[LLVMdev] crash in JIT when running the inliner

[Nuno Lopes]

>> Today I've been trying to debug a weird bug that makes JIT crash with
>> certain code and when using the inliner. This may sound weird, but if I
>> disable the inliner, it doesn't crash.
>> I include an example gdb dump below. Does something looks wrong? Do you
>> think it's a bug in JIT or it's just some other piece of code that is
>> writing on the JIT memory?.. I don't really know how to debug this..
>
> my guess is that the code you are jitting is scribbling over
> memory.

ok, so, my previous code was making bad things, because it was writing the 
bitcode to file after each function translation. The problem is that 
WriteBitcodeToFile() releases the memory and thus the 2nd compilation would 
have pointers to IR that had been already freed.
After fixing this problem in my code, I still get the very same problem: the 
program crashes when I run the inliner. Running valgrind on the program 
without the inliner doesn't show any error. If I run the program with the 
inliner (just uncoment 1 line), valgrind gives a few errors.

Example of one of the errors:

==11384== Invalid read of size 4
==11384==    at 0x54B6F04: llvm::StringMapEntryBase::getKeyLength() const 
(StringMap.h:47)
==11384==    by 0x59C6CFD: llvm::Value::getNameStr() const (Value.cpp:162)
==11384==    by 0x544FE54: llvm::Value::getName() const (Value.h:110)
==11384==    by 0x55E7DA8: (anonymous 
namespace)::JITResolver::JITCompilerFn(void*) (JITEmitter.cpp:269)
==11384==    by 0x54AA47B: X86CompilationCallback2 (X86JITInfo.cpp:350)
==11384==    by 0x54AA0C8: (within 
/usr/local/lib/php/extensions/no-debug-non-zts-20071006/phpllvm.so)
==11384==    by 0x8F74D78: ???
==11384==    by 0x55E15BF: llvm::JIT::runFunction(llvm::Function*, 
std::vector<llvm::GenericValue, std::allocator<llvm::GenericValue> > const&) 
(JIT.cpp:323)
==11384==    by 0x544D9B6: phpllvm::execute(_zend_op_array*) 
(phpllvm_execute.cpp:200)
==11384==    by 0x8FA3365: ???
==11384==    by 0x55E15BF: llvm::JIT::runFunction(llvm::Function*, 
std::vector<llvm::GenericValue, std::allocator<llvm::GenericValue> > const&) 
(JIT.cpp:323)
==11384==    by 0x544D9B6: phpllvm::execute(_zend_op_array*) 
(phpllvm_execute.cpp:200)
==11384==  Address 0x5ec7778 is 0 bytes inside a block of size 32 free'd
==11384==    at 0x402266C: operator delete(void*) (in 
/usr/lib/valgrind/x86-linux/vgpreload_memcheck.so)
==11384==    by 0x54C5034: 
__gnu_cxx::new_allocator<llvm::SDValue>::deallocate(llvm::SDValue*, 
unsigned) (new_allocator.h:96)
==11384==    by 0x54C505E: std::_Vector_base<llvm::SDValue, 
std::allocator<llvm::SDValue> >::_M_deallocate(llvm::SDValue*, unsigned) 
(stl_vector.h:133)
==11384==    by 0x54C5097: std::_Vector_base<llvm::SDValue, 
std::allocator<llvm::SDValue> >::~_Vector_base() (stl_vector.h:119)
==11384==    by 0x54C50F9: std::vector<llvm::SDValue, 
std::allocator<llvm::SDValue> >::~vector() (stl_vector.h:272)
==11384==    by 0x5683471: 
llvm::SelectionDAGLowering::~SelectionDAGLowering() 
(SelectionDAGISel.cpp:496)
==11384==    by 0x567683D: 
llvm::SelectionDAGISel::BuildSelectionDAG(llvm::SelectionDAG&, 
llvm::BasicBlock*, std::vector<std::pair<llvm::MachineInstr*, unsigned>, 
std::allocator<std::pair<llvm::MachineInstr*, unsigned> > >&, 
llvm::FunctionLoweringInfo&) (SelectionDAGISel.cpp:5252)
==11384==    by 0x56768C0: 
llvm::SelectionDAGISel::SelectBasicBlock(llvm::BasicBlock*, 
llvm::MachineFunction&, llvm::FunctionLoweringInfo&, 
std::vector<std::pair<llvm::MachineInstr*, unsigned>, 
std::allocator<std::pair<llvm::MachineInstr*, unsigned> > >&, 
llvm::RecyclingAllocator<llvm::BumpPtrAllocator, llvm::SDNode, 136, 4>&) 
(SelectionDAGISel.cpp:5469)
==11384==    by 0x5676A14: 
llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function&, 
llvm::MachineFunction&, llvm::FunctionLoweringInfo&) 
(SelectionDAGISel.cpp:5452)
==11384==    by 0x5677609: 
llvm::SelectionDAGISel::runOnFunction(llvm::Function&) 
(SelectionDAGISel.cpp:4904)
==11384==    by 0x54C4BCC: (anonymous 
namespace)::X86DAGToDAGISel::runOnFunction(llvm::Function&) 
(X86ISelDAGToDAG.cpp:123)
==11384==    by 0x59A59CF: 
llvm::FPPassManager::runOnFunction(llvm::Function&) (PassManager.cpp:1260)


Does this error makes sense to anyone?

Thanks,
Nuno