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* [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
@ 2008-08-06 21:30 lennox at cs dot columbia dot edu
2008-08-07 8:52 ` [Bug middle-end/37042] " rguenth at gcc dot gnu dot org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: lennox at cs dot columbia dot edu @ 2008-08-06 21:30 UTC (permalink / raw)
To: gcc-bugs
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The Intel SSE intrinsic function _mm_load_si128 prints a warning when the data
being loaded from is actually an array of int16_t, even though its argument
(__m128i*) is declared with __attribute__((__may_alias__)).
$ cat alias-warn-emmintrin.c
#include <emmintrin.h>
#include <stdint.h>
static const int16_t __attribute__((__aligned__(16))) tbl[8] =
{ 1, 2, 3, 4, 5, 6, 7, 8};
__m128i get_vec(void)
{
__m128i ret;
ret = _mm_load_si128((__m128i *)tbl);
return ret;
}
$ ~/GCC/bin/gcc-4.3 -O2 -Wall -msse2 -c alias-warn-emmintrin.c
alias-warn-emmintrin.c: In function get_vec:
alias-warn-emmintrin.c:12: warning: likely type-punning may break
strict-aliasing rules: object *{unknown} of main type long long int
__vector__ is referenced at or around
/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/include/emmintrin.h:681
and may be aliased to object tbl of main type short int which is referenced
at or around alias-warn-emmintrin.c:12.
$ ~/GCC/bin/gcc-4.3 -v -O2 -Wall -msse2 -c alias-warn-emmintrin.c
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.3-20080731/configure --enable-threads=posix
--prefix=/home/jonathan/GCC --with-local-prefix=/usr/local
--enable-languages=c,c++,objc,fortran,obj-c++,java --enable-checking=release
--enable-ssp --disable-libssp --disable-libgcj --with-system-zlib
--enable-shared --enable-__cxa_atexit --enable-libstdcxx-allocator=new
--disable-libstdcxx-pch --program-suffix=-4.3
--enable-version-specific-runtime-libs --without-system-libunwind
--with-cpu=generic
Thread model: posix
gcc version 4.3.2 20080731 (prerelease) (GCC)
COLLECT_GCC_OPTIONS='-v' '-O2' '-Wall' '-msse2' '-c' '-mtune=generic'
/mnt/int_drive/jonathan/GCC/bin/../libexec/gcc/i686-pc-linux-gnu/4.3.2/cc1
-quiet -v -iprefix
/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/
alias-warn-emmintrin.c -quiet -dumpbase alias-warn-emmintrin.c -msse2
-mtune=generic -auxbase alias-warn-emmintrin -O2 -Wall -version -o
/tmp/ccKGNLjp.s
ignoring nonexistent directory
"/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/../../../../i686-pc-linux-gnu/include"
ignoring duplicate directory
"/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/../../lib/gcc/i686-pc-linux-gnu/4.3.2/include"
ignoring duplicate directory
"/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/../../lib/gcc/i686-pc-linux-gnu/4.3.2/include-fixed"
ignoring nonexistent directory
"/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/../../lib/gcc/i686-pc-linux-gnu/4.3.2/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/include
/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/include-fixed
/usr/local/include
/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/../../include
/usr/include
End of search list.
GNU C (GCC) version 4.3.2 20080731 (prerelease) (i686-pc-linux-gnu)
compiled by GNU C version 4.3.2 20080731 (prerelease), GMP version
4.2.1, MPFR version 2.2.1.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 3f9a15ebf1f37358d0142d31f7849434
alias-warn-emmintrin.c: In function get_vec:
alias-warn-emmintrin.c:12: warning: likely type-punning may break
strict-aliasing rules: object *{unknown} of main type long long int
__vector__ is referenced at or around
/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/include/emmintrin.h:681
and may be aliased to object tbl of main type short int which is referenced
at or around alias-warn-emmintrin.c:12.
COLLECT_GCC_OPTIONS='-v' '-O2' '-Wall' '-msse2' '-c' '-mtune=generic'
as -V -Qy -o alias-warn-emmintrin.o /tmp/ccKGNLjp.s
GNU assembler version 2.17.50 (i586-suse-linux) using BFD version (GNU
Binutils) 2.17.50.20070726-14 (SUSE Linux)
COMPILER_PATH=/mnt/int_drive/jonathan/GCC/bin/../libexec/gcc/i686-pc-linux-gnu/4.3.2/:/mnt/int_drive/jonathan/GCC/bin/../libexec/gcc/
LIBRARY_PATH=/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/:/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/:/mnt/int_drive/jonathan/GCC/bin/../lib/gcc/i686-pc-linux-gnu/4.3.2/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-O2' '-Wall' '-msse2' '-c' '-mtune=generic'
--
Summary: Strict-aliasing warnings are printed for _mm_load_si128,
even though __m128i is __attribute__((__may_alias__)).
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: lennox at cs dot columbia dot edu
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
@ 2008-08-07 8:52 ` rguenth at gcc dot gnu dot org
2008-08-07 8:52 ` rguenth at gcc dot gnu dot org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-08-07 8:52 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2008-08-07 08:50 -------
Confirmed. This is the other machinery.
typedef long long __m128i __attribute__ ((__vector_size__ (16),
__may_alias__));
extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__,
__artificial__))
_mm_load_si128 (__m128i const *__P)
{
return *__P;
}
static const short __attribute__((__aligned__(16))) tbl[8] =
{ 1, 2, 3, 4, 5, 6, 7, 8};
__m128i get_vec(void)
{
__m128i ret;
ret = _mm_load_si128((__m128i *)tbl);
return ret;
}
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |diagnostic
Last reconfirmed|0000-00-00 00:00:00 |2008-08-07 08:50:50
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
2008-08-07 8:52 ` [Bug middle-end/37042] " rguenth at gcc dot gnu dot org
@ 2008-08-07 8:52 ` rguenth at gcc dot gnu dot org
2008-08-07 10:02 ` rguenth at gcc dot gnu dot org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-08-07 8:52 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rguenth at gcc dot gnu dot org 2008-08-07 08:51 -------
Mine.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2008-08-07 08:50:50 |2008-08-07 08:51:06
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
2008-08-07 8:52 ` [Bug middle-end/37042] " rguenth at gcc dot gnu dot org
2008-08-07 8:52 ` rguenth at gcc dot gnu dot org
@ 2008-08-07 10:02 ` rguenth at gcc dot gnu dot org
2008-08-07 10:03 ` rguenth at gcc dot gnu dot org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-08-07 10:02 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rguenth at gcc dot gnu dot org 2008-08-07 10:01 -------
Subject: Bug 37042
Author: rguenth
Date: Thu Aug 7 09:59:58 2008
New Revision: 138836
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=138836
Log:
2008-08-07 Richard Guenther <rguenther@suse.de>
PR middle-end/37042
* tree-ssa-alias-warnings.c (nonstandard_alias_p): Ref-all
pointers can access anything.
* gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c: New testcase.
Added:
branches/gcc-4_3-branch/gcc/testsuite/gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c
Modified:
branches/gcc-4_3-branch/gcc/ChangeLog
branches/gcc-4_3-branch/gcc/testsuite/ChangeLog
branches/gcc-4_3-branch/gcc/tree-ssa-alias-warnings.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
` (2 preceding siblings ...)
2008-08-07 10:02 ` rguenth at gcc dot gnu dot org
@ 2008-08-07 10:03 ` rguenth at gcc dot gnu dot org
2008-08-07 10:04 ` rguenth at gcc dot gnu dot org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-08-07 10:03 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from rguenth at gcc dot gnu dot org 2008-08-07 10:02 -------
Fixed.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.3.2
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
` (3 preceding siblings ...)
2008-08-07 10:03 ` rguenth at gcc dot gnu dot org
@ 2008-08-07 10:04 ` rguenth at gcc dot gnu dot org
2008-08-10 20:20 ` pinskia at gcc dot gnu dot org
2008-08-11 14:12 ` lennox at cs dot columbia dot edu
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-08-07 10:04 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from rguenth at gcc dot gnu dot org 2008-08-07 10:03 -------
Subject: Bug 37042
Author: rguenth
Date: Thu Aug 7 10:01:48 2008
New Revision: 138837
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=138837
Log:
2008-08-07 Richard Guenther <rguenther@suse.de>
PR middle-end/37042
* tree-ssa-alias-warnings.c (nonstandard_alias_p): Ref-all
pointers can access anything.
* gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-alias-warnings.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
` (4 preceding siblings ...)
2008-08-07 10:04 ` rguenth at gcc dot gnu dot org
@ 2008-08-10 20:20 ` pinskia at gcc dot gnu dot org
2008-08-11 14:12 ` lennox at cs dot columbia dot edu
6 siblings, 0 replies; 8+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2008-08-10 20:20 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from pinskia at gcc dot gnu dot org 2008-08-10 20:19 -------
Note this testcase fails on powerpc64-linux-gnu with the following warning:
/home/apinski/src/local/gcc/gcc/testsuite/gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c:8:
warning: GCC vector returned by reference: non-standard ABI extension
with no compatibility guarantee
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug middle-end/37042] Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).
2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
` (5 preceding siblings ...)
2008-08-10 20:20 ` pinskia at gcc dot gnu dot org
@ 2008-08-11 14:12 ` lennox at cs dot columbia dot edu
6 siblings, 0 replies; 8+ messages in thread
From: lennox at cs dot columbia dot edu @ 2008-08-11 14:12 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from lennox at cs dot columbia dot edu 2008-08-11 14:11 -------
The fact that the function returns the vector is not an essential part of the
test; the return value of the load function just needs not to be optimized out
as unused. So changing the test for broader compatibility is fine as far as
I'm concerned.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37042
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2008-08-11 14:12 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2008-08-06 21:30 [Bug c/37042] New: Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)) lennox at cs dot columbia dot edu
2008-08-07 8:52 ` [Bug middle-end/37042] " rguenth at gcc dot gnu dot org
2008-08-07 8:52 ` rguenth at gcc dot gnu dot org
2008-08-07 10:02 ` rguenth at gcc dot gnu dot org
2008-08-07 10:03 ` rguenth at gcc dot gnu dot org
2008-08-07 10:04 ` rguenth at gcc dot gnu dot org
2008-08-10 20:20 ` pinskia at gcc dot gnu dot org
2008-08-11 14:12 ` lennox at cs dot columbia dot edu
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