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Re: Quadratic bottleneck in SSA propagation engine


> Yes, please.  Let's wait for 4.3, unless you can prove good speedups
> across the board.

OK, I will get some numbers tomorrow.
> simulate_block will already ignore blocks that have already been
> executed.  I'm not sure why you need this.

I see, I missed that bit - the problem is that simulate_block uses it's
own queue meaning that the PHI bypass my expensive/nonexpensive stmt
list trick.  (other alternative would be to have expensive/nonexpensive
BB queue as well).
> 
> Spelling nit: s/incomming/incoming/
> 
> I'm interested in the VRP patch.  This propagator patch will paper over
> the real problem.  It's useful, though.

I will clean it up and send too (I got part of anti-intervals wrong
causing some regresisons).  It is not solving the whole problem - it
saves about 20% overhead (if my memory is correct) but the quadratic
behaviour of ssa_propagate keeps VRP very top in profile, so both
patches are needed.

Honza


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