[Bug c/53071] New: Wrong instruction replacement when compiling for xop

[Bug c/53071] New: Wrong instruction replacement when compiling for xop

[agner at agner dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53071

             Bug #: 53071
           Summary: Wrong instruction replacement when compiling for xop
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: agner@agner.org


Created attachment 27216
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27216
source code and asm output

An intrinsic vector multiply function is replaced by xop instructions when the
attached file is compiled with -mxop. Perhaps the compiler is trying to combine
a shift instruction and a multiply instruction into a single xop instruction,
but it ends up with something wrong.

This is perhaps related to bugs # 52908 and 52910.

[Bug target/53071] Wrong instruction replacement when compiling for xop

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53071

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
           Severity|critical                    |normal

[Bug target/53071] Wrong instruction replacement when compiling for xop

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53071

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-04-23
         Depends on|                            |52908, 52910
     Ever Confirmed|0                           |1

[Bug target/53071] Wrong instruction replacement when compiling for xop

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53071

--- Comment #1 from Uros Bizjak <ubizjak at gmail dot com> 2012-11-23 07:49:41 UTC ---
Resulting asm is quite different w/ current mainline:

_Z4testU8__vectorxS_S_:
    vmovdqa    %xmm2, -24(%rsp)
    vpsrlq    $32, %xmm0, %xmm3
    vpmuldq    %xmm1, %xmm0, %xmm2
    vpmuldq    %xmm1, %xmm3, %xmm1
    vpand    .LC0(%rip), %xmm1, %xmm1
    vpsrlq    $32, %xmm2, %xmm2
    vmovd    -24(%rsp), %xmm4
    vpor    %xmm1, %xmm2, %xmm1
    vpaddd    %xmm0, %xmm1, %xmm1
    vpsrad    $31, %xmm0, %xmm0
    vpsrad    %xmm4, %xmm1, %xmm1
    vpsubd    %xmm0, %xmm1, %xmm0
    ret

_Z5test2U8__vectorxS_S_:
    vpxor    %xmm3, %xmm3, %xmm3
    vmovdqa    %xmm2, -24(%rsp)
    vpmuldq    %xmm1, %xmm0, %xmm2
    vpsrlq    $32, %xmm2, %xmm2
    vpmacsdqh    %xmm3, %xmm1, %xmm0, %xmm1
    vpand    .LC0(%rip), %xmm1, %xmm1
    vmovd    -24(%rsp), %xmm4
    vpor    %xmm1, %xmm2, %xmm1
    vpaddd    %xmm0, %xmm1, %xmm1
    vpsrad    $31, %xmm0, %xmm0
    vpsrad    %xmm4, %xmm1, %xmm1
    vpsubd    %xmm0, %xmm1, %xmm0
    ret

[Bug target/53071] Wrong instruction replacement when compiling for xop

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53071
Bug 53071 depends on bug 52908, which changed state.

Bug 52908 Summary: xop-mul-1:f9 miscompiled on bulldozer (-mxop)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52908

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