https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38474
--- Comment #92 from Richard Biener <rguenth at gcc dot gnu.org> ---
Simple and stupid like the below works and does
store merging : 0.42 ( 1%) 0.00 ( 0%) 0.43 ( 1%)
3858k ( 1%)
TOTAL : 56.86 0.56 57.45
557M
we have a limit of 64 stores in a single chain, so the product of both limits
limit the number of alias queries done in terminate_all_aliasing_chains. I'll
polish it up tomorrow (and will refrain from trying to avoid the linear
walk here and keeping a counter or even a pointer to the last element).
diff --git a/gcc/gimple-ssa-store-merging.c b/gcc/gimple-ssa-store-merging.c
index f0f4a068de5..c6ec6b2cbce 100644
--- a/gcc/gimple-ssa-store-merging.c
+++ b/gcc/gimple-ssa-store-merging.c
@@ -5175,6 +5175,19 @@ pass_store_merging::process_store (gimple *stmt)
/* Store aliases any existing chain? */
ret |= terminate_all_aliasing_chains (NULL, stmt);
+ unsigned cnt = 0;
+ imm_store_chain_info **e = &m_stores_head;
+ while (*e)
+ if (++cnt > 16)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "Too many chains, terminating oldest before "
+ "starting a new chain.\n");
+ terminate_and_process_chain (*e);
+ }
+ else
+ e = &(*e)->next;
+
/* Start a new chain. */
class imm_store_chain_info *new_chain
= new imm_store_chain_info (m_stores_head, base_addr);
