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Re: [Qemu-ppc] [Qemu-devel] [PATCH 12/14] VSX Stage 4: Add Scalar SP Fus
From: |
Richard Henderson |
Subject: |
Re: [Qemu-ppc] [Qemu-devel] [PATCH 12/14] VSX Stage 4: Add Scalar SP Fused Multiply-Adds |
Date: |
Fri, 08 Nov 2013 09:30:31 +1000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 |
On 11/08/2013 09:28 AM, Richard Henderson wrote:
> On 11/07/2013 06:31 AM, Tom Musta wrote:
>> }
>> \
>> +
>> \
>> + if (r2sp) {
>> \
>> + float32 tmp32 = float64_to_float32(xt_out.fld[i],
>> \
>> + &env->fp_status);
>> \
>> + xt_out.fld[i] = float32_to_float64(tmp32, &env->fp_status);
>> \
>> + }
>> \
>> +
>> \
>
> You can't get correct results for a single-precision fma from a
> double-precision fma and merely rounding the results.
>
> See e.g. glibc's sysdeps/ieee754/dbl-64/s_fmaf.c.
Blah, nevermind. That would be using separate add+mul in double-precision, not
using a double-precision fma primitive.
r~
- [Qemu-ppc] [PATCH 05/14] VSX Stage 4: Add stxsiwx and stxsspx, (continued)
- [Qemu-ppc] [PATCH 05/14] VSX Stage 4: Add stxsiwx and stxsspx, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 07/14] VSX Stage 4: Add xsmulsp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 06/14] VSX Stage 4: Add xsaddsp and xssubsp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 08/14] VSX Stage 4: Add xsdivsp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 10/14] VSX Stage 4: Add xssqrtsp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 09/14] VSX Stage 4: Add xsresp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 11/14] VSX Stage 4: add xsrsqrtesp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 13/14] VSX Stage 4: Add xscvsxdsp and xscvuxdsp, Tom Musta, 2013/11/06
- [Qemu-ppc] [PATCH 12/14] VSX Stage 4: Add Scalar SP Fused Multiply-Adds, Tom Musta, 2013/11/06
[Qemu-ppc] [PATCH 14/14] VSX Stage 4: Add xxleqv, xxlnand and xxlorc, Tom Musta, 2013/11/06
Re: [Qemu-ppc] [Qemu-devel] [PATCH 00/14] VSX Stage 4, Richard Henderson, 2013/11/07
Re: [Qemu-ppc] [Qemu-devel] [PATCH 00/14] VSX Stage 4, Andreas Färber, 2013/11/08