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toolchain: Define a HAS_BUILTIN(x) macro in toolchain.h.

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Compilers based on Clang provide a __has_builtin(x) macro which can be
used to detect in the preprocessor if a given builtin function is
supported by the compiler.

For other compilers (notably GCC), we provide an alternative definition
of HAS_BUILTIN(x) that depends on the toolchain-specific header file to
declare which builtin functions are supported based on the current
compiler version.

Signed-off-by: Jakob Olesen <jolesen@fb.com>
This commit is contained in:
Jakob Olesen 2019-05-08 15:46:07 -07:00 • committed by Kumar Gala
commit f4f09dd7cd
2 changed files with 34 additions and 0 deletions
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18
include/toolchain.h
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@ -15,6 +15,24 @@
#ifndef ZEPHYR_INCLUDE_TOOLCHAIN_H_
#define ZEPHYR_INCLUDE_TOOLCHAIN_H_
/**
* @def HAS_BUILTIN(x)
* @brief Check if the compiler supports the built-in function \a x.
*
* This macro is for use with conditional compilation to enable code using a
* builtin function that may not be available in every compiler.
*/
#ifdef __has_builtin
#define HAS_BUILTIN(x) __has_builtin(x)
#else
/*
* The compiler doesn't provide the __has_builtin() macro, so instead we depend
* on the toolchain-specific headers to define HAS_BUILTIN_x for the builtins
* supported.
*/
#define HAS_BUILTIN(x) HAS_BUILTIN_##x
#endif
#if defined(__XCC__)
#include <toolchain/xcc.h>
#elif defined(__GNUC__) || (defined(_LINKER) && defined(__GCC_LINKER_CMD__))