re PR inline-asm/50571 (Undesirable folding in "m" constrained asm operands)

	PR inline-asm/50571
	* gimple-fold.c (fold_stmt_1) <case GIMPLE_ASM>: If
	input constraints allow mem and not reg, pass true instead of
	false as second argument to maybe_fold_reference.

	* gcc.dg/pr50571.c: New test.

From-SVN: r179389

gcc/ChangeLog

 2011-09-30  Jakub Jelinek  <jakub@redhat.com>
 
+	PR inline-asm/50571
+	* gimple-fold.c (fold_stmt_1) <case GIMPLE_ASM>: If
+	input constraints allow mem and not reg, pass true instead of
+	false as second argument to maybe_fold_reference.
+
 	PR tree-optimization/46309
 	* fold-const.c (make_range, merge_ranges): Remove prototypes.
 	(make_range_step): New function.

gcc/gimple-fold.c

@@ -1201,28 +1201,45 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
 
     case GIMPLE_ASM:
       /* Fold *& in asm operands.  */
-      for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
-	{
-	  tree link = gimple_asm_output_op (stmt, i);
-	  tree op = TREE_VALUE (link);
-	  if (REFERENCE_CLASS_P (op)
-	      && (op = maybe_fold_reference (op, true)) != NULL_TREE)
-	    {
-	      TREE_VALUE (link) = op;
-	      changed = true;
-	    }
-	}
-      for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
-	{
-	  tree link = gimple_asm_input_op (stmt, i);
-	  tree op = TREE_VALUE (link);
-	  if (REFERENCE_CLASS_P (op)
-	      && (op = maybe_fold_reference (op, false)) != NULL_TREE)
-	    {
-	      TREE_VALUE (link) = op;
-	      changed = true;
-	    }
-	}
+      {
+	size_t noutputs;
+	const char **oconstraints;
+	const char *constraint;
+	bool allows_mem, allows_reg;
+
+	noutputs = gimple_asm_noutputs (stmt);
+	oconstraints = XALLOCAVEC (const char *, noutputs);
+
+	for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
+	  {
+	    tree link = gimple_asm_output_op (stmt, i);
+	    tree op = TREE_VALUE (link);
+	    oconstraints[i]
+	      = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
+	    if (REFERENCE_CLASS_P (op)
+		&& (op = maybe_fold_reference (op, true)) != NULL_TREE)
+	      {
+		TREE_VALUE (link) = op;
+		changed = true;
+	      }
+	  }
+	for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
+	  {
+	    tree link = gimple_asm_input_op (stmt, i);
+	    tree op = TREE_VALUE (link);
+	    constraint
+	      = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
+	    parse_input_constraint (&constraint, 0, 0, noutputs, 0,
+				    oconstraints, &allows_mem, &allows_reg);
+	    if (REFERENCE_CLASS_P (op)
+		&& (op = maybe_fold_reference (op, !allows_reg && allows_mem))
+		   != NULL_TREE)
+	      {
+		TREE_VALUE (link) = op;
+		changed = true;
+	      }
+	  }
+      }
       break;
 
     case GIMPLE_DEBUG:

gcc/testsuite/ChangeLog

 2011-09-30  Jakub Jelinek  <jakub@redhat.com>
 
+	PR inline-asm/50571
+	* gcc.dg/pr50571.c: New test.
+
 	PR tree-optimization/46309
 	* gcc.dg/pr46309.c: New test.
 

gcc/testsuite/gcc.dg/pr50571.c

+/* PR inline-asm/50571 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+static const int var[4] = { 1, 2, 3, 4 };
+
+void
+foo (void)
+{
+  __asm volatile ("" : : "m" (*(int *) var));
+}