[fpc-devel] Peephole optimizer tai class change proposals
J. Gareth Moreton
gareth at moreton-family.com
Mon Oct 11 10:00:15 CEST 2021
One for Jonas mainly, but also for Florian. This is a new "extra
optimisation information" feature that allows the peephole optimizer to
leave 'notes' and other extra information on individual tai objects for
later reference. An initial showcase is to store a link to the
destination label if it's not available in the lookup table (becuase it
was created later by a peephole optimisation).
Currently the showcase doesn't appear to show any additional
optimisations in the x86-64 RTL because the jump optimisation that
creates a new label is almost never called.
I'll use this feature more extensively in the future, such as for
storing information on the values of registers or making a note of a
label that should be removed if possible because it would cause a
long-term optimisation (something that a peephole optimisation that
removes the label may not be able to determine because its own
optimisation is questionable without that information). See previous
e-mails in this chain for an example.
Gareth aka. Kit
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