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Re: Loop optimizer issues
On Tuesday, July 29, 2003, at 2:49 PM, Jason Merrill wrote:
I think there's been a bit of a disconnect in this discussion.
Some people are arguing against merging the rtlopt changes into
tree-ssa.
Some people are arguing for merging Zdenek's loop optimizer work into
tree-ssa.
Nobody, AFAICT, is arguing for merging all of rtlopt into tree-ssa.
It seems to me that Zdenek is interested in making his loop optimizer
work
at the tree level, and therefore it makes sense to bring it into
tree-ssa.
As long as it's going to work on the tree-ssa SSA form, and not just
GIMPLE trees (without SSA), i have no problem with it.
If it's not going to work on the SSA form, i'm against it because it
would mean that we have three options:
1. Run all loop opts based on the loop optimizer before going into SSA.
(Bad)
2. Run all loop opts based on the loop optimizer after going out of SSA
(Bad, since we want to lower at some point to allow the optimizers work
remove redundant address arithmetic and whatnot)
3. Go into and out of SSA multiple times (expensive).
Jason