[Bug testsuite/51693] New: New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[Bug testsuite/51693] New: New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[irar at il dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

             Bug #: 51693
           Summary: New XPASSes in vectorizer testsuite on
                    powerpc64-suse-linux
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: testsuite
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: irar@il.ibm.com
                CC: michael.v.zolotukhin@gmail.com
              Host: powerpc64-suse-linux
            Target: powerpc64-suse-linux
             Build: powerpc64-suse-linux


Revision 182583 http://gcc.gnu.org/viewcvs?view=revision&revision=182583 caused
several XPASSes on powerpc64-suse-linux:

XPASS: gcc.dg/vect/vect-multitypes-1.c scan-tree-dump-times vect "Alignment of
access forced using peeling" 2
XPASS: gcc.dg/vect/vect-multitypes-1.c scan-tree-dump-times vect "Vectorizing
an unaligned access" 4
XPASS: gcc.dg/vect/vect-peel-3.c scan-tree-dump-times vect "Vectorizing an
unaligned access" 1
XPASS: gcc.dg/vect/vect-peel-3.c scan-tree-dump-times vect "Alignment of access
forced using peeling" 1
XPASS: gcc.dg/vect/vect-multitypes-1.c -flto scan-tree-dump-times vect
"Alignment of access forced using peeling" 2
XPASS: gcc.dg/vect/vect-multitypes-1.c -flto scan-tree-dump-times vect
"Vectorizing an unaligned access" 4
XPASS: gcc.dg/vect/vect-peel-3.c -flto scan-tree-dump-times vect "Vectorizing
an unaligned access" 1
XPASS: gcc.dg/vect/vect-peel-3.c -flto scan-tree-dump-times vect "Alignment of
access forced using peeling" 1
XPASS: gcc.dg/vect/no-section-anchors-vect-69.c scan-tree-dump-times vect
"Alignment of access forced using peeling" 2

The reason is that {!vect_aligned_arrays} was added to xfail of the above
checks, while vect_aligned_arrays is false for power.

Changing that, i.e.:
Index: ../../lib/target-supports.exp
===================================================================
--- ../../lib/target-supports.exp       (revision 182703)
+++ ../../lib/target-supports.exp       (working copy)
@@ -3222,7 +3222,8 @@ proc check_effective_target_vect_aligned_arrays {
                 set et_vect_aligned_arrays_saved 1
            }
        }
-        if [istarget spu-*-*] {
+        if {[istarget spu-*-*]
+           || [istarget powerpc*-*-*] } {
            set et_vect_aligned_arrays_saved 1
        }
     }

fixes the XPASSes and doesn't cause any problems (on powerpc64-suse-linux), but
AFAIU arrays are not always vector aligned on power, so this is not a good
idea, unless we change the definition of
check_effective_target_vect_aligned_arrays.

What was the purpose of adding {!vect_aligned_arrays} to these tests? If
peeling is impossible on AVX because arrays are never vector aligned, maybe we
need a new target check instead of vect_aligned_arrays?

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[michael.v.zolotukhin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #1 from Michael Zolotukhin <michael.v.zolotukhin at gmail dot com> 2011-12-28 11:08:36 UTC ---
I though that if {vect_aligned_arrays} isn't true, than arrays could
be aligned even after peeling - that's why I added such check.
Unfortunately, I can't reproduce these fails, as I have no PowerPC. By
the way, if arrays aren't aligned on Power, why does GCC produce such
messages - does it really try to peel something? Maybe we should just
refine the check?
Anyway, if everything is ok with the tests (in original version) and
with gcc itself - we could check not for vect_aligned_arrays, but for
AVX. Please check
http://gcc.gnu.org/ml/gcc-patches/2011-12/msg01600.html and the
attached to that letter patch.

Thanks, Michael


On 28 December 2011 14:51, irar at il dot ibm.com
<gcc-bugzilla@gcc.gnu.org> wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693
>
>             Bug #: 51693
>           Summary: New XPASSes in vectorizer testsuite on
>                    powerpc64-suse-linux
>    Classification: Unclassified
>           Product: gcc
>           Version: 4.7.0
>            Status: UNCONFIRMED
>          Severity: normal
>          Priority: P3
>         Component: testsuite
>        AssignedTo: unassigned@gcc.gnu.org
>        ReportedBy: irar@il.ibm.com
>                CC: michael.v.zolotukhin@gmail.com
>              Host: powerpc64-suse-linux
>            Target: powerpc64-suse-linux
>             Build: powerpc64-suse-linux
>
>
> Revision 182583 http://gcc.gnu.org/viewcvs?view=revision&revision=182583 caused
> several XPASSes on powerpc64-suse-linux:
>
> XPASS: gcc.dg/vect/vect-multitypes-1.c scan-tree-dump-times vect "Alignment of
> access forced using peeling" 2
> XPASS: gcc.dg/vect/vect-multitypes-1.c scan-tree-dump-times vect "Vectorizing
> an unaligned access" 4
> XPASS: gcc.dg/vect/vect-peel-3.c scan-tree-dump-times vect "Vectorizing an
> unaligned access" 1
> XPASS: gcc.dg/vect/vect-peel-3.c scan-tree-dump-times vect "Alignment of access
> forced using peeling" 1
> XPASS: gcc.dg/vect/vect-multitypes-1.c -flto scan-tree-dump-times vect
> "Alignment of access forced using peeling" 2
> XPASS: gcc.dg/vect/vect-multitypes-1.c -flto scan-tree-dump-times vect
> "Vectorizing an unaligned access" 4
> XPASS: gcc.dg/vect/vect-peel-3.c -flto scan-tree-dump-times vect "Vectorizing
> an unaligned access" 1
> XPASS: gcc.dg/vect/vect-peel-3.c -flto scan-tree-dump-times vect "Alignment of
> access forced using peeling" 1
> XPASS: gcc.dg/vect/no-section-anchors-vect-69.c scan-tree-dump-times vect
> "Alignment of access forced using peeling" 2
>
> The reason is that {!vect_aligned_arrays} was added to xfail of the above
> checks, while vect_aligned_arrays is false for power.
>
> Changing that, i.e.:
> Index: ../../lib/target-supports.exp
> ===================================================================
> --- ../../lib/target-supports.exp       (revision 182703)
> +++ ../../lib/target-supports.exp       (working copy)
> @@ -3222,7 +3222,8 @@ proc check_effective_target_vect_aligned_arrays {
>                 set et_vect_aligned_arrays_saved 1
>            }
>        }
> -        if [istarget spu-*-*] {
> +        if {[istarget spu-*-*]
> +           || [istarget powerpc*-*-*] } {
>            set et_vect_aligned_arrays_saved 1
>        }
>     }
>
> fixes the XPASSes and doesn't cause any problems (on powerpc64-suse-linux), but
> AFAIU arrays are not always vector aligned on power, so this is not a good
> idea, unless we change the definition of
> check_effective_target_vect_aligned_arrays.
>
> What was the purpose of adding {!vect_aligned_arrays} to these tests? If
> peeling is impossible on AVX because arrays are never vector aligned, maybe we
> need a new target check instead of vect_aligned_arrays?
>
> --
> Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email
> ------- You are receiving this mail because: -------
> You are on the CC list for the bug.

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[irar at il dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #2 from Ira Rosen <irar at il dot ibm.com> 2011-12-28 12:27:18 UTC ---
(In reply to comment #1)
> I though that if {vect_aligned_arrays} isn't true, than arrays could
> be aligned even after peeling - that's why I added such check.

Sorry, I don't understand this sentence. What do you mean by aligned after
peeling? Could you please explain what exactly happens on AVX (a dump file with
-fdump-tree-vect-details would be the best thing).

> Unfortunately, I can't reproduce these fails, as I have no PowerPC. By
> the way, if arrays aren't aligned on Power, why does GCC produce such
> messages - does it really try to peel something? 

The arrays in the tests are aligned. I said that I think that we can't promise
that all the arrays are vector aligned on power. BTW, we can peel for unknown
misalignment as well.

> Maybe we should just
> refine the check?
> Anyway, if everything is ok with the tests (in original version) and
> with gcc itself - we could check not for vect_aligned_arrays, but for
> AVX. Please check
> http://gcc.gnu.org/ml/gcc-patches/2011-12/msg01600.html and the
> attached to that letter patch.

I think that everything was ok, but I don't think that using vect_sizes_32B_16B
is a good idea. I would really like to see an AVX vect dump for eg.
vect-peel-3.c.

Thanks,
Ira

> 
> Thanks, Michael
>

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[michael.v.zolotukhin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #3 from Michael Zolotukhin <michael.v.zolotukhin at gmail dot com> 2011-12-28 12:59:24 UTC ---
Created attachment 26195
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26195
AVX2 vect dump

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[michael.v.zolotukhin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #4 from Michael Zolotukhin <michael.v.zolotukhin at gmail dot com> 2011-12-28 13:01:51 UTC ---
(In reply to comment #2)
> > I though that if {vect_aligned_arrays} isn't true, than arrays could
> > be aligned even after peeling - that's why I added such check.
> 
> Sorry, I don't understand this sentence. What do you mean by aligned after
> peeling? Could you please explain what exactly happens on AVX (a dump file with
> -fdump-tree-vect-details would be the best thing).
Sorry, I misspelled. I meant "than arrays couldn't be aligned" - at least
without some runtime checks. I.e. we can't peel some compile-time-known number
of iterations and be sure that array become aligned.

E.g., if we have array IA of ints aligned to 16-bytes, and we have access
IA[i+3], then peeling of one iteration will guarantee alignment to 16-byte. But
we don't know, how much iterations needs to be peeled to reach alignment to
32-bytes (as needed for AVX operations).

> > Unfortunately, I can't reproduce these fails, as I have no PowerPC. By
> > the way, if arrays aren't aligned on Power, why does GCC produce such
> > messages - does it really try to peel something? 
> 
> The arrays in the tests are aligned. I said that I think that we can't promise
> that all the arrays are vector aligned on power. BTW, we can peel for unknown
> misalignment as well.

In this case we shouldn't add Power to vector_aligned_arrays, I guess.

> > Maybe we should just
> > refine the check?
> > Anyway, if everything is ok with the tests (in original version) and
> > with gcc itself - we could check not for vect_aligned_arrays, but for
> > AVX. Please check
> > http://gcc.gnu.org/ml/gcc-patches/2011-12/msg01600.html and the
> > attached to that letter patch.
> 
> I think that everything was ok, but I don't think that using vect_sizes_32B_16B
> is a good idea. I would really like to see an AVX vect dump for eg.
> vect-peel-3.c.

In vect-peel-3.c we actually assume that vector length is 16 byte. Here is the
loop body:
      suma += ia[i];
      sumb += ib[i+5];
      sumc += ic[i+1];
When vector-size is 16, then peeling can make two of three accesses aligned,
but when vector size is 32 that's impossible. That's why using
vector_sizes_32B_16B might be correct here.

Also, I uploaded the dump you asked.

Michael

> Thanks,
> Ira
>

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[irar at il dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #5 from Ira Rosen <irar at il dot ibm.com> 2011-12-28 13:11:53 UTC ---
(In reply to comment #4)

> In vect-peel-3.c we actually assume that vector length is 16 byte. Here is the
> loop body:
>       suma += ia[i];
>       sumb += ib[i+5];
>       sumc += ic[i+1];
> When vector-size is 16, then peeling can make two of three accesses aligned,
> but when vector size is 32 that's impossible. That's why using
> vector_sizes_32B_16B might be correct here.

Ah, now I understand. I was confused by vect_aligned_arrays, and it's
irrelevant here, right?

Yes, vector_sizes_32B_16B seems to be ok in that case.

Thanks,
Ira

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[michael.v.zolotukhin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #6 from Michael Zolotukhin <michael.v.zolotukhin at gmail dot com> 2011-12-28 16:19:54 UTC ---
(In reply to comment #5)
> > In vect-peel-3.c we actually assume that vector length is 16 byte. Here is the
> > loop body:
> >       suma += ia[i];
> >       sumb += ib[i+5];
> >       sumc += ic[i+1];
> > When vector-size is 16, then peeling can make two of three accesses aligned,
> > but when vector size is 32 that's impossible. That's why using
> > vector_sizes_32B_16B might be correct here.
> 
> Ah, now I understand. I was confused by vect_aligned_arrays, and it's
> irrelevant here, right?
Actually yes, you're right. I think, ideally, vect_aligned_arrays should be
somehow checked in such tests, as in them we assume that array's beginning is
aligned - but that's not the rootcause of the xpasses.

> Yes, vector_sizes_32B_16B seems to be ok in that case.
Other two tests (vect-multitypes-1.c and no-section-anchors-vect-69.c) look
like having the same problem - are you ok for similar fix for them too, i.e. is
patch
http://gcc.gnu.org/ml/gcc-patches/2011-12/msg01600/vec-tests-avx2_fixes-7.patch
ok for trunk?

Thanks, Michael

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[irar at il dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

--- Comment #7 from Ira Rosen <irar at il dot ibm.com> 2011-12-29 07:37:53 UTC ---
(In reply to comment #6)

> > Yes, vector_sizes_32B_16B seems to be ok in that case.
> Other two tests (vect-multitypes-1.c and no-section-anchors-vect-69.c) look
> like having the same problem - are you ok for similar fix for them too, i.e. is
> patch
> http://gcc.gnu.org/ml/gcc-patches/2011-12/msg01600/vec-tests-avx2_fixes-7.patch
> ok for trunk?

Yes, just please don't forget to update testsuite/ChangeLog.

Thanks,
Ira

> 
> Thanks, Michael

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[ro at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|powerpc64-suse-linux        |powerpc64-suse-linux,
                   |                            |i386-pc-solaris2*
                 CC|                            |ro at gcc dot gnu.org
               Host|powerpc64-suse-linux        |powerpc64-suse-linux,
                   |                            |i386-pc-solaris2*
   Target Milestone|---                         |4.7.0
              Build|powerpc64-suse-linux        |powerpc64-suse-linux,
                   |                            |i386-pc-solaris2*

--- Comment #8 from Rainer Orth <ro at gcc dot gnu.org> 2012-01-04 17:35:36 UTC ---
This also affects 32-bit Solaris/x86.

  Rainer

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.0                       |4.7.1

--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-03-22 08:27:01 UTC ---
GCC 4.7.0 is being released, adjusting target milestone.

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.1                       |---

[Bug testsuite/51693] New XPASSes in vectorizer testsuite on powerpc64-suse-linux

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51693

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED
   Target Milestone|---                         |4.7.0

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed by r0-114550.