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Re: Delay branch scheduling vs. the CFG


On Wed, 2005-11-16 at 12:06 -0800, Richard Henderson wrote:
> On Sun, Nov 13, 2005 at 02:26:31PM -0700, Jeffrey A Law wrote:
> > On Sun, 2005-11-13 at 22:20 +0100, Steven Bosscher wrote:
> > > On Sunday 13 November 2005 22:02, Jeffrey A Law wrote:
> > > > No great insights on how to make dbr_schedule CFG aware -- just
> > > > remember that a filled delay slot can represent 3 different cases:
> > > >
> > > >   1. An extension of the block containing the sequence.
> > > >
> > > >   2. An extension of the block at the target of a branch.
> > > >
> > > >   3. An extension of the fall-thru block.
> > > >
> > > >   4. An entirely new basic block on its own.
> > > 
> > > When can option 4 happen??
> > IIRC it occurs when there was only 1 insn in either the target
> > or fall-thru block.    When it gets sucked into the delay
> > slot of a branch, then it is effectively its own basic
> > block.
> 
> I'd be comfortable modeling all of these as (1), with the
> understanding that the delay slots may be conditionally
> executed, as if with cond_exec.
Seems clean enough to me.
jeff



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