[llvm-dev] Pattern transformation between scalar and vector on IR.

Jojo Ma via llvm-dev llvm-dev at lists.llvm.org
Thu Sep 8 02:32:17 PDT 2016

Hi All,

I'm tring to use RSQRT instructions on follow case for ARM
(now what using is sqrt):

    1.0 / sqrt(x)

The RSQRT instructions(VRSQRTE/VRSQRTS) are vector type,
but above operation is scalar type. So a transformation must be
done(transform sqrt pattern to rsqrt).

I have completed a patch for this, but I made the transformation in the
backend which will leads to additional latencies.And actually it's not
reasonable doing transformation in backend.
I think it would be better done that on IR. I am a novice to llvm.I don't
know  anything about this subject. If anyone could
give me some advice would be appreciated.


Best Regards,
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160908/8f56b21a/attachment.html>

More information about the llvm-dev mailing list