[PATCH] Fix PR67285

[Richard Biener]

The following patch avoids breaking virtual SSA form in fold_stmt by
making sure we only ever generate calls to const functions in
simplify expression replacements.

Bootstrap & regtest running on x86_64-unknown-linux-gnu.

Richard.

2015-08-20  Richard Biener  <rguenther@suse.de>

	PR middle-end/67285
	* gimple-fold.c (replace_stmt_with_simplification): Assert
	seq is empty when replacing a call with itself but different
	arguments.
	* gimple-match-head.c (maybe_push_res_to_seq): When pushing
	a call require that it is const.

Index: gcc/gimple-fold.c
===================================================================
--- gcc/gimple-fold.c	(revision 227031)
+++ gcc/gimple-fold.c	(working copy)
@@ -3308,6 +3308,7 @@ replace_stmt_with_simplification (gimple
 	}
       if (i < 3)
 	gcc_assert (ops[i] == NULL_TREE);
+      gcc_assert (gimple_seq_empty_p (*seq));
       return true;
     }
   else if (!inplace)
Index: gcc/gimple-match-head.c
===================================================================
--- gcc/gimple-match-head.c	(revision 227031)
+++ gcc/gimple-match-head.c	(working copy)
@@ -338,6 +338,9 @@ maybe_push_res_to_seq (code_helper rcode
       tree decl = builtin_decl_implicit (rcode);
       if (!decl)
 	return NULL_TREE;
+      /* We can't and should not emit calls to non-const functions.  */
+      if (!(flags_from_decl_or_type (decl) & ECF_CONST))
+	return NULL_TREE;
       /* Play safe and do not allow abnormals to be mentioned in
          newly created statements.  */
       unsigned nargs;