From: Tejas Joshi <tejasjoshi9673@gmail.com>
To: gcc@gcc.gnu.org
Cc: Martin Jambor <mjambor@suse.cz>,
hubicka@ucw.cz, segher@kernel.crashing.org,
joseph@codesourcery.com
Subject: Re: Expansion of narrowing math built-ins into power instructions
Date: Thu, 15 Aug 2019 09:52:00 -0000 [thread overview]
Message-ID: <CACMrGjCcY_b4zDb2MprOCJa1Z3H-_1SdP+2XkCsf0ckeyY5A9w@mail.gmail.com> (raw)
In-Reply-To: <20190814210015.GJ31406@gate.crashing.org>
Hello.
I just wanted to make sure that I am looking at the correct code here.
Except for rtl.def where I should be introducing something like
float_contract (or float_narrow?) and also simplify-rtx.c, breakpoints
set on functions around expr.c, cfgexpand.c where I grep for
float_truncate/FLOAT_TRUNCATE did not hit.
Also, in what manner should float_contract/narrow be different from
float_truncate as both are trying to do similar things? (truncation
from DF to SF)
Thanks,
Tejas
On Thu, 15 Aug 2019 at 02:30, Segher Boessenkool
<segher@kernel.crashing.org> wrote:
>
> On Wed, Aug 14, 2019 at 08:23:27PM +0000, Joseph Myers wrote:
> > On Wed, 14 Aug 2019, Segher Boessenkool wrote:
> >
> > > Does something like
> > > float d; double a, b, x;
> > > ...
> > > d = fadd (a + x, b - x);
> > > work as wanted, with such a representation? It would simplify (does it?) to
> > > d = fadd (a, b);
> > > but is that allowed?
> >
> > It's not allowed, but neither is simplifying (a + x) + (b - x) into (a +
> > b), when contraction isn't allowed.
>
> Ah of course. And we already should not do such simplification on RTL,
> when contraction is disallowed.
>
> So yeah it should work fine I think. A new RTL code would be best (it
> would be silly to have to make an unspec for it in every port separately),
> but an unspec is of course easiest for now.
>
>
> Segher
next prev parent reply other threads:[~2019-08-15 9:52 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 17:37 Martin Jambor
2019-07-29 18:40 ` Segher Boessenkool
2019-07-30 19:47 ` Joseph Myers
2019-07-30 9:20 ` Florian Weimer
2019-07-30 19:49 ` Joseph Myers
2019-07-31 6:47 ` Tejas Joshi
2019-07-31 14:47 ` Segher Boessenkool
2019-08-08 18:39 ` Tejas Joshi
2019-08-08 20:05 ` Segher Boessenkool
2019-08-08 23:09 ` Joseph Myers
2019-08-10 10:24 ` Tejas Joshi
2019-08-10 16:46 ` Segher Boessenkool
2019-08-11 4:58 ` Tejas Joshi
2019-08-11 7:20 ` Segher Boessenkool
2019-08-11 12:46 ` Tejas Joshi
2019-08-11 16:59 ` Segher Boessenkool
2019-08-12 17:25 ` Tejas Joshi
2019-08-12 17:55 ` Segher Boessenkool
2019-08-12 21:20 ` Joseph Myers
2019-08-12 21:52 ` Segher Boessenkool
2019-08-14 6:15 ` Tejas Joshi
2019-08-14 7:21 ` Segher Boessenkool
2019-08-14 16:11 ` Joseph Myers
2019-08-14 20:21 ` Segher Boessenkool
2019-08-14 20:23 ` Joseph Myers
2019-08-14 21:00 ` Segher Boessenkool
2019-08-15 9:52 ` Tejas Joshi [this message]
2019-08-15 12:47 ` Richard Sandiford
2019-08-15 13:55 ` Tejas Joshi
2019-08-15 18:45 ` Segher Boessenkool
2019-08-16 10:23 ` Richard Sandiford
2019-08-17 5:40 ` Tejas Joshi
2019-08-17 8:21 ` Richard Sandiford
2019-08-19 10:46 ` Tejas Joshi
2019-08-19 13:07 ` Segher Boessenkool
2019-08-20 7:41 ` Richard Sandiford
2019-08-20 12:11 ` Segher Boessenkool
2019-08-20 12:59 ` Richard Sandiford
2019-08-20 13:46 ` Segher Boessenkool
2019-08-20 14:43 ` Richard Sandiford
2019-08-20 15:12 ` Richard Sandiford
2019-08-20 19:42 ` Segher Boessenkool
2019-08-21 17:20 ` Tejas Joshi
2019-08-21 18:28 ` Segher Boessenkool
2019-08-21 19:17 ` Segher Boessenkool
2019-08-22 3:33 ` Tejas Joshi
2019-08-22 6:25 ` Segher Boessenkool
2019-08-22 7:57 ` Tejas Joshi
2019-08-22 9:56 ` Segher Boessenkool
2019-08-23 17:17 ` Martin Jambor
2019-08-23 19:13 ` Segher Boessenkool
2019-08-24 9:53 ` Richard Sandiford
2019-08-25 13:55 ` Tejas Joshi
2019-08-25 16:47 ` Segher Boessenkool
2019-08-26 7:07 ` Tejas Joshi
2019-08-26 7:42 ` Segher Boessenkool
2019-08-30 19:12 ` Tejas Joshi
2019-08-30 20:35 ` Segher Boessenkool
2019-09-02 3:19 ` Tejas Joshi
2019-09-02 11:30 ` Segher Boessenkool
2019-08-26 13:23 ` Martin Jambor
2019-08-20 16:04 ` Joseph Myers
2019-08-15 18:54 ` Segher Boessenkool
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