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Re: [Qemu-arm] [RFC PATCH for 2.11 00/23] Implementing FP16 for ARMv8.2
From: |
Peter Maydell |
Subject: |
Re: [Qemu-arm] [RFC PATCH for 2.11 00/23] Implementing FP16 for ARMv8.2 using SoftFloat2a and 3c |
Date: |
Thu, 20 Jul 2017 16:17:46 +0100 |
On 20 July 2017 at 16:04, Alex Bennée <address@hidden> wrote:
> So while any review is gratefully accepted my main interest is if this
> sort of duel approach is worth it?
>
> I think the long term aim would be to move fully over to the newer
> library if we can but I appreciate a not inconsiderable amount of work
> has gone into the existing 2a code. Having said that as long as the
> testing is good we are likely to pick up bugs in both implementations.
> While its nice to have a more modern SoftFloat library it still lags
> somewhat on QEMUs general requirements claiming only direct support
> for IEEE754 1985 whereas most modern CPUs are closer to the 2008
> revision of the specification.
I'm definitely not a fan of having two different implementations
of softfloat in the codebase, except perhaps for some well defined
*short* transition period. Otherwise we'll end up carrying both
of them around forever, given our past history at success in
transitioning things to new APIs.
I don't have a strong view about whether we're better off
moving to softfloat3c and forward porting any bugfixes and
improvements, or backporting 16-bit fp code from 3c to our
current codebase.
thanks
-- PMM
- [Qemu-arm] [RFC PATCH for 2.11 22/23] fpu/softfloat2a: improve comments on ARM NaN propagation, (continued)
- [Qemu-arm] [RFC PATCH for 2.11 22/23] fpu/softfloat2a: improve comments on ARM NaN propagation, Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 23/23] target/arm: implement half-precision F(MIN|MAX)(V|NMV), Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 18/23] fpu/softfloat2a: implement float16_squash_input_denormal, Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 16/23] include/exec/helper-head.h: support f16 in helper calls, Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 14/23] target/arm/translate-a64.c: add ARMv8.2 fadd scalar half-precision, Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 19/23] fpu/softfloat2a: implement float16_abs helper, Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 21/23] fpu/softfloat2a: propagate signalling NaNs in MINMAX, Alex Bennée, 2017/07/20
- [Qemu-arm] [RFC PATCH for 2.11 20/23] fpu/softfloat2a: add half-precision expansions for MINMAX fns, Alex Bennée, 2017/07/20
- Re: [Qemu-arm] [RFC PATCH for 2.11 00/23] Implementing FP16 for ARMv8.2 using SoftFloat2a and 3c,
Peter Maydell <=
- [Qemu-arm] [RFC PATCH for 2.11 03/23] softfloat3c: dos2unix all files, Alex Bennée, 2017/07/20
[Qemu-arm] [RFC PATCH for 2.11 02/23] fpu: import SoftFloat3c, Alex Bennée, 2017/07/20