My nightly test last night was stalled by the PassManager incurring an exception
in operator delete that caused an abort that went into a deadlock. 

The test case is llvm/test/CFrontend/2004-02-13-IllegalVararg.c.tr which is:
// RUN: %llvmgcc -xc %s -c -o - | llc

#include <stdarg.h>

float test(int X, ...) {
  va_list ap;
  float F;
  va_start(ap, X);
  F = va_arg(ap, float);
  return F;
}

During compilation of this, llvm-gcc warned about the following:

/proj/llvm/nightly/build/llvm/test/CFrontend/2004-02-13-IllegalVararg.c.tr: In
function 'test':
/proj/llvm/nightly/build/llvm/test/CFrontend/2004-02-13-IllegalVararg.c.tr:9:
warning: 'float' is promoted to 'double' when passed through '...'
/proj/llvm/nightly/build/llvm/test/CFrontend/2004-02-13-IllegalVararg.c.tr:9:
warning: (so you should pass 'double' not 'float' to 'va_arg')
/proj/llvm/nightly/build/llvm/test/CFrontend/2004-02-13-IllegalVararg.c.tr:9:
note: if this code is reached, the program will abort

When llc tried to compile llvm-gcc's output, the program goes into a deadlock
when PMTopLevelMgr's map is destructed. During destruction of one of the map's
nodes the libc free() method generated this error:

*** glibc detected *** llc: double free or corruption (!prev): 0x098e3938 ***

The stack looks like this:

#0  0x00bfd402 in __kernel_vsyscall ()
#1  0x003cecce in __lll_mutex_lock_wait () from /lib/libc.so.6
#2  0x003614e8 in _L_lock_43 () from /lib/libc.so.6
#3  0x0035b35d in ptmalloc_lock_all () from /lib/libc.so.6
#4  0x003849e0 in fork () from /lib/libc.so.6
#5  0x0059bad0 in fork () from /lib/libpthread.so.0
#6  0x0888b952 in (anonymous namespace)::PrintStackTrace () at Unix/Signals.inc:78
#7  0x0888bc3e in (anonymous namespace)::SignalHandler (Sig=6) at
Unix/Signals.inc:139
#8  <signal handler called>
#9  0x00bfd402 in __kernel_vsyscall ()
#10 0x00321ee9 in raise () from /lib/libc.so.6
#11 0x003234f1 in abort () from /lib/libc.so.6
#12 0x0035653b in __libc_message () from /lib/libc.so.6
#13 0x0035da68 in _int_free () from /lib/libc.so.6
#14 0x00360f6f in free () from /lib/libc.so.6
#15 0x001bf3e1 in operator delete (ptr=0x98e3938) at
../../../../svn-4.0.3/libstdc++-v3/libsupc++/del_op.cc:49
#16 0x088276eb in
__gnu_cxx::new_allocator<std::_Rb_tree_node<std::pair<llvm::Pass* const,
llvm::Pass*> > >::deallocate (this=0x98e2550,
    __p=0x98e3938) at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/ext/new_allocator.h:94
#17 0x08827710 in std::_Rb_tree<llvm::Pass*, std::pair<llvm::Pass* const,
llvm::Pass*>, std::_Select1st<std::pair<llvm::Pass* const, llvm::Pass*> >,
std::less<llvm::Pass*>, std::allocator<std::pair<llvm::Pass* const, llvm::Pass*>
> >::_M_put_node (this=0x98e2550,
    __p=0x98e3938) at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/stl_tree.h:360
#18 0x08827760 in std::_Rb_tree<llvm::Pass*, std::pair<llvm::Pass* const,
llvm::Pass*>, std::_Select1st<std::pair<llvm::Pass* const, llvm::Pass*> >,
std::less<llvm::Pass*>, std::allocator<std::pair<llvm::Pass* const, llvm::Pass*>
> >::destroy_node (this=0x98e2550,
    __p=0x98e3938) at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/stl_tree.h:390
#19 0x088277a8 in std::_Rb_tree<llvm::Pass*, std::pair<llvm::Pass* const,
llvm::Pass*>, std::_Select1st<std::pair<llvm::Pass* const, llvm::Pass*> >,
std::less<llvm::Pass*>, std::allocator<std::pair<llvm::Pass* const, llvm::Pass*>
> >::_M_erase (this=0x98e2550, __x=0x98e3938)
    at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/stl_tree.h:1097
#20 0x08827788 in std::_Rb_tree<llvm::Pass*, std::pair<llvm::Pass* const,
llvm::Pass*>, std::_Select1st<std::pair<llvm::Pass* const, llvm::Pass*> >,
std::less<llvm::Pass*>, std::allocator<std::pair<llvm::Pass* const, llvm::Pass*>
> >::_M_erase (this=0x98e2550, __x=0x98e2120)
    at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/stl_tree.h:1095
#21 0x088277d6 in ~_Rb_tree (this=0x98e2550)
    at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/stl_tree.h:571
#22 0x088277f5 in ~map (this=0x98e2550) at
/proj/install/lib/gcc/i686-pc-linux-gnu/4.0.3/../../../../include/c++/4.0.3/bits/stl_map.h:92
#23 0x0882158e in ~PMTopLevelManager (this=0x98e250c) at PassManager.cpp:498
#24 0x0882926e in ~FunctionPassManagerImpl (this=0x98e24b8) at PassManager.cpp:116
#25 0x0881f7ff in ~FunctionPassManager (this=0xbff8e224) at PassManager.cpp:867
#26 0x083b3083 in main (argc=1, argv=0xbff8e314) at llc.cpp:292

As this occurs on destruction, llc managed to produce this output anyway:


.text
        .align  16
        .globl  test
        .type test,@function
test:
        subl $24, %esp
        movl 28(%esp), %eax
        movl %eax, 20(%esp)
        leal 32(%esp), %eax
        movl %eax, 8(%esp)
        movss 0, %xmm0
        movss %xmm0, 4(%esp)
        movss %xmm0, 12(%esp)
        movss %xmm0, 16(%esp)
.LBB1_1:        #return
        movss 16(%esp), %xmm0
        movss %xmm0, (%esp)
        flds (%esp)
        addl $24, %esp
        ret
        .size test, .-test