diff mbox series

Ignore debug insns with CONCAT and CONCATN for insn scheduling

Message ID 20220902143639.2464892-1-hjl.tools@gmail.com
State New, archived
Headers
Series Ignore debug insns with CONCAT and CONCATN for insn scheduling |

Commit Message

H.J. Lu Sept. 2, 2022, 2:36 p.m. UTC 
  CONCAT and CONCATN never appear in the insn chain.  They are only used
in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
scheduling to avoid different insn orders with and without debug insn.

gcc/

	PR rtl-optimization/106746
	* sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
	and CONCATN.

gcc/testsuite/

	PR rtl-optimization/106746
	* gcc.dg/pr106746.c: New test.
---
 gcc/sched-deps.cc               | 14 ++++++++++++++
 gcc/testsuite/gcc.dg/pr106746.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/pr106746.c

Comments

Jeff Law Sept. 7, 2022, 5:02 p.m. UTC | #1 
On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
> CONCAT and CONCATN never appear in the insn chain.  They are only used
> in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
> scheduling to avoid different insn orders with and without debug insn.
>
> gcc/
>
> 	PR rtl-optimization/106746
> 	* sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
> 	and CONCATN.
Shouldn't we be ignoring everything in a debug insn?   I don't see why 
CONCAT/CONCATN are special here.

jeff
H.J. Lu Sept. 21, 2022, 10:11 p.m. UTC | #2 
On Wed, Sep 7, 2022 at 10:03 AM Jeff Law via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
>
>
> On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
> > CONCAT and CONCATN never appear in the insn chain.  They are only used
> > in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
> > scheduling to avoid different insn orders with and without debug insn.
> >
> > gcc/
> >
> >       PR rtl-optimization/106746
> >       * sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
> >       and CONCATN.
> Shouldn't we be ignoring everything in a debug insn?   I don't see why
> CONCAT/CONCATN are special here.

Debug insns are processed by insn scheduling.   I think it is to improve debug
experiences.  It is just that there are no matching usages of CONCAT/CONCATN
in non-debug insns.

--
H.J.
Jeff Law Sept. 24, 2022, 8:37 p.m. UTC | #3 
On 9/21/22 16:11, H.J. Lu wrote:
> On Wed, Sep 7, 2022 at 10:03 AM Jeff Law via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>>
>> On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
>>> CONCAT and CONCATN never appear in the insn chain.  They are only used
>>> in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
>>> scheduling to avoid different insn orders with and without debug insn.
>>>
>>> gcc/
>>>
>>>        PR rtl-optimization/106746
>>>        * sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
>>>        and CONCATN.
>> Shouldn't we be ignoring everything in a debug insn?   I don't see why
>> CONCAT/CONCATN are special here.
> Debug insns are processed by insn scheduling.   I think it is to improve debug
> experiences.  It is just that there are no matching usages of CONCAT/CONCATN
> in non-debug insns.

But from a dependency standpoint ISTM all debug insn can be ignored.  I 
still don't see why concat/concatn should be special here.


jeff
H.J. Lu Sept. 26, 2022, 7:52 p.m. UTC | #4 
On Sat, Sep 24, 2022 at 1:37 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
>
>
> On 9/21/22 16:11, H.J. Lu wrote:
> > On Wed, Sep 7, 2022 at 10:03 AM Jeff Law via Gcc-patches
> > <gcc-patches@gcc.gnu.org> wrote:
> >>
> >>
> >> On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
> >>> CONCAT and CONCATN never appear in the insn chain.  They are only used
> >>> in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
> >>> scheduling to avoid different insn orders with and without debug insn.
> >>>
> >>> gcc/
> >>>
> >>>        PR rtl-optimization/106746
> >>>        * sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
> >>>        and CONCATN.
> >> Shouldn't we be ignoring everything in a debug insn?   I don't see why
> >> CONCAT/CONCATN are special here.
> > Debug insns are processed by insn scheduling.   I think it is to improve debug
> > experiences.  It is just that there are no matching usages of CONCAT/CONCATN
> > in non-debug insns.
>
> But from a dependency standpoint ISTM all debug insn can be ignored.  I
> still don't see why concat/concatn should be special here.
>

I tried to ignore everything in a debug insn.  It caused many regressions in
the GCC testsuite.
Jeff Law Sept. 26, 2022, 11:23 p.m. UTC | #5 
On 9/26/22 13:52, H.J. Lu wrote:
> On Sat, Sep 24, 2022 at 1:37 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
>>
>> On 9/21/22 16:11, H.J. Lu wrote:
>>> On Wed, Sep 7, 2022 at 10:03 AM Jeff Law via Gcc-patches
>>> <gcc-patches@gcc.gnu.org> wrote:
>>>>
>>>> On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
>>>>> CONCAT and CONCATN never appear in the insn chain.  They are only used
>>>>> in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
>>>>> scheduling to avoid different insn orders with and without debug insn.
>>>>>
>>>>> gcc/
>>>>>
>>>>>         PR rtl-optimization/106746
>>>>>         * sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
>>>>>         and CONCATN.
>>>> Shouldn't we be ignoring everything in a debug insn?   I don't see why
>>>> CONCAT/CONCATN are special here.
>>> Debug insns are processed by insn scheduling.   I think it is to improve debug
>>> experiences.  It is just that there are no matching usages of CONCAT/CONCATN
>>> in non-debug insns.
>> But from a dependency standpoint ISTM all debug insn can be ignored.  I
>> still don't see why concat/concatn should be special here.
>>
> I tried to ignore everything in a debug insn.  It caused many regressions in
> the GCC testsuite.
Not terribly useful -- what failed and why?

jeff
Jakub Jelinek Sept. 26, 2022, 11:43 p.m. UTC | #6 
On Mon, Sep 26, 2022 at 05:23:45PM -0600, Jeff Law via Gcc-patches wrote:
> 
> On 9/26/22 13:52, H.J. Lu wrote:
> > On Sat, Sep 24, 2022 at 1:37 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
> > > 
> > > On 9/21/22 16:11, H.J. Lu wrote:
> > > > On Wed, Sep 7, 2022 at 10:03 AM Jeff Law via Gcc-patches
> > > > <gcc-patches@gcc.gnu.org> wrote:
> > > > > 
> > > > > On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
> > > > > > CONCAT and CONCATN never appear in the insn chain.  They are only used
> > > > > > in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
> > > > > > scheduling to avoid different insn orders with and without debug insn.
> > > > > > 
> > > > > > gcc/
> > > > > > 
> > > > > >         PR rtl-optimization/106746
> > > > > >         * sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
> > > > > >         and CONCATN.
> > > > > Shouldn't we be ignoring everything in a debug insn?   I don't see why
> > > > > CONCAT/CONCATN are special here.
> > > > Debug insns are processed by insn scheduling.   I think it is to improve debug
> > > > experiences.  It is just that there are no matching usages of CONCAT/CONCATN
> > > > in non-debug insns.
> > > But from a dependency standpoint ISTM all debug insn can be ignored.  I
> > > still don't see why concat/concatn should be special here.
> > > 
> > I tried to ignore everything in a debug insn.  It caused many regressions in
> > the GCC testsuite.
> Not terribly useful -- what failed and why?

I think the design for debug insns in the scheduler is that they do affect
scheduling decisions, but what is in debug insns should only affect actual
scheduling of the debug insns and not the rest.
So it wouldn't surprise me if ignoring everything in a debug insn broke a
lot.  But I admit I never fully understood how it works, hopefully Alex or
Vlad do.

	Jakub
Jeff Law Sept. 27, 2022, 1:40 a.m. UTC | #7 
On 9/26/22 17:43, Jakub Jelinek wrote:
> On Mon, Sep 26, 2022 at 05:23:45PM -0600, Jeff Law via Gcc-patches wrote:
>> On 9/26/22 13:52, H.J. Lu wrote:
>>> On Sat, Sep 24, 2022 at 1:37 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
>>>> On 9/21/22 16:11, H.J. Lu wrote:
>>>>> On Wed, Sep 7, 2022 at 10:03 AM Jeff Law via Gcc-patches
>>>>> <gcc-patches@gcc.gnu.org> wrote:
>>>>>> On 9/2/2022 8:36 AM, H.J. Lu via Gcc-patches wrote:
>>>>>>> CONCAT and CONCATN never appear in the insn chain.  They are only used
>>>>>>> in debug insn.  Ignore debug insns with CONCAT and CONCATN for insn
>>>>>>> scheduling to avoid different insn orders with and without debug insn.
>>>>>>>
>>>>>>> gcc/
>>>>>>>
>>>>>>>          PR rtl-optimization/106746
>>>>>>>          * sched-deps.cc (sched_analyze_2): Ignore debug insns with CONCAT
>>>>>>>          and CONCATN.
>>>>>> Shouldn't we be ignoring everything in a debug insn?   I don't see why
>>>>>> CONCAT/CONCATN are special here.
>>>>> Debug insns are processed by insn scheduling.   I think it is to improve debug
>>>>> experiences.  It is just that there are no matching usages of CONCAT/CONCATN
>>>>> in non-debug insns.
>>>> But from a dependency standpoint ISTM all debug insn can be ignored.  I
>>>> still don't see why concat/concatn should be special here.
>>>>
>>> I tried to ignore everything in a debug insn.  It caused many regressions in
>>> the GCC testsuite.
>> Not terribly useful -- what failed and why?
> I think the design for debug insns in the scheduler is that they do affect
> scheduling decisions, but what is in debug insns should only affect actual
> scheduling of the debug insns and not the rest.
> So it wouldn't surprise me if ignoring everything in a debug insn broke a
> lot.  But I admit I never fully understood how it works, hopefully Alex or
> Vlad do.

But if we  look at debug insns in scheduling decisions, wouldn't that 
likely trigger a variety of compare-debug failures. Something here 
doesn't make sense.


jeff
diff mbox series

Patch

diff --git a/gcc/sched-deps.cc b/gcc/sched-deps.cc
index 948aa0c3b60..b472e4fbb09 100644
--- a/gcc/sched-deps.cc
+++ b/gcc/sched-deps.cc
@@ -2794,6 +2794,20 @@  sched_analyze_2 (class deps_desc *deps, rtx x, rtx_insn *insn)
 
       return;
 
+    case VAR_LOCATION:
+      if (GET_CODE (PAT_VAR_LOCATION_LOC (x)) == CONCAT
+	  || GET_CODE (PAT_VAR_LOCATION_LOC (x)) == CONCATN)
+	{
+	  /* CONCAT and CONCATN never appear in the insn chain.  They
+	     are only used in debug insn.  Ignore insns with CONCAT and
+	     CONCATN for insn scheduling to avoid different insn orders
+	     with and without debug insn.  */
+	  if (cslr_p && sched_deps_info->finish_rhs)
+	    sched_deps_info->finish_rhs ();
+	  return;
+	}
+      break;
+
     default:
       break;
     }
diff --git a/gcc/testsuite/gcc.dg/pr106746.c b/gcc/testsuite/gcc.dg/pr106746.c
new file mode 100644
index 00000000000..1fc29de28c3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr106746.c
@@ -0,0 +1,30 @@ 
+/* { dg-do compile } */
+/* { dg-options "-Wno-psabi -O2 -fsched2-use-superblocks -fcompare-debug" } */
+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;
+}