This fixes a wrong re-association which can introduce undefined
overflow. The fix is to perform this only when overflow is known
to wrap.
Bootstrap and regtest pending on x86_64-unknown-linux-gnu.
Richard.
2011-08-03 Richard Guenther <rguent...@suse.de>
PR middle-end/49958
* fold-const.c (fold_binary_loc): Only associate
(+ (+ (* a b) c) (* d e)) as (+ (+ (* a b) (* d e)) c) if
overflow wraps.
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 177094)
+++ gcc/fold-const.c (working copy)
@@ -9712,12 +9712,13 @@ fold_binary_loc (location_t loc,
/* Reassociate (plus (plus (mult) (foo)) (mult)) as
(plus (plus (mult) (mult)) (foo)) so that we can
take advantage of the factoring cases below. */
- if (((TREE_CODE (arg0) == PLUS_EXPR
- || TREE_CODE (arg0) == MINUS_EXPR)
- && TREE_CODE (arg1) == MULT_EXPR)
- || ((TREE_CODE (arg1) == PLUS_EXPR
- || TREE_CODE (arg1) == MINUS_EXPR)
- && TREE_CODE (arg0) == MULT_EXPR))
+ if (TYPE_OVERFLOW_WRAPS (type)
+ && (((TREE_CODE (arg0) == PLUS_EXPR
+ || TREE_CODE (arg0) == MINUS_EXPR)
+ && TREE_CODE (arg1) == MULT_EXPR)
+ || ((TREE_CODE (arg1) == PLUS_EXPR
+ || TREE_CODE (arg1) == MINUS_EXPR)
+ && TREE_CODE (arg0) == MULT_EXPR)))
{
tree parg0, parg1, parg, marg;
enum tree_code pcode;
Index: gcc/testsuite/gcc.dg/torture/pr49958.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr49958.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr49958.c (revision 0)
@@ -0,0 +1,11 @@
+/* { dg-do run } */
+/* { dg-options "-fstrict-overflow" } */
+
+extern void abort (void);
+int foo (int i, int j, int o, int m) { return i*o + 1 + j*m > 1; }
+int main()
+{
+ if (foo (- __INT_MAX__ - 1, -1, 1, 1))
+ abort ();
+ return 0;
+}
