From: Segher Boessenkool <segher@kernel.crashing.org>
To: luoxhu <luoxhu@linux.ibm.com>
Cc: gcc-patches@gcc.gnu.org, wschmidt@linux.ibm.com,
guojiufu@linux.ibm.com, linkw@gcc.gnu.org
Subject: Re: [PATCH] rs6000: Don't split constant oprator when add, move to temp register for future optimization
Date: Fri, 3 Apr 2020 16:08:52 -0500 [thread overview]
Message-ID: <20200403210852.GK26902@gate.crashing.org> (raw)
In-Reply-To: <596ce54a-996c-3180-dbf1-df5e94ded4cb@linux.ibm.com>
Hi!
On Fri, Apr 03, 2020 at 02:13:06PM +0800, luoxhu wrote:
> Currently 286r.split2 will split "12:%9:DI=0x87654321" to lis+ori by
> rs6000_emit_set_const of define_split, do you mean add new define_insn_and_split
> to do the split? Another patch to do this after this one goes upstream in stage 1?
I mean a splitter that recognises
reg := reg + imm
for a big immediate, and then does addis+addi again if that is the best
way to do it.
We expand as a load of the 32-bit constant, which means it can be hoisted
just fine, and when we can use paddi we can; but when we cannot, we can
still split it again.
> > This also links in with Alan's work on big immediates, and with paddi
> > insns, etc.
>
> Seems PR94393?
Yes, PR94393. And everything else that will show up if we start pulling
at that string (which we should now, btw, for paddi).
Segher
prev parent reply other threads:[~2020-04-03 21:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 10:06 luoxhu
2020-03-26 15:18 ` will schmidt
2020-03-27 14:33 ` Segher Boessenkool
2020-03-30 3:59 ` luoxhu
2020-04-02 22:16 ` Segher Boessenkool
2020-04-03 6:13 ` luoxhu
2020-04-03 12:13 ` Alan Modra
2020-04-03 21:11 ` Segher Boessenkool
2020-04-03 23:51 ` Alan Modra
2020-04-07 21:47 ` Segher Boessenkool
2020-04-03 21:08 ` Segher Boessenkool [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200403210852.GK26902@gate.crashing.org \
--to=segher@kernel.crashing.org \
--cc=gcc-patches@gcc.gnu.org \
--cc=guojiufu@linux.ibm.com \
--cc=linkw@gcc.gnu.org \
--cc=luoxhu@linux.ibm.com \
--cc=wschmidt@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).