| Summary: | many unaligned accesses in libgomp tests | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Jay <jay.krell> |
| Component: | libgomp | Assignee: | Rainer Orth <ro> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | gcc-bugs, jakub, ro |
| Priority: | P3 | ||
| Version: | 4.7.0 | ||
| Target Milestone: | 4.7.0 | ||
| URL: | http://gcc.gnu.org/ml/gcc-patches/2011-07/msg02162.html | ||
| Host: | Target: | alphaev67-dec-osf5.1 | |
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | 2011-07-19 12:46:17 | |
Can you possibly reduce one testcase? Confirmed, easy to see with uac p noprint nofix sigbus, i.e. unaligned accesses not fixed up, but instead generating SIGBUS. Will rebuild libgomp with -g3 -O0 to allow for debugging/investigation. I see what's happening now: the unaligned access is happending inside
librt (sem_wait), with uac p noprint nofix sigbus:
Program received signal SIGBUS, Bus error.
[Switching to Thread 1]
0x000003ff81086c98 in sem_init () from /usr/shlib/librt.so
(gdb) Erroneous arithmetic operation.
(gdb) where
#0 0x000003ff81086c98 in sem_init () from /usr/shlib/librt.so
#1 0x000003ffbffefdec in gomp_sem_init (sem=0x3ffbfff02a0, value=536854016)
at /vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.h:72
#2 0x000003ffbfff02a0 in gomp_init_task (task=0x14002bf00, parent_task=0x0,
prev_icv=0x3ffffff0020) at /vol/gcc/src/hg/trunk/local/libgomp/task.c:45
#3 0x000003ffbfff1eb4 in gomp_team_start (fn=0x11fffe300, data=0x11fffe310,
nthreads=536863560, team=0x11fffe358)
at /vol/gcc/src/hg/trunk/local/libgomp/team.c:292
#4 0x000003ffbffef148 in GOMP_parallel_start (
fn=0x120002db4 <sub1._omp_fn.0>, data=0x11fffbfd0, num_threads=1)
at /vol/gcc/src/hg/trunk/local/libgomp/parallel.c:108
#5 0x0000000120002cfc in sub1 (n=2)
at /vol/gcc/src/hg/trunk/local/libgomp/testsuite/libgomp.c/appendix-a/a.15.1.c:30
#6 0x0000000120002d68 in main ()
at /vol/gcc/src/hg/trunk/local/libgomp/testsuite/libgomp.c/appendix-a/a.15.1.c:40
The actual unaligned access is one insn before:
(gdb) x/i 0x3ff81086c94
0x3ff81086c94 <sem_init+308>: stl zero,0(s0)
(gdb) p/x $s0
$17 = 0x14002bf5e
Unaligned access pid=391884 <a.15.1.exe> va=0x14002bf5e pc=0x3ff81086c94 ra=0x3ff81086bf4 inst=0xb3e90000
And indeed *s0 isn't 4-byte aligned, as required by the stl insn.
I could trace this as follows:
* gomp_sem_t is sem_t (config/posix/sem.h)
* sem_t is psx4_key_t (from <semaphore.h>)
* psx4_key_t is defined in <psx4_nspace_ts.h>:
typedef unsigned short psx4_key_version_t;
typedef unsigned short psx4_key_index_t;
typedef struct psx4_key
{
psx4_key_index_t index; /* Index of entry */
psx4_key_version_t version; /* Version number of key */
} psx4_key_t;
Looking at the Tru64 UNIX V5.1 sources, I find (in
src/usr/ccs/lib/librt/psx4_csem.c (sem_init)):
int
sem_init(sem_t *sem, int pshared, unsigned int value)
[...]
*(int *)sem = 0;
i.e. the code assumes int (4-byte) alignment, but only gets short
(2-byte) alignment instead.
An appropriate attribute should fix this. Don't know how best to fit
this into libgomp.
Rainer
Jakuk, what would be the best/least intrusive way to handle this target-specific gomp_sem_t alignment requirement? Rainer You mean that __alignof (sem_t) is 2, yet librt assumes it is 4 byte aligned? These proprietary OSes are of terrible quality. You could add config/osf/sem.h, which would be a copy of config/posix/sem.h, just gomp_sem_t would be typedef sem_t gomp_sem_t __attribute__((aligned (__alignof__ (int)))); or something similar, and in configury ensure that this directory is searched on these buggy OSes before config/posix/. > --- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-07-19 14:14:22 UTC --- > You mean that __alignof (sem_t) is 2, yet librt assumes it is 4 byte aligned? > These proprietary OSes are of terrible quality. Perhaps not in general, but this is clearly bullshit ;-) > You could add config/osf/sem.h, which would be a copy of config/posix/sem.h, > just gomp_sem_t would be typedef sem_t gomp_sem_t __attribute__((aligned > (__alignof__ (int)))); > or something similar, and in configury ensure that this directory is searched > on these buggy OSes before config/posix/. Ok, this is probably the least invasive way, especially since the HAVE_BROKEN_POSIX_SEMAPHORES part isn't needed and the file will be quite small. I'll try this. Thanks. Rainer Mine. Is there no annotation in /usr/include/whatever.h to get the required alignment? Maybe that gcc doesn't-but-maybe-should understand? - Jay (phone) On Jul 19, 2011, at 7:33 AM, "ro at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45351 > > Rainer Orth <ro at gcc dot gnu.org> changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > Status|NEW |ASSIGNED > AssignedTo|unassigned at gcc dot |ro at gcc dot gnu.org > |gnu.org | > > --- Comment #7 from Rainer Orth <ro at gcc dot gnu.org> 2011-07-19 14:32:25 UTC --- > Mine. > > -- > Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email > ------- You are receiving this mail because: ------- > You reported the bug. > --- Comment #8 from Jay <jay.krell at cornell dot edu> 2011-07-19 15:15:46 UTC ---
> Is there no annotation in /usr/include/whatever.h to get the required
> alignment? Maybe that gcc doesn't-but-maybe-should understand?
No, the section I cited is all there is. No idea why this error doesn't
show up otherwise.
Rainer
>> Is there no annotation in /usr/include/whatever.h to get the required >> alignment? Maybe that gcc doesn't-but-maybe-should understand? > > No, the section I cited is all there is. No idea why this error doesn't > show up otherwise. Do struct alignment rules on Tru64 have an effect? Not that I looked-up/read the ABI details.. I'm not sure I have Tru64 access any longer (and my time/work/money-to-burn has dramatically declined, sorry, it was fun!) But I'd be curious what this does: #include something #include stddef.h int main() { typedef struct { char a; sem_t b; } t1; printf("%u %u\n", sizeof(t1), offsetof(t1, b)); return 0; } 5 or 6 or 8 or other? and 1 or 2 or 4 or other? If the alignment is really only 2, then I'd expect 6 and 2. If the alignment is somehow bumped up, then 8 and 4. The code cited does seem poor. Personally I'm a big fan of memset(p, 0, n) (or #define ZeroMemory(p, n)). - Jay > Do struct alignment rules on Tru64 have an effect? Not that I > looked-up/read the ABI details.. I had a look at `Calling Standard for Alpha Systems', and the rules seemed as expected and straight-forward. > But I'd be curious what this does: > > #include something > #include stddef.h > > > int main() > { > typedef struct { char a; sem_t b; } t1; > printf("%u %u\n", sizeof(t1), offsetof(t1, b)); > return 0; > } > > 5 or 6 or 8 or other? > and 1 or 2 or 4 or other? > If the alignment is really only 2, then I'd expect 6 and 2. This is what I get, with both cc and gcc. Rainer To make completely sure that this isn't a gcc problem of some sort, I've derived a testcase from libgomp. If built with cc -c99 or gcc, it shows the same unaligned access, so this is really just a silly librt bug, nothing else. Rainer Author: ro Date: Mon Jul 25 15:39:52 2011 New Revision: 176755 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=176755 Log: PR libgomp/45351 * config/osf/sem.h: New file. * configure.tgt (alpha*-dec-osf*): Prepend osf to config_path. Added: trunk/libgomp/config/osf/ trunk/libgomp/config/osf/sem.h Modified: trunk/libgomp/ChangeLog trunk/libgomp/configure.tgt Fixed for 4.7.0. |
I'm not sure if all of these are within libgomp, definitely some are, maybe all. alphaev67-dec-osf5.1 === libgomp tests === Schedule of variations: unix Running target unix Using /home/jayk/share/dejagnu/baseboards/unix.exp as board description file for target. Using /home/jayk/share/dejagnu/config/unix.exp as generic interface file for target. Using /home/jayk/src/gcc-4.5.1/libgomp/testsuite/config/default.exp as tool-and-target-specific interface file. Running /home/jayk/src/gcc-4.5.1/libgomp/testsuite/libgomp.c/c.exp ... Unaligned access pid=152418 <a.15.1.exe> va=0x14000a35e pc=0x3ff80ba63d4 ra=0x3ff80ba63 ... I removed all the pids and addresses and sort | uniq... Unaligned access <a.15.1.exe> Unaligned access <a.16.1.exe> Unaligned access <a.18.1.exe> Unaligned access <a.19.1.exe> Unaligned access <a.2.1.exe> Unaligned access <a.21.1.exe> Unaligned access <a.22.7.exe> Unaligned access <a.22.8.exe> Unaligned access <a.26.1.exe> Unaligned access <a.28.1.exe> Unaligned access <a.28.2.exe> Unaligned access <a.28.3.exe> Unaligned access <a.28.4.exe> Unaligned access <a.29.1.exe> Unaligned access <a.31.4.exe> Unaligned access <a.31.5.exe> Unaligned access <a.36.1.exe> Unaligned access <a.39.1.exe> Unaligned access <a.4.1.exe> Unaligned access <a.5.1.exe> Unaligned access <a10.1.exe> Unaligned access <allocatable1.exe> Unaligned access <allocatable2.exe> Unaligned access <allocatable3.exe> Unaligned access <allocatable4.exe> Unaligned access <allocatable5.exe> Unaligned access <atomic-3.exe> Unaligned access <atomic-4.exe> Unaligned access <atomic-5.exe> Unaligned access <barrier-1.exe> Unaligned access <character1.exe> Unaligned access <character2.exe> Unaligned access <collapse-1.exe> Unaligned access <collapse-2.exe> Unaligned access <collapse-3.exe> Unaligned access <collapse1.exe> Unaligned access <collapse2.exe> Unaligned access <collapse3.exe> Unaligned access <collapse4.exe> Unaligned access <copyin-1.exe> Unaligned access <copyin-2.exe> Unaligned access <copyin-3.exe> Unaligned access <crayptr1.exe> Unaligned access <crayptr2.exe> Unaligned access <critical-1.exe> Unaligned access <critical-2.exe> Unaligned access <ctor-1.exe> Unaligned access <ctor-10.exe> Unaligned access <ctor-11.exe> Unaligned access <ctor-12.exe> Unaligned access <ctor-2.exe> Unaligned access <ctor-3.exe> Unaligned access <ctor-4.exe> Unaligned access <ctor-5.exe> Unaligned access <ctor-6.exe> Unaligned access <ctor-7.exe> Unaligned access <ctor-8.exe> Unaligned access <ctor-9.exe> Unaligned access <debug-1.exe> Unaligned access <do1.exe> Unaligned access <do2.exe> Unaligned access <for-1.exe> Unaligned access <for-2.exe> Unaligned access <for-3.exe> Unaligned access <for-4.exe> Unaligned access <for-5.exe> Unaligned access <for-6.exe> Unaligned access <for-7.exe> Unaligned access <for-8.exe> Unaligned access <icv-1.exe> Unaligned access <jacobi.exe> Unaligned access <lastprivate1.exe> Unaligned access <lastprivate2.exe> Unaligned access <lib-1.exe> Unaligned access <lib-2.exe> Unaligned access <lib1.exe> Unaligned access <lib2.exe> Unaligned access <lib3.exe> Unaligned access <lib4.exe> Unaligned access <lock-1.exe> Unaligned access <lock-2.exe> Unaligned access <loop-1.exe> Unaligned access <loop-10.exe> Unaligned access <loop-11.exe> Unaligned access <loop-12.exe> Unaligned access <loop-2.exe> Unaligned access <loop-3.exe> Unaligned access <loop-4.exe> Unaligned access <loop-5.exe> Unaligned access <loop-6.exe> Unaligned access <loop-7.exe> Unaligned access <loop-8.exe> Unaligned access <loop-9.exe> Unaligned access <master-1.exe> Unaligned access <nested-1.exe> Unaligned access <nested-2.exe> Unaligned access <nested-3.exe> Unaligned access <nested1.exe> Unaligned access <nestedfn-1.exe> Unaligned access <nestedfn-3.exe> Unaligned access <nestedfn-4.exe> Unaligned access <nestedfn-5.exe> Unaligned access <nestedfn-6.exe> Unaligned access <nestedfn1.exe> Unaligned access <nestedfn2.exe> Unaligned access <nestedfn3.exe> Unaligned access <nestedfn4.exe> Unaligned access <nqueens-1.exe> Unaligned access <omp-loop01.exe> Unaligned access <omp-loop02.exe> Unaligned access <omp-loop03.exe> Unaligned access <omp-nested-1.exe> Unaligned access <omp-parallel-for> Unaligned access <omp-parallel-if.> Unaligned access <omp-single-1.exe> Unaligned access <omp-single-2.exe> Unaligned access <omp-single-3.exe> Unaligned access <omp_hello.exe> Unaligned access <omp_matvec.exe> Unaligned access <omp_orphan.exe> Unaligned access <omp_parse1.exe> Unaligned access <omp_parse2.exe> Unaligned access <omp_parse3.exe> Unaligned access <omp_parse4.exe> Unaligned access <omp_reduction.ex> Unaligned access <omp_workshare1.e> Unaligned access <omp_workshare2.e> Unaligned access <omp_workshare4.e> Unaligned access <ordered-1.exe> Unaligned access <ordered-2.exe> Unaligned access <ordered-3.exe> Unaligned access <parallel-1.exe> Unaligned access <pr24455.exe> Unaligned access <pr25162.exe> Unaligned access <pr25219.exe> Unaligned access <pr26691.exe> Unaligned access <pr26943-1.exe> Unaligned access <pr26943-2.exe> Unaligned access <pr26943-3.exe> Unaligned access <pr26943-4.exe> Unaligned access <pr26943.exe> Unaligned access <pr27337.exe> Unaligned access <pr27395-1.exe> Unaligned access <pr27395-2.exe> Unaligned access <pr27416-1.exe> Unaligned access <pr27916-1.exe> Unaligned access <pr27916-2.exe> Unaligned access <pr28390.exe> Unaligned access <pr29629.exe> Unaligned access <pr29947-1.exe> Unaligned access <pr29947-2.exe> Unaligned access <pr30494.exe> Unaligned access <pr30703.exe> Unaligned access <pr32362-1.exe> Unaligned access <pr32362-2.exe> Unaligned access <pr32362-3.exe> Unaligned access <pr32468.exe> Unaligned access <pr32550.exe> Unaligned access <pr33880.exe> Unaligned access <pr34020.exe> Unaligned access <pr34513.exe> Unaligned access <pr35130.exe> Unaligned access <pr35185.exe> Unaligned access <pr35196.exe> Unaligned access <pr35549.exe> Unaligned access <pr35625.exe> Unaligned access <pr36802-1.exe> Unaligned access <pr36802-2.exe> Unaligned access <pr36802-3.exe> Unaligned access <pr38650.exe> Unaligned access <pr39573.exe> Unaligned access <pr39591-1.exe> Unaligned access <pr39591-2.exe> Unaligned access <pr39591-3.exe> Unaligned access <pr42029.exe> Unaligned access <pr42162.exe> Unaligned access <pr42942.exe> Unaligned access <pr43893.exe> Unaligned access <private-1.exe> Unaligned access <recursion1.exe> Unaligned access <reduction-1.exe> Unaligned access <reduction-2.exe> Unaligned access <reduction-3.exe> Unaligned access <reduction-4.exe> Unaligned access <reduction-5.exe> Unaligned access <reduction1.exe> Unaligned access <reduction2.exe> Unaligned access <reduction3.exe> Unaligned access <reduction4.exe> Unaligned access <reduction5.exe> Unaligned access <reduction6.exe> Unaligned access <reference1.exe> Unaligned access <reference2.exe> Unaligned access <retval1.exe> Unaligned access <retval2.exe> Unaligned access <sections-1.exe> Unaligned access <shared-1.exe> Unaligned access <shared-2.exe> Unaligned access <shared-3.exe> Unaligned access <sharing1.exe> Unaligned access <sharing2.exe> Unaligned access <single-1.exe> Unaligned access <single-2.exe> Unaligned access <single-3.exe> Unaligned access <sort-1.exe> Unaligned access <stack.exe> Unaligned access <strassen.exe> Unaligned access <task-1.exe> Unaligned access <task-2.exe> Unaligned access <task-3.exe> Unaligned access <task-4.exe> Unaligned access <task-5.exe> Unaligned access <task-6.exe> Unaligned access <task-7.exe> Unaligned access <task1.exe> Unaligned access <task2.exe> Unaligned access <threadprivate1.e> Unaligned access <threadprivate2.e> Unaligned access <threadprivate3.e> Unaligned access <vla-1.exe> Unaligned access <vla1.exe> Unaligned access <vla2.exe> Unaligned access <vla3.exe> Unaligned access <vla4.exe> Unaligned access <vla5.exe> Unaligned access <vla6.exe> Unaligned access <vla7.exe> Unaligned access <vla8.exe> Unaligned access <workshare1.exe> Unaligned access <workshare2.exe>