/* * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2016, 2017 Nicira, Inc. * * 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 OPENVSWITCH_COMPILER_H #define OPENVSWITCH_COMPILER_H 1 #include #include #ifndef __has_feature #define __has_feature(x) 0 #endif #ifndef __has_extension #define __has_extension(x) 0 #endif /* To make OVS_NO_RETURN portable across gcc/clang and MSVC, it should be * added at the beginning of the function declaration. */ #if __GNUC__ && !__CHECKER__ #define OVS_NO_RETURN __attribute__((__noreturn__)) #elif _MSC_VER #define OVS_NO_RETURN __declspec(noreturn) #else #define OVS_NO_RETURN #endif #if __GNUC__ && !__CHECKER__ #define OVS_UNUSED __attribute__((__unused__)) #define OVS_PRINTF_FORMAT(FMT, ARG1) __attribute__((__format__(printf, FMT, ARG1))) #define OVS_SCANF_FORMAT(FMT, ARG1) __attribute__((__format__(scanf, FMT, ARG1))) #define OVS_WARN_UNUSED_RESULT __attribute__((__warn_unused_result__)) #define OVS_LIKELY(CONDITION) __builtin_expect(!!(CONDITION), 1) #define OVS_UNLIKELY(CONDITION) __builtin_expect(!!(CONDITION), 0) #else #define OVS_UNUSED #define OVS_PRINTF_FORMAT(FMT, ARG1) #define OVS_SCANF_FORMAT(FMT, ARG1) #define OVS_WARN_UNUSED_RESULT #define OVS_LIKELY(CONDITION) (!!(CONDITION)) #define OVS_UNLIKELY(CONDITION) (!!(CONDITION)) #endif #if __has_feature(c_thread_safety_attributes) /* "clang" annotations for thread safety check. * * OVS_LOCKABLE indicates that the struct contains mutex element * which can be locked by functions like ovs_mutex_lock(). * * Below, the word MUTEX stands for the name of an object with an OVS_LOCKABLE * struct type. It can also be a comma-separated list of multiple structs, * e.g. to require a function to hold multiple locks while invoked. * * * On a variable: * * - OVS_GUARDED indicates that the variable may only be accessed some mutex * is held. * * - OVS_GUARDED_BY(MUTEX) indicates that the variable may only be accessed * while the specific MUTEX is held. * * * On a variable A of mutex type: * * - OVS_ACQ_BEFORE(B), where B is a mutex or a comma-separated list of * mutexes, declare that if both A and B are acquired at the same time, * then A must be acquired before B. That is, B nests inside A. * * - OVS_ACQ_AFTER(B) is the opposite of OVS_ACQ_BEFORE(B), that is, it * declares that A nests inside B. * * * On a function, the following attributes apply to mutexes: * * - OVS_ACQUIRES(MUTEX) indicate that the function must be called without * holding MUTEX and that it returns holding MUTEX. * * - OVS_RELEASES(MUTEX) indicates that the function may only be called with * MUTEX held and that it returns with MUTEX released. It can be used for * all types of MUTEX. * * - OVS_TRY_LOCK(RETVAL, MUTEX) indicate that the function will try to * acquire MUTEX. RETVAL is an integer or boolean value specifying the * return value of a successful lock acquisition. * * - OVS_REQUIRES(MUTEX) indicate that the function may only be called with * MUTEX held and that the function does not release MUTEX. * * - OVS_EXCLUDED(MUTEX) indicates that the function may only be called when * MUTEX is not held. * * * The following variants, with the same syntax, apply to reader-writer locks: * * mutex rwlock, for reading rwlock, for writing * ------------------- ------------------- ------------------- * OVS_ACQUIRES OVS_ACQ_RDLOCK OVS_ACQ_WRLOCK * OVS_RELEASES OVS_RELEASES OVS_RELEASES * OVS_TRY_LOCK OVS_TRY_RDLOCK OVS_TRY_WRLOCK * OVS_REQUIRES OVS_REQ_RDLOCK OVS_REQ_WRLOCK * OVS_EXCLUDED OVS_EXCLUDED OVS_EXCLUDED */ /* Please keep OVS_CTAGS_IDENTIFIERS up-to-date in acinclude.m4. */ #define OVS_LOCKABLE __attribute__((lockable)) #define OVS_REQ_RDLOCK(...) __attribute__((shared_locks_required(__VA_ARGS__))) #define OVS_ACQ_RDLOCK(...) __attribute__((shared_lock_function(__VA_ARGS__))) #define OVS_REQ_WRLOCK(...) \ __attribute__((exclusive_locks_required(__VA_ARGS__))) #define OVS_ACQ_WRLOCK(...) \ __attribute__((exclusive_lock_function(__VA_ARGS__))) #define OVS_REQUIRES(...) \ __attribute__((exclusive_locks_required(__VA_ARGS__))) #define OVS_ACQUIRES(...) \ __attribute__((exclusive_lock_function(__VA_ARGS__))) #define OVS_TRY_WRLOCK(RETVAL, ...) \ __attribute__((exclusive_trylock_function(RETVAL, __VA_ARGS__))) #define OVS_TRY_RDLOCK(RETVAL, ...) \ __attribute__((shared_trylock_function(RETVAL, __VA_ARGS__))) #define OVS_TRY_LOCK(RETVAL, ...) \ __attribute__((exclusive_trylock_function(RETVAL, __VA_ARGS__))) #define OVS_GUARDED __attribute__((guarded_var)) #define OVS_GUARDED_BY(...) __attribute__((guarded_by(__VA_ARGS__))) #define OVS_RELEASES(...) __attribute__((unlock_function(__VA_ARGS__))) #define OVS_EXCLUDED(...) __attribute__((locks_excluded(__VA_ARGS__))) #define OVS_ACQ_BEFORE(...) __attribute__((acquired_before(__VA_ARGS__))) #define OVS_ACQ_AFTER(...) __attribute__((acquired_after(__VA_ARGS__))) #define OVS_NO_THREAD_SAFETY_ANALYSIS \ __attribute__((no_thread_safety_analysis)) #else /* not Clang */ #define OVS_LOCKABLE #define OVS_REQ_RDLOCK(...) #define OVS_ACQ_RDLOCK(...) #define OVS_REQ_WRLOCK(...) #define OVS_ACQ_WRLOCK(...) #define OVS_REQUIRES(...) #define OVS_ACQUIRES(...) #define OVS_TRY_WRLOCK(...) #define OVS_TRY_RDLOCK(...) #define OVS_TRY_LOCK(...) #define OVS_GUARDED #define OVS_GUARDED_BY(...) #define OVS_EXCLUDED(...) #define OVS_RELEASES(...) #define OVS_ACQ_BEFORE(...) #define OVS_ACQ_AFTER(...) #define OVS_NO_THREAD_SAFETY_ANALYSIS #endif /* ISO C says that a C implementation may choose any integer type for an enum * that is sufficient to hold all of its values. Common ABIs (such as the * System V ABI used on i386 GNU/Linux) always use a full-sized "int", even * when a smaller type would suffice. * * In GNU C, "enum __attribute__((packed)) name { ... }" defines 'name' as an * enum compatible with a type that is no bigger than necessary. This is the * intended use of OVS_PACKED_ENUM. * * OVS_PACKED_ENUM is intended for use only as a space optimization, since it * only works with GCC. That means that it must not be used in wire protocols * or otherwise exposed outside of a single process. */ #if __GNUC__ && !__CHECKER__ #define OVS_PACKED_ENUM __attribute__((__packed__)) #define HAVE_PACKED_ENUM #else #define OVS_PACKED_ENUM #endif #ifndef _MSC_VER #define OVS_PACKED(DECL) DECL __attribute__((__packed__)) #else #define OVS_PACKED(DECL) __pragma(pack(push, 1)) DECL __pragma(pack(pop)) #endif /* OVS_ALIGNED_STRUCT may be used to define a structure whose instances should * aligned on an N-byte boundary. This: * OVS_ALIGNED_STRUCT(64, mystruct) { ... }; * is equivalent to the following except that it specifies 64-byte alignment: * struct mystruct { ... }; * * OVS_ALIGNED_VAR defines a variable aligned on an N-byte boundary. For * example, * OVS_ALIGNED_VAR(64) int x; * defines a "int" variable that is aligned on a 64-byte boundary. */ #ifndef _MSC_VER #define OVS_ALIGNED_STRUCT(N, TAG) struct __attribute__((aligned(N))) TAG #define OVS_ALIGNED_VAR(N) __attribute__((aligned(N))) #else #define OVS_ALIGNED_STRUCT(N, TAG) __declspec(align(N)) struct TAG #define OVS_ALIGNED_VAR(N) __declspec(align(N)) #endif /* Supplies code to be run at startup time before invoking main(). * Use as: * * OVS_CONSTRUCTOR(my_constructor) { * ...some code... * } */ #ifdef _MSC_VER #define CCALL __cdecl #pragma section(".CRT$XCU",read) #define OVS_CONSTRUCTOR(f) \ static void __cdecl f(void); \ __declspec(allocate(".CRT$XCU")) static void (__cdecl*f##_)(void) = f; \ static void __cdecl f(void) #else #define OVS_CONSTRUCTOR(f) \ static void f(void) __attribute__((constructor)); \ static void f(void) #endif /* OVS_PREFETCH() can be used to instruct the CPU to fetch the cache * line containing the given address to a CPU cache. * OVS_PREFETCH_WRITE() should be used when the memory is going to be * written to. Depending on the target CPU, this can generate the same * instruction as OVS_PREFETCH(), or bring the data into the cache in an * exclusive state. */ #if __GNUC__ #define OVS_PREFETCH(addr) __builtin_prefetch((addr)) #define OVS_PREFETCH_WRITE(addr) __builtin_prefetch((addr), 1) #else #define OVS_PREFETCH(addr) #define OVS_PREFETCH_WRITE(addr) #endif /* Since Visual Studio 2015 there has been an effort to make offsetof a * builtin_offsetof, unfortunately both implementation (the regular define and * the built in one) are buggy and cause issues when using them via * the C compiler. * e.g.: https://bit.ly/2UvWwti */ #if _MSC_VER >= 1900 #undef offsetof #define offsetof(type, member) \ ((size_t)((char *)&(((type *)0)->member) - (char *)0)) #endif /* Build assertions. * * Use BUILD_ASSERT_DECL as a declaration or a statement, or BUILD_ASSERT as * part of an expression. */ #ifdef __CHECKER__ #define BUILD_ASSERT(EXPR) ((void) 0) #define BUILD_ASSERT_DECL(EXPR) extern int (*build_assert(void))[1] #elif defined(__cplusplus) && __cplusplus >= 201103L #define BUILD_ASSERT(EXPR) static_assert(EXPR, "assertion failed") #define BUILD_ASSERT_DECL(EXPR) static_assert(EXPR, "assertion failed") #elif defined(__cplusplus) && __cplusplus < 201103L #include #define BUILD_ASSERT BOOST_STATIC_ASSERT #define BUILD_ASSERT_DECL BOOST_STATIC_ASSERT #elif (__GNUC__ * 256 + __GNUC_MINOR__ >= 0x403 \ || __has_extension(c_static_assert)) #define BUILD_ASSERT_DECL(EXPR) _Static_assert(EXPR, #EXPR) #define BUILD_ASSERT(EXPR) (void) ({ _Static_assert(EXPR, #EXPR); }) #else #define BUILD_ASSERT__(EXPR) \ sizeof(struct { unsigned int build_assert_failed : (EXPR) ? 1 : -1; }) #define BUILD_ASSERT(EXPR) (void) BUILD_ASSERT__(EXPR) #define BUILD_ASSERT_DECL(EXPR) \ extern int (*build_assert(void))[BUILD_ASSERT__(EXPR)] #endif #ifdef __GNUC__ #define BUILD_ASSERT_GCCONLY(EXPR) BUILD_ASSERT(EXPR) #define BUILD_ASSERT_DECL_GCCONLY(EXPR) BUILD_ASSERT_DECL(EXPR) #else #define BUILD_ASSERT_GCCONLY(EXPR) ((void) 0) #define BUILD_ASSERT_DECL_GCCONLY(EXPR) ((void) 0) #endif #endif /* compiler.h */