loop.c bugfix

Bernd Schmidt bernds@redhat.co.uk
Mon Oct 23 02:29:00 GMT 2000

On Fri, 20 Oct 2000, Richard Kenner wrote:

> On HP PA, certain patterns are only valid if one register has
> REGNO_POINTER_FLAG (e.g., reg + reg in a MEM).  But loop.c will substitute
> one pseudo for another and assume it's OK.  It is only if REGNO_POINTER_FLAG
> is copied.

This could be argued to be a bug in the PA backend.
I'm sure that quite a few of the optimizer passes assume that substituting one
pseudo for another is always valid.  If we decide to disallow this, then I'm
pretty sure we'll need to add a whole lot more code than this patch in loop.c.
We certainly should add documentation.

IMHO this patch is a bad idea, and we should change the PA port instead.
These special cases for one particular port will make gcc much less
maintainable in the long run.


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