[LLVMbugs] [Bug 11400] New: Loop::isLCSSAForm crashes

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11400

             Bug #: 11400
           Summary: Loop::isLCSSAForm crashes
           Product: libraries
           Version: 2.9
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Global Analyses
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: wujingyue at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Created attachment 7626
  --> http://llvm.org/bugs/attachment.cgi?id=7626
a pass that causes the crash

Hi, 

I got a segmentation fault when running the attached pass. I did compile LLVM
with debug+asserts, but I didn't see any assertion failure before the crash. 

dumped stack: 
0  opt             0x0000000000d895c2
1  opt             0x0000000000d893be
2  libpthread.so.0 0x00007f4fa6aa7060
3  opt             0x0000000000b1ef44 void llvm::SmallPtrSet<llvm::BasicBlock*,
16u>::insert<__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > >
>(__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > >,
__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > >) + 34
4  opt             0x0000000000b1e80b llvm::SmallPtrSet<llvm::BasicBlock*,
16u>::SmallPtrSet<__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > >
>(__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > >,
__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > >) + 71
5  opt             0x0000000000b1d879
llvm::Loop::isLCSSAForm(llvm::DominatorTree&) const + 83
6  misc.so         0x00007f4fa5b4f2d7
slicer::IdentifyLoops::process(llvm::Loop*, llvm::Function*) + 71
7  misc.so         0x00007f4fa5b4f3d3
slicer::IdentifyLoops::runOnModule(llvm::Module&) + 211
8  opt             0x0000000000d0aa40
llvm::MPPassManager::runOnModule(llvm::Module&) + 456
9  opt             0x0000000000d0af37 llvm::PassManagerImpl::run(llvm::Module&)
+ 125
10 opt             0x0000000000d0b33f llvm::PassManager::run(llvm::Module&) +
39
11 opt             0x00000000008c242a main + 4339
12 libc.so.6       0x00007f4fa5d7430d __libc_start_main + 237
13 opt             0x00000000008b3089
Stack dump:
0.      Program arguments: opt -load
/home/jingyue/Research/llvm/install/lib/misc.so -identify-loops -disable-output 
1.      Running pass 'Identify loops' on module '<stdin>'.
Segmentation fault

Attaching GDB shows more detailed info: 
Program received signal SIGSEGV, Segmentation fault.
0x0000000000b1ef44 in llvm::SmallPtrSet<llvm::BasicBlock*,
16u>::insert<__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > > >
(this=0x7fffffffd570, I=..., E=...)
    at /home/jingyue/Research/llvm/llvm-2.9/include/llvm/ADT/SmallPtrSet.h:270
270           insert(*I);
(gdb) bt
#0  0x0000000000b1ef44 in llvm::SmallPtrSet<llvm::BasicBlock*,
16u>::insert<__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > > >
(this=0x7fffffffd570, I=..., E=...)
    at /home/jingyue/Research/llvm/llvm-2.9/include/llvm/ADT/SmallPtrSet.h:270
#1  0x0000000000b1e80b in llvm::SmallPtrSet<llvm::BasicBlock*,
16u>::SmallPtrSet<__gnu_cxx::__normal_iterator<llvm::BasicBlock* const*,
std::vector<llvm::BasicBlock*, std::allocator<llvm::BasicBlock*> > > >
(this=0x7fffffffd570, I=..., E=...)
    at /home/jingyue/Research/llvm/llvm-2.9/include/llvm/ADT/SmallPtrSet.h:247
#2  0x0000000000b1d879 in llvm::Loop::isLCSSAForm (this=0x13492c0, DT=...)
    at LoopInfo.cpp:261
#3  0x00007ffff6c772d7 in slicer::IdentifyLoops::process (this=0x134fa10, 
    l=0x13492c0, f=0x133c660) at identify-loops.cpp:42
#4  0x00007ffff6c773d3 in slicer::IdentifyLoops::runOnModule (this=0x134fa10,
M=...)
    at identify-loops.cpp:52
#5  0x0000000000d0aa40 in llvm::MPPassManager::runOnModule (this=0x1337630,
M=...)
    at PassManager.cpp:1557
#6  0x0000000000d0af37 in llvm::PassManagerImpl::run (this=0x13403b0, M=...)
    at PassManager.cpp:1640
#7  0x0000000000d0b33f in llvm::PassManager::run (this=0x7fffffffd930, M=...)
    at PassManager.cpp:1684
#8  0x00000000008c242a in main (argc=5, argv=0x7fffffffdb38) at opt.cpp:689

What's more interesting is that the pass runs fine if I remove Line 41 (in
Function process): 
DT = &getAnalysis<DominatorTree>(*f);

I tried diagnosing this issue more, but didn't get anything more useful due to
my superficial knowledge on LLVM. It would be great if you could take a look.
Thanks much. 

Best,

Jingyue

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