From: David Edelsohn <dje.gcc@gmail.com>
To: Michael Meissner <meissner@linux.vnet.ibm.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] PR target/65240, Fix Power{7,8} insn constraint issue with -O3 -ffast-math
Date: Thu, 12 Mar 2015 15:37:00 -0000 [thread overview]
Message-ID: <CAGWvnykFGnTxN+m2-fF9aZ6VtmXx3bXKD+MzMGvrH-U0=kMjeA@mail.gmail.com> (raw)
In-Reply-To: <20150312152952.GA11678@ibm-tiger.the-meissners.org>
On Thu, Mar 12, 2015 at 11:29 AM, Michael Meissner
<meissner@linux.vnet.ibm.com> wrote:
> On Wed, Mar 11, 2015 at 08:52:54PM -0400, David Edelsohn wrote:
>> On Wed, Mar 11, 2015 at 6:21 PM, Michael Meissner
>> <meissner@linux.vnet.ibm.com> wrote:
>> > On Wed, Mar 11, 2015 at 01:02:06PM -0400, David Edelsohn wrote:
>> >> I am concerned with the create_TOC_reference use for TARGET_TOC. Has
>> >> this been tested with big endian -mcmodel=small?
>> >
>> > Yes, that was a problem. Patch coming up soon. Thanks.
>>
>> Can you call rs6000_emit_move_directly?
>
> Well, I can, but I would have to have some sort of flag that says after the
> split1 pass not to allow FP constants in move (other than 0.0). It is doable,
> but it does touch more areas in the rs6000 back end.
>
> I am starting to think that it is just simpler to rip out all of the special
> fast math handling of constants, considering the multiply by reciprocal support
> has moved to SSA/tree and away from RTL. Did you want me to investigate the
> performance implications of removing it now (rather than waiting to GCC 6.0),
> or just do the more limited patch that I've been pursuing.
Please check on the performance implications of removing the special
constant support. I know that it is late, but I think that ripping it
out is less risky than trying to fix this, if the performance impact
is not bad.
Thanks, David
next prev parent reply other threads:[~2015-03-12 15:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-05 20:07 Michael Meissner
2015-03-06 12:05 ` Richard Biener
2015-03-09 15:59 ` Michael Meissner
2015-03-11 17:02 ` David Edelsohn
2015-03-11 22:21 ` Michael Meissner
2015-03-12 0:52 ` David Edelsohn
2015-03-12 15:30 ` Michael Meissner
2015-03-12 15:37 ` David Edelsohn [this message]
2015-03-17 23:19 ` Michael Meissner
2015-03-18 11:08 ` Richard Biener
2015-03-20 17:44 ` Michael Meissner
2015-04-04 18:25 ` Andreas Schwab
2015-04-04 23:07 ` Alan Modra
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