[PATCH] Fix bug in GPR to FPR moves in PPC64LE

[Samuel F Antao]

Hal, Bill,

Thanks for the review and suggestions! Committed in r219441.

I'll create a new patch with the new move instructions. Creating the new
feature sounds like a good idea!

Thanks again,
Samuel

2014-10-09 14:57 GMT-04:00 Bill Schmidt <wschmidt at linux.vnet.ibm.com>:

> On Thu, 2014-10-09 at 14:16 -0400, Samuel F Antao wrote:
> > Hi all,
> >
> >
> > The current implementation of GPR->FPR register moves uses a stack
> > slot. This mechanism writes a double word and reads a word. In
> > big-endian the load address must be displaced by 4-bytes in order to
> > get the right value. In little endian this is no longer required. This
> > patch fixes the issue and adds LE regression tests to
> > fast-isel-conversion which currently expose this problem.
> >
> Thanks, Samuel!  LGTM.
>
> > This move can be done using the VSX capabilities that are currently
> > deactivated due to some other problems. I understand Bill and Bill are
> > fixing some of the VSX issues in FastISel, but this patch seems to be
> > orthogonal to that. I can contribute another implementation of the
> > moves using these instructions, which I've already implemented, once
> > it is okay to activate VSX for little endian.
> >
> Well, we will need to add a feature for ISA 2.07 (thanks for that fix,
> btw) vector support before the direct move instructions can be used.
> Currently FeatureVSX implies only ISA 2.06 support, which is all that's
> been (partially) implemented at this point.  Probably something like
> FeatureP8Vector to denote the changes to both VMX and VSX instructions
> for 2.07.
>
> Bill
> >
> > Thanks!
> > Samuel
>
>
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