From patchwork Thu Nov 17 11:07:13 2011
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Subject: powerpc lack of memory_barrier
Date: Thu, 17 Nov 2011 01:07:13 -0000
From: Alan Modra <amodra@gmail.com>
X-Patchwork-Id: 126184
Message-Id: <20111117110713.GZ14325@bubble.grove.modra.org>
To: gcc-patches@gcc.gnu.org
Cc: David Edelsohn <dje.gcc@gmail.com>

Lacking this pattern means the builtin __sync_synchronize() on powerpc
is just an asm with a memory clobber (see builtins.c), which is hardly
a "full memory barrier" as extend.texi says it should be.  This patch
fixes multiple libgomp testsuite failures.  Bootstrapped and
regression tested powerpc-linux.  OK for mainline?

	* config/rs6000/sync.md: Duplicate hwsync as memory_barrier.


Index: gcc/config/rs6000/sync.md
===================================================================
--- gcc/config/rs6000/sync.md	(revision 181425)
+++ gcc/config/rs6000/sync.md	(working copy)
@@ -53,6 +53,15 @@ (define_expand "mem_thread_fence"
   DONE;
 })
 
+(define_expand "memory_barrier"
+  [(set (match_dup 0)
+	(unspec:BLK [(match_dup 0)] UNSPEC_SYNC))]
+  ""
+{
+  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
+  MEM_VOLATILE_P (operands[0]) = 1;
+})
+
 (define_expand "hwsync"
   [(set (match_dup 0)
 	(unspec:BLK [(match_dup 0)] UNSPEC_SYNC))]