From 6a6082c27c148eb452d804af306e8745f6e49b36 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 7 Oct 2011 23:32:30 -0400
Subject: [PATCH] Try to fix memory barriers on x86_64.
%esp is no good; must use %rsp there.
---
src/include/storage/barrier.h | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/src/include/storage/barrier.h b/src/include/storage/barrier.h
index 0286817a38f..b5cc60735e0 100644
--- a/src/include/storage/barrier.h
+++ b/src/include/storage/barrier.h
@@ -62,14 +62,24 @@ extern slock_t dummy_spinlock;
/* This works on any architecture, since it's only talking to GCC itself. */
#define pg_compiler_barrier() __asm__ __volatile__("" : : : "memory")
-#if defined(__i386__) || defined(__x86_64__) /* 32 or 64 bit x86 */
+#if defined(__i386__)
/*
- * x86 and x86_64 do not allow loads to be reorded with other loads, or
- * stores to be reordered with other stores, but a load can be performed
- * before a subsequent store.
+ * i386 does not allow loads to be reorded with other loads, or stores to be
+ * reordered with other stores, but a load can be performed before a subsequent
+ * store.
*
* "lock; addl" has worked for longer than "mfence".
+ */
+#define pg_memory_barrier() \
+ __asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
+#define pg_read_barrier() pg_compiler_barrier()
+#define pg_write_barrier() pg_compiler_barrier()
+
+#elif defined(__x86_64__) /* 64 bit x86 */
+
+/*
+ * x86_64 has similar ordering characteristics to i386.
*
* Technically, some x86-ish chips support uncached memory access and/or
* special instructions that are weakly ordered. In those cases we'd need
@@ -77,7 +87,7 @@ extern slock_t dummy_spinlock;
* do those things, a compiler barrier should be enough.
*/
#define pg_memory_barrier() \
- __asm__ __volatile__ ("lock; addl $0,0(%%esp)" : : : "memory")
+ __asm__ __volatile__ ("lock; addl $0,0(%%rsp)" : : : "memory")
#define pg_read_barrier() pg_compiler_barrier()
#define pg_write_barrier() pg_compiler_barrier()
--
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