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 <jolesen@fb.com>
2 files changed
