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From: "aoliva at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/87600] Fix for PRs 86939 and 87479 causes build issues for several targets
Date: Thu, 18 Jun 2020 11:11:25 +0000	[thread overview]
Message-ID: <bug-87600-4-oqndm2R669@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-87600-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87600

Alexandre Oliva <aoliva at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aoliva at gcc dot gnu.org

--- Comment #8 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
I've noticed regressions caused by make_more_copies, in scenarios that used
subreg s for the low part of promoted incoming parms.  With hard regs, the
substitution into a subreg became a reg, but with a pseudo, it remains a
subreg, which prevents further combines in some cases, as in e.g.
gcc_target/powerpc/20050603-3.c on ppc64.

I thought one way to go about it could be to scan for subregs of pseudos copied
from hard regs before introducing the additional copies, and introduce the
intermediate pseudo with the widest subreg mode if there aren't uses of the
full pseudo.

       reply	other threads:[~2020-06-18 11:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-87600-4@http.gcc.gnu.org/bugzilla/>
2020-06-18 11:11 ` aoliva at gcc dot gnu.org [this message]
2020-06-18 14:39 ` segher at gcc dot gnu.org
2024-03-26 22:21 ` pinskia at gcc dot gnu.org
2024-03-26 22:23 ` pinskia at gcc dot gnu.org

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