[Bug tree-optimization/58762] New: [missed optimization] Vectorizing abs(int).

[Bug tree-optimization/58762] New: [missed optimization] Vectorizing abs(int).

[congh at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58762

            Bug ID: 58762
           Summary: [missed optimization] Vectorizing abs(int).
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: congh at google dot com

pabsd in SSSE3 makes it quite straightforward to vectorize abs(int) operation.
But with only SSE2 available, GCC won't vectorize this operation. GCC
translates the abs(int) operation into three instructions: sar, xor, and sub.
Each of them can be vectorized. So I am wondering why GCC does not vectorize
abs(int) in this way? Are there any platform or safety concerns?


Thank you!

Cong

[Bug target/58762] [missed optimization] Vectorizing abs(int).

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58762

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Target|                            |x86_64-*-*, i?86-*-*
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-10-17
          Component|tree-optimization           |target
     Ever confirmed|0                           |1
           Severity|normal                      |enhancement

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The backend simply doesn't implement an expander for abs I think.  The
vectorizer
simply checks if an optab is available for the mode in question.  See
ix86_expand_fp_absneg_operator.

[Bug target/58762] [missed optimization] Vectorizing abs(int).

[congh at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58762

--- Comment #2 from congh at gcc dot gnu.org ---
Author: congh
Date: Wed Oct 30 20:01:47 2013
New Revision: 204229

URL: http://gcc.gnu.org/viewcvs?rev=204229&root=gcc&view=rev
Log:
2013-10-30  Cong Hou  <congh@google.com>

    PR target/58762
    * config/i386/i386-protos.h (ix86_expand_sse2_abs): New function.
    * config/i386/i386.c (ix86_expand_sse2_abs): New function.
    * config/i386/sse.md: Add SSE2 support to abs (8/16/32-bit-int).

2013-10-30  Cong Hou  <congh@google.com>

    * gcc.target/i386/vect-abs-s8.c: New test.
    * gcc.target/i386/vect-abs-s16.c: New test.
    * gcc.target/i386/vect-abs-s32.c: New test.


Added:
    trunk/gcc/testsuite/gcc.target/i386/vect-abs-s16.c
    trunk/gcc/testsuite/gcc.target/i386/vect-abs-s32.c
    trunk/gcc/testsuite/gcc.target/i386/vect-abs-s8.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/i386-protos.h
    trunk/gcc/config/i386/i386.c
    trunk/gcc/config/i386/sse.md
    trunk/gcc/testsuite/ChangeLog

[Bug target/58762] [missed optimization] Vectorizing abs(int).

[congh at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58762

--- Comment #3 from congh at gcc dot gnu.org ---
Author: congh
Date: Thu Oct 31 00:50:47 2013
New Revision: 204241

URL: http://gcc.gnu.org/viewcvs?rev=204241&root=gcc&view=rev
Log:
2013-10-30  Cong Hou  <congh@google.com>

    Backport from mainline:
    2013-10-30  Cong Hou  <congh@google.com>

    PR target/58762
    * config/i386/i386-protos.h (ix86_expand_sse2_abs): New function.
    * config/i386/i386.c (ix86_expand_sse2_abs): New function.
    * config/i386/sse.md: Add SSE2 support to abs (8/16/32-bit-int).


Modified:
    branches/google/gcc-4_8/gcc/ChangeLog
    branches/google/gcc-4_8/gcc/config/i386/i386-protos.h
    branches/google/gcc-4_8/gcc/config/i386/i386.c
    branches/google/gcc-4_8/gcc/config/i386/sse.md

[Bug target/58762] [missed optimization] Vectorizing abs(int).

[congh at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58762

Cong Hou <congh at google dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Cong Hou <congh at google dot com> ---
(In reply to Cong Hou from comment #3)
> Author: congh
> Date: Thu Oct 31 00:50:47 2013
> New Revision: 204241
> 
> URL: http://gcc.gnu.org/viewcvs?rev=204241&root=gcc&view=rev
> Log:
> 2013-10-30  Cong Hou  <congh@google.com>
> 
>     Backport from mainline:
>     2013-10-30  Cong Hou  <congh@google.com>
> 
>     PR target/58762
>     * config/i386/i386-protos.h (ix86_expand_sse2_abs): New function.
>     * config/i386/i386.c (ix86_expand_sse2_abs): New function.
>     * config/i386/sse.md: Add SSE2 support to abs (8/16/32-bit-int).
> 
> 
> Modified:
>     branches/google/gcc-4_8/gcc/ChangeLog
>     branches/google/gcc-4_8/gcc/config/i386/i386-protos.h
>     branches/google/gcc-4_8/gcc/config/i386/i386.c
>     branches/google/gcc-4_8/gcc/config/i386/sse.md