !defined(UNLIKELY)
215#if defined(COMPILER_GCC)
216#define UNLIKELY(x) __builtin_expect(!!(x), 0)
217#else
218#define UNLIKELY(x) (x)
219#endif  // defined(COMPILER_GCC)
220#endif  // !defined(UNLIKELY)
221
222#if !defined(LIKELY)
223#if defined(COMPILER_GCC)
224#define LIKELY(x) __builtin_expect(!!(x), 1)
225#else
226#define LIKELY(x) (x)
227#endif  // defined(COMPILER_GCC)
228#endif  // !defined(LIKELY)
229
230// Compiler feature-detection.
231// clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension
232#if defined(__has_feature)
233#define HAS_FEATURE(FEATURE) __has_feature(FEATURE)
234#else
235#define HAS_FEATURE(FEATURE) 0
236#endif
237
238#endif  // BASE_COMPILER_SPECIFIC_H_
239