libgcc: Fix __gthr_i486_lock_cmp_xchg clobber for Windows

2022-01-14  David  <gccbugzilla@limegreensocks.com>

libgcc/
	* config/i386/gthr-win32.c (__gthr_i486_lock_cmp_xchg):
	Remove inlined version, Windows 95 is no longer relevant.
	* config/i386/gthr-win32.h
	(__GTHREAD_I486_INLINE_LOCK_PRIMITIVES): unset.

diff --git a/libgcc/config/i386/gthr-win32.c b/libgcc/config/i386/gthr-win32.c
index 0ad29be..fad8f8a 100644 (file)
--- a/libgcc/config/i386/gthr-win32.c
+++ b/libgcc/config/i386/gthr-win32.c
@@ -31,8 +31,6 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #ifndef __GTHREAD_HIDE_WIN32API
 # define __GTHREAD_HIDE_WIN32API 1
 #endif
-#undef  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
-#define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
 #include "gthr-win32.h"
 
 /* Windows32 threads specific definitions. The windows32 threading model

diff --git a/libgcc/config/i386/gthr-win32.h b/libgcc/config/i386/gthr-win32.h
index cbc7a2d..6f70e9b 100644 (file)
--- a/libgcc/config/i386/gthr-win32.h
+++ b/libgcc/config/i386/gthr-win32.h
@@ -374,28 +374,9 @@ extern int _CRT_MT;
 extern int __mingwthr_key_dtor (unsigned long, void (*) (void *));
 #endif /* _WIN32 && !__CYGWIN__ */
 
-/* The Windows95 kernel does not export InterlockedCompareExchange.
-   This provides a substitute.   When building apps that reference
-   gthread_mutex_try_lock, the  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
-   macro  must be defined if Windows95 is a target.  Currently
-   gthread_mutex_try_lock is not referenced by libgcc or libstdc++.  */
-#ifdef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
-static inline long
-__gthr_i486_lock_cmp_xchg(long *__dest, long __xchg, long __comperand)
-{
-  long result;
-  __asm__ __volatile__ ("\n\
-       lock\n\
-       cmpxchg{l} {%4, %1|%1, %4}\n"
-       : "=a" (result), "=m" (*__dest)
-       : "0" (__comperand), "m" (*__dest), "r" (__xchg)
-       : "cc");
-  return result;
-}
-#define __GTHR_W32_InterlockedCompareExchange __gthr_i486_lock_cmp_xchg
-#else  /* __GTHREAD_I486_INLINE_LOCK_PRIMITIVES */
+/* __GTHR_W32_InterlockedCompareExchange is left over from win95,
+   which did not support InterlockedCompareExchange. */
 #define __GTHR_W32_InterlockedCompareExchange InterlockedCompareExchange
-#endif /* __GTHREAD_I486_INLINE_LOCK_PRIMITIVES */
 
 static inline int
 __gthread_active_p (void)