The following tries to reduce the number of cases we use an unsigned
type for the addition when we know the original signed increment was
OK which is when the total unsigned increment computed fits the signed
type as well.
This fixes the observed testsuite fallout.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/112344
* tree-chrec.cc (chrec_apply): Only use an unsigned add
when the overall increment doesn't fit the signed type.
---
gcc/tree-chrec.cc | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/gcc/tree-chrec.cc b/gcc/tree-chrec.cc
index f4ba130ba20..e2864e8d131 100644
--- a/gcc/tree-chrec.cc
+++ b/gcc/tree-chrec.cc
@@ -646,9 +646,21 @@ chrec_apply (unsigned var,
res = chrec_fold_multiply (utype,
chrec_convert (utype, chrecr, NULL),
res);
- res = chrec_fold_plus (utype,
- chrec_convert (utype, chrecl, NULL), res);
- res = chrec_convert (type, res, NULL);
+ /* When the resulting increment fits the original type
+ do the increment in it. */
+ if (TREE_CODE (res) == INTEGER_CST
+ && int_fits_type_p (res, TREE_TYPE (chrecr)))
+ {
+ res = chrec_convert (TREE_TYPE (chrecr), res, NULL);
+ res = chrec_fold_plus (type, chrecl, res);
+ }
+ else
+ {
+ res = chrec_fold_plus (utype,
+ chrec_convert (utype, chrecl, NULL),
+ res);
+ res = chrec_convert (type, res, NULL);
+ }
}
}
else if (TREE_CODE (x) == INTEGER_CST
--
2.35.3
