* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
@ 2004-09-30 4:28 ` bkoz at gcc dot gnu dot org
2004-09-30 4:29 ` bkoz at gcc dot gnu dot org
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From: bkoz at gcc dot gnu dot org @ 2004-09-30 4:28 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at gcc dot gnu dot org 2004-09-30 04:28 -------
Created an attachment (id=7244)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=7244&action=view)
test case
test case
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
2004-09-30 4:28 ` [Bug c++/17743] " bkoz at gcc dot gnu dot org
@ 2004-09-30 4:29 ` bkoz at gcc dot gnu dot org
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From: bkoz at gcc dot gnu dot org @ 2004-09-30 4:29 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |gdr at cs dot tamu dot edu,
| |mark at codesourcery dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
2004-09-30 4:28 ` [Bug c++/17743] " bkoz at gcc dot gnu dot org
2004-09-30 4:29 ` bkoz at gcc dot gnu dot org
@ 2004-09-30 4:30 ` bkoz at gcc dot gnu dot org
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From: bkoz at gcc dot gnu dot org @ 2004-09-30 4:30 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at gcc dot gnu dot org 2004-09-30 04:30 -------
Add deps...
--
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO| |8670
nThis| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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From: bkoz at gcc dot gnu dot org @ 2004-09-30 4:33 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Known to fail| |3.4.0 3.4.1 3.4.2 4.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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From: bkoz at gcc dot gnu dot org @ 2004-09-30 4:33 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Known to fail|3.4.0 3.4.1 3.4.2 4.0.0 |3.3.3 3.4.0 3.4.1 3.4.2
| |4.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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From: pinskia at gcc dot gnu dot org @ 2004-09-30 4:45 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-09-30 04:45 -------
Actually this is the attribute aligned vs arrays.
I cannot decode what the documenation means:
Note that although you can ask the compiler to select a time-efficient alignment for a given type and
then declare only individual stand-alone objects of that type, the compiler's ability to select a time-
efficient alignment is primarily useful only when you plan to create arrays of variables having the
relevant (efficiently aligned) type. If you declare or use arrays of variables of an efficiently-aligned type,
then it is likely that your program will also be doing pointer arithmetic (or subscripting, which amounts
to the same thing) on pointers to the relevant type, and the code that the compiler generates for these
pointer arithmetic operations will often be more efficient for efficiently-aligned types than for other
types.
--
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO|8670 |
nThis| |
Known to fail|3.3.3 3.4.0 3.4.1 3.4.2 |
|4.0.0 |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (5 preceding siblings ...)
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From: pinskia at gcc dot gnu dot org @ 2004-09-30 4:47 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-09-30 04:47 -------
Revert back some changes that I did not mean to do.
--
What |Removed |Added
----------------------------------------------------------------------------
OtherBugsDependingO| |8670
nThis| |
Known to fail| |3.3.3 3.4.0 3.4.1 3.4.2
| |4.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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From: gdr at cs dot tamu dot edu @ 2004-09-30 11:12 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From gdr at cs dot tamu dot edu 2004-09-30 11:12 -------
Subject: Re: __alignof__ vs. typedefs
"pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:
| Actually this is the attribute aligned vs arrays.
|
| I cannot decode what the documenation means:
| Note that although you can ask the compiler to select a
| time-efficient alignment for a given type and
| then declare only individual stand-alone objects of that type, the
| compiler's ability to select a time-
| efficient alignment is primarily useful only when you plan to create
| arrays of variables having the
| relevant (efficiently aligned) type. If you declare or use arrays of
| variables of an efficiently-aligned type,
| then it is likely that your program will also be doing pointer
| arithmetic (or subscripting, which amounts
| to the same thing) on pointers to the relevant type, and the code
| that the compiler generates for these
| pointer arithmetic operations will often be more efficient for
| efficiently-aligned types than for other types.
I don't see how much this is relevant to the different uses of the
aligned attribute in the library. Right now, the compiler is just
ignoring the aligned attribute. We're more intersted in the semantics
than in the speed.
What we want is to align a given *array object* at some alignment
boundaries. We're not interested in pointer arithmetics on array
types or speed -- although we may be doing pointer arithmetic on
individual elements of the array, but that is a separate issue.
The primarily thing is the ability to align an array object on a given
boundary.
-- Gaby
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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From: giovannibajo at libero dot it @ 2004-09-30 12:27 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From giovannibajo at libero dot it 2004-09-30 12:27 -------
Benj, having a fix in time for 4.0 would help, or is it going to be 4.1
material anyway?
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |giovannibajo at libero dot
| |it
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (8 preceding siblings ...)
2004-09-30 12:27 ` giovannibajo at libero dot it
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From: bkoz at redhat dot com @ 2004-09-30 14:48 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at redhat dot com 2004-09-30 14:48 -------
Subject: Re: __alignof__ vs. typedefs
>Benj, having a fix in time for 4.0 would help, or is it going to be 4.1
>material anyway?
Having a fix for this for 4.0.0 will definitely be useful. I'm kind of
surprised that this isn't working right now, actually: I thought it was.
See libstdc++-v3/src/globals*.cc.
If somebody wants to change the subjet to something better go for it.
-benjamin
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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From: giovannibajo at libero dot it @ 2004-10-15 1:49 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |giovannibajo at libero dot
|dot org |it
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2004-10-15 01:49:31
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (10 preceding siblings ...)
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From: giovannibajo at libero dot it @ 2004-10-16 2:00 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From giovannibajo at libero dot it 2004-10-16 02:00 -------
Patch submitted:
http://gcc.gnu.org/ml/gcc-patches/2004-10/msg01320.html
--
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (11 preceding siblings ...)
2004-10-16 2:00 ` giovannibajo at libero dot it
@ 2004-10-16 3:37 ` mark at codesourcery dot com
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From: mark at codesourcery dot com @ 2004-10-16 3:37 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From mark at codesourcery dot com 2004-10-16 03:37 -------
Subject: Re: __alignof__ vs. typedefs
giovannibajo at libero dot it wrote:
>------- Additional Comments From giovannibajo at libero dot it 2004-10-16 02:00 -------
>Patch submitted:
>http://gcc.gnu.org/ml/gcc-patches/2004-10/msg01320.html
>
>
OK. But XFAIL the tr1 test cases so those do not show up as new FAILs.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (12 preceding siblings ...)
2004-10-16 3:37 ` mark at codesourcery dot com
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From: bkoz at redhat dot com @ 2004-10-16 13:52 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at redhat dot com 2004-10-16 13:52 -------
Subject: Re: __alignof__ vs. typedefs
>OK. But XFAIL the tr1 test cases so those do not show up as new FAILs.
I think I just took care of this.
Giovanni, thanks!
-benjamin
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] __alignof__ vs. typedefs
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
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2004-10-16 13:52 ` bkoz at redhat dot com
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2004-10-17 4:48 ` [Bug c++/17743] dependent expressions in attributes giovannibajo at libero dot it
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From: cvs-commit at gcc dot gnu dot org @ 2004-10-17 4:39 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From cvs-commit at gcc dot gnu dot org 2004-10-17 04:39 -------
Subject: Bug 17743
CVSROOT: /cvs/gcc
Module name: gcc
Changes by: giovannibajo@gcc.gnu.org 2004-10-17 04:39:46
Modified files:
gcc/cp : ChangeLog decl2.c
gcc/testsuite : ChangeLog
Added files:
gcc/testsuite/g++.dg/ext: attrib17.C
Log message:
PR c++/17743
* decl2.c (grokfield): Apply attributes also to TYPE_DECLs.
PR c++/17743
* g++.dg/ext/attrib17.C: New test.
Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.4440&r2=1.4441
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/decl2.c.diff?cvsroot=gcc&r1=1.753&r2=1.754
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.4463&r2=1.4464
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/attrib17.C.diff?cvsroot=gcc&r1=NONE&r2=1.1
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (14 preceding siblings ...)
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From: giovannibajo at libero dot it @ 2004-10-17 4:48 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From giovannibajo at libero dot it 2004-10-17 04:47 -------
OK, I fixed part of this for 4.0. The missing part is when the expression in
attributes is dependent, like:
template <class T>
struct A {
char foo __attribute__((aligned(__alignof__(T))));
};
This is non-trivial to fix. Benjamin, if you want you can keep this bugreport
open to track this. I do not plan to be able to fix this in the 4.0 timeframe,
so I have unassigned the bug (I will attempt something though). If somebody
more expert than me wants to help the v3 guys, feel free.
Otherwise, if you do not care about this, just close this bug.
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|giovannibajo at libero dot |unassigned at gcc dot gnu
|it |dot org
Status|ASSIGNED |NEW
Summary|__alignof__ vs. typedefs |dependent expressions in
| |attributes
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (15 preceding siblings ...)
2004-10-17 4:48 ` [Bug c++/17743] dependent expressions in attributes giovannibajo at libero dot it
@ 2004-10-17 7:50 ` gdr at cs dot tamu dot edu
2004-10-18 3:51 ` giovannibajo at libero dot it
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From: gdr at cs dot tamu dot edu @ 2004-10-17 7:50 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From gdr at cs dot tamu dot edu 2004-10-17 07:50 -------
Subject: Re: dependent expressions in attributes
On Sat, 17 Oct 2004, giovannibajo at libero dot it wrote:
| OK, I fixed part of this for 4.0. The missing part is when the expression in
| attributes is dependent, like:
|
| template <class T>
| struct A {
| char foo __attribute__((aligned(__alignof__(T))));
| };
|
| This is non-trivial to fix. Benjamin, if you want you can keep this bugreport
| open to track this. I do not plan to be able to fix this in the 4.0 timeframe,
| so I have unassigned the bug (I will attempt something though). If somebody
| more expert than me wants to help the v3 guys, feel free.
|
| Otherwise, if you do not care about this, just close this bug.
I do care.
-- Gaby
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (16 preceding siblings ...)
2004-10-17 7:50 ` gdr at cs dot tamu dot edu
@ 2004-10-18 3:51 ` giovannibajo at libero dot it
2004-10-18 5:23 ` bkoz at redhat dot com
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From: giovannibajo at libero dot it @ 2004-10-18 3:51 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From giovannibajo at libero dot it 2004-10-18 03:51 -------
Subject: Re: dependent expressions in attributes
>> template <class T>
>> struct A {
>> char foo __attribute__((aligned(__alignof__(T))));
>> };
>
> I do care.
Is this a showstopper for tr1 work?
Giovanni Bajo
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
^ permalink raw reply [flat|nested] 25+ messages in thread
* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (17 preceding siblings ...)
2004-10-18 3:51 ` giovannibajo at libero dot it
@ 2004-10-18 5:23 ` bkoz at redhat dot com
2004-10-18 16:38 ` giovannibajo at libero dot it
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From: bkoz at redhat dot com @ 2004-10-18 5:23 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at redhat dot com 2004-10-18 05:23 -------
Subject: Re: dependent expressions in attributes
>Is this a showstopper for tr1 work?
Not that I can see. From what I can tell, tr1::array is going to require
default-constructable types.
I think the library hackers are interested in this kind of stuff for our
own selfish reasons.
I guess I don't see why/how alignof should be different than sizeof
here (which works):
template <class T>
struct A
{
char foo[sizeof(T)];
};
-benjamin
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (18 preceding siblings ...)
2004-10-18 5:23 ` bkoz at redhat dot com
@ 2004-10-18 16:38 ` giovannibajo at libero dot it
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From: giovannibajo at libero dot it @ 2004-10-18 16:38 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From giovannibajo at libero dot it 2004-10-18 16:38 -------
(In reply to comment #15)
> I guess I don't see why/how alignof should be different than sizeof
> here (which works):
> template <class T>
> struct A
> {
> char foo[sizeof(T)];
> };
Yes, but how do you force the compiler to ensure that the alignment of char foo
[] is sufficient to placement-allocate an object of type T into it?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
^ permalink raw reply [flat|nested] 25+ messages in thread
* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (19 preceding siblings ...)
2004-10-18 16:38 ` giovannibajo at libero dot it
@ 2004-10-18 18:57 ` bkoz at gcc dot gnu dot org
2004-10-19 6:23 ` bkoz at redhat dot com
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From: bkoz at gcc dot gnu dot org @ 2004-10-18 18:57 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at gcc dot gnu dot org 2004-10-18 18:57 -------
Giovanni, this is applicable to TR1 via
4.5.5 Other transformations [tr.meta.trans.other] template <std :: size_t Len ,
std :: size_t Align > struct aligned_storage { typedef unspecified type ; }; 1
type: an implementation defined POD type with size Len and alignment Align, and
suitable for use as uninitialized storage for any object of a type whose size is
Len and whose alignment is Align.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
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* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (20 preceding siblings ...)
2004-10-18 18:57 ` bkoz at gcc dot gnu dot org
@ 2004-10-19 6:23 ` bkoz at redhat dot com
2004-10-27 17:19 ` bkoz at gcc dot gnu dot org
2004-10-28 3:38 ` giovannibajo at libero dot it
23 siblings, 0 replies; 25+ messages in thread
From: bkoz at redhat dot com @ 2004-10-19 6:23 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at redhat dot com 2004-10-19 06:23 -------
Subject: Re: dependent expressions in attributes
>Yes, but how do you force the compiler to ensure that the alignment of char foo
>[] is sufficient to placement-allocate an object of type T into it?
...get __alignof__(T) working?
I don't see any other way, really.
-benjamin
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
^ permalink raw reply [flat|nested] 25+ messages in thread
* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (21 preceding siblings ...)
2004-10-19 6:23 ` bkoz at redhat dot com
@ 2004-10-27 17:19 ` bkoz at gcc dot gnu dot org
2004-10-28 3:38 ` giovannibajo at libero dot it
23 siblings, 0 replies; 25+ messages in thread
From: bkoz at gcc dot gnu dot org @ 2004-10-27 17:19 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bkoz at gcc dot gnu dot org 2004-10-27 17:19 -------
Jason, this is the bug I talked about briefly. Do you think the Redmond offsetof
work is also applicable here?
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What |Removed |Added
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CC| |jason at redhat dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
^ permalink raw reply [flat|nested] 25+ messages in thread
* [Bug c++/17743] dependent expressions in attributes
2004-09-30 4:26 [Bug c++/17743] New: __alignof__ vs. typedefs bkoz at gcc dot gnu dot org
` (22 preceding siblings ...)
2004-10-27 17:19 ` bkoz at gcc dot gnu dot org
@ 2004-10-28 3:38 ` giovannibajo at libero dot it
23 siblings, 0 replies; 25+ messages in thread
From: giovannibajo at libero dot it @ 2004-10-28 3:38 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From giovannibajo at libero dot it 2004-10-28 03:38 -------
(In reply to comment #19)
> Jason, this is the bug I talked about briefly. Do you think
> the Redmond offsetof work is also applicable here?
Mind to share that?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17743
^ permalink raw reply [flat|nested] 25+ messages in thread