https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92262
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Actually I can, but for some reason I had to use explicit -fchecking, dunno how
I've configured this cross.
Anyway, I don't see a tree sharing issue in the newly added code, but
get_computation_at doesn't unshare, which can be perhaps ok with the way it is
used in non-debug stmts, but it is not ok for debug stmts.
Now, we could unshare_expr in get_debug_computation_at when get_computation_at
succeeds, but as we now iterate over possibly several IVs, I think it is better
to unshare only when we pick the best candidate.
So:
--- gcc/tree-ssa-loop-ivopts.c.jj 2019-10-23 14:35:42.994753407 +0200
+++ gcc/tree-ssa-loop-ivopts.c 2019-10-29 09:45:47.418217336 +0100
@@ -4152,8 +4152,6 @@ get_debug_computation_at (class loop *lo
var = fold_convert (ctype, var);
}
- ubase = unshare_expr (ubase);
- cbase = unshare_expr (cbase);
if (stmt_after_increment (loop, cand, at))
var = fold_build2 (MINUS_EXPR, TREE_TYPE (var), var,
unshare_expr (cstep));
@@ -7648,6 +7646,7 @@ remove_unused_ivs (struct ivopts_data *d
if (!best_cand)
continue;
+ comp = unshare_expr (comp);
if (count > 1)
{
tree vexpr = make_node (DEBUG_EXPR_DECL);
