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From: Richard Biener <richard.guenther@gmail.com>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: will_schmidt@vnet.ibm.com,GCC Patches
	<gcc-patches@gcc.gnu.org>,David Edelsohn
	<dje.gcc@gmail.com>,Bill Schmidt <wschmidt@linux.vnet.ibm.com>
Subject: Re: [PATCH, rs6000] Fold vector absolutes in GIMPLE
Date: Mon, 29 May 2017 11:55:00 -0000	[thread overview]
Message-ID: <A41966D2-362E-4278-9989-0A2474541696@gmail.com> (raw)
In-Reply-To: <20170529102444.GI19687@gate.crashing.org>

On May 29, 2017 12:24:44 PM GMT+02:00, Segher Boessenkool <segher@kernel.crashing.org> wrote:
>On Mon, May 29, 2017 at 10:32:18AM +0200, Richard Biener wrote:
>> On Fri, May 26, 2017 at 7:19 PM, Will Schmidt
><will_schmidt@vnet.ibm.com> wrote:
>> > Add support for early expansion of vector absolute built-ins.
>> >
>> > Bootstraps currently running (p7,p8le,p8be).
>> >
>> > OK for trunk?
>> 
>> What's the documented behavior for vec_abs with respect to an
>argument
>> of value INT_MIN?
>
>The documentation says:
>
>	"For integer vectors, the arithmetic is modular."

This means that folding as ABS_EXPR is not safe for !TYPE_OVERFLOW_WRAPS
Integral vector types.

Richard.

>http://openpowerfoundation.org/wp-content/uploads/resources/leabi-prd/
>(appendix A; the PDF is easier to read).
>
>
>Segher

  reply	other threads:[~2017-05-29 11:35 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-26 17:19 Will Schmidt
2017-05-29  8:39 ` Richard Biener
2017-05-29 10:29   ` Segher Boessenkool
2017-05-29 11:55     ` Richard Biener [this message]
2017-05-29 12:23       ` Segher Boessenkool
2017-05-30  7:05         ` Richard Biener
2017-05-31 14:02           ` Will Schmidt
2017-05-31 14:04             ` Richard Biener
2017-05-31 14:06               ` Ramana Radhakrishnan

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