Dropping of old loop optimizer

[tm_gccmail@mail.kloo.net]

On Thu, 27 Feb 2003, Zdenek Dvorak wrote:

> Hello,
> 
> > > I would like to know your opinion on this subject. Why I believe old
> > > loop optimizer should be dropped as soon as possible:
...
> > The "old" loop optimizer does BIV-to-GIV flattening which is important on
> > processors without double-register addressing modes such as the SH,
> > MIPS16, Thumb, and a few others.
> > 
> > Does the new loop optimizer support this feature?
> 
> no; as I said, anything related to iv's is problem.

Then I personally (and probably most users of the SH) would prefer the old
loop optimizer be retained until the new loop optimizer supports BIV
flattening. 

This one optimization is extremely important; if we don't have it, the
compiler will generate a move/shift/add operation for each IV-related
load/store within the loop, which kills performance.

> Zdenek

Toshi