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Re: [RFC] third liveness pass
- From: Jan Hubicka <jh at suse dot cz>
- To: law at redhat dot com
- Cc: Richard Henderson <rth at redhat dot com>, Jan Hubicka <jh at suse dot cz>,Roger Sayle <roger at eyesopen dot com>, gcc at gcc dot gnu dot org,gcc-pdo at atrey dot karlin dot mff dot cuni dot cz
- Date: Tue, 28 May 2002 11:01:08 +0200
- Subject: Re: [RFC] third liveness pass
- References: <20020526191956.B2011@redhat.com> <22499.1022508616@porcupine.cygnus.com>
> In message <20020526191956.B2011@redhat.com>, Richard Henderson writes:
> > On Sun, May 26, 2002 at 02:21:47PM +0200, Jan Hubicka wrote:
> > > + cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
> > > + life_analysis (insns, rtl_dump_file, PROP_DEATH_NOTES
> > > + | PROP_KILL_DEAD_CODE | PROP_SCAN_DEAD_CODE
> > > + | PROP_EQUAL_NOTES);
> > > + cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_UPDATE_LIFE | CLEANUP_PRE
> > _LOOP
> > > + | (flag_thread_jumps ? CLEANUP_THREADING : 0));
> > > + if (flag_if_conversion)
> > > + if_convert (1);
> > > + count_or_remove_death_notes (NULL, 1);
> > > + reg_scan (insns, max_reg_num (), 1);
> > > + close_dump_file (DFI_lifeearly, print_rtl_with_bb, insns);
> > > + }
> > > +
> > > /* Perform global cse. */
> >
> > Hum. Except for the call to if_convert, this might be exactly
> > what Roger needs for his gcse jump threading pass. Not sure if
> > there are any transformations in gcse that would invalidate this
> > information...
> Well, gcse is going to create new registers and may change the lifetimes of
> existing registers (on a global basis). gcse can also remove basic blocks
> as well.
This is not problem for the liveness updating algorithm.
Honza
>
> jeff