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Re: Do less generous pointer globbing in alias.c
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Jan Hubicka <hubicka at ucw dot cz>
- Cc: Richard Biener <rguenther at suse dot de>, gcc-patches at gcc dot gnu dot org
- Date: Wed, 27 May 2015 16:58:22 +0200
- Subject: Re: Do less generous pointer globbing in alias.c
- Authentication-results: sourceware.org; auth=none
- References: <20150527052850 dot GB88897 at kam dot mff dot cuni dot cz> <alpine dot LSU dot 2 dot 11 dot 1505271046320 dot 30088 at zhemvz dot fhfr dot qr> <20150527144221 dot GB51385 at kam dot mff dot cuni dot cz>
> Yes, so is
>
> struct foo {struct bar a;};
>
> a.a = ...
> ... = a;
>
> and
>
> a = ...
> ... = a.a;
>
> this is why conflict is symmetrization of the subset relation.
OK the statement above is true, but subsets alone are not quite right for use
in aliasing_component_refs_p
void *a;
char **ptr=&a;
*ptr = ....
is defined for us, but the structure-substructure equivalent is not.
I will implement the variant with extra flag after teaching and send updated
patch.
Thanks,
Honza