Will tree-ssa be GCC 3.5?

Richard Kenner kenner@vlsi1.ultra.nyu.edu
Mon Dec 1 14:56:00 GMT 2003


    Is tree-ssa going to become mainline, and if so, when under the
    current circumstances? 

Nobody can answer that.

For one thing, tree-ssa is a experiment, a research project.  Lots of
work has been done on it, but lots more needs to be done.  At this
point, it does some things well and some things not so well.

Like any other optimization added to GCC, one needs to weigh the gains
from the optimization against the performance cost of the optimization
and other things.  The people working on tree-ssa believe that, once
the work is finished, the scale will tip towards it being something
worth adding to GCC.  There's no reason at this point to doubt that's
the case, but it's way too early in the project to be able to *prove*
it's the case either.  So nobody can say with certainty whether it'll
be in the mainline or not.

As to schedule, people have said many times that this is a *volunteer*
effort, which is not funded.  So people are doing it in their spare
time.  It's impossible to predict how much spare time these people
will have in the future.  Moreover, the research nature of this work
means it's quite likely there will be some surprises in the future
that could well cause significant schedule hits even if one were to
try to make a schedule.
 
    In other words, is it worth expending tax dollars on the GCC project, or
    should the National labs support or produce another project?

Can you explain what tree-ssa has to do with this question?



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