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From: Segher Boessenkool <segher@kernel.crashing.org>
To: HAO CHEN GUI <guihaoc@linux.ibm.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>, David <dje.gcc@gmail.com>,
	"Kewen.Lin" <linkw@linux.ibm.com>,
	Peter Bergner <bergner@linux.ibm.com>
Subject: Re: [PATCH v6, rs6000] Implemented f[min/max]_optab by xs[min/max]dp [PR103605]
Date: Wed, 21 Sep 2022 16:56:52 -0500	[thread overview]
Message-ID: <20220921215652.GG25951@gate.crashing.org> (raw)
In-Reply-To: <df790a93-52bf-761a-6586-78d540934f96@linux.ibm.com>

Hi!

On Fri, Jun 24, 2022 at 10:02:19AM +0800, HAO CHEN GUI wrote:
>   This patch also binds __builtin_vsx_xs[min/max]dp to fmin/max instead
> of smin/max. So the builtins always generate xs[min/max]dp on all
> platforms.

But how does this not blow up with -ffast-math?

In the other direction I am worried that the unspecs will degrade
performance (relative to smin/smax) when -ffast-math *is* active (and
this new builtin code and pattern doesn't blow up).

I still think we should get RTL codes for this, to have access to proper
floating point min/max semantics always and everywhere.  "fmin" and
"fmax" seem to be good names :-)


Segher

  parent reply	other threads:[~2022-09-21 21:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-24  2:02 HAO CHEN GUI
2022-07-04  6:32 ` Ping " HAO CHEN GUI
2022-08-01  2:03   ` Ping^2 " HAO CHEN GUI
2022-09-21  5:20     ` Ping^3 " HAO CHEN GUI
2022-09-21  9:34 ` Kewen.Lin
2022-09-21 21:56 ` Segher Boessenkool [this message]
2022-09-22  2:28   ` Kewen.Lin
2022-09-22  9:59     ` HAO CHEN GUI
2022-09-22 13:56       ` Segher Boessenkool
2022-09-22 14:05     ` Segher Boessenkool
2022-09-26  5:58       ` Kewen.Lin

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