[cfe-commits] r154046 - in /cfe/trunk: include/clang/Driver/Options.td lib/Basic/Targets.cpp lib/Driver/Tools.cpp test/Driver/arm-mfpmath.c

Sandeep Patel deeppatel1987 at gmail.com
Fri Apr 6 15:53:04 PDT 2012

On Fri, Apr 6, 2012 at 10:16 PM, Chad Rosier <michael_rosier at apple.com> wrote:
> On Apr 6, 2012, at 3:13 PM, Sandeep Patel wrote:
>> Is this really necessary as a driver-level option?
>> Can't this be inferred from other existing tuning choice (e.g. which
>> core IP is used)?
> No, that's why it was added.

If we have a Cortex-A8 vs A9, we can know which approach is going to
be faster always, don't we?

>> How likely is somebody going to want to change this?
> One of our internal teams requires the ability to use VFP as opposed to NEON.

This is on a core with Neon that we know from other flags we're
targeting? (I can't quite see why this would be needed except as a
workaround for a performance edge case when neonfp is slower.)

I'm generally against providing tweakable driver-level params to
people that won't understand them and will constantly fiddle with
them, hoping to get better performance. Can't we keep this as a cc1
flag only?


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