Re: [Qemu-devel] [PATCH 7/7] target/ppc: Use non-arithmetic conversions for fp load/store

[Programmingkid]

> On Jul 5, 2018, at 12:48 PM, Richard Henderson <address@hidden> wrote:
> 
> On 07/05/2018 09:31 AM, Programmingkid wrote:
>>> On Jul 3, 2018, at 11:17 AM, Richard Henderson <address@hidden> wrote:
>>> 
>>> Memory operations have no side effects on fp state.
>>> The use of a "real" conversions between float64 and float32
>>> would raise exceptions for SNaN and out-of-range inputs.
>> 
>> Would you have any documentation that tells us about converting
>> between 64 bit and 32 bit floating points?
> 
> Spelled out right at the beginning of sections 4.6 (load) and 4.7 (store) of
> Book 1 of the Power ISA manual (version 3.0B) [0].
> 
> I've double-checked vs RISU[1] testing of LFS and STFS, with master traces
> generated on Power 8 ppc64le, so I don't see anything immediately wrong with
> the patch.  But I haven't had time to look further than that.
> 
> 
> r~
> 
> 
> [0] https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0
> [1] https://git.linaro.org/people/peter.maydell/risu.git

Thank you for the documentation. My guess is there are differences between the 
PowerPC and Power 8 implementations. PowerPC is big endian. Would you be able 
to do your testing again with your Power 8 CPU in big endian mode?