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Re: Some thoughts and quetsions about the data flow infrastracture
I even have own tool for
this NONA http://cocom.sf.net . Although it might be a good research to
make it work on insns from diffrent BBs.
Of course instruction selection is usually done intra-BB. However, some
analyses that combine performs, such as nonzero_bits and
num_sign_bit_copies, maybe could be extended to use the new framework.
The problem is that to use the modern approach you need another
description of insns (with one pattern - one machine insn relation) in
tree representation with given cost for the tree. And it is a huge work
to rewrite current machine descriptions even only for this.
This is not really necessary. I have a stripped down version of NONA
working on RTL. It is possible to build the tree using a mechanism
similar to subst in combine, simplify the resulting expression, and use
NONA (which is actually the same algorithms as iburg) to split it.
Paolo