https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61538
--- Comment #3 from Joshua Kinard <kumba at gentoo dot org> ---
(In reply to Jonathan Wakely from comment #2)
> Can you provide a stack trace to show which constructor/destructor it's
> hanging in?
Hopefully you mean a backtrace from gdb. Not finding a lot of info on doing a
C++ stacktrace (I haven't messed with C++ in years).
The testcase isn't stripped and has debugging info, but glibc-2.19, and
gcc-4.8.2 are stripped and built w/o debugging, so the backtrace doesn't
provide a lot of info. I might be able to rebuild them w/ debugging, but gcc
takes almost 13+ hours on the Octane to build, while glibc takes another 3-4.
First, here is what strace shows:
set_tid_address(0x7797f2e8) = 2532
set_robust_list(0x7797f2f0, 12) = 0
futex(0x7fb06690, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fb06690, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, NULL, 0) =
-1 EINVAL (Invalid argument)
rt_sigaction(SIGRT_0, {0x8, [],
SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_NOCLDWAIT|0x7921a94}, NULL, 16) = 0
rt_sigaction(SIGRT_1, {0x10000008, [],
SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_SIGINFO|SA_NOCLDWAIT|0x7921940}, NULL,
16) = 0
rt_sigprocmask(SIG_UNBLOCK, [RT_0 RT_1], NULL, 16) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=2147483647}) = 0
syscall(0x108e, 0x77929500, 0, 0, 0, 0, 0x77929160) = -1 EAGAIN (Resource
temporarily unavailable)
syscall(0x108e, 0x77929500, 0, 0x10100, 0, 0, 0x77929160
That last line is where you see it hanging until I send ctrl+c, with the first
argument to both being 0x108e (4238 in decimal, I typoed it as '4328' in my
original post), which is a futex call, per mips-o32-linux.xml in GDB:
<syscall name="futex" number="4238"/>
Running in GDB, setting a catchpoint on syscall 4238 and upping the
heuristic-fence-post limit a fair bit to quiet some warnings down:
This first catchpoint doesn't hang:
¦0x77f9dc1c <__pthread_initialize_minimal_internal+148> addiu a0,s8,32
¦0x77f9dc20 <__pthread_initialize_minimal_internal+152> li a1,129
¦0x77f9dc24 <__pthread_initialize_minimal_internal+156> li a2,1
¦0x77f9dc28 <__pthread_initialize_minimal_internal+160> li v0,4238
¦0x77f9dc2c <__pthread_initialize_minimal_internal+164> syscall
>¦0x77f9dc30 <__pthread_initialize_minimal_internal+168> bnez a3,0x77f9df9c
><__pthread_initialize_minimal_internal+1044>
Catchpoint 1 (call to syscall 4238), 0x77f9dc30 in
__pthread_initialize_minimal_internal () from /lib/libpthread.so.0
(gdb) thread apply all bt
Thread 1 (process 2584):
#0 0x77f9dc30 in __pthread_initialize_minimal_internal () from
/lib/libpthread.so.0
#1 0x77f9c5a4 in _init () from /lib/libpthread.so.0
Cannot access memory at address 0x77fc3ffe
Here's the second catchpoint for syscall #4238:
¦0x77f9dc64 <__pthread_initialize_minimal_internal+220> addiu sp,sp,-32
¦0x77f9dc68 <__pthread_initialize_minimal_internal+224> sw v0,16(sp)
¦0x77f9dc6c <__pthread_initialize_minimal_internal+228> li v0,4238
¦0x77f9dc70 <__pthread_initialize_minimal_internal+232> syscall
>¦0x77f9dc74 <__pthread_initialize_minimal_internal+236> addiu sp,sp,32
Catchpoint 1 (call to syscall 4238), 0x77f9dc74 in
__pthread_initialize_minimal_internal () from /lib/libpthread.so.0
(gdb) thread apply all bt
Thread 1 (process 2584):
#0 0x77f9dc74 in __pthread_initialize_minimal_internal () from
/lib/libpthread.so.0
#1 0x77f9c5a4 in _init () from /lib/libpthread.so.0
Cannot access memory at address 0x77fc3ffe
After I type continue again, it hangs until interrupted:
(gdb) c
Continuing.
<HANGS HERE>
Program received signal SIGINT, Interrupt.
0x77d50864 in syscall () from /lib/libc.so.6
(gdb) thread apply all bt
Thread 1 (Thread 0x77feb000 (LWP 2591)):
#0 0x77d50864 in syscall () from /lib/libc.so.6
#1 0x77ed9160 in __cxa_guard_acquire () from
/usr/lib/gcc/mips-unknown-linux-gnu/4.8.2/libstdc++.so.6
#2 0x77f4325c in std::future_category() () from
/usr/lib/gcc/mips-unknown-linux-gnu/4.8.2/libstdc++.so.6
#3 0x77ed406c in ?? () from
/usr/lib/gcc/mips-unknown-linux-gnu/4.8.2/libstdc++.so.6
Cannot access memory at address 0x77fc3ffe
(gdb)
