[Bug libgcj/33479] New: SyncTest Intermittent failing on MIPS

[Bug libgcj/33479] New: SyncTest Intermittent failing on MIPS

[daney at gcc dot gnu dot org]

As noted in:
http://gcc.gnu.org/ml/gcc-testresults/2007-09/msg00818.html

With this configuration:

../trunk/configure --prefix=/home/ddaney/gccsvn/trunk-install
--target=mipsel-linux --build=mipsel-linux --host=mipsel-linux
--with-gmp=/home/ddaney/mp --with-mpfr=/home/ddaney/mp --with-arch=sb1
--disable-java-awt --without-x --enable-__cxa_atexit --disable-jvmpi
--disable-static

The SyncTest test fails sometimes.


-- 
           Summary: SyncTest Intermittent failing on MIPS
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgcj
        AssignedTo: daney at gcc dot gnu dot org
        ReportedBy: daney at gcc dot gnu dot org
 GCC build triplet: mipsel-linux-gnu
  GCC host triplet: mipsel-linux-gnu
GCC target triplet: mipsel-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479

[Bug libgcj/33479] SyncTest Intermittent failing on MIPS

[daney at gcc dot gnu dot org]

------- Comment #1 from daney at gcc dot gnu dot org  2007-09-18 18:48 -------
SyncTest never completes.  When it gets into this state the threads are in the
followin state:

(gdb) thread 6
[Switching to thread 6 (Thread 758265024 (LWP 29566))]#0  0x2ce68fac in
pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
(gdb) bt
#0  0x2ce68fac in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x2b7190fc in _Jv_CondWait (cv=0x2cd84e00, mu=0x2cd84de0, 
    millis=<value optimized out>, nanos=0)
    at ../../../trunk/libjava/posix-threads.cc:212
#2  0x2b6f37c8 in gnu::gcj::runtime::FinalizerThread::run (
    this=<value optimized out>)
    at ../../../trunk/libjava/gnu/gcj/runtime/natFinalizerThread.cc:57
#3  0x2b70cb78 in _Jv_ThreadRun (thread=0x2d086f50)
    at ../../../trunk/libjava/java/lang/natThread.cc:335
#4  0x2b718838 in really_start (x=0x2d04bb68)
    at ../../../trunk/libjava/posix-threads.cc:616
#5  0x2c389e18 in GC_start_routine (arg=<value optimized out>)
    at ../../../trunk/boehm-gc/pthread_support.c:1301
#6  0x2ce62130 in start_thread () from /lib/libpthread.so.0
#7  0x2cf9ef48 in ?? () from /lib/libc.so.6
(gdb) thread 5
[Switching to thread 5 (Thread 760362176 (LWP 29567))]#0  0x2cf5d820 in
nanosleep () from /lib/libc.so.6
(gdb) bt
#0  0x2cf5d820 in nanosleep () from /lib/libc.so.6
#1  0x2cf9678c in usleep () from /lib/libc.so.6
#2  0x2b706d28 in wait_unlocked (he=0x2cd861d0)
    at ../../../trunk/libjava/java/lang/natObject.cc:634
#3  0x2b7079a0 in _Jv_MonitorEnter (obj=0x411870)
    at ../../../trunk/libjava/java/lang/natObject.cc:966
#4  0x00401070 in SyncTest.run()void (this=<value optimized out>)
    at SyncTest.java:10
#5  0x2bc40420 in java.lang.Thread.run()void (this=<value optimized out>)
    at /home/ddaney/gccsvn/trunk/libjava/java/lang/Thread.java:755
#6  0x2b70cb78 in _Jv_ThreadRun (thread=0x2d086f00)
    at ../../../trunk/libjava/java/lang/natThread.cc:335
#7  0x2b718838 in really_start (x=0x2d04bb40)
    at ../../../trunk/libjava/posix-threads.cc:616
#8  0x2c389e18 in GC_start_routine (arg=<value optimized out>)
    at ../../../trunk/boehm-gc/pthread_support.c:1301
#9  0x2ce62130 in start_thread () from /lib/libpthread.so.0

(gdb) thread 4
[Switching to thread 4 (Thread 762459328 (LWP 29568))]#0  0x2cf5d820 in
nanosleep () from /lib/libc.so.6
(gdb) bt
#0  0x2cf5d820 in nanosleep () from /lib/libc.so.6
#1  0x2cf9678c in usleep () from /lib/libc.so.6
#2  0x2b706d28 in wait_unlocked (he=0x2cd861d0)
    at ../../../trunk/libjava/java/lang/natObject.cc:634
#3  0x2b7079a0 in _Jv_MonitorEnter (obj=0x411870)
    at ../../../trunk/libjava/java/lang/natObject.cc:966
#4  0x00401070 in SyncTest.run()void (this=<value optimized out>)
    at SyncTest.java:10
#5  0x2bc40420 in java.lang.Thread.run()void (this=<value optimized out>)
    at /home/ddaney/gccsvn/trunk/libjava/java/lang/Thread.java:755
#6  0x2b70cb78 in _Jv_ThreadRun (thread=0x2d086eb0)
    at ../../../trunk/libjava/java/lang/natThread.cc:335
#7  0x2b718838 in really_start (x=0x2d04bb38)
    at ../../../trunk/libjava/posix-threads.cc:616
#8  0x2c389e18 in GC_start_routine (arg=<value optimized out>)
    at ../../../trunk/boehm-gc/pthread_support.c:1301
#9  0x2ce62130 in start_thread () from /lib/libpthread.so.0

(gdb) thread 3
[Switching to thread 3 (Thread 764556480 (LWP 29569))]#0  0x2cf5d820 in
nanosleep () from /lib/libc.so.6
(gdb) bt
#0  0x2cf5d820 in nanosleep () from /lib/libc.so.6
#1  0x2cf9678c in usleep () from /lib/libc.so.6
#2  0x2b706d28 in wait_unlocked (he=0x2cd861d0)
    at ../../../trunk/libjava/java/lang/natObject.cc:634
#3  0x2b7079a0 in _Jv_MonitorEnter (obj=0x411870)
    at ../../../trunk/libjava/java/lang/natObject.cc:966
#4  0x00401070 in SyncTest.run()void (this=<value optimized out>)
    at SyncTest.java:10
#5  0x2bc40420 in java.lang.Thread.run()void (this=<value optimized out>)
    at /home/ddaney/gccsvn/trunk/libjava/java/lang/Thread.java:755
#6  0x2b70cb78 in _Jv_ThreadRun (thread=0x2d086e60)
    at ../../../trunk/libjava/java/lang/natThread.cc:335
#7  0x2b718838 in really_start (x=0x2d04bb30)
    at ../../../trunk/libjava/posix-threads.cc:616
#8  0x2c389e18 in GC_start_routine (arg=<value optimized out>)
    at ../../../trunk/boehm-gc/pthread_support.c:1301
#9  0x2ce62130 in start_thread () from /lib/libpthread.so.0

(gdb) thread 2
[Switching to thread 2 (Thread 766653632 (LWP 29570))]#0  0x2cf5d820 in
nanosleep () from /lib/libc.so.6
(gdb) bt
#0  0x2cf5d820 in nanosleep () from /lib/libc.so.6
#1  0x2cf9678c in usleep () from /lib/libc.so.6
#2  0x2b706d28 in wait_unlocked (he=0x2cd861d0)
    at ../../../trunk/libjava/java/lang/natObject.cc:634
#3  0x2b7079a0 in _Jv_MonitorEnter (obj=0x411870)
    at ../../../trunk/libjava/java/lang/natObject.cc:966
#4  0x00401070 in SyncTest.run()void (this=<value optimized out>)
    at SyncTest.java:10
#5  0x2bc40420 in java.lang.Thread.run()void (this=<value optimized out>)
    at /home/ddaney/gccsvn/trunk/libjava/java/lang/Thread.java:755
#6  0x2b70cb78 in _Jv_ThreadRun (thread=0x2d086e10)
    at ../../../trunk/libjava/java/lang/natThread.cc:335
#7  0x2b718838 in really_start (x=0x2d04bb28)
    at ../../../trunk/libjava/posix-threads.cc:616
#8  0x2c389e18 in GC_start_routine (arg=<value optimized out>)
    at ../../../trunk/boehm-gc/pthread_support.c:1301
#9  0x2ce62130 in start_thread () from /lib/libpthread.so.0

(gdb) thread 1
[Switching to thread 1 (Thread 755130368 (LWP 29565))]#0  0x2ce68fac in
pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
(gdb) bt
#0  0x2ce68fac in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x2b7190fc in _Jv_CondWait (cv=0x2d078c24, mu=0x2d078c04, 
    millis=<value optimized out>, nanos=0)
    at ../../../trunk/libjava/posix-threads.cc:212
#2  0x2b70ce94 in java::lang::Thread::join (this=0x2d086f00, millis=0, nanos=0)
    at ../../../trunk/libjava/java/lang/natThread.cc:160
#3  0x2bc40374 in java.lang.Thread.join()void (this=0x2d078c24)
    at /home/ddaney/gccsvn/trunk/libjava/java/lang/Thread.java:677
#4  0x00401268 in SyncTest.main(java.lang.String[])void (
    args=<value optimized out>) at SyncTest.java:26
#5  0x2b6f5304 in gnu::java::lang::MainThread::call_main (this=0x2d11ef60)
    at ../../../trunk/libjava/gnu/java/lang/natMainThread.cc:54
#6  0x2b70cb78 in _Jv_ThreadRun (thread=0x2d11ef60)
    at ../../../trunk/libjava/java/lang/natThread.cc:335
#7  0x2b6acb5c in _Jv_RunMain (vm_args=<value optimized out>, klass=0x411870, 
    name=0x0, argc=<value optimized out>, argv=0x7fc39b24, is_jar=false)
    at ../../../trunk/libjava/prims.cc:1789
#8  0x2b6acd54 in _Jv_RunMain (klass=0x2d026000, 
    name=0xa <Address 0xa out of bounds>, argc=0, argv=<value optimized out>, 
    is_jar=false) at ../../../trunk/libjava/prims.cc:1814
#9  0x2b6acde4 in JvRunMain (klass=0x2d078c24, argc=755130368, argv=0x7fc39b24)
    at ../../../trunk/libjava/prims.cc:1820
#10 0x2cecb2e0 in __libc_start_main () from /lib/libc.so.6


-- 

daney at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-09-18 18:48:53
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479

[Bug libgcj/33479] SyncTest Intermittent failing on MIPS

[Hans dot Boehm at hp dot com]

------- Comment #2 from Hans dot Boehm at hp dot com  2007-09-18 22:26 -------
I assume the LOCKED bit in *he is actually set when gdb looks at it?  What does
the rest of the hash entry look like?  That might give you a hint as to the
culprit.

Clearly someone sets the LOCKED bit on a hash entry and neglects to clear it. 
If a compare_and_swap succeeded but returned failure anyway, that might explain
it.  A misimplementation of release_set might also cause the problem.  I don't
immediately see how this can be explained by a memory ordering issue.


-- 

Hans dot Boehm at hp dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Hans dot Boehm at hp dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479

[Bug libgcj/33479] SyncTest Intermittent failing on MIPS

[daney at gcc dot gnu dot org]

------- Comment #3 from daney at gcc dot gnu dot org  2007-09-18 23:35 -------
The LOCKED bit is set.  All the other fields in the hash entry are zero.

I think adding a memory barrier at the end of compare_and_swap fixes the
problem.

Currently I have:

inline static bool
compare_and_swap(volatile obj_addr_t *addr,
                 obj_addr_t old,
                 obj_addr_t new_val)
{
  bool b = __sync_bool_compare_and_swap(addr, old, new_val);
  __sync_synchronize();
  return b;
}

inline static bool
compare_and_swap_release(volatile obj_addr_t *addr,
                         obj_addr_t old,
                         obj_addr_t new_val)
{
  return __sync_bool_compare_and_swap(addr, old, new_val);
}

I would have thought that the 'sc' instruction emitted by
__sync_bool_compare_and_swap made the swap visible to other CPUs, but it
appears that the 'sync' emitted by __sync_synchronize() is required.  Hmm.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479

[Bug libgcj/33479] SyncTest Intermittent failing on MIPS

[daney at gcc dot gnu dot org]

------- Comment #4 from daney at gcc dot gnu dot org  2007-09-20 07:03 -------
Created an attachment (id=14227)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14227&action=view)
Proposed patch.

I am testing this patch.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479

[Bug target/33479] SyncTest Intermittent failing on MIPS

[daney at gcc dot gnu dot org]

------- Comment #5 from daney at gcc dot gnu dot org  2007-09-26 16:45 -------
Subject: Bug 33479

Author: daney
Date: Wed Sep 26 16:45:39 2007
New Revision: 128821

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=128821
Log:
2007-09-26  David Daney  <ddaney@avtrex.com>

        PR target/33479
        * config/mips/mips.md (sync_compare_and_swap<mode>, sync_old_add<mode>,
        sync_new_add<mode>, sync_old_<optab><mode>, sync_new_<optab><mode>,
        sync_old_nand<mode>, sync_new_nand<mode>,
        sync_lock_test_and_set<mode>): Fix '&' constraint modifiers.
        Update length attributes.
        (sync_add<mode>, sync_sub<mode>, sync_old_sub<mode>,
        sync_new_sub<mode>, sync_<optab><mode>, sync_nand<mode>): Update
        length attributes.
        * config/mips/mips.h (MIPS_COMPARE_AND_SWAP, MIPS_SYNC_OP,
        MIPS_SYNC_OLD_OP, MIPS_SYNC_NEW_OP, MIPS_SYNC_NAND,
        MIPS_SYNC_OLD_NAND, MIPS_SYNC_NEW_NAND, MIPS_SYNC_EXCHANGE): Add
        post-loop sync.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/mips/mips.h
    trunk/gcc/config/mips/mips.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479

[Bug target/33479] SyncTest Intermittent failing on MIPS

[daney at gcc dot gnu dot org]

------- Comment #6 from daney at gcc dot gnu dot org  2007-09-27 15:53 -------
Fixed now.


-- 

daney at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33479