------- Comment #6 from rguenth at gcc dot gnu dot org 2007-09-21 10:20 -------
The problem is that fold_binary converts (long)ptr * -1 to (long)-ptr:
/* Transform x * -1 into -x. */
if (integer_all_onesp (arg1))
return fold_convert (type, negate_expr (arg0));
we shouldn't negate a pointer I think. Still if we negate op0 here,
negate_expr
strips sing-nops and ends up producing -ptr again :/
Sort of a mess... (asserting that we do not call negate_expr on pointers
reveals even more problems)
Anyway, the following fixes it:
Index: fold-const.c
===================================================================
--- fold-const.c (revision 128644)
+++ fold-const.c (working copy)
@@ -10242,7 +10242,7 @@ fold_binary (enum tree_code code, tree t
return non_lvalue (fold_convert (type, arg0));
/* Transform x * -1 into -x. */
if (integer_all_onesp (arg1))
- return fold_convert (type, negate_expr (arg0));
+ return fold_convert (type, negate_expr (op0));
/* Transform x * -C into -x * C if x is easily negatable. */
if (TREE_CODE (arg1) == INTEGER_CST
&& tree_int_cst_sgn (arg1) == -1
Index: tree.h
===================================================================
--- tree.h (revision 128644)
+++ tree.h (working copy)
@@ -1019,7 +1019,9 @@ extern void omp_clause_range_check_faile
&& (TYPE_MODE (TREE_TYPE (EXP)) \
== TYPE_MODE (TREE_TYPE (TREE_OPERAND (EXP, 0)))) \
&& (TYPE_UNSIGNED (TREE_TYPE (EXP)) \
- == TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (EXP, 0))))) \
+ == TYPE_UNSIGNED (TREE_TYPE (TREE_OPERAND (EXP, 0)))) \
+ && (POINTER_TYPE_P (TREE_TYPE (EXP)) \
+ == POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (EXP, 0))))) \
(EXP) = TREE_OPERAND (EXP, 0)
/* Like STRIP_NOPS, but don't alter the TREE_TYPE either. */
Andrew, with POINTER_PLUS_EXPR, do we still "allow" negating a pointer?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33146
