https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82389
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So the fix is very easy:
--- gcc/tree-ssa-dse.c.jj 2017-09-29 23:05:40.000000000 +0200
+++ gcc/tree-ssa-dse.c 2017-10-02 10:40:21.962488571 +0200
@@ -577,10 +577,10 @@ dse_classify_store (ao_ref *ref, gimple
/* If the statement is a use the store is not dead. */
else if (ref_maybe_used_by_stmt_p (use_stmt, ref))
{
- /* Handle common cases where we can easily build a ao_ref
+ /* Handle common cases where we can easily build an ao_ref
structure for USE_STMT and in doing so we find that the
references hit non-live bytes and thus can be ignored. */
- if (live_bytes && (!gimple_vdef (use_stmt) || !temp))
+ if (byte_tracking_enabled && (!gimple_vdef (use_stmt) || !temp))
{
if (is_gimple_assign (use_stmt))
{
But I want to also think about overflows in the case where ref has small size
(otherwise byte_tracking_enabled is false), but use_ref has huge size.
