From: Richard Henderson <rth@twiddle.net>
To: Tom Musta <tommusta@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>
Cc: "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 13/19] Add VSX ISA2.06 Multiply Add Instructions
Date: Fri, 25 Oct 2013 10:29:10 -0700 [thread overview]
Message-ID: <526AAA66.90508@twiddle.net> (raw)
In-Reply-To: <526AA6C4.3070507@gmail.com>
On 10/25/2013 10:13 AM, Tom Musta wrote:
> On 10/25/2013 11:42 AM, Richard Henderson wrote:
>> I believe that a better implementation could use float*_muladd, and check the
>> result for float_flag_invalid. If set, compute the intermediate product so you
>> can figure out the VXISI setting. But we'd expect that to be an unlikely path.
>
> Interesting thought. I think I see a way to re-arrange the code. Thanks,
> Richard.
Actually, you don't even have to compute the intermediate product.
The only way you can have VXISI for a*b+c is for
isinf(c) && (isinf(a) || isinf(b))
since the intermediate product a*b is infinite precision, and thus cannot
overflow to inf unless one of the multiplicands is already inf.
r~
next prev parent reply other threads:[~2013-10-25 17:30 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-24 16:16 [Qemu-devel] [PATCH 00/19] PowerPC VSX Stage 3 Tom Musta
2013-10-24 16:17 ` [Qemu-devel] [PATCH 01/19] Add New softfloat Routines for VSX Tom Musta
2013-10-24 18:34 ` Richard Henderson
2013-10-25 11:34 ` Alex Bennée
2013-10-25 11:44 ` Peter Maydell
2013-10-25 13:09 ` Alex Bennée
2013-10-25 13:24 ` Tom Musta
2013-10-25 11:55 ` Peter Maydell
2013-10-25 13:01 ` Tom Musta
2013-10-25 13:37 ` Peter Maydell
2013-10-24 16:18 ` [Qemu-devel] [PATCH 02/19] Add set_fprf Argument to fload_invalid_op_excp() Tom Musta
2013-10-24 16:19 ` [Qemu-devel] [PATCH 03/19] General Support for VSX Helpers Tom Musta
2013-10-24 18:51 ` Richard Henderson
2013-10-24 20:42 ` Tom Musta
2013-10-24 21:00 ` Richard Henderson
2013-10-24 16:20 ` [Qemu-devel] [PATCH 04/19] Add VSX ISA2.06 xadd Instructions Tom Musta
2013-10-24 19:44 ` Richard Henderson
2013-10-24 16:20 ` [Qemu-devel] [PATCH 05/19] Add VSX ISA2.06 xsub Instructions Tom Musta
2013-10-24 19:48 ` Richard Henderson
2013-10-24 16:21 ` [Qemu-devel] [PATCH 06/19] Add VSX ISA2.06 xmul Instructions Tom Musta
2013-10-24 20:07 ` Richard Henderson
2013-10-24 16:21 ` [Qemu-devel] [PATCH 07/19] Add VSX ISA2.06 xdiv Instructions Tom Musta
2013-10-24 20:08 ` Richard Henderson
2013-10-24 16:22 ` [Qemu-devel] [PATCH 08/19] Add VSX ISA2.06 xre Instructions Tom Musta
2013-10-24 20:11 ` Richard Henderson
2013-10-24 16:22 ` [Qemu-devel] [PATCH 09/19] Add VSX ISA2.06 xsqrt Instructions Tom Musta
2013-10-24 20:23 ` Richard Henderson
2013-10-24 16:23 ` [Qemu-devel] [PATCH 10/19] Add VSX ISA2.06 xrsqrte Instructions Tom Musta
2013-10-24 20:25 ` Richard Henderson
2013-10-24 16:23 ` [Qemu-devel] [PATCH 11/19] Add VSX ISA2.06 xtdiv Instructions Tom Musta
2013-10-24 20:30 ` Richard Henderson
2013-10-24 16:24 ` [Qemu-devel] [PATCH 12/19] Add VSX ISA2.06 xtsqrt Instructions Tom Musta
2013-10-24 20:34 ` Richard Henderson
2013-10-24 16:25 ` [Qemu-devel] [PATCH 13/19] Add VSX ISA2.06 Multiply Add Instructions Tom Musta
2013-10-24 20:38 ` Richard Henderson
2013-10-25 13:49 ` Tom Musta
2013-10-25 16:25 ` Tom Musta
2013-10-25 16:42 ` Richard Henderson
2013-10-25 17:13 ` Tom Musta
2013-10-25 17:29 ` Richard Henderson [this message]
2013-10-25 17:20 ` Peter Maydell
2013-10-25 17:34 ` Richard Henderson
2013-10-24 16:25 ` [Qemu-devel] [PATCH 14/19] Add VSX xscmp*dp Instructions Tom Musta
2013-10-24 20:39 ` Richard Henderson
2013-10-24 16:26 ` [Qemu-devel] [PATCH 15/19] Add VSX xmax/xmin Instructions Tom Musta
2013-10-24 20:45 ` Richard Henderson
2013-10-24 21:07 ` Tom Musta
2013-10-24 21:18 ` Richard Henderson
2013-10-24 22:10 ` Peter Maydell
2013-10-25 13:52 ` Tom Musta
2013-10-25 13:55 ` Peter Maydell
2013-10-24 16:26 ` [Qemu-devel] [PATCH 16/19] Add VSX Vector Compare Instructions Tom Musta
2013-10-24 16:27 ` [Qemu-devel] [PATCH 17/19] Add VSX Floating Point to Floating Point Conversion Instructions Tom Musta
2013-10-24 20:49 ` Richard Henderson
2013-10-24 16:27 ` [Qemu-devel] [PATCH 18/19] Add VSX ISA2.06 Integer " Tom Musta
2013-10-24 20:51 ` Richard Henderson
2013-10-24 16:28 ` [Qemu-devel] [PATCH 19/19] Add VSX Rounding Instructions Tom Musta
2013-10-24 20:54 ` Richard Henderson
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