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Re: [tree-ssa] Copy prop into virtual operands
On Tue, 2003-07-29 at 11:17, Diego Novillo wrote:
> On Tue, 2003-07-29 at 11:14, Andrew MacLeod wrote:
>
> > > Right. But I don't see how we would get into this situation. After
> > > all, we only do constant propagation on real operands.
> > >
> > How do you know what a real operand is now? you don't have a flag any
> > more...
> >
> CCP only propagates from def_ops() into use_ops(). We only follow
> use-def chains on real operands, not virtual. And any definition coming
> from anything but the LHS of a MODIFY_EXPR is considered VARYING.
>
Ah. I asked because when I took out SSA_NAME_HAS_REAL_REF, there was a
check in ccp for the flag, and it set the variable to VARYING if the
flag was true....
Andrew