[lttng-ust.git] / include / lttng / ust-compiler.h

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 * Copyright (C) 2011-2012 Paul Woegerer <paul_woegerer@mentor.com>
 */

#ifndef _LTTNG_UST_COMPILER_H
#define _LTTNG_UST_COMPILER_H

#include <assert.h>

#define lttng_ust_notrace __attribute__((no_instrument_function))

/*
 * Clang supports the no_sanitize variable attribute on global variables.
 * GCC only supports the no_sanitize_address function attribute, which is
 * not what we need.
 */
#if defined(__clang__)
# if __has_feature(address_sanitizer)
#  define __lttng_ust_variable_attribute_no_sanitize_address \
	__attribute__((no_sanitize("address")))
# else
#  define __lttng_ust_variable_attribute_no_sanitize_address
# endif
#else
#  define __lttng_ust_variable_attribute_no_sanitize_address
#endif

/*
 * g++ 4.8 and prior do not support C99 compound literals. Therefore,
 * force allocating those on the heap with these C++ compilers.
 */
#if defined (__cplusplus) && defined (__GNUC__) && \
	(__GNUC__ < 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ <= 8))
# ifndef LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
#  define LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
# endif
#endif

/*
 * Compound literals with static storage are needed by LTTng.
 * Compound literals are part of the C99 and C11 standards, but not
 * part of the C++ standards. However, those are supported by both g++ and
 * clang. In order to be strictly C++11 compliant, defining
 * LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP before including this header
 * allocates those on the heap in C++.
 *
 * Example use:
 * static struct mystruct *var = LTTNG_UST_COMPOUND_LITERAL(struct mystruct, { 1, 2, 3 });
 */
#if defined (__cplusplus) && defined (LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP)
#define LTTNG_UST_COMPOUND_LITERAL(type, ...)	new (type) __VA_ARGS__
#else
#define LTTNG_UST_COMPOUND_LITERAL(type, ...)	(type[]) { __VA_ARGS__ }
#endif

/*
 * Compile time assertion.
 * - predicate: boolean expression to evaluate,
 * - msg: string to print to the user on failure when `static_assert()` is
 *   supported,
 * - c_identifier_msg: message to be included in the typedef to emulate a
 *   static assertion. This parameter must be a valid C identifier as it will
 *   be used as a typedef name.
 */
#if defined (__cplusplus) || __STDC_VERSION__ >= 201112L
#define lttng_ust_static_assert(predicate, msg, c_identifier_msg)  \
	static_assert(predicate, msg)
#else
/*
 * Evaluates the predicate and emit a compilation error on failure.
 *
 * If the predicate evaluates to true, this macro emits a typedef of an array
 * of size 0.
 *
 * If the predicate evaluates to false, this macro emits a typedef of an array
 * of negative size which is invalid in C and forces a compiler error. The msg
 * parameter is used in the tentative typedef so it is printed to the user.
 */
#define lttng_ust_static_assert(predicate, msg, c_identifier_msg)  \
    typedef char lttng_ust_static_assert_##c_identifier_msg[2*!!(predicate)-1]
#endif

#endif /* _LTTNG_UST_COMPILER_H */
Commit	Line	Data
	1	/*
	2	* SPDX-License-Identifier: MIT
	3	*
	4	* Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	* Copyright (C) 2011-2012 Paul Woegerer <paul_woegerer@mentor.com>
	6	*/
	7
	8	#ifndef _LTTNG_UST_COMPILER_H
	9	#define _LTTNG_UST_COMPILER_H
	10
	11	#include <assert.h>
	12
	13	#define lttng_ust_notrace __attribute__((no_instrument_function))
	14
	15	/*
	16	* Clang supports the no_sanitize variable attribute on global variables.
	17	* GCC only supports the no_sanitize_address function attribute, which is
	18	* not what we need.
	19	*/
	20	#if defined(__clang__)
	21	# if __has_feature(address_sanitizer)
	22	# define __lttng_ust_variable_attribute_no_sanitize_address \
	23	__attribute__((no_sanitize("address")))
	24	# else
	25	# define __lttng_ust_variable_attribute_no_sanitize_address
	26	# endif
	27	#else
	28	# define __lttng_ust_variable_attribute_no_sanitize_address
	29	#endif
	30
	31	/*
	32	* g++ 4.8 and prior do not support C99 compound literals. Therefore,
	33	* force allocating those on the heap with these C++ compilers.
	34	*/
	35	#if defined (__cplusplus) && defined (__GNUC__) && \
	36	(__GNUC__ < 4) \|\| ((__GNUC__ == 4) && (__GNUC_MINOR__ <= 8))
	37	# ifndef LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
	38	# define LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
	39	# endif
	40	#endif
	41
	42	/*
	43	* Compound literals with static storage are needed by LTTng.
	44	* Compound literals are part of the C99 and C11 standards, but not
	45	* part of the C++ standards. However, those are supported by both g++ and
	46	* clang. In order to be strictly C++11 compliant, defining
	47	* LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP before including this header
	48	* allocates those on the heap in C++.
	49	*
	50	* Example use:
	51	* static struct mystruct *var = LTTNG_UST_COMPOUND_LITERAL(struct mystruct, { 1, 2, 3 });
	52	*/
	53	#if defined (__cplusplus) && defined (LTTNG_UST_ALLOCATE_COMPOUND_LITERAL_ON_HEAP)
	54	#define LTTNG_UST_COMPOUND_LITERAL(type, ...) new (type) __VA_ARGS__
	55	#else
	56	#define LTTNG_UST_COMPOUND_LITERAL(type, ...) (type[]) { __VA_ARGS__ }
	57	#endif
	58
	59	/*
	60	* Compile time assertion.
	61	* - predicate: boolean expression to evaluate,
	62	* - msg: string to print to the user on failure when `static_assert()` is
	63	* supported,
	64	* - c_identifier_msg: message to be included in the typedef to emulate a
	65	* static assertion. This parameter must be a valid C identifier as it will
	66	* be used as a typedef name.
	67	*/
	68	#if defined (__cplusplus) \|\| __STDC_VERSION__ >= 201112L
	69	#define lttng_ust_static_assert(predicate, msg, c_identifier_msg) \
	70	static_assert(predicate, msg)
	71	#else
	72	/*
	73	* Evaluates the predicate and emit a compilation error on failure.
	74	*
	75	* If the predicate evaluates to true, this macro emits a typedef of an array
	76	* of size 0.
	77	*
	78	* If the predicate evaluates to false, this macro emits a typedef of an array
	79	* of negative size which is invalid in C and forces a compiler error. The msg
	80	* parameter is used in the tentative typedef so it is printed to the user.
	81	*/
	82	#define lttng_ust_static_assert(predicate, msg, c_identifier_msg) \
	83	typedef char lttng_ust_static_assert_##c_identifier_msg[2*!!(predicate)-1]
	84	#endif
	85
	86	#endif /* _LTTNG_UST_COMPILER_H */