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From: "segher at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/96017] Powerpc suboptimal register spill in likely path
Date: Thu, 02 Jul 2020 21:22:20 +0000	[thread overview]
Message-ID: <bug-96017-4-BNFDqDWNBA@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-96017-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96017

--- Comment #10 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Peter Bergner from comment #6)
> Right, that's why we need to add the copies before RA, so we don't have to
> look for unused regs.  But we don't want to add the copies too early just
> for the optimizer to remove them on us.

RA itself will want to use the same hard register most of the time, already.
And that *is* the best choice, except when you need to split the range later.

We would need to do (some of) shrink wrapping before RA, but that means we
need to change our abstraction of prologue/epilogue.  Not a bad idea probably,
but a lot of work.  Many targets do many special things in their own *logue
hooks (and patterns and code called from those) currently, it all would need
to be disentangled.

  parent reply	other threads:[~2020-07-02 21:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-01  9:57 [Bug target/96017] New: " npiggin at gmail dot com
2020-07-01 10:01 ` [Bug target/96017] " wschmidt at gcc dot gnu.org
2020-07-01 10:02 ` wschmidt at gcc dot gnu.org
2020-07-01 10:06 ` wschmidt at gcc dot gnu.org
2020-07-01 10:21 ` npiggin at gmail dot com
2020-07-01 14:00 ` bergner at gcc dot gnu.org
2020-07-01 23:58 ` segher at gcc dot gnu.org
2020-07-02  1:18 ` bergner at gcc dot gnu.org
2020-07-02  1:24 ` bergner at gcc dot gnu.org
2020-07-02  2:06 ` bergner at gcc dot gnu.org
2020-07-02  2:45 ` bergner at gcc dot gnu.org
2020-07-02 21:22 ` segher at gcc dot gnu.org [this message]
2020-07-02 21:24 ` segher at gcc dot gnu.org
2021-04-27 11:39 ` jakub at gcc dot gnu.org
2021-07-28  7:04 ` rguenth at gcc dot gnu.org
2023-11-24  8:46 ` jskumari at gcc dot gnu.org
2023-11-24  9:22 ` jskumari at gcc dot gnu.org

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