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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/107167] It looks like GCC wastes registers on
 trivial computations when result can be cached
Date: Thu, 06 Oct 2022 05:55:55 +0000
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X-Bugzilla-Component: rtl-optimization
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X-Bugzilla-Keywords: missed-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107167

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
           Keywords|                            |missed-optimization

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is a reassociation, scheduling issue and register allocation issue.

Plus your example might be slower due to dependencies.

Without a full example of where gcc ra goes wrong, gcc actually produces mu=
ch
better code for this example due to register renaming in hw.
Note many x86_64 also does register renaming for the stack too=