Loop optimizer issues

[David Edelsohn]

>>>>> Zdenek Dvorak writes:

>> tree-ssa does regular merges with mainline, so once this was merged into
>> mainline, it would become part of tree-ssa very shortly thereafter, and
>> the code sharing could begin :-)
>> 
>> That way there are no multiple-experimental code base merge issues. 

Zdenek> but there is also no way how the merge you propose could be done in this
Zdenek> stage of development.

	I think it would be clearer if you proposed this as part of the
Tree-SSA loop optimization work than RTL loop optimizations on the
Tree-SSA branch.  The Tree-SSA branch is for Tree-SSA work, it is not
gcc-3_5-basic_improvements_branch.

	If you want experiment with using the new CFG infrastructure for
Tree-SSA loop optimizations, great.  Sebastian Pop, Daniel Berlin, and I
all are experimenting with loop optimizations on the Tree-SSA branch as
well.

	I do not know enough about your new loop optimization framework to
advise whether you should convert the loop optimizations to Tree-SSA in
your own private tree and only propose those patches or whether it is more
effective for you to apply the rtl loop optimizations to the Tree-SSA
branch and work on the conversion in place, which seems to be your intent.
Maybe you can explain why you think it is better to have all of the rtl
loop optimization changes in place before reusing it for the Tree-SSA loop
optimization work.

Thanks, David