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Re: PR83648


> On Wed, Jan 03, 2018 at 10:05:30AM +0100, Richard Biener wrote:
> > >One concern I have is that with the patch, malloc_candidate_p will
> > >return true if all the args to PHI are NULL:
> > >retval = PHI<0, 0>
> > >return retval
> > >
> > >However I expect that PHI with all 0 args would be constant folded to
> > >0 earlier, so this case shouldn't occur in practice ?
> > 
> > You may not rely on folding for correctness. 

.. and at this level i would say even for code quality. Early optimizers are
facing a lot of garbage and they are not repeated, so we get code at various
intermediate levels of optimizations thorugh the IPA queue.

Honza
> 
> Yeah.  Will the patch handle (I mean punt on) also unfolded
>   if (n) ? 0 : __builtin_malloc (n);
> and similar?
> 
> 	Jakub


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