On Sat, Jan 14, 2023 at 12:26 PM Alexandre Oliva via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
>
> The testcase used to get scheduled differently depending on the
> presence of debug insns with MEMs. It's not clear to me why those
> MEMs affected scheduling, but the cselib pre-canonicalization of the
> MEM address is not used at all when analyzing debug insns, so the
> memory allocation and lookup are pure waste. Somehow, avoiding that
> waste fixes the problem, or makes it go latent.
>
> Regstrapped on x86_64-linux-gnu. Ok to install?
OK.
Richard.
>
> for gcc/ChangeLog
>
> PR debug/106746
> * sched-deps.cc (sched_analyze_2): Skip cselib address lookup
> within debug insns.
>
> for gcc/testsuite/ChangeLog
>
> PR debug/106746
> * gcc.dg/target/i386/pr106746.c: New.
> ---
> gcc/sched-deps.cc | 36
> +++++++++++++++---------------
> gcc/testsuite/gcc.target/i386/pr106746.c | 29 ++++++++++++++++++++++++
> 2 files changed, 47 insertions(+), 18 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr106746.c
>
> diff --git a/gcc/sched-deps.cc b/gcc/sched-deps.cc
> index f9371b81fb41e..a9214f674329a 100644
> --- a/gcc/sched-deps.cc
> +++ b/gcc/sched-deps.cc
> @@ -2605,26 +2605,26 @@ sched_analyze_2 (class deps_desc *deps, rtx x,
> rtx_insn *insn)
>
> case MEM:
> {
> - /* Reading memory. */
> - rtx_insn_list *u;
> - rtx_insn_list *pending;
> - rtx_expr_list *pending_mem;
> - rtx t = x;
> -
> - if (sched_deps_info->use_cselib)
> - {
> - machine_mode address_mode = get_address_mode (t);
> -
> - t = shallow_copy_rtx (t);
> - cselib_lookup_from_insn (XEXP (t, 0), address_mode, 1,
> - GET_MODE (t), insn);
> - XEXP (t, 0)
> - = cselib_subst_to_values_from_insn (XEXP (t, 0), GET_MODE (t),
> - insn);
> - }
> -
> if (!DEBUG_INSN_P (insn))
> {
> + /* Reading memory. */
> + rtx_insn_list *u;
> + rtx_insn_list *pending;
> + rtx_expr_list *pending_mem;
> + rtx t = x;
> +
> + if (sched_deps_info->use_cselib)
> + {
> + machine_mode address_mode = get_address_mode (t);
> +
> + t = shallow_copy_rtx (t);
> + cselib_lookup_from_insn (XEXP (t, 0), address_mode, 1,
> + GET_MODE (t), insn);
> + XEXP (t, 0)
> + = cselib_subst_to_values_from_insn (XEXP (t, 0), GET_MODE
> (t),
> + insn);
> + }
> +
> t = canon_rtx (t);
> pending = deps->pending_read_insns;
> pending_mem = deps->pending_read_mems;
> diff --git a/gcc/testsuite/gcc.target/i386/pr106746.c
> b/gcc/testsuite/gcc.target/i386/pr106746.c
> new file mode 100644
> index 0000000000000..14f7dab71d691
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr106746.c
> @@ -0,0 +1,29 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fsched2-use-superblocks -fcompare-debug -Wno-psabi" }
> */
> +
> +typedef char __attribute__((__vector_size__ (64))) U;
> +typedef short __attribute__((__vector_size__ (64))) V;
> +typedef int __attribute__((__vector_size__ (64))) W;
> +
> +char c;
> +U a;
> +U *r;
> +W foo0_v512u32_0;
> +
> +void
> +foo (W)
> +{
> + U u;
> + V v;
> + W w = __builtin_shuffle (foo0_v512u32_0, foo0_v512u32_0);
> + u =
> + __builtin_shufflevector (a, u, 3, 0, 4, 9, 9, 6, 7, 8, 5,
> + 0, 6, 1, 8, 1, 2, 8, 6,
> + 1, 8, 4, 9, 3, 8, 4, 6, 0, 9, 0, 1, 8, 2, 3, 3,
> + 0, 4, 9, 9, 6, 7, 8, 5,
> + 0, 6, 1, 8, 1, 2, 8, 6,
> + 1, 8, 4, 9, 3, 8, 4, 6, 0, 9, 0, 1, 8, 2, 3);
> + v *= c;
> + w &= c;
> + *r = (U) v + (U) w;
> +}
>
>
> --
> Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
> Free Software Activist GNU Toolchain Engineer
> Disinformation flourishes because many people care deeply about injustice
> but very few check the facts. Ask me about <https://stallmansupport.org>
