::      0x00bf1015:               0xf0  lock xaddb  %dl,(%rax)
          0x00bf1016:               0x0f
          0x00bf1017:               0xc0
          0x00bf1018:               0x10

Inspection of the assembly code leads me to think it is the above instruction that isn't handled.

Reproducible: Sometimes

Steps to Reproduce:
The instruction comes from using intel's thread building blocks (tbb) toolkit and the class::method below

tbb::queuing_mutex::scoped_lock::scoped_lock( queuing_mutex& m )

Actual Results:  
vex amd64->IR: unhandled instruction bytes: 0xF0 0xF 0xC0 0x10 0x80 0xFA 0x1 0xF
vex amd64->IR:   REX=0 REX.W=0 REX.R=0 REX.X=0 REX.B=0
vex amd64->IR:   VEX=0 VEX.L=0 VEX.nVVVV=0x0 ESC=0F
vex amd64->IR:   PFX.66=0 PFX.F2=0 PFX.F3=0
==32386== valgrind: Unrecognised instruction at address 0xbf1015.


Expected Results:  
Keep running.


Although we have been using tbb for a while, this is the first time we hit this problem, probably because we have introduced a lock in a high-contention area.

To run with tbb, we did have to suppress two tbb related issues, that don't seem to be the cause of the problem:

 {
   tbb::isLargeObject 
   Memcheck:Cond
   fun:_ZN3rml8internal13isLargeObjectEPv
   fun:_ZN3rml8internalL16internalPoolFreeEPNS0_10MemoryPoolEPv
}

{
   tbb::getBackRef
   Memcheck:Cond
   fun:_ZN3rml8internal10getBackRefENS0_10BackRefIdxE
   fun:_ZN3rml8internal13isLargeObjectEPv
   fun:_ZN3rml8internalL16internalPoolFreeEPNS0_10MemoryPoolEPv
}