[Bug rtl-optimization/107167] It looks like GCC wastes registers on trivial computations when result can be cached

pinskia at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Thu Oct 6 05:55:55 GMT 2022


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107167

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 much
better code for this example due to register renaming in hw.
Note many x86_64 also does register renaming for the stack too


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