Compilation performance comparison of 3.5.0 and TreeSSA trees on MICO sources as requested in: [tree-ssa] Merge status 2004-05-03

[law@redhat.com]

In message < 10405081026.AA17987@vlsi1.ultra.nyu.edu >, Richard Kenner writes:
 >    Mostly because of the breaking down of expressions into small trees,
 >    which are friendlier to the RTL expanders.  That's the reason we have a
 >    tree recombination pass at the end of tree optimization.
 >
 >Sure, but my question is why do that breaking down and recombining with -O0?
We don't do recombination at -O0, or at least we shouldn't.  Long term I
don't expect we'll continue to recombine expressions at the tree level.

Breaking the expressions down to gimple is a long term requirement if we are
to make any significant headway in simplifying the tree->rtl expanders.

Jeff