Hi!
The bswap infrastructure uses the vuse field to make sure all the loads are
having the same gimple_vuse and also uses it in bswap_replace.
When this infrastructure is used inside of the store-merging pass, the
problem is that the old stores are being removed and new added, so
gimple_vuse of the loads we record during process_stmt can change.
So, this patch updates the vuse fields before we plan to use it (in
try_coalesce_bswap for the checking and in output_merged_stores for the
bswap_replace purposes).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2017-12-01 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/83170
PR tree-optimization/83241
* gimple-ssa-store-merging.c
(imm_store_chain_info::try_coalesce_bswap): Update vuse field from
gimple_vuse (ins_stmt) in case it has changed.
(imm_store_chain_info::output_merged_store): Likewise.
* gcc.dg/store_merging_17.c: New test.
--- gcc/gimple-ssa-store-merging.c.jj 2017-12-01 09:17:36.000000000 +0100
+++ gcc/gimple-ssa-store-merging.c 2017-12-01 16:03:40.806918965 +0100
@@ -2384,6 +2384,9 @@ imm_store_chain_info::try_coalesce_bswap
this_n.type = type;
if (!this_n.base_addr)
this_n.range = try_size / BITS_PER_UNIT;
+ else
+ /* Update vuse in case it has changed by output_merged_stores. */
+ this_n.vuse = gimple_vuse (info->ins_stmt);
unsigned int bitpos = info->bitpos - infof->bitpos;
if (!do_shift_rotate (LSHIFT_EXPR, &this_n,
BYTES_BIG_ENDIAN
@@ -3341,10 +3344,16 @@ imm_store_chain_info::output_merged_stor
we've checked the aliasing already in try_coalesce_bswap and
we want to sink the need load into seq. So need to use new_vuse
on the load. */
- if (n->base_addr && n->vuse == NULL)
+ if (n->base_addr)
{
- n->vuse = new_vuse;
- ins_stmt = NULL;
+ if (n->vuse == NULL)
+ {
+ n->vuse = new_vuse;
+ ins_stmt = NULL;
+ }
+ else
+ /* Update vuse in case it has changed by output_merged_stores. */
+ n->vuse = gimple_vuse (ins_stmt);
}
bswap_res = bswap_replace (gsi_start (seq), ins_stmt, fndecl,
bswap_type, load_type, n, bswap);
--- gcc/testsuite/gcc.dg/store_merging_17.c.jj 2017-12-01 16:07:20.590224536
+0100
+++ gcc/testsuite/gcc.dg/store_merging_17.c 2017-12-01 16:07:01.000000000
+0100
@@ -0,0 +1,17 @@
+/* PR tree-optimization/83241 */
+/* { dg-do compile { target store_merge } } */
+/* { dg-options "-O2" } */
+
+struct S { int a; short b[32]; } e;
+struct T { volatile int c; int d; } f;
+
+void
+foo ()
+{
+ struct T g = f;
+ e.b[0] = 6;
+ e.b[1] = 6;
+ e.b[4] = g.d;
+ e.b[5] = g.d >> 16;
+ e.a = 1;
+}
Jakub
