Hi Richard,
your guess is correct, it is applied to the outer pointer.
Best regards,
Alexey Bataev
=============
Software Engineer
Intel Compiler Team
30.09.2014 4:50, Richard Smith пишет:
On Mon, Sep 29, 2014 at 11:36 AM, Hal Finkel <[email protected]
<mailto:[email protected]>> wrote:
Hi Richard,
What does all of this suggest to you about the right design?
One more question. Given:
typedef int * __attribute__((align_value(32))) *Y;
... does the attribute apply to the outer pointer or the inner
pointer? (My guess: it surprisingly applies to the outer pointer.) If
that's the case, then I think align_value should live entirely outside
the type system, in the same way that __attribute__((aligned)) does.
Note that, given:
typedef int __attribute__((aligned(64))) *p __attribute__((aligned(8)))
p is a 64-byte-aligned pointer to int, not an 8-byte-aligned pointer
to a 64-byte-aligned int.
If that's the case, I suggest you model it exactly like AlignedAttr --
as an attribute on the TypedefDecl -- and look for it explicitly in
the cases where you want to use it by walking the type sugar and
looking for a TypedefDecl.
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" <[email protected]
<mailto:[email protected]>>
> To: "Hal Finkel" <[email protected] <mailto:[email protected]>>,
[email protected]
<mailto:reviews%2bd4635%2bpublic%[email protected]>
> Cc: [email protected] <mailto:[email protected]>,
"aaron ballman" <[email protected]
<mailto:[email protected]>>, [email protected]
<mailto:[email protected]>, [email protected]
<mailto:[email protected]>
> 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" <[email protected]
<mailto:[email protected]>>
> >> To: [email protected] <mailto:[email protected]>, "aaron ballman"
<[email protected] <mailto:[email protected]>>,
> >> [email protected] <mailto:[email protected]>,
[email protected] <mailto:[email protected]>, "a
> >> bataev" <[email protected] <mailto:[email protected]>>
> >> Cc: [email protected] <mailto:[email protected]>
> >> 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
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