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Re: PATCH RFA: PR 29286: Handle placement new aliasing issues
Hi,
On Tue, 12 Jun 2007, Ian Lance Taylor wrote:
> I don't understand the reference to points-to; if you mean the alias
> analysis code, that is exactly how the flag is propagated in my proposed
> patch.
I meant that, yes. Okay.
> When I tried not using CHANGE_DYNAMIC_TYPE_EXPR at all, and just
> setting DECL_NO_TBAA_P on D.XXXXX,
Yes, that's what I had in mind, but ...
> the problem was that in several test cases the temporary variable
> D.XXXXX simply dropped out.
... of course this might happen before the flag propagation actually
happens, so yes, the new expression code is the cleanest solution here.
> I hope this makes sense.
It does, yes.
> Frankly, to me, the decision as to whether to use my patch or whether to
> use implicit dependencies is a no-brainer. As another argument, my
> patch only affects programs which use placement new, but implicit
> dependencies could affect any program.
Yes, and there we simply disagree if that's good or bad, but lets leave it
at that ;-) It's good that this particular bug is fixed at all, it's an
ugly one.
Ciao,
Michael.