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Christian Schafmeister

2013-Oct-14 05:51 UTC

[LLVMdev] A weird, reproducable problem with MCJIT

I switched my Common Lisp compiler to use MCJIT on the weekend and ran
into a weird problem compiling one particular function.

It crashes with an EXC_BAD_ACCESS error in MCJIT::finalizeObject when
calling processFDE.

The weird part is that the function does not appear to do anything
special and I've whittled it down to
the minimum size that still causes the crash. If I remove even one
statement it compiles fine.  Note: The function doesn't make much sense
anymore but it does compile fine.
It does have a lot of nested scopes.

I can single step through processFDE and I see it pulls up a Length in
processFDE of 1 and then a length of 16#1000000  - clearly something has
been corrupted.
   
Here is the top of the backtrace from lldb:
----------------------
* thread #1: tid = 0x557509, 0x0000000107e6e066
libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 134 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35,
stop reason = EXC_BAD_ACCESS (code=2, address=0x1102adad1)
    frame #0: 0x0000000107e6e066 libLLVM-3.4svn.dylib`llvm::processFDE(unsigned
char*, long, long) + 134 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35
    frame #1: 0x0000000107e6df04
libLLVM-3.4svn.dylib`llvm::RuntimeDyldMachO::registerEHFrames() + 356 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
    frame #2: 0x0000000107e36f39
libLLVM-3.4svn.dylib`llvm::RuntimeDyld::registerEHFrames() + 25 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp:595
    frame #3: 0x0000000107aca9c7
libLLVM-3.4svn.dylib`llvm::MCJIT::finalizeObject() + 775 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp:226
    frame #4: 0x0000000103da55d3
libllvmo_dbg.dylib`llvmo::ExecutionEngine_O::getCompiledFunction(mem::smart_ptr<core::Symbol_O>,
mem::smart_ptr<llvmo::Function_O>,
mem::smart_ptr<core::ActivationFrame_O>,
mem::smart_ptr<core::Symbol_O>) + 115 at
/Users/meister/Development/cando/brcl/src/llvmo/../../src/llvmo/llvmoExpose.cc:811


Here is the function that causes the crash (it's Common Lisp and all
macros have been expanded).

(defun match-dimensions (array pat)
  (let ((zzz (eq pat '*)))
    (if zzz
	zzz
	(let ((rank (array-rank array) ))
	  (if (listp pat)
	      (BLOCK NIL
		(LET* (
		       (%DOTIMES-VAR 100)
		       (I 0)
		       )
		  (TAGBODY
		     (GO bot)
		   top
		     (if (not t) (progn))
		     (SETQ PAT (CDR PAT))
		     (SETQ I (1+ I))
		   bot
		     (if (< I %DOTIMES-VAR) (GO top))
		     ) 
		  (NULL PAT))))))))



The LLVM-IR file generated by compiling this function definition is
here: https://dl.dropboxusercontent.com/u/6229900/broken.ll

Any suggestions or pointers on how to debug this are welcome.

Kaylor, Andrew

2013-Oct-14 17:18 UTC

head link

[LLVMdev] A weird, reproducable problem with MCJIT

Hi Christian,

Thanks for sharing this.

Yaron Keren has been investigating some problems in the EH frame registration
code recently, and I think this may be related.  It at least sounds similar to
the type of variations in behavior based on code size that Yaron was seeing.

-Andy

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Christian Schafmeister
Sent: Sunday, October 13, 2013 10:52 PM
To: llvmdev at cs.uiuc.edu
Subject: [LLVMdev] A weird, reproducable problem with MCJIT


I switched my Common Lisp compiler to use MCJIT on the weekend and ran into a
weird problem compiling one particular function.

It crashes with an EXC_BAD_ACCESS error in MCJIT::finalizeObject when calling
processFDE.

The weird part is that the function does not appear to do anything special and
I've whittled it down to the minimum size that still causes the crash. If I
remove even one statement it compiles fine.  Note: The function doesn't make
much sense anymore but it does compile fine.
It does have a lot of nested scopes.

I can single step through processFDE and I see it pulls up a Length in
processFDE of 1 and then a length of 16#1000000  - clearly something has been
corrupted.
   
Here is the top of the backtrace from lldb:
----------------------
* thread #1: tid = 0x557509, 0x0000000107e6e066
libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 134 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35,
stop reason = EXC_BAD_ACCESS (code=2, address=0x1102adad1)
    frame #0: 0x0000000107e6e066 libLLVM-3.4svn.dylib`llvm::processFDE(unsigned
char*, long, long) + 134 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35
    frame #1: 0x0000000107e6df04
libLLVM-3.4svn.dylib`llvm::RuntimeDyldMachO::registerEHFrames() + 356 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
    frame #2: 0x0000000107e36f39
libLLVM-3.4svn.dylib`llvm::RuntimeDyld::registerEHFrames() + 25 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp:595
    frame #3: 0x0000000107aca9c7
libLLVM-3.4svn.dylib`llvm::MCJIT::finalizeObject() + 775 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp:226
    frame #4: 0x0000000103da55d3
libllvmo_dbg.dylib`llvmo::ExecutionEngine_O::getCompiledFunction(mem::smart_ptr<core::Symbol_O>,
mem::smart_ptr<llvmo::Function_O>,
mem::smart_ptr<core::ActivationFrame_O>,
mem::smart_ptr<core::Symbol_O>) + 115 at
/Users/meister/Development/cando/brcl/src/llvmo/../../src/llvmo/llvmoExpose.cc:811


Here is the function that causes the crash (it's Common Lisp and all macros
have been expanded).

(defun match-dimensions (array pat)
  (let ((zzz (eq pat '*)))
    (if zzz
	zzz
	(let ((rank (array-rank array) ))
	  (if (listp pat)
	      (BLOCK NIL
		(LET* (
		       (%DOTIMES-VAR 100)
		       (I 0)
		       )
		  (TAGBODY
		     (GO bot)
		   top
		     (if (not t) (progn))
		     (SETQ PAT (CDR PAT))
		     (SETQ I (1+ I))
		   bot
		     (if (< I %DOTIMES-VAR) (GO top))
		     ) 
		  (NULL PAT))))))))



The LLVM-IR file generated by compiling this function definition is
here: https://dl.dropboxusercontent.com/u/6229900/broken.ll

Any suggestions or pointers on how to debug this are welcome.

_______________________________________________
LLVM Developers mailing list
LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Yaron Keren

2013-Oct-14 18:36 UTC

head link

[LLVMdev] A weird, reproducable problem with MCJIT

Hi,

I had similar problems with EH in ELF in
RTDyldMemoryManager::registerEHFrames() calling __register_frame().

I'm not sure these problems are related to this problem since your crash
happens in  RuntimeDyldMachO::registerEHFrames() in its own processFDE
(there are two functions named processFDE(), one in
RuntimeDyldMachO.cpp and one in RTDyldMemoryManager.cpp)  *before*
RTDyldMemoryManager::registerEHFrames()
and __register_frame() are called.

It would seem that even if  RTDyldMemoryManager::registerEHFrames() and
__register_frame() got problematic input (as with the ELF dyn. linker) it
should not cause a crash in the calling code but either a malfunction of
exceptions or crash in RTDyldMemoryManager::registerEHFrames() /
__register_frame(). A crash like the one you see should be related
to RuntimeDyldMachO::registerEHFrames() inputs only.

Yaron



2013/10/14 Kaylor, Andrew <andrew.kaylor at intel.com>
> Hi Christian,
>
> Thanks for sharing this.
>
> Yaron Keren has been investigating some problems in the EH frame
> registration code recently, and I think this may be related.  It at least
> sounds similar to the type of variations in behavior based on code size
> that Yaron was seeing.
>
> -Andy
>
> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu] On
> Behalf Of Christian Schafmeister
> Sent: Sunday, October 13, 2013 10:52 PM
> To: llvmdev at cs.uiuc.edu
> Subject: [LLVMdev] A weird, reproducable problem with MCJIT
>
>
> I switched my Common Lisp compiler to use MCJIT on the weekend and ran
> into a weird problem compiling one particular function.
>
> It crashes with an EXC_BAD_ACCESS error in MCJIT::finalizeObject when
> calling processFDE.
>
> The weird part is that the function does not appear to do anything special
> and I've whittled it down to the minimum size that still causes the
crash.
> If I remove even one statement it compiles fine.  Note: The function
> doesn't make much sense anymore but it does compile fine.
> It does have a lot of nested scopes.
>
> I can single step through processFDE and I see it pulls up a Length in
> processFDE of 1 and then a length of 16#1000000  - clearly something has
> been corrupted.
>
> Here is the top of the backtrace from lldb:
> ----------------------
> * thread #1: tid = 0x557509, 0x0000000107e6e066
> libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 134 at
>
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35,
> stop reason = EXC_BAD_ACCESS (code=2, address=0x1102adad1)
>     frame #0: 0x0000000107e6e066
> libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 134 at
>
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35
>     frame #1: 0x0000000107e6df04
> libLLVM-3.4svn.dylib`llvm::RuntimeDyldMachO::registerEHFrames() + 356 at
>
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
>     frame #2: 0x0000000107e36f39
> libLLVM-3.4svn.dylib`llvm::RuntimeDyld::registerEHFrames() + 25 at
>
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp:595
>     frame #3: 0x0000000107aca9c7
> libLLVM-3.4svn.dylib`llvm::MCJIT::finalizeObject() + 775 at
>
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp:226
>     frame #4: 0x0000000103da55d3
>
libllvmo_dbg.dylib`llvmo::ExecutionEngine_O::getCompiledFunction(mem::smart_ptr<core::Symbol_O>,
> mem::smart_ptr<llvmo::Function_O>,
mem::smart_ptr<core::ActivationFrame_O>,
> mem::smart_ptr<core::Symbol_O>) + 115 at
>
/Users/meister/Development/cando/brcl/src/llvmo/../../src/llvmo/llvmoExpose.cc:811
>
>
> Here is the function that causes the crash (it's Common Lisp and all
> macros have been expanded).
>
> (defun match-dimensions (array pat)
>   (let ((zzz (eq pat '*)))
>     (if zzz
>         zzz
>         (let ((rank (array-rank array) ))
>           (if (listp pat)
>               (BLOCK NIL
>                 (LET* (
>                        (%DOTIMES-VAR 100)
>                        (I 0)
>                        )
>                   (TAGBODY
>                      (GO bot)
>                    top
>                      (if (not t) (progn))
>                      (SETQ PAT (CDR PAT))
>                      (SETQ I (1+ I))
>                    bot
>                      (if (< I %DOTIMES-VAR) (GO top))
>                      )
>                   (NULL PAT))))))))
>
>
>
> The LLVM-IR file generated by compiling this function definition is
> here: https://dl.dropboxusercontent.com/u/6229900/broken.ll
>
> Any suggestions or pointers on how to debug this are welcome.
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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Christian Schafmeister

2013-Oct-14 18:53 UTC

head link

[LLVMdev] A weird, reproducable problem with MCJIT

Andrew,

Thanks for following up.  
Some people on IRC suggested that perhaps my BasicBlocks that contain
only an "unreachable" IR instruction were being removed and two
BasicBlock labels were getting the same address.   I inserted a "call
@unreachableError()" instruction before every "unreachable"
instruction
that I generated and that caused the function below to compile fine but
another function now exhibits the same crash.

It seems very sensitive to the size of something within the function.

Another thing.   When processFDE get's called I inserted printf
statements to print the lengths of the FDE's.  Here's what it looks like
when everything compiles and finalizeObject doesn't crash:

"/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
In registerEHFrames  P = 0x10975ec20
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 28/1c
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 68/44
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 44/2c
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 68/44
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 68/44
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 68/44
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 52/34
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 20/14
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 28/1c
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 28/1c
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 44/2c
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 36/24
"Loading bitcode file:
/Users/meister/Development/cando/brcl/src/lisp/kernel/lsp/setf.bc
"/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
In registerEHFrames  P = 0x231875000
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 28/1c
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 68/44
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 44/2c
... and so on


Here's what it looks like when it crashes:
""               In environment: COMMON-LISP:NIL
"/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
In registerEHFrames  P = 0x27ddf71b8
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 1/1
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 16777216/1000000
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 17267682/1077be2
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:26
processFDE Length = 1515870810/5a5a5a5a
Process 85800 stopped
* thread #1: tid = 0x59640d, 0x0000000106627f2c
libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 44 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:25,
stop reason = EXC_BAD_ACCESS (code=1, address=0x2da414805)
    frame #0: 0x0000000106627f2c libLLVM-3.4svn.dylib`llvm::processFDE(unsigned
char*, long, long) + 44 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:25
   22  	namespace llvm {
   23  	
   24  	static unsigned char *processFDE(unsigned char *P, intptr_t
DeltaForText, intptr_t DeltaForEH) {
-> 25  	  uint32_t Length = *((uint32_t*)P);
   26  	  printf("%s:%d processFDE Length = %u/%x\n", __FILE__,
__LINE__, Length, Length);
   27  	  P += 4;
   28  	  unsigned char *Ret = P + Length;


Notice that the "Length" field of the very first FDE is 1 byte long
which is crazy - after that it it crashes.

I'm trying to track down where the FDE entries are created - I don't
know the code well at all.

I can run any other tests you suggest.  This problem is reproducable.

Best,

.Chris.




"Kaylor, Andrew" <andrew.kaylor at intel.com> writes:
> Hi Christian,
>
> Thanks for sharing this.
>
> Yaron Keren has been investigating some problems in the EH frame
> registration code recently, and I think this may be related.  It at
> least sounds similar to the type of variations in behavior based on
> code size that Yaron was seeing.
>
> -Andy
>
> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu] On Behalf Of Christian Schafmeister
> Sent: Sunday, October 13, 2013 10:52 PM
> To: llvmdev at cs.uiuc.edu
> Subject: [LLVMdev] A weird, reproducable problem with MCJIT
>
>
> I switched my Common Lisp compiler to use MCJIT on the weekend and ran into
a weird problem compiling one particular function.
>
> It crashes with an EXC_BAD_ACCESS error in MCJIT::finalizeObject when
calling processFDE.
>
> The weird part is that the function does not appear to do anything special
and I've whittled it down to the minimum size that still causes the crash.
If I remove even one statement it compiles fine.  Note: The function doesn't
make much sense anymore but it does compile fine.
> It does have a lot of nested scopes.
>
> I can single step through processFDE and I see it pulls up a Length in
processFDE of 1 and then a length of 16#1000000  - clearly something has been
corrupted.
>    
> Here is the top of the backtrace from lldb:
> ----------------------
> * thread #1: tid = 0x557509, 0x0000000107e6e066
libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 134 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35,
stop reason = EXC_BAD_ACCESS (code=2, address=0x1102adad1)
>     frame #0: 0x0000000107e6e066
libLLVM-3.4svn.dylib`llvm::processFDE(unsigned char*, long, long) + 134 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:35
>     frame #1: 0x0000000107e6df04
libLLVM-3.4svn.dylib`llvm::RuntimeDyldMachO::registerEHFrames() + 356 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp:81
>     frame #2: 0x0000000107e36f39
libLLVM-3.4svn.dylib`llvm::RuntimeDyld::registerEHFrames() + 25 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp:595
>     frame #3: 0x0000000107aca9c7
libLLVM-3.4svn.dylib`llvm::MCJIT::finalizeObject() + 775 at
/Users/meister/Development/cando/brcl/externals/src/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp:226
>     frame #4: 0x0000000103da55d3
libllvmo_dbg.dylib`llvmo::ExecutionEngine_O::getCompiledFunction(mem::smart_ptr<core::Symbol_O>,
mem::smart_ptr<llvmo::Function_O>,
mem::smart_ptr<core::ActivationFrame_O>,
mem::smart_ptr<core::Symbol_O>) + 115 at
/Users/meister/Development/cando/brcl/src/llvmo/../../src/llvmo/llvmoExpose.cc:811
>
>
> Here is the function that causes the crash (it's Common Lisp and all
macros have been expanded).
>
> (defun match-dimensions (array pat)
>   (let ((zzz (eq pat '*)))
>     (if zzz
> 	zzz
> 	(let ((rank (array-rank array) ))
> 	  (if (listp pat)
> 	      (BLOCK NIL
> 		(LET* (
> 		       (%DOTIMES-VAR 100)
> 		       (I 0)
> 		       )
> 		  (TAGBODY
> 		     (GO bot)
> 		   top
> 		     (if (not t) (progn))
> 		     (SETQ PAT (CDR PAT))
> 		     (SETQ I (1+ I))
> 		   bot
> 		     (if (< I %DOTIMES-VAR) (GO top))
> 		     ) 
> 		  (NULL PAT))))))))
>
>
>
> The LLVM-IR file generated by compiling this function definition is
> here: https://dl.dropboxusercontent.com/u/6229900/broken.ll
>
> Any suggestions or pointers on how to debug this are welcome.
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

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