Re: Any plan for rewriting loop.c using cfgloop.c

[Jie Zhang <zhangjie at magima dot com dot cn>]

Jan Hubicka wrote:

> Yes, this is understood problem.  In particular expample, of strength
> reduction, to do it strength reduction effectivly, one should know what
> are the costs and addressing modes not available at tree-ssa level.  To
> do it correctly one should know about overflow semantics of input
> language not available at RTL level.
>
> It is however not very well understood how to best deal with it.  It is
> probably best to experiment with both implmentations and
> we will likely end up with loop optimizer split into multiple parts some
> running at tree-ssa and some running at RTL level.  THat is why I do
> believe that Zdenek's work on RTL loop optimizer is important even after
> merging tree-ssa.
>
>  
Yes, I do think so. Most of the existing loop optimizations in loop.c 
are well suited at RTL level. What I want is rewriting these RTL level 
loop optimizations using the natural loop discovery code in cfgloop.c. 
The current loop optimization code in loop.c using the RTL codes, e.g. 
NOTE_INSN_LOOP_BEG and NOTE_INSN_LOOP_CONT, to find loops. It cannot 
find loop resulted from the code other than loop statements. Sometimes 
tt mistakes one-entry loop for multi-enty one and ignores it.

Where can I find the information and status of Zdenek's work on RTL loop 
optimizer?

Jie