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Re: [Qemu-ppc] [PATCH 7/7] target/ppc: Use non-arithmetic conversions fo
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From: |
Richard Henderson |
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Subject: |
Re: [Qemu-ppc] [PATCH 7/7] target/ppc: Use non-arithmetic conversions for fp load/store |
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Date: |
Thu, 5 Jul 2018 09:48:17 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
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
- [Qemu-ppc] [PATCH for-3.1 0/7] target/ppc fp cleanups, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 1/7] target/ppc: Enable fp exceptions for user-only, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 2/7] target/ppc: Honor fpscr_ze semantics and tidy fdiv, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 4/7] target/ppc: Tidy helper_fadd, helper_fsub, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 3/7] target/ppc: Tidy helper_fmul, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 5/7] target/ppc: Tidy helper_fsqrt, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 6/7] target/ppc: Honor fpscr_ze semantics and tidy fre, fresqrt, Richard Henderson, 2018/07/03
- [Qemu-ppc] [PATCH 7/7] target/ppc: Use non-arithmetic conversions for fp load/store, Richard Henderson, 2018/07/03
Re: [Qemu-ppc] [PATCH for-3.1 0/7] target/ppc fp cleanups, David Gibson, 2018/07/04
Re: [Qemu-ppc] [Qemu-devel] [PATCH for-3.1 0/7] target/ppc fp cleanups, Alex Bennée, 2018/07/04