------- Comment #19 from rguenth at gcc dot gnu dot org 2006-05-17 14:21
-------
if we are checking in scev_probably_wraps_p if the chrec does wrap in the
target
type we should _not_ use signed-types-don't-wrap as we do now:
/* After having set INIT_IS_MAX, we can return false: when not using
wrapping arithmetic, signed types don't wrap. */
if (!flag_wrapv && !TYPE_UNSIGNED (type))
return false;
but instead assert that on TREE_TYPE (base). So, the following is another try
to fix the problem (allow mixed-type questions):
Index: tree-ssa-loop-niter.c
===================================================================
--- tree-ssa-loop-niter.c (revision 113852)
+++ tree-ssa-loop-niter.c (working copy)
@@ -1979,9 +1979,9 @@ scev_probably_wraps_p (tree type, tree b
}
*unknown_max = false;
- base_plus_step = fold_build2 (PLUS_EXPR, type, base, step);
- bpsps = fold_build2 (PLUS_EXPR, type, base_plus_step, step);
- cps = compare_trees (base_plus_step, base);
+ base_plus_step = fold_convert (type, fold_build2 (PLUS_EXPR, TREE_TYPE
(base), base, step));
+ bpsps = fold_convert (type, fold_build2 (PLUS_EXPR, TREE_TYPE (base),
base_plus_step, step));
+ cps = compare_trees (base_plus_step, fold_convert (type, base));
cpsps = compare_trees (bpsps, base_plus_step);
/* Check that the sequence is not wrapping in the first step: it
@@ -1995,7 +1995,8 @@ scev_probably_wraps_p (tree type, tree b
case -1:
{
tree extreme = upper_bound_in_type (type, TREE_TYPE (base));
- delta = fold_build2 (MINUS_EXPR, type, extreme, base);
+ delta = fold_build2 (MINUS_EXPR, type, extreme,
+ fold_convert (type, base));
step_abs = step;
*init_is_max = false;
break;
@@ -2004,8 +2005,9 @@ scev_probably_wraps_p (tree type, tree b
case 1:
{
tree extreme = lower_bound_in_type (type, TREE_TYPE (base));
- delta = fold_build2 (MINUS_EXPR, type, base, extreme);
- step_abs = fold_build1 (NEGATE_EXPR, type, step);
+ delta = fold_build2 (MINUS_EXPR, type,
+ fold_convert (type, base), extreme);
+ step_abs = fold_convert (type, fold_build1 (NEGATE_EXPR, TREE_TYPE
(step), step));
*init_is_max = true;
break;
}
@@ -2065,7 +2067,7 @@ scev_probably_wraps_p (tree type, tree b
/* After having set INIT_IS_MAX, we can return false: when not using
wrapping arithmetic, signed types don't wrap. */
- if (!flag_wrapv && !TYPE_UNSIGNED (type))
+ if (!flag_wrapv && !TYPE_UNSIGNED (TREE_TYPE (base)))
return false;
unsigned_type = unsigned_type_for (type);
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27639
