PATCH: PR libgcj/49193: __sync_xxxx builtins aren't used in sysdep/*/locks.h

H.J. Lu hongjiu.lu@intel.com
Sat May 28 01:08:00 GMT 2011


Hi,

This patch uses __sync_bool_compare_and_swap and removes
sysdep/x86-64/locks.h.  OK for trunk if there is no regression?

Thanks.

H.J.
---
2011-05-27  H.J. Lu  <hongjiu.lu@intel.com>

	PR libgcj/49193
	* configure.host (sysdeps_dir): Set to i386 for x86_64.

	* sysdep/i386/locks.h (compare_and_swap): Call
	__sync_bool_compare_and_swap.
	(release_set): Call write_barrier ().

	* sysdep/x86-64/locks.h: Removed.

diff --git a/libjava/configure.host b/libjava/configure.host
index 5b88478..9d4f2b6 100644
--- a/libjava/configure.host
+++ b/libjava/configure.host
@@ -132,7 +132,7 @@ case "${host}" in
 	slow_pthread_self=yes
 	;;
   x86_64-*)
-	sysdeps_dir=x86-64
+	sysdeps_dir=i386
 	# For 64-bit we always use SSE registers for arithmetic,
 	# which doesn't have the extra precision problems of the fpu.
 	# But be careful about 32-bit multilibs.
@@ -279,7 +279,7 @@ EOF
         slow_pthread_self=
         ;;
   i[34567]86-*-solaris2.1[0-9]* )
-	sysdeps_dir=x86-64
+	sysdeps_dir=i386
 	DIVIDESPEC=-f%{m32:no-}%{!m32:%{!m64:no-}}%{m64:}use-divide-subroutine
 	;;
   mips-sgi-irix6* )
diff --git a/libjava/sysdep/i386/locks.h b/libjava/sysdep/i386/locks.h
index 9d130b0..7b99f0b 100644
--- a/libjava/sysdep/i386/locks.h
+++ b/libjava/sysdep/i386/locks.h
@@ -1,6 +1,6 @@
 /* locks.h - Thread synchronization primitives. X86/x86-64 implementation.
 
-   Copyright (C) 2002  Free Software Foundation
+   Copyright (C) 2002, 2011  Free Software Foundation
 
    This file is part of libgcj.
 
@@ -23,19 +23,25 @@ compare_and_swap(volatile obj_addr_t *addr,
 		 obj_addr_t old,
 		 obj_addr_t new_val)
 {
-  char result;
-#ifdef __x86_64__
-  __asm__ __volatile__("lock; cmpxchgq %2, %0; setz %1"
-	      : "=m"(*(addr)), "=q"(result)
-	      : "r" (new_val), "a"(old), "m"(*addr)
-	      : "memory");
-#else
-  __asm__ __volatile__("lock; cmpxchgl %2, %0; setz %1"
-		       : "=m"(*addr), "=q"(result)
-		       : "r" (new_val), "a"(old), "m"(*addr)
-		       : "memory");
-#endif
-  return (bool) result;
+  return __sync_bool_compare_and_swap (addr, old, new_val);
+}
+
+// Ensure that subsequent instructions do not execute on stale
+// data that was loaded from memory before the barrier.
+// On X86/x86-64, the hardware ensures that reads are properly ordered.
+inline static void
+read_barrier()
+{
+}
+
+// Ensure that prior stores to memory are completed with respect to other
+// processors.
+inline static void
+write_barrier()
+{
+  /* x86-64/X86 does not reorder writes. We just need to ensure that
+     gcc also doesn't.  */
+  __asm__ __volatile__(" " : : : "memory");
 }
 
 // Set *addr to new_val with release semantics, i.e. making sure
@@ -46,7 +52,7 @@ compare_and_swap(volatile obj_addr_t *addr,
 inline static void
 release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
 {
-  __asm__ __volatile__(" " : : : "memory");
+  write_barrier ();
   *(addr) = new_val;
 }
 
@@ -60,22 +66,4 @@ compare_and_swap_release(volatile obj_addr_t *addr,
 {
   return compare_and_swap(addr, old, new_val);
 }
-
-// Ensure that subsequent instructions do not execute on stale
-// data that was loaded from memory before the barrier.
-// On X86/x86-64, the hardware ensures that reads are properly ordered.
-inline static void
-read_barrier()
-{
-}
-
-// Ensure that prior stores to memory are completed with respect to other
-// processors.
-inline static void
-write_barrier()
-{
-  /* x86-64/X86 does not reorder writes. We just need to ensure that
-     gcc also doesn't.  */
-  __asm__ __volatile__(" " : : : "memory");
-}
 #endif
diff --git a/libjava/sysdep/x86-64/locks.h b/libjava/sysdep/x86-64/locks.h
deleted file mode 100644
index fdc0a3e..0000000
--- a/libjava/sysdep/x86-64/locks.h
+++ /dev/null
@@ -1,83 +0,0 @@
-/* locks.h - Thread synchronization primitives. X86/x86-64 implementation.
-
-   Copyright (C) 2002  Free Software Foundation
-
-   Contributed by Bo Thorsen <bo@suse.de>.
-
-   This file is part of libgcj.
-
-This software is copyrighted work licensed under the terms of the
-Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
-details.  */
-
-#ifndef __SYSDEP_LOCKS_H__
-#define __SYSDEP_LOCKS_H__
-
-typedef size_t obj_addr_t;	/* Integer type big enough for object	*/
-				/* address.				*/
-
-// Atomically replace *addr by new_val if it was initially equal to old.
-// Return true if the comparison succeeded.
-// Assumed to have acquire semantics, i.e. later memory operations
-// cannot execute before the compare_and_swap finishes.
-inline static bool
-compare_and_swap(volatile obj_addr_t *addr,
-		 obj_addr_t old,
-		 obj_addr_t new_val)
-{
-  char result;
-#ifdef __x86_64__
-  __asm__ __volatile__("lock; cmpxchgq %2, %0; setz %1"
-	      : "=m"(*(addr)), "=q"(result)
-	      : "r" (new_val), "a"(old), "m"(*addr)
-	      : "memory");
-#else
-  __asm__ __volatile__("lock; cmpxchgl %2, %0; setz %1"
-		       : "=m"(*addr), "=q"(result)
-		       : "r" (new_val), "a"(old), "m"(*addr)
-		       : "memory");
-#endif
-  return (bool) result;
-}
-
-// Set *addr to new_val with release semantics, i.e. making sure
-// that prior loads and stores complete before this
-// assignment.
-// On X86/x86-64, the hardware shouldn't reorder reads and writes,
-// so we just have to convince gcc not to do it either.
-inline static void
-release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
-{
-  __asm__ __volatile__(" " : : : "memory");
-  *(addr) = new_val;
-}
-
-// Compare_and_swap with release semantics instead of acquire semantics.
-// On many architecture, the operation makes both guarantees, so the
-// implementation can be the same.
-inline static bool
-compare_and_swap_release(volatile obj_addr_t *addr,
-			 obj_addr_t old,
-			 obj_addr_t new_val)
-{
-  return compare_and_swap(addr, old, new_val);
-}
-
-// Ensure that subsequent instructions do not execute on stale
-// data that was loaded from memory before the barrier.
-// On X86/x86-64, the hardware ensures that reads are properly ordered.
-inline static void
-read_barrier()
-{
-}
-
-// Ensure that prior stores to memory are completed with respect to other
-// processors.
-inline static void
-write_barrier()
-{
-  /* x86-64/X86 does not reorder writes. We just need to ensure that
-     gcc also doesn't.  */
-  __asm__ __volatile__(" " : : : "memory");
-}
-#endif



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