From: "Roger Sayle" <roger@nextmovesoftware.com>
To: "'Segher Boessenkool'" <segher@kernel.crashing.org>
Cc: <gcc-patches@gcc.gnu.org>
Subject: RE: [PATCH] Add new target hook: simplify_modecc_const.
Date: Wed, 27 Jul 2022 08:51:58 +0100 [thread overview]
Message-ID: <003501d8a18d$c22ed760$468c8620$@nextmovesoftware.com> (raw)
In-Reply-To: <20220726221116.GC25951@gate.crashing.org>
Hi Segher,
> Thank you for telling the maintainer of combine the basics of what all of
this
> does! I hadn't noticed any of that before.
You're welcome. I've also been maintaining combine for some time now:
https://gcc.gnu.org/legacy-ml/gcc/2003-10/msg00455.html
> They can be, as clearly documented (and obvious from the code), but you
can
> not ever have that in the RTL stream, which is needed for your patch to do
> anything.
That's the misunderstanding; neither this nor the previous SUBREG patch,
affect/change what is in the RTL stream, no COMPARE nodes are every
changed or modified, only eliminated by the propagation/fusion in combine
(or CSE).
We have --enable-checking=rtl to guarantee that the documented invariants
always hold in the RTL stream.
Cheers,
Roger
next prev parent reply other threads:[~2022-07-27 7:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 21:08 [PATCH] Be careful with MODE_CC in simplify_const_relational_operation Roger Sayle
2022-07-07 22:38 ` Segher Boessenkool
2022-07-26 12:13 ` [PATCH] Add new target hook: simplify_modecc_const Roger Sayle
2022-07-26 17:44 ` Segher Boessenkool
2022-07-26 21:04 ` Roger Sayle
2022-07-26 22:11 ` Segher Boessenkool
2022-07-27 7:51 ` Roger Sayle [this message]
2022-07-27 18:37 ` Segher Boessenkool
2022-07-28 12:39 ` Richard Sandiford
2022-10-10 15:50 ` H.J. Lu
2022-10-14 20:31 ` Jeff Law
2022-10-14 21:05 ` H.J. Lu
2022-10-14 20:26 ` Jeff Law
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