swift234

SILPassManager: Further reduce the number of pass runs.

Avoid running a pass a second time if the pass has its own optimize-until-no-more-changes loop.
This pass property can be configured.
Currently I assume that all our function passes don't need to run a second time (without other changes in between).

It further reduces the number of pass runs by about 6%. But this improvement is cosmetic. There is no significant compile time reduction.

There are no performance changes.



Swift SVN r26760