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Re: [Qemu-ppc] [PATCH for-3.1 0/7] target/ppc fp cleanups

From: David Gibson
Subject: Re: [Qemu-ppc] [PATCH for-3.1 0/7] target/ppc fp cleanups
Date: Wed, 4 Jul 2018 13:31:34 +1000
User-agent: Mutt/1.10.0 (2018-05-17)

On Tue, Jul 03, 2018 at 08:17:25AM -0700, Richard Henderson wrote:
> Beginning with John Arbuckle's fdiv test case, clean up some
> of the fp helpers.  As with fdiv, fre and fresqrt are missing
> divide-by-zero exceptions.
> I've also noticed that load/store were using arithmetic conversions
> to/from float32.  These should be using the non-arithmetic algorithms
> listed in the manual.
> Aside from cleaning up all of the rest of the helpers, I believe that
> the implementation of the single-precision operations are incorrect.
> They are currently implemented with the double-precision operation
> followed by a round-to-single.  This causes incorrect results via
> double rounding.  I believe better results could be had by using
> these non-arithmetic converters to produce float32 operands, use the
> proper float32 softfloat operations, and then convert back.
> Anyway, all of this has been broken long enough that it'll need to
> wait til next devel cycle before anything further gets done.

Applied to ppc-for-3.1 (newly created).

David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!

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