llvm dev - Oct 2011 - [LLVMdev] Codgen for popcnt intrinsic falls over on MacOSX

I'm having a problem with the code generated for the popcnt intrinsic on
MacOSX. The `llc` program will generate the assembly just fine, but the
assembler fails with the error:

   suffix or operands invalid for `popcnt'

The problem is that the mac assembler does not support length suffixes on the
popcnt instruction (e.g. {w,l,q} suffixes). GCC handles this by not adding the
suffixes to popcnt for darwin targets [1].

Indeed if I change the instruction definition in lib/Target/X86/X86InstrSSE.td
to drop the suffix, then it works fine. I can submit a patch to that effect, but
what is the proper way to handle this?

[1]: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34497#c14

Hi,

On Sat, Oct 22, 2011 at 12:03 PM, David Peixotto <dmp at rice.edu>
wrote:
> I'm having a problem with the code generated for the popcnt intrinsic
on MacOSX. The `llc` program will generate the assembly just fine, but the
assembler fails with the error:
>
>   suffix or operands invalid for `popcnt'
>
> The problem is that the mac assembler does not support length suffixes on
the popcnt instruction (e.g. {w,l,q} suffixes). GCC handles this by not adding
the suffixes to popcnt for darwin targets [1].
>
> Indeed if I change the instruction definition in
lib/Target/X86/X86InstrSSE.td to drop the suffix, then it works fine. I can
submit a patch to that effect, but what is the proper way to handle this?
>
> [1]: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34497#c14
> _______________________________________________
Have you tried "llc -filetype=obj ..."? The integrated assembler may
do the work!

-- 
Bruno Cardoso Lopes
http://www.brunocardoso.cc

On Oct 22, 2011, at 7:19 PM, Bruno Cardoso Lopes wrote:
> Hi,
> 
> On Sat, Oct 22, 2011 at 12:03 PM, David Peixotto <dmp at rice.edu>
wrote:
>> I'm having a problem with the code generated for the popcnt
intrinsic on MacOSX. The `llc` program will generate the assembly just fine, but
the assembler fails with the error:
>> 
>>   suffix or operands invalid for `popcnt'
>> 
>> The problem is that the mac assembler does not support length suffixes
on the popcnt instruction (e.g. {w,l,q} suffixes). GCC handles this by not
adding the suffixes to popcnt for darwin targets [1].
>> 
>> Indeed if I change the instruction definition in
lib/Target/X86/X86InstrSSE.td to drop the suffix, then it works fine. I can
submit a patch to that effect, but what is the proper way to handle this?
>> 
>> [1]: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34497#c14
>> _______________________________________________
> 
> Have you tried "llc -filetype=obj ..."? The integrated assembler
may
> do the work!
Yes, I believe the integrated assembler gets it right, but unfortunately I'm
using a toolchain that needs to use the mac assembler so I'd like to get it
working with that if possible.

Removing the suffix seems to work ok, I just need to know if it needs to be done
conditionally for mac os x to get the patch accepted, and if so how to do that.