pointer to pointer crashes __sync_lock_release backend

[llvmbot]

Bugzilla Link	12040
Resolution	FIXED
Resolved on	Mar 15, 2012 20:48
Version	trunk
OS	MacOS X
Reporter	LLVM Bugzilla Contributor
CC	@efriedma-quic

Extended Description

This bug affects: Apple clang version 3.1 (tags/Apple/clang-318.0.45) (based on LLVM 3.1svn)

Kyoto's Cabinet (http://fallabs.com/kyotocabinet/) kcthread.cc/SpinLock
uses a void* pointer to embed several kinds of locks depending of the platform.

If __sync_bool_compare_and_swap is avaliable it uses _sync_bool_compare_and_swap(&opq,0, 1) as a lock mechanism.

This won't compile in clang++ (but compiles on gcc) because the last elements are int and &opq_ is void**. Casting the argumets to void*

__sync_bool_compare_and_swap(&opq_, (void*)0, (void*)1)

makes clang accept the program but the backend crash with:

fatal error: error in backend: Cannot select: 0x106ed2510: i64,ch = AtomicSwap
      0x7ff8084ce648, 0x106ed2610, 0x106eac710
      [ID=5]
  0x106ed2610: i64,ch = CopyFromReg 0x7ff8084ce648, 0x106eac010 [ORD=940] [ID=4]
    0x106eac010: i64 = Register %vreg0 [ORD=940] [ID=1]
  0x106eac710: i64 = Constant<0> [ID=2]

[efriedma-quic]

Please attach preprocessed source for the file which fails to compile.

[llvmbot]

The preprocessed offending file
The relevant lines are 43294 and 43319.
If the integer constants are cast to (void*) the crash is triggered.

Note: the file is compressed due to it's size.

[llvmbot]

Reduced the test case to

#include 

int main ()
{
  long long **opq_ = NULL;
  __sync_lock_release(&opq_);
  return 0;
}

Backned crashes with error:

fatal error: error in backend: Cannot select: 0x7fa2a110e610: i64,ch = AtomicSwap 0x7fa2a110e410, 0x7fa2a110e310,
      0x7fa2a110e010 [ID=8]
  0x7fa2a110e310: i64 = FrameIndex<1> [ORD=2] [ID=5]
  0x7fa2a110e010: i64 = Constant<0> [ORD=2] [ID=3]

[efriedma-quic]

r152891.