include/lttng/ust-compiler.h

   1 #ifndef _LTTNG_UST_COMPILER_H
   2 #define _LTTNG_UST_COMPILER_H
   3
   4 /*
   5  * Copyright 2011-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *                       Paul Woegerer <paul_woegerer@mentor.com>
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  24  * SOFTWARE.
  25  */
  26
  27 #include <assert.h>
  28
  29 #define lttng_ust_notrace __attribute__((no_instrument_function))
  30 #define LTTNG_PACKED    __attribute__((__packed__))
  31
  32 /*
  33  * Clang supports the no_sanitize variable attribute on global variables.
  34  * GCC only supports the no_sanitize_address function attribute, which is
  35  * not what we need.
  36  */
  37 #if defined(__clang__)
  38 # if __has_feature(address_sanitizer)
  39 #  define __lttng_ust_variable_attribute_no_sanitize_address \
  40         __attribute__((no_sanitize("address")))
  41 # else
  42 #  define __lttng_ust_variable_attribute_no_sanitize_address
  43 # endif
  44 #else
  45 #  define __lttng_ust_variable_attribute_no_sanitize_address
  46 #endif
  47
  48 /*
  49  * g++ 4.8 and prior do not support C99 compound literals. Therefore,
  50  * force allocating those on the heap with these C++ compilers.
  51  */
  52 #if defined (__cplusplus) && defined (__GNUC__) && \
  53         (__GNUC__ < 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ <= 8))
  54 # ifndef LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
  55 #  define LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
  56 # endif
  57 #endif
  58
  59 /*
  60  * Compound literals with static storage are needed by LTTng.
  61  * Compound literals are part of the C99 and C11 standards, but not
  62  * part of the C++ standards. However, those are supported by both g++ and
  63  * clang. In order to be strictly C++11 compliant, defining
  64  * LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP before including this header
  65  * allocates those on the heap in C++.
  66  *
  67  * Example use:
  68  * static struct mystruct *var = __LTTNG_COMPOUND_LITERAL(struct mystruct, { 1, 2, 3 });
  69  */
  70 #if defined (__cplusplus) && defined (LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP)
  71 #define __LTTNG_COMPOUND_LITERAL(type, ...)     new (type) __VA_ARGS__
  72 #else
  73 #define __LTTNG_COMPOUND_LITERAL(type, ...)     (type[]) { __VA_ARGS__ }
  74 #endif
  75
  76 /*
  77  * Compile time assertion.
  78  * - predicate: boolean expression to evaluate,
  79  * - msg: string to print to the user on failure when `static_assert()` is
  80  *   supported,
  81  * - c_identifier_msg: message to be included in the typedef to emulate a
  82  *   static assertion. This parameter must be a valid C identifier as it will
  83  *   be used as a typedef name.
  84  */
  85 #if defined (__cplusplus) || __STDC_VERSION__ >= 201112L
  86 #define lttng_static_assert(predicate, msg, c_identifier_msg)  \
  87         static_assert(predicate, msg)
  88 #else
  89 /*
  90  * Evaluates the predicate and emit a compilation error on failure.
  91  *
  92  * If the predicate evaluates to true, this macro emits a typedef of an array
  93  * of size 0.
  94  *
  95  * If the predicate evaluates to false, this macro emits a typedef of an array
  96  * of negative size which is invalid in C and forces a compiler error. The msg
  97  * parameter is used in the tentative typedef so it is printed to the user.
  98  */
  99 #define lttng_static_assert(predicate, msg, c_identifier_msg)  \
 100     typedef char lttng_static_assert_##c_identifier_msg[2*!!(predicate)-1];
 101 #endif
 102
 103 #endif /* _LTTNG_UST_COMPILER_H */