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

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 <>
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stoklund authored and galak committed May 8, 2019
1 parent e66c0da commit f4f09dd7cdb8a90690f81d1b4c1305532bcefb02
Showing with 34 additions and 0 deletions.
  1. +18 −0 include/toolchain.h
  2. +16 −0 include/toolchain/gcc.h
@@ -15,6 +15,24 @@

* @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)
* 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.

#if defined(__XCC__)
#include <toolchain/xcc.h>
#elif defined(__GNUC__) || (defined(_LINKER) && defined(__GCC_LINKER_CMD__))
@@ -152,6 +152,22 @@ do { \
#define __unused __attribute__((__unused__))

/* Builtins with availability that depend on the compiler version. */
#if __GNUC__ >= 5
#define HAS_BUILTIN___builtin_add_overflow 1
#define HAS_BUILTIN___builtin_sub_overflow 1
#define HAS_BUILTIN___builtin_mul_overflow 1
#define HAS_BUILTIN___builtin_div_overflow 1
#if __GNUC__ >= 4
#define HAS_BUILTIN___builtin_clz 1
#define HAS_BUILTIN___builtin_clzl 1
#define HAS_BUILTIN___builtin_clzll 1
#define HAS_BUILTIN___builtin_ctz 1
#define HAS_BUILTIN___builtin_ctzl 1
#define HAS_BUILTIN___builtin_ctzll 1

/* Be *very* careful with this, you cannot filter out with -wno-deprecated,
* which has implications for -Werror

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