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[Bug tree-optimization/78035] Inconsistency between address comparison and alias analysis
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 19 Oct 2016 13:20:42 +0000
- Subject: [Bug tree-optimization/78035] Inconsistency between address comparison and alias analysis
- Auto-submitted: auto-generated
- References: <bug-78035-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78035
--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 19 Oct 2016, amonakov at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78035
>
> Alexander Monakov <amonakov at gcc dot gnu.org> changed:
>
> What |Removed |Added
> ----------------------------------------------------------------------------
> CC| |amonakov at gcc dot gnu.org
>
> --- Comment #5 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
> Note that for external function symbols from the standard library there's an
> old DR that clarifies that their addresses may compare equal, since the library
> may be implemented in a language other than C. See point c) in
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_078.html
"Not implemented in C" would apply to any extern function pair as the
compiler does not know wheter it's part of a "standard library"
(I think restricting the answer to standard library function is
misguided).
> But that is only for function declarations, I don't know if for object
> declarations it's the same or different. Credit goes to Szabolcs Nagy for
> pointing me to this DR.
Usually it's out of the scope of the C standard but we generally try
to honor ELF possibilities.