Re: [LTO] Flattening memory expressions?

[Michael Matz <matz at suse dot de>]

Hi,

On Thu, 8 Jun 2006, Daniel Berlin wrote:

> >>> 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.
> 
> Not for data dependence it's not. :)

You mean tests based on the actual index vector, instead of the final 
offset vector?  I still sometimes think that one should be able to 
recover the index vector reasonably well, when given only offsets (and 
perhaps adjusted bases).  It's a tradeoff of having only one way to 
express memory accesses (which I find quite sexy) and having to do a 
bit more work when trying to get at the offsets.


Ciao,
Michael.