From: Richard Henderson <rth@twiddle.net>
To: Tom Musta <tommusta@gmail.com>, qemu-devel@nongnu.org
Cc: qemu-ppc@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 12/14] VSX Stage 4: Add Scalar SP Fused Multiply-Adds
Date: Fri, 08 Nov 2013 09:30:31 +1000 [thread overview]
Message-ID: <527C2297.7040407@twiddle.net> (raw)
In-Reply-To: <527C221A.5000609@twiddle.net>
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~
next prev parent reply other threads:[~2013-11-07 23:30 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-06 20:31 [Qemu-devel] [PATCH 00/14] VSX Stage 4 Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 01/14] VSX Stage 4: Add VSX 2.07 Flag Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 02/14] VSX Stage 4: Refactor lxsdx Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 03/14] VSX Stage 4: Add lxsiwax, lxsiwzx and lxsspx Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 04/14] VSX Stage 4: Refactor stxsdx Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 05/14] VSX Stage 4: Add stxsiwx and stxsspx Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 06/14] VSX Stage 4: Add xsaddsp and xssubsp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 07/14] VSX Stage 4: Add xsmulsp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 08/14] VSX Stage 4: Add xsdivsp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 09/14] VSX Stage 4: Add xsresp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 10/14] VSX Stage 4: Add xssqrtsp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 11/14] VSX Stage 4: add xsrsqrtesp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 12/14] VSX Stage 4: Add Scalar SP Fused Multiply-Adds Tom Musta
2013-11-07 23:28 ` Richard Henderson
2013-11-07 23:30 ` Richard Henderson [this message]
2013-11-08 0:13 ` Richard Henderson
2013-11-13 20:49 ` Tom Musta
2013-11-13 23:14 ` Richard Henderson
2013-11-14 20:58 ` Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 13/14] VSX Stage 4: Add xscvsxdsp and xscvuxdsp Tom Musta
2013-11-06 20:31 ` [Qemu-devel] [PATCH 14/14] VSX Stage 4: Add xxleqv, xxlnand and xxlorc Tom Musta
2013-11-08 0:23 ` [Qemu-devel] [PATCH 00/14] VSX Stage 4 Richard Henderson
2013-11-08 14:53 ` Tom Musta
2013-11-13 14:35 ` Tom Musta
2013-11-08 15:55 ` Andreas Färber
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