[llvm-dev] XMMs unused

[Dangeti Tharun kumar via llvm-dev]

Hi Craig,

The test case is from spec-17.

The attached is the assembly file for the function MeanShiftImage from
spec17/538.imagick_r/src/magick/feature.c.
As I was saying, registers XMM10-15 are not used.


On Thu, Oct 25, 2018 at 2:16 PM Dangeti Tharun kumar <
cs15mtech11002 at iith.ac.in> wrote:

> Hi,
>
> It can be reproduced with the following command:
>
> clang -S -I spec17/benchspec/CPU/538.imagick_r/src/ -O3 -mavx spec17/benchspec/CPU/538.imagick_r/src/magick/feature.c -DMAGICKCORE_HDRI_ENABLE
>
> I don't see any register above *xmm9* been used in any function.
>
>
> On Thu, Oct 25, 2018 at 10:44 AM Craig Topper <craig.topper at gmail.com>
> wrote:
>
>> Can you provide an example?
>>
>> ~Craig
>>
>>
>> On Wed, Oct 24, 2018 at 9:52 PM Dangeti Tharun kumar via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hi,
>>>
>>> I see that, in Greedy register allocation not all the XMM registers are
>>> used(even there is a need) if there is a function call crossing the live
>>> range.
>>> There are spills which can be avoided just by using them.
>>>
>>> The reason I see is the CCC declares XMMs are not callee saved. This
>>> means they are caller saved, correct me if I am wrong.
>>> Is the greedy RA intentionally not using XMMs in order to avoid saving
>>> and restoring regs at call site?
>>>
>>>
>>> --
>>> Regards,
>>> DTharun
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>
>
> --
> Regards,
> DTharun
>


-- 
Regards,
DTharun
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20181030/ce42273d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: meanshift.s
Type: application/octet-stream
Size: 27806 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20181030/ce42273d/attachment.obj>