Re: [LTO] Flattening memory expressions?

[Michael Matz <matz at suse dot de>]

Hi,

On Thu, 8 Jun 2006, Daniel Berlin wrote:

> >> Thoughts?
> > 
> > We (me and Matz) thought over this as well and concluded it would be
> > nice to have
> > 
> >  - MEM_REF ( base, offset, alias_tag )
> > 
> > with base being either some memory object or an INDIRECT_REF of a
> > pointer and be done with that tree code.
> 
> So if you have MEM_REF(INDIRECT_REF(a),i,0), you really haven't done any
> better in removing recursion :)

What type the first operand would be could be a one-bit flag in the 
MEM_REF itself.  I.e. if there's an implicit INDIRECT_REF around the 
first operand, or not.  The important part is only that the target address 
of that memory reference is computable completely trivially, namely by A + 
i, where A is either a or &a depending on that flag.  And the more 
important thing anyway is that alias information of this specific mem 
reference encoded therein.

> > The MEM_REF would also contain an alias tag for easy oracle queries
> 
> Tag has some meaning in our current structure. I'd support some sort of
> generic token that associates the alias info with it, however.

All a matter of naming, sure :-)


Ciao,
Michael.