[Bug c/60847] New: x86 BMI intrinsics not recognized

[Bug c/60847] New: x86 BMI intrinsics not recognized

[spatel at rotateright dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

            Bug ID: 60847
           Summary: x86 BMI intrinsics not recognized
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: spatel at rotateright dot com

With gcc 4.9.0 (version details below), the x86 bit manipulation instruction
(BMI) C intrinsics are not being recognized. This appears to be a regression
from gcc 4.8.2.

$ cat bmi.c
#include <x86intrin.h>
int foo(int a) { return _blsmsk_u32(a); }
int foo2(int a) { return _blsr_u32(a); }

$ gcc -O1 bmi.c -mbmi -S -o -
    .text
    .globl _foo
_foo:
LFB2449:
    subq    $8, %rsp
LCFI0:
    movl    $0, %eax
    call    __blsmsk_u32  <--- this should be a 'blsmsk' instruction
    addq    $8, %rsp
LCFI1:
    ret
LFE2449:
    .globl _foo2
_foo2:
LFB2450:
    subq    $8, %rsp
LCFI2:
    movl    $0, %eax
    call    __blsr_u32  <--- this should be a 'blsr' instruction
    addq    $8, %rsp


$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/opt/local/libexec/gcc/x86_64-apple-darwin13/4.9.0/lto-wrapper
Target: x86_64-apple-darwin13
Configured with:
/opt/local/var/macports/build/_opt_mports_dports_lang_gcc49/gcc49/work/gcc-4.9-20140406/configure
--prefix=/opt/local --build=x86_64-apple-darwin13
--enable-languages=c,c++,objc,obj-c++,fortran,java
--libdir=/opt/local/lib/gcc49 --includedir=/opt/local/include/gcc49
--infodir=/opt/local/share/info --mandir=/opt/local/share/man
--datarootdir=/opt/local/share/gcc-4.9 --with-local-prefix=/opt/local
--with-system-zlib --disable-nls --program-suffix=-mp-4.9
--with-gxx-include-dir=/opt/local/include/gcc49/c++/ --with-gmp=/opt/local
--with-mpfr=/opt/local --with-mpc=/opt/local --with-cloog=/opt/local
--enable-cloog-backend=isl --disable-cloog-version-check
--enable-stage1-checking --disable-multilib --enable-lto
--enable-libstdcxx-time --with-as=/opt/local/bin/as --with-ld=/opt/local/bin/ld
--with-ar=/opt/local/bin/ar --with-bugurl=https://trac.macports.org/newticket
--with-pkgversion='MacPorts gcc49 4.9-20140406_0'
Thread model: posix
gcc version 4.9.0 20140406 (experimental) (MacPorts gcc49 4.9-20140406_0)

[Bug c/60847] x86 BMI intrinsics not recognized

[spatel at rotateright dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

--- Comment #1 from Sanjay Patel <spatel at rotateright dot com> ---
It looks like an extra leading underscore is required to recognize the BMI
intrinsics. This is not happening with other (BMI2, SSE4) intrinsics. 

According to the Intel reference docs and previous versions of gcc, a single
underscore is the correct usage.

[Bug target/60847] x86 BMI intrinsics not recognized

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |kyukhin at gcc dot gnu.org
          Component|c                           |target

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
These were added to 4.8 branch with r201047, but I can't find corresponding
checkin to the trunk.
It has been acked for the trunk:
http://gcc.gnu.org/ml/gcc-patches/2013-07/msg00111.html

[Bug c/60847] x86 BMI intrinsics not recognized

[spatel at rotateright dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

Sanjay Patel <spatel at rotateright dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|target                      |c

--- Comment #3 from Sanjay Patel <spatel at rotateright dot com> ---
Here's the evidence of the extra leading underscore being the cause of the bug:

$ cat bmi.c
#include <x86intrin.h>
int foo(int a) { return __blsmsk_u32(a); }
int foo2(int a) { return __blsr_u32(a); }

$ gcc -O1 bmi.c -mbmi -S -o -
    .text
    .globl _foo
_foo:
LFB2449:
    blsmsk    %edi, %eax
    ret
LFE2449:
    .globl _foo2
_foo2:
LFB2450:
    blsr    %edi, %eax
    ret


Thanks to Craig Topper for noticing the underscore problem. Corresponding bug
in LLVM where this was first noted is here:
http://llvm.org/bugs/show_bug.cgi?id=19431

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-04-15
          Component|c                           |target
   Target Milestone|---                         |4.9.0
            Summary|x86 BMI intrinsics not      |[4.9/4.10 Regression] x86
                   |recognized                  |BMI intrinsics not
                   |                            |recognized
     Ever confirmed|0                           |1

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
As the aliases have been added to 4.8 branch only, this makes it a regression
from 4.8.x.

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Apr 17 10:02:36 2014
New Revision: 209471

URL: http://gcc.gnu.org/viewcvs?rev=209471&root=gcc&view=rev
Log:
    PR target/60847
    Forward port from 4.8 branch
    2013-07-19  Kirill Yukhin  <kirill.yukhin@intel.com>

    * config/i386/bmiintrin.h (_blsi_u32): New.
    (_blsi_u64): Ditto.
    (_blsr_u32): Ditto.
    (_blsr_u64): Ditto.
    (_blsmsk_u32): Ditto.
    (_blsmsk_u64): Ditto.
    (_tzcnt_u32): Ditto.
    (_tzcnt_u64): Ditto.

    * gcc.target/i386/bmi-1.c: Extend with new instrinsics.
    Fix scan patterns.
    * gcc.target/i386/bmi-2.c: Ditto.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/bmiintrin.h
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.target/i386/bmi-1.c
    trunk/gcc/testsuite/gcc.target/i386/bmi-2.c

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Apr 17 10:09:45 2014
New Revision: 209472

URL: http://gcc.gnu.org/viewcvs?rev=209472&root=gcc&view=rev
Log:
    PR target/60847
    Forward port from 4.8 branch
    2013-07-19  Kirill Yukhin  <kirill.yukhin@intel.com>

    * config/i386/bmiintrin.h (_blsi_u32): New.
    (_blsi_u64): Ditto.
    (_blsr_u32): Ditto.
    (_blsr_u64): Ditto.
    (_blsmsk_u32): Ditto.
    (_blsmsk_u64): Ditto.
    (_tzcnt_u32): Ditto.
    (_tzcnt_u64): Ditto.

    * gcc.target/i386/bmi-1.c: Extend with new instrinsics.
    Fix scan patterns.
    * gcc.target/i386/bmi-2.c: Ditto.

Modified:
    branches/gcc-4_9-branch/gcc/ChangeLog
    branches/gcc-4_9-branch/gcc/config/i386/bmiintrin.h
    branches/gcc-4_9-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_9-branch/gcc/testsuite/gcc.target/i386/bmi-1.c
    branches/gcc-4_9-branch/gcc/testsuite/gcc.target/i386/bmi-2.c

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Should be fixed now.

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[spatel at rotateright dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

--- Comment #8 from Sanjay Patel <spatel at rotateright dot com> ---
Thanks, Jakub. 

I see that the fix duplicates all of the intrinsics with a
double-leading-underscore variant. Why do we need that? AFAIK, no other x86
intrinsics have this kind of duplication.

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Sanjay Patel from comment #8)
> Thanks, Jakub. 
> 
> I see that the fix duplicates all of the intrinsics with a
> double-leading-underscore variant. Why do we need that? AFAIK, no other x86
> intrinsics have this kind of duplication.

That is because one kind of these intrinsics originates from AMD (support for
AMD BMI is what went into GCC first) and the other from ICC which chose to
provide different names.  So, for backwards compatibility we need both sets.

[Bug target/60847] [4.9/4.10 Regression] x86 BMI intrinsics not recognized

[spatel at rotateright dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60847

--- Comment #10 from Sanjay Patel <spatel at rotateright dot com> ---
Ah - thank you for the explanation! I found the original checkin from AMD:
http://gcc.gnu.org/ml/gcc-patches/2010-10/msg01356.html

Strangely, I can't find any documentation for those double-underscores from AMD
though.