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merging for 3.4 (was Re: [Patch] Qualify min(), max() ...)


On Wed, 04 Dec 2002, Mark Mitchell wrote:

> After that, I expect the sequence you said: BIB->mainline, the new
> C++ parser, and then (perhaps) some tree optimizer stuff, although
> I haven't really gotten the impression that stuff is fully ready yet.
> 
Whether tree SSA can be merged for 3.4 will depend on the state
of the branch by the time the Stage 1 window closes.  We are
making rapid progress but I would like to have the following in
place:

- At least two front ends working.  We already have C and it
  looks like C++ is getting there.


- General acceptance for GENERIC and GIMPLE.  GENERIC will impact
  all the front ends, as we need every front end to emit GENERIC
  so that it can then be converted into GIMPLE, which is the IL
  that all the tree optimizers operate on.
  
  Of course, a front end need only be converted to GENERIC if it
  wants to use the tree optimizers, otherwise they don't need to
  be modified at all.


- Performance issues.  Right now the code generated by the tree
  optimizers is worse than the RTL optimizers.  This is to be
  expected at this stage and the whole tree optimization process
  can be disabled.  So, in principle I don't see a real problem
  with merging the infrastructure in.
  
I see two possible scenarios regarding optimization:

(a) We merge the infrastructure with the optimizers disabled and
    keep working on them in mainline.  This has the advantage of
    exposing the code for more testing, but it might disrupt
    development.

(b) We don't merge anything for 3.4, keep working on the branch
    and merge everything for 3.5 or whenever we close the
    performance gap.


Sometimes I'm more inclined towards (b), it seems safer.


Diego.


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