On December 1, 2017 11:36:19 PM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>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?
OK.
Richard.
>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
