[PATCH] Fix IVOPTs problem

[Richard Guenther]

On 8/13/05, Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz> wrote:
> Hello,
> 
> > On Fri, 2005-08-05 at 11:48 +0200, Richard Guenther wrote:
> > > Compiling gcc.c-torture/execute/20010910-1.c with IVOPTs enabled
> > > leads to ssa verification failures because
> > > tree-ssa-loop-ivopts.c:rewrite_use does not update ssa form
> > > (it calls update_stmt but misses mark_new_vars_to_rename).
> > But are the transformations performed by ivopts supposed to
> > be changing the aliasing information?
> 
> no, ivopts should not change virtual operands of any statement.  So
> there is indeed a bug in ivopts, but this is not the right fix.

Presumably IVOPTs should not choose &ep as base in this case,
but rather &ep.rx_skbuff[0] - or would this be worse in any case?
I can only think of the case of a structure with two or more embedded
arrays where we could end up with more IV bases than before.
Maybe we need to add range information to TMR.

Richard.