[LLVMdev] Itineraries in the powerpc backend

Carter Cheng cartercheng at gmail.com
Fri Oct 28 23:49:04 CDT 2011


I hope you don't mind if do have a follow up question- is code in place in
the code generation supporting "proper" scheduling via the processor
itineraries in LLVM?



On Fri, Oct 28, 2011 at 8:47 PM, Carter Cheng <cartercheng at gmail.com> wrote:

> Thanks Hal.
>
> On Fri, Oct 28, 2011 at 2:19 AM, Hal Finkel <hfinkel at anl.gov> wrote:
>
>> Carter,
>>
>> In my opinion (and I was the one who committed the changes in question),
>> it depends on the hardware. The pipeline descriptions are for the PPC
>> 440, which is an embedded PPC chip use in a variety of places. As such,
>> it is a fairly specific target, and using pipeline-hazard-based
>> scheduling for specific embedded targets is not uncommon. The backends
>> for ARM and MBlaze have similar pipeline information for use by their
>> schedulers.
>>
>>  -Hal
>>
>> On Thu, 2011-10-27 at 13:28 -0700, Carter Cheng wrote:
>> > Hello,
>> >
>> > I was looking over some of the Target commits. I did notice some
>> > detailed pipeline descriptions in the ppc backends. I havent noticed
>> > anything in the literature describing this technique. Is this a
>> > standard approach for mapping SSA to hardware?
>> >
>> > Thanks in advance,
>> >
>> > Carter.
>> > _______________________________________________
>> > LLVM Developers mailing list
>> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>> --
>> Hal Finkel
>> Postdoctoral Appointee
>> Leadership Computing Facility
>> Argonne National Laboratory
>>
>>
>
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