re PR middle-end/56098 (conditional write through volatile pointer produces unintended read)

	PR tree-optimization/56098
	* tree-ssa-phiopt.c (nt_init_block): Don't call add_or_mark_expr
	for stmts with volatile ops.
	(cond_store_replacement): Don't optimize if assign has volatile ops.
	(cond_if_else_store_replacement_1): Don't optimize if either
	then_assign or else_assign have volatile ops.
	(hoist_adjacent_loads): Don't optimize if either def1 or def2 have
	volatile ops.

	* gcc.dg/pr56098-1.c: New test.
	* gcc.dg/pr56098-2.c: New test.

From-SVN: r195475

gcc/ChangeLog

+2013-01-25  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/56098
+	* tree-ssa-phiopt.c (nt_init_block): Don't call add_or_mark_expr
+	for stmts with volatile ops.
+	(cond_store_replacement): Don't optimize if assign has volatile ops.
+	(cond_if_else_store_replacement_1): Don't optimize if either
+	then_assign or else_assign have volatile ops.
+	(hoist_adjacent_loads): Don't optimize if either def1 or def2 have
+	volatile ops.
+
 2013-01-25  Georg-Johann Lay  <avr@gjlay.de>
 
 	* doc/invoke.texi (AVR Built-in Macros): Document __XMEGA__.

gcc/testsuite/ChangeLog

+2013-01-25  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/56098
+	* gcc.dg/pr56098-1.c: New test.
+	* gcc.dg/pr56098-2.c: New test.
+
 2013-01-25  Georg-Johann Lay  <avr@gjlay.de>
 
 	PR target/54222

gcc/testsuite/gcc.dg/pr56098-1.c

+/* PR tree-optimization/56098 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+volatile int *p;
+
+void
+foo (int x)
+{
+  *p = 1;
+  if (x)
+    *p = 2;
+}
+
+/* { dg-final { scan-tree-dump-not "=\[^\n\r]*\\*p" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/testsuite/gcc.dg/pr56098-2.c

+/* PR tree-optimization/56098 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fhoist-adjacent-loads -fdump-tree-optimized" } */
+
+struct S { volatile int i; volatile int j; };
+
+int
+bar (struct S *x, int y)
+{
+  int r;
+  if (y)
+    r = x->i;
+  else
+    r = x->j;
+  return r;
+}
+
+/* { dg-final { scan-tree-dump-not "r_\[0-9]* =.v. \[^\n\r]*;\[\n\r]*  r_\[0-9]* =.v. " "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

gcc/tree-ssa-phiopt.c

@@ -1342,7 +1342,7 @@ nt_init_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb)
     {
       gimple stmt = gsi_stmt (gsi);
 
-      if (gimple_assign_single_p (stmt))
+      if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt))
 	{
 	  add_or_mark_expr (bb, gimple_assign_lhs (stmt), nontrap_set, true);
 	  add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), nontrap_set, false);
@@ -1419,7 +1419,8 @@ cond_store_replacement (basic_block middle_bb, basic_block join_bb,
 
   /* Check if middle_bb contains of only one store.  */
   if (!assign
-      || !gimple_assign_single_p (assign))
+      || !gimple_assign_single_p (assign)
+      || gimple_has_volatile_ops (assign))
     return false;
 
   locus = gimple_location (assign);
@@ -1490,9 +1491,11 @@ cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb,
   if (then_assign == NULL
       || !gimple_assign_single_p (then_assign)
       || gimple_clobber_p (then_assign)
+      || gimple_has_volatile_ops (then_assign)
       || else_assign == NULL
       || !gimple_assign_single_p (else_assign)
-      || gimple_clobber_p (else_assign))
+      || gimple_clobber_p (else_assign)
+      || gimple_has_volatile_ops (else_assign))
     return false;
 
   lhs = gimple_assign_lhs (then_assign);
@@ -1829,7 +1832,9 @@ hoist_adjacent_loads (basic_block bb0, basic_block bb1,
 
       /* Both statements must be assignments whose RHS is a COMPONENT_REF.  */
       if (!gimple_assign_single_p (def1)
-	  || !gimple_assign_single_p (def2))
+	  || !gimple_assign_single_p (def2)
+	  || gimple_has_volatile_ops (def1)
+	  || gimple_has_volatile_ops (def2))
 	continue;
 
       ref1 = gimple_assign_rhs1 (def1);