How to reverse patch reversal in cfgcleanup.c (Was: RFA: re-instate struct_equiv code)

[Ian Lance Taylor]

Bernd Schmidt <bernds_cb1@t-online.de> writes:

> Let me ask a really stupid question.  Where are we supposed to be
> clearing BB_DIRTY flags?
> 
> I instrumented the old version of the struct-equiv patches to give me
> some information about the basic blocks it's being called for, and
> noticed that blocks always remain dirty, even though we're calling
> update_life_info_in_dirty_blocks.  A quick grep showed no place in the
> compiler where the flag is cleared.  Under these circumstances, it's
> no surprise that we keep doing global liveness updates during
> crossjumping.

The function clear_bb_flags clears the BB_DIRTY flag.  It is called
from a few places, including cleanup_cfg.

Ian