https://gcc.gnu.org/g:0135a90de5a99b51001b6152d8b548151ebfa1c3
commit r15-2099-g0135a90de5a99b51001b6152d8b548151ebfa1c3
Author: Tamar Christina <tamar.christ...@arm.com>
Date: Wed Jul 17 16:22:14 2024 +0100
middle-end: fix 0 offset creation and folding [PR115936]
As shown in PR115936 SCEV and IVOPTS create an invalidate IV when the IV is
a pointer type:
ivtmp.39_65 = ivtmp.39_59 + 0B;
where the IVs are DI mode and the offset is a pointer.
This comes from this weird candidate:
Candidate 8:
Var befor: ivtmp.39_59
Var after: ivtmp.39_65
Incr POS: before exit test
IV struct:
Type: sizetype
Base: 0
Step: 0B
Biv: N
Overflowness wrto loop niter: No-overflow
This IV was always created just ended up not being used.
This is created by SCEV.
simple_iv_with_niters in the case where no CHREC is found creates an IV with
base == ev, offset == 0;
however in this case EV is a POINTER_PLUS_EXPR and so the type is a pointer.
it ends up creating an unusable expression.
gcc/ChangeLog:
PR tree-optimization/115936
* tree-scalar-evolution.cc (simple_iv_with_niters): Use sizetype for
pointers.
Diff:
---
gcc/tree-scalar-evolution.cc | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-scalar-evolution.cc b/gcc/tree-scalar-evolution.cc
index 5aa95a2497a3..abb2bad77737 100644
--- a/gcc/tree-scalar-evolution.cc
+++ b/gcc/tree-scalar-evolution.cc
@@ -3243,7 +3243,11 @@ simple_iv_with_niters (class loop *wrto_loop, class loop
*use_loop,
if (tree_does_not_contain_chrecs (ev))
{
iv->base = ev;
- iv->step = build_int_cst (TREE_TYPE (ev), 0);
+ tree ev_type = TREE_TYPE (ev);
+ if (POINTER_TYPE_P (ev_type))
+ ev_type = sizetype;
+
+ iv->step = build_int_cst (ev_type, 0);
iv->no_overflow = true;
return true;
}
