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[PATCH] Fix #pragma omp atomic
- From: Jakub Jelinek <jakub at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Thu, 6 Mar 2008 12:36:53 -0500
- Subject: [PATCH] Fix #pragma omp atomic
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
This patch fixes
char e[10];
...
#pragma omp atomic
e[0] += i;
which isn't actually atomic in pr26943-2.c testcase at -O0 and thus
intermitently fails. e[0] is read twice, one of those values is
incremented, the other passed to __sync_val_compare_and_swap as expected
old argument.
The newly added testcase triggers on quadcore always with unfixed gcc,
so is a better reproducer for that bug.
Regtested on x86_64-linux, committed to trunk. Will commit to 4.3
branch once I test it there.
2008-03-06 Jakub Jelinek <jakub@redhat.com>
* gimplify.c (goa_lhs_expr_p): Allow different ADDR_EXPR nodes
for the same VAR_DECL.
* testsuite/libgomp.c/atomic-3.c: New test.
--- gcc/gimplify.c.jj 2008-02-15 18:43:03.000000000 +0100
+++ gcc/gimplify.c 2008-03-06 14:29:02.000000000 +0100
@@ -5464,7 +5464,10 @@ goa_lhs_expr_p (tree expr, tree addr)
expr = TREE_OPERAND (expr, 0);
addr = TREE_OPERAND (addr, 0);
}
- return expr == addr;
+ if (expr == addr)
+ return true;
+ return (TREE_CODE (addr) == ADDR_EXPR && TREE_CODE (expr) == ADDR_EXPR
+ && TREE_OPERAND (addr, 0) == TREE_OPERAND (expr, 0));
}
if (TREE_CODE (addr) == ADDR_EXPR && expr == TREE_OPERAND (addr, 0))
return true;
--- libgomp/testsuite/libgomp.c/atomic-3.c.jj 2008-03-06 15:53:56.000000000 +0100
+++ libgomp/testsuite/libgomp.c/atomic-3.c 2008-03-06 15:49:36.000000000 +0100
@@ -0,0 +1,50 @@
+/* { dg-do run } */
+/* { dg-options "-fopenmp -O0" } */
+
+#include <omp.h>
+#include <stdlib.h>
+
+short e[64];
+int g;
+_Complex double d, f;
+int num_threads;
+
+__attribute__((noinline)) void
+foo (int x, long long y)
+{
+#pragma omp parallel num_threads (4)
+ {
+ int i;
+ #pragma omp barrier
+ for (i = 0; i < 2400; i++)
+ {
+ if (i == 0)
+ num_threads = omp_get_num_threads ();
+ #pragma omp atomic
+ e[0] += x;
+ #pragma omp atomic
+ e[16] += x;
+ #pragma omp atomic
+ g += y;
+ #pragma omp atomic
+ __real__ d += x;
+ #pragma omp atomic
+ __imag__ f += x;
+ }
+ }
+}
+
+int
+main (void)
+{
+ int i;
+ foo (3, 3LL);
+ if (g != 3 * 2400 * num_threads
+ || __real__ d != g || __imag__ d != 0
+ || __real__ f != 0 || __imag__ f != g)
+ abort ();
+ for (i = 0; i < 64; i++)
+ if (e[i] != ((i && i != 16) ? 0 : g))
+ abort ();
+ return 0;
+}
Jakub