[PATCH] Fix #pragma omp atomic

[Jakub Jelinek]

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