[PULL 6/9] include/qemu: Use builtins for bswap

[Richard Henderson]

All supported compilers have builtins for this.
Drop all of the complicated system detection stuff.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210708181743.750220-1-richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 meson.build          |  6 -----
 include/qemu/bswap.h | 53 +++-----------------------------------------
 2 files changed, 3 insertions(+), 56 deletions(-)

diff --git a/meson.build b/meson.build
index 9a64d16943..306797c604 100644
--- a/meson.build
+++ b/meson.build
@@ -1332,8 +1332,6 @@ config_host_data.set('HAVE_STRCHRNUL', 
cc.has_function('strchrnul'))
 config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system', prefix: 
'#include <stdlib.h>'))
 
 # has_header_symbol
-config_host_data.set('CONFIG_BYTESWAP_H',
-                     cc.has_header_symbol('byteswap.h', 'bswap_32'))
 config_host_data.set('CONFIG_EPOLL_CREATE1',
                      cc.has_header_symbol('sys/epoll.h', 'epoll_create1'))
 config_host_data.set('CONFIG_HAS_ENVIRON',
@@ -1353,10 +1351,6 @@ config_host_data.set('CONFIG_INOTIFY',
                      cc.has_header_symbol('sys/inotify.h', 'inotify_init'))
 config_host_data.set('CONFIG_INOTIFY1',
                      cc.has_header_symbol('sys/inotify.h', 'inotify_init1'))
-config_host_data.set('CONFIG_MACHINE_BSWAP_H',
-                     cc.has_header_symbol('machine/bswap.h', 'bswap32',
-                                          prefix: '''#include <sys/endian.h>
-                                                     #include 
<sys/types.h>'''))
 config_host_data.set('CONFIG_PRCTL_PR_SET_TIMERSLACK',
                      cc.has_header_symbol('sys/prctl.h', 'PR_SET_TIMERSLACK'))
 config_host_data.set('CONFIG_RTNETLINK',
diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
index 2d3bb8bbed..9e12bd8073 100644
--- a/include/qemu/bswap.h
+++ b/include/qemu/bswap.h
@@ -1,73 +1,26 @@
 #ifndef BSWAP_H
 #define BSWAP_H
 
-#ifdef CONFIG_MACHINE_BSWAP_H
-# include <sys/endian.h>
-# include <machine/bswap.h>
-#elif defined(__FreeBSD__)
-# include <sys/endian.h>
-#elif defined(__HAIKU__)
-# include <endian.h>
-#elif defined(CONFIG_BYTESWAP_H)
-# include <byteswap.h>
-#define BSWAP_FROM_BYTESWAP
-# else
-#define BSWAP_FROM_FALLBACKS
-#endif /* ! CONFIG_MACHINE_BSWAP_H */
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #include "fpu/softfloat-types.h"
 
-#ifdef BSWAP_FROM_BYTESWAP
 static inline uint16_t bswap16(uint16_t x)
 {
-    return bswap_16(x);
+    return __builtin_bswap16(x);
 }
 
 static inline uint32_t bswap32(uint32_t x)
 {
-    return bswap_32(x);
+    return __builtin_bswap32(x);
 }
 
 static inline uint64_t bswap64(uint64_t x)
 {
-    return bswap_64(x);
+    return __builtin_bswap64(x);
 }
-#endif
-
-#ifdef BSWAP_FROM_FALLBACKS
-static inline uint16_t bswap16(uint16_t x)
-{
-    return (((x & 0x00ff) << 8) |
-            ((x & 0xff00) >> 8));
-}
-
-static inline uint32_t bswap32(uint32_t x)
-{
-    return (((x & 0x000000ffU) << 24) |
-            ((x & 0x0000ff00U) <<  8) |
-            ((x & 0x00ff0000U) >>  8) |
-            ((x & 0xff000000U) >> 24));
-}
-
-static inline uint64_t bswap64(uint64_t x)
-{
-    return (((x & 0x00000000000000ffULL) << 56) |
-            ((x & 0x000000000000ff00ULL) << 40) |
-            ((x & 0x0000000000ff0000ULL) << 24) |
-            ((x & 0x00000000ff000000ULL) <<  8) |
-            ((x & 0x000000ff00000000ULL) >>  8) |
-            ((x & 0x0000ff0000000000ULL) >> 24) |
-            ((x & 0x00ff000000000000ULL) >> 40) |
-            ((x & 0xff00000000000000ULL) >> 56));
-}
-#endif
-
-#undef BSWAP_FROM_BYTESWAP
-#undef BSWAP_FROM_FALLBACKS
 
 static inline void bswap16s(uint16_t *s)
 {
-- 
2.25.1