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From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/111096] Frame pointer is not used even when
 -fomit-frame-pointer is specified
Date: Wed, 23 Aug 2023 10:51:47 +0000
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X-Bugzilla-Type: changed
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X-Bugzilla-Product: gcc
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X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: rearnsha at gcc dot gnu.org
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: WONTFIX
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111096

Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #5 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
This was a deliberate design choice.  Although the frame chain is not set u=
p by
code that omits the frame pointer, the chain of frames that are set up by o=
ther
functions is still valid this way.  This ensures that any code that does tr=
y to
walk the frame chain will not crash.  If we reused the frame pointer for ot=
her
purposes, then any code trying to walk the frame chain (eg backtrace()) wou=
ld
encounter an invalid record and likely crash.

With 31 main registers, the benefit from one additional one is not especial=
ly
large.=