[PATCH] align_value attribute in Clang

[Hal Finkel]

Hi Richard,

What does all of this suggest to you about the right design?

FWIW, maybe creating some kind of synthetic typedef type for the return value from DeduceTemplateArgumentsByTypeMatch would work?

Thanks again,
Hal

----- Original Message -----
> From: "Alexey Bataev" <a.bataev at hotmail.com>
> To: "Hal Finkel" <hfinkel at anl.gov>, reviews+D4635+public+b7e82bdc1d8c324a at reviews.llvm.org
> Cc: cfe-commits at cs.uiuc.edu, "aaron ballman" <aaron.ballman at gmail.com>, bigcheesegs at gmail.com, richard at metafoo.co.uk
> Sent: Friday, September 26, 2014 12:26:29 AM
> Subject: Re: [PATCH] align_value attribute in Clang
> 
> 1. ICC does not create a new type for type with this attribute. All
> types are still the same.
> 2.
> 
> int n __attribute__((aligned(32)));
> decltype(&n) - int*.
>   
> 
> Best regards,
> Alexey Bataev
> =============
> Software Engineer
> Intel Compiler Team
> 
> 26.09.2014 4:28, Hal Finkel пишет:
> > ----- Original Message -----
> >> From: "Richard Smith" <richard at metafoo.co.uk>
> >> To: hfinkel at anl.gov, "aaron ballman" <aaron.ballman at gmail.com>,
> >> bigcheesegs at gmail.com, richard at metafoo.co.uk, "a
> >> bataev" <a.bataev at hotmail.com>
> >> Cc: cfe-commits at cs.uiuc.edu
> >> Sent: Thursday, September 25, 2014 7:06:33 PM
> >> Subject: Re: [PATCH] align_value attribute in Clang
> >>
> >> I'd like some more information about how ICC treats this
> >> attribute.
> >> Does it produce a new type? For instance:
> > I did a quick experiment with icc (ICC) 14.0.1 20131008 (with -Wall
> > -O3 -pedantic):
> >
> >>    typedef int *I32 __attribute__((align_value(32)));
> >>    typedef int *I64 __attribute__((align_value(64)));
> >>
> >>    typedef I32 X; typedef I64 X; // ill-formed?
> > No diagnostic.
> >
> >>    template<typename> struct Y;
> >>    typedef Y<I32> Z; typedef Y<I64> Z; // ill-formed?
> > No diagnostic.
> >
> >>    extern I32 i32;
> >>    I64 i64 = i32; // ill-formed? Is an explicit cast required?
> > No diagnostic.
> >
> >>    I32 i32 = i64; // ill-formed? Is there an implicit conversion
> >>    that
> >>    discards alignment?
> > No diagnostic.
> >
> > Alexey, can you please comment on the specifics?
> >
> >   -Hal
> >
> >> ... and if there's an implicit conversion that discards alignment,
> >> what is its conversion rank?
> >>
> >> If I have:
> >>
> >>    int n __attribute__((aligned(32)));
> >>
> >> ... then what is `decltype(&n)`? Is it `int*`, or `int*
> >> __attribute__((align_value(32)))`?
> >>
> >> http://reviews.llvm.org/D4635
> >>
> >>
> >>
> 
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory