Commit 9bf6557585f9d5df1b2c8cfc1e20f93eb38a27fd
2021-08-13T06:36:49
Correctly check for bswap builtins before using 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
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diff --git a/include/SDL_endian.h b/include/SDL_endian.h
index 205b793..9f88cb1 100644
--- a/include/SDL_endian.h
+++ b/include/SDL_endian.h
@@ -91,7 +91,7 @@ extern "C" {
/**
* \file SDL_endian.h
*/
-#if (defined(__clang__) && (__clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 2))) || \
+#if (_SDL_HAS_BUILTIN(__builtin_bswap16)) || \
(defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))
#define SDL_Swap16(x) __builtin_bswap16(x)
#elif defined(__GNUC__) && defined(__i386__) && \
@@ -149,7 +149,7 @@ SDL_Swap16(Uint16 x)
}
#endif
-#if (defined(__clang__) && (__clang_major__ > 2 || (__clang_major__ == 2 && __clang_minor__ >= 6))) || \
+#if (_SDL_HAS_BUILTIN(__builtin_bswap32)) || \
(defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
#define SDL_Swap32(x) __builtin_bswap32(x)
#elif defined(__GNUC__) && defined(__i386__) && \
@@ -210,7 +210,7 @@ SDL_Swap32(Uint32 x)
}
#endif
-#if (defined(__clang__) && (__clang_major__ > 2 || (__clang_major__ == 2 && __clang_minor__ >= 6))) || \
+#if (_SDL_HAS_BUILTIN(__builtin_bswap64)) || \
(defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)))
#define SDL_Swap64(x) __builtin_bswap64(x)
#elif defined(__GNUC__) && defined(__i386__) && \
diff --git a/include/SDL_stdinc.h b/include/SDL_stdinc.h
index 3732854..c7f9068 100644
--- a/include/SDL_stdinc.h
+++ b/include/SDL_stdinc.h
@@ -116,6 +116,17 @@ char *alloca();
#endif
/**
+ * Check if the compiler supports a given builtin.
+ * Supported by virtually all clang versions and recent gcc. Use this
+ * instead of checking the clang version if possible.
+ */
+#ifdef __has_builtin
+#define _SDL_HAS_BUILTIN(x) __has_builtin(x)
+#else
+#define _SDL_HAS_BUILTIN(x) 0
+#endif
+
+/**
* The number of elements in an array.
*/
#define SDL_arraysize(array) (sizeof(array)/sizeof(array[0]))