https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97721
--- Comment #6 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #5)
> (In reply to Aldy Hernandez from comment #2)
> Yes, the IL is "correct", just inefficent and possibly confusing to passes.
>
> The OVF flag on INTEGER_CST have _no_ semantic meaning in the IL so making
> them "invalid" in ranger doesn't make sense.
The ranger treating them invalid was a precaution since the conversion to trees
brought the use of compare_values_warnv(), which claims overflowed values
cannot be compared. But if in fact they can be compared, then perhaps
compare_values_warnv is wrong in claiming the opposite:
/* We cannot say anything more for non-constants. */
if (!cst1 || !cst2)
return -2;
if (!POINTER_TYPE_P (TREE_TYPE (val1)))
{
/* We cannot compare overflowed values. */
if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
return -2;
What do you think?
It would seem to me that removing this restriction would work, especially since
tree_int_cst_compare, which this function uses, just degrades to wide ints,
which don't care about TREE_OVERFLOW.
[untested]
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index e00c034fee3..8702ad1ae8d 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -609,10 +609,6 @@ compare_values_warnv (tree val1, tree val2, bool
*strict_overflow_p)
if (!POINTER_TYPE_P (TREE_TYPE (val1)))
{
- /* We cannot compare overflowed values. */
- if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
- return -2;
-
if (TREE_CODE (val1) == INTEGER_CST
&& TREE_CODE (val2) == INTEGER_CST)
return tree_int_cst_compare (val1, val2);
@@ -635,13 +631,7 @@ compare_values_warnv (tree val1, tree val2, bool
*strict_overflow_p)
else
{
if (TREE_CODE (val1) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
- {
- /* We cannot compare overflowed values. */
- if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
- return -2;
-
- return tree_int_cst_compare (val1, val2);
- }
+ return tree_int_cst_compare (val1, val2);
/* First see if VAL1 and VAL2 are not the same. */
if (operand_equal_p (val1, val2, 0))
