endian: Replace explicit byte swapping with compiler builtin

gcc seems to have some stupid problem with deciding when to inline byte
swapping functions (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92716).
Using the compiler builtin instead seems to solve the problem.

(This doesn't yet solve the issue for the read_be32()-family of
functions, which we should maybe just get rid of at some point?)

Change-Id: Ia2a6d8ea98987266ccc32ffaa0a7f78965fca1cd
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37343
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

2 files changed, 6 insertions, 67 deletions

diff --git a/payloads/libpayload/include/endian.h b/payloads/libpayload/include/endian.h
index ec0825dc31..dee45f227b 100644
--- a/payloads/libpayload/include/endian.h
+++ b/payloads/libpayload/include/endian.h
@@ -34,23 +34,6 @@
 #include <arch/types.h>
 #include <libpayload-config.h>
 
-static inline uint16_t swap_bytes16(uint16_t in)
-{
-	return ((in & 0xFF) << 8) | ((in & 0xFF00) >> 8);
-}
-
-static inline uint32_t swap_bytes32(uint32_t in)
-{
-	return ((in & 0xFF) << 24) | ((in & 0xFF00) << 8) |
-		((in & 0xFF0000) >> 8) | ((in & 0xFF000000) >> 24);
-}
-
-static inline uint64_t swap_bytes64(uint64_t in)
-{
-	return ((uint64_t)swap_bytes32((uint32_t)in) << 32) |
-		((uint64_t)swap_bytes32((uint32_t)(in >> 32)));
-}
-
 /* Endian functions from glibc 2.9 / BSD "endian.h" */
 
 #if CONFIG(LP_BIG_ENDIAN)
@@ -59,15 +42,15 @@ static inline uint64_t swap_bytes64(uint64_t in)
 #define htobe32(in) (in)
 #define htobe64(in) (in)
 
-#define htole16(in) swap_bytes16(in)
-#define htole32(in) swap_bytes32(in)
-#define htole64(in) swap_bytes64(in)
+#define htole16(in) ((uint16_t)__builtin_bswap16(in))
+#define htole32(in) ((uint32_t)__builtin_bswap32(in))
+#define htole64(in) ((uint64_t)__builtin_bswap64(in))
 
 #elif CONFIG(LP_LITTLE_ENDIAN)
 
-#define htobe16(in) swap_bytes16(in)
-#define htobe32(in) swap_bytes32(in)
-#define htobe64(in) swap_bytes64(in)
+#define htobe16(in) ((uint16_t)__builtin_bswap16(in))
+#define htobe32(in) ((uint32_t)__builtin_bswap32(in))
+#define htobe64(in) ((uint64_t)__builtin_bswap64(in))
 
 #define htole16(in) (in)
 #define htole32(in) (in)
diff --git a/payloads/libpayload/include/swab.h b/payloads/libpayload/include/swab.h
deleted file mode 100644
index 2198077ad2..0000000000
--- a/payloads/libpayload/include/swab.h
+++ /dev/null
@@ -1,44 +0,0 @@
-#ifndef _SWAB_H
-#define _SWAB_H
-
-/*
- * linux/byteorder/swab.h
- * Byte-swapping, independently from CPU endianness
- *	swabXX[ps]?(foo)
- *
- * Francois-Rene Rideau <fare@tunes.org> 19971205
- *    separated swab functions from cpu_to_XX,
- *    to clean up support for bizarre-endian architectures.
- *
- * See asm-i386/byteorder.h and suches for examples of how to provide
- * architecture-dependent optimized versions
- *
- */
-
-/* casts are necessary for constants, because we never know for sure
- * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
- */
-#define swab16(x) \
-	((unsigned short)( \
-		(((unsigned short)(x) & (unsigned short)0x00ffU) << 8) | \
-		(((unsigned short)(x) & (unsigned short)0xff00U) >> 8)))
-
-#define swab32(x) \
-	((unsigned int)( \
-		(((unsigned int)(x) & (unsigned int)0x000000ffUL) << 24) | \
-		(((unsigned int)(x) & (unsigned int)0x0000ff00UL) <<  8) | \
-		(((unsigned int)(x) & (unsigned int)0x00ff0000UL) >>  8) | \
-		(((unsigned int)(x) & (unsigned int)0xff000000UL) >> 24)))
-
-#define swab64(x) \
-	((uint64_t)( \
-		(((uint64_t)(x) & (uint64_t)0x00000000000000ffULL) << 56) | \
-		(((uint64_t)(x) & (uint64_t)0x000000000000ff00ULL) << 40) | \
-		(((uint64_t)(x) & (uint64_t)0x0000000000ff0000ULL) << 24) | \
-		(((uint64_t)(x) & (uint64_t)0x00000000ff000000ULL) <<  8) | \
-		(((uint64_t)(x) & (uint64_t)0x000000ff00000000ULL) >>  8) | \
-		(((uint64_t)(x) & (uint64_t)0x0000ff0000000000ULL) >> 24) | \
-		(((uint64_t)(x) & (uint64_t)0x00ff000000000000ULL) >> 40) | \
-		(((uint64_t)(x) & (uint64_t)0xff00000000000000ULL) >> 56)))
-
-#endif /* _SWAB_H */