The asm has been reported broken in at least optimized Apple M1 builds;
and besides, the compiler builtins have precedence over the asm anyway.
Closes https://github.com/libsdl-org/SDL/issues/3943
The __clang_major__ and __clang_minor__ macros provide a marketing
version, which is not necessarily comparable for clang distributions
from different vendors[1]. In practice, the versioning scheme for
Apple's clang is indeed completely different to that of the llvm.org
releases. It is thus preferable to check for features directly rather
than comparing versions.
In this specific case, __builtin_bswap16 was being used with older
Apple clang versions that don't support it.
[1] https://clang.llvm.org/docs/LanguageExtensions.html#builtin-macros
vladius
In SDL_cpuinfo.h it seems like <intrin.h> is not included when __clang__ is defined, as the comment in the file explicitly reads:
"Many of the intrinsics SDL uses are not implemented by clang with Visual Studio"
However, the SDL_endian.h header does include <intrin.h> without any precautions like:
>#ifdef _MSC_VER
>#include <intrin.h>
>#endif
Maybe it should be changed to something like:
>#ifdef _MSC_VER
>#ifndef __clang__
>#include <intrin.h>
>#endif
>#endif
__builtin_bswap32/64 were introduced in GCC 4.3. __builtin_bswap16 was
not available on x86 until GCC 4.8 due to a bug.
__builtin_bswap32/64 were introduced in Clang 2.6. __builtin_bswap16
was introduced in Clang 3.2.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
