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* [Bug libc/12872] New: Wrong alignment of La_x86_64_vector
@ 2011-06-10 5:29 hjl.tools at gmail dot com
2011-07-07 3:57 ` [Bug libc/12872] " drepper.fsp at gmail dot com
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: hjl.tools at gmail dot com @ 2011-06-10 5:29 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
Summary: Wrong alignment of La_x86_64_vector
Product: glibc
Version: 2.14
Status: NEW
Severity: normal
Priority: P2
Component: libc
AssignedTo: drepper.fsp@gmail.com
ReportedBy: hjl.tools@gmail.com
sysdeps/x86_64/bits/link.h has
/* Registers for entry into PLT on x86-64. */
# if __GNUC_PREREQ (4,0)
typedef float La_x86_64_xmm __attribute__ ((__vector_size__ (16)));
typedef float La_x86_64_ymm __attribute__ ((__vector_size__ (32)));
# else
typedef float La_x86_64_xmm __attribute__ ((__mode__ (__V4SF__)));
# endif
typedef union
{
# if __GNUC_PREREQ (4,0)
La_x86_64_ymm ymm[2];
# endif
La_x86_64_xmm xmm[4];
} La_x86_64_vector __attribute__ ((aligned(16)));
It makes La_x86_64_vector aligned at 16byte. Any access
to ymm field may cause unaligned access.
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
@ 2011-07-07 3:57 ` drepper.fsp at gmail dot com
2011-07-07 4:12 ` hjl.tools at gmail dot com
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: drepper.fsp at gmail dot com @ 2011-07-07 3:57 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
Ulrich Drepper <drepper.fsp at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |WONTFIX
--- Comment #1 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-07-07 03:57:19 UTC ---
The alignment is what it is. This is an data structure which is part of the
interface of . It cannot be changed. Use unaligned accesses.
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
2011-07-07 3:57 ` [Bug libc/12872] " drepper.fsp at gmail dot com
@ 2011-07-07 4:12 ` hjl.tools at gmail dot com
2011-07-08 17:10 ` drepper.fsp at gmail dot com
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: hjl.tools at gmail dot com @ 2011-07-07 4:12 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-07-07 04:12:20 UTC ---
(In reply to comment #1)
> The alignment is what it is. This is an data structure which is part of the
> interface of . It cannot be changed. Use unaligned accesses.
Then La_x86_64_ymm should be marked as 16byte aligned.
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
2011-07-07 3:57 ` [Bug libc/12872] " drepper.fsp at gmail dot com
2011-07-07 4:12 ` hjl.tools at gmail dot com
@ 2011-07-08 17:10 ` drepper.fsp at gmail dot com
2011-07-08 17:16 ` hjl.tools at gmail dot com
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: drepper.fsp at gmail dot com @ 2011-07-08 17:10 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
--- Comment #3 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-07-08 17:09:57 UTC ---
(In reply to comment #2)
> (In reply to comment #1)
> > The alignment is what it is. This is an data structure which is part of the
> > interface of . It cannot be changed. Use unaligned accesses.
>
> Then La_x86_64_ymm should be marked as 16byte aligned.
Why is this necessary? The La_x86_64_ymm values are never accessed directly.
They are part of La_x86_64_vector and that union (thanks to one of your
patches) is aligned to 16 bytes. This should be enough. Where exactly are the
problematic uses?
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
` (2 preceding siblings ...)
2011-07-08 17:10 ` drepper.fsp at gmail dot com
@ 2011-07-08 17:16 ` hjl.tools at gmail dot com
2011-07-09 23:58 ` drepper.fsp at gmail dot com
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: hjl.tools at gmail dot com @ 2011-07-08 17:16 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-07-08 17:15:55 UTC ---
(In reply to comment #3)
> (In reply to comment #2)
> > (In reply to comment #1)
> > > The alignment is what it is. This is an data structure which is part of the
> > > interface of . It cannot be changed. Use unaligned accesses.
> >
> > Then La_x86_64_ymm should be marked as 16byte aligned.
>
> Why is this necessary? The La_x86_64_ymm values are never accessed directly.
> They are part of La_x86_64_vector and that union (thanks to one of your
> patches) is aligned to 16 bytes. This should be enough. Where exactly are the
> problematic uses?
The ymm field may be used:
[hjl@gnu-6 elf]$ grep La_x86_64_ymm *.c
tst-auditmod4b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (i + 1);
tst-auditmod4b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (0x12349876);
tst-auditmod6b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (i + 2);
tst-auditmod6b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (0x12349876);
tst-auditmod6c.c: = (La_x86_64_ymm) _mm256_set1_epi32 (i + 0x101);
tst-auditmod6c.c: = (La_x86_64_ymm) _mm256_set1_epi32 (0x98abcdef);
tst-auditmod7b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (i + 0x101);
tst-auditmod7b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (0x98abcdef);
[hjl@gnu-6 elf]$
Compiler thinks it is aligned at 32byte and generates aligned 32bye vector
move.
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
` (3 preceding siblings ...)
2011-07-08 17:16 ` hjl.tools at gmail dot com
@ 2011-07-09 23:58 ` drepper.fsp at gmail dot com
2011-07-11 1:27 ` hjl.tools at gmail dot com
2014-06-24 8:37 ` fweimer at redhat dot com
6 siblings, 0 replies; 8+ messages in thread
From: drepper.fsp at gmail dot com @ 2011-07-09 23:58 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
--- Comment #5 from Ulrich Drepper <drepper.fsp at gmail dot com> 2011-07-09 23:58:08 UTC ---
(In reply to comment #4)
> The ymm field may be used:
>
> [hjl@gnu-6 elf]$ grep La_x86_64_ymm *.c
> tst-auditmod4b.c: = (La_x86_64_ymm) _mm256_set1_epi32 (i + 1);
But in all these cases the ymm field is in an La_x86_64_vector which is aligned
ti 16 bytes. The compiler should recognize this.
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
` (4 preceding siblings ...)
2011-07-09 23:58 ` drepper.fsp at gmail dot com
@ 2011-07-11 1:27 ` hjl.tools at gmail dot com
2014-06-24 8:37 ` fweimer at redhat dot com
6 siblings, 0 replies; 8+ messages in thread
From: hjl.tools at gmail dot com @ 2011-07-11 1:27 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=12872
--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> 2011-07-11 01:27:01 UTC ---
I opened:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49699
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* [Bug libc/12872] Wrong alignment of La_x86_64_vector
2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
` (5 preceding siblings ...)
2011-07-11 1:27 ` hjl.tools at gmail dot com
@ 2014-06-24 8:37 ` fweimer at redhat dot com
6 siblings, 0 replies; 8+ messages in thread
From: fweimer at redhat dot com @ 2014-06-24 8:37 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=12872
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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2011-06-10 5:29 [Bug libc/12872] New: Wrong alignment of La_x86_64_vector hjl.tools at gmail dot com
2011-07-07 3:57 ` [Bug libc/12872] " drepper.fsp at gmail dot com
2011-07-07 4:12 ` hjl.tools at gmail dot com
2011-07-08 17:10 ` drepper.fsp at gmail dot com
2011-07-08 17:16 ` hjl.tools at gmail dot com
2011-07-09 23:58 ` drepper.fsp at gmail dot com
2011-07-11 1:27 ` hjl.tools at gmail dot com
2014-06-24 8:37 ` fweimer at redhat dot com
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