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Re: Fix more of C/fortran canonical type issues
- From: Richard Biener <rguenther at suse dot de>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: Jan Hubicka <hubicka at ucw dot cz>, gcc-patches at gcc dot gnu dot org, burnus at net-b dot de
- Date: Mon, 8 Jun 2015 16:09:21 +0200 (CEST)
- Subject: Re: Fix more of C/fortran canonical type issues
- Authentication-results: sourceware.org; auth=none
- References: <20150608001957 dot GA35779 at kam dot mff dot cuni dot cz> <20150608050047 dot GA10381 at kam dot mff dot cuni dot cz> <20150608054500 dot GA58209 at kam dot mff dot cuni dot cz> <alpine dot LSU dot 2 dot 11 dot 1506081536560 dot 30088 at zhemvz dot fhfr dot qr> <alpine dot DEB dot 2 dot 10 dot 1506081354460 dot 25225 at digraph dot polyomino dot org dot uk>
On Mon, 8 Jun 2015, Joseph Myers wrote:
> On Mon, 8 Jun 2015, Richard Biener wrote:
>
> > I'm not sure the C standard mandates compatibility between
> >
> > struct { int i; } and struct { unsigned i; } for purposes of TBAA.
> > Joseph?
>
> I don't think they are necessarily compatible for TBAA.
Ok, but as int and unsigned are reading either structs element
via a pointer to int or a pointer to unsigned must be supported?
(The C FE ensures this via alias-subsets and the get_alias_set
langhook returning the same alias sets for int and unsigned)
Richard.
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Dilip Upmanyu, Graham Norton, HRB 21284 (AG Nuernberg)