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Re: [patch] Avoid ssa update in cfg cleanup
On Thu, 2006-02-23 at 17:40 +0100, Zdenek Dvorak wrote:
> Hello,
>
> > On Wed, 2006-02-15 at 10:56 -0500, Diego Novillo wrote:
> > > Zdenek Dvorak wrote:
> > >
> > I also prefer not to unite the maydef and mustdef structures. They are
> > conceptually different and should remain separate I think.
>
> I do not see them as that much different -- in fact, I would find it
> much more natural to have only single type of VDEF operands, with a
> single bit telling whether the definition is killing or not.
And I see it the other way. I prefer that this information be contextual
rather than a bit in the structure. From a design point of view they
represent different conceptual things and if one ever needs to change
one of them to a different representation, it is much easier.
> > Its simple
> > enough to provide a function to convert a maydef to a mustdef while
> > maintaining use links if that is what is needed.
>
> I have considered this; however, it is fairly difficult to get this work
> with the way tree-ssa-opfinalize.h.
I don't understand why. Perhaps I'm a bit dense right now, but exactly
How/when do you know you need to change a maydef to a mustdef? and why
does it need to be in the opfinalize hunk?
Andrew