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Re: PATCH: remove bb_ann_d's num_preds field
On Wed, 2004-09-29 at 14:29, Jeffrey A Law wrote:
> On Wed, 2004-09-29 at 12:20, Andrew MacLeod wrote:
>
> > Immediate_uses will give you direct access to the stmt from the operand,
> > so that gets you the result of a PHI node pretty easily too.
> >
> > Its just a matter of how much memory I can chew up :-). Its a continual
> > trade off of memory for speed, and the balance is delicate. sigh. I
> > trying yet another angle now.
> Well, I was thinking about this in terms of the only representation
> for PHIs -- ie, we'd drop PHI nodes as we know them today and
> replace them with a new scheme.
They will have to be associated with the PHI results somehow, so either
the vector of today, or the list of tomorrow :-) Believe me, I have
seriously considered trying to implement the PHI arguments as a linked
list. It makes keeping the immediate-use information quicker, as well
as resolves any PHI node resizing issues, but again, more memory :-(.
We do look through all the arguments of a PHI frequently I think, so we
need to be able to traverse the arguments as well. I have envisioned a
*9* word PHI argument, and it makes me shiver a bit. It would be very
good to work with, but seems like a lot of memory.
*shiver*
Andrew