[LLVMdev] PointerIntPair causing trouble

Nicolas Capens nicolas at capens.net
Fri May 1 03:32:37 PDT 2009

Hi all,


I've located a regression that causes my project to crash. It's in revision
67979, where PointerIntPair is changed from storing the integer in the upper
bits instead of the lower bits. My project is an experimental JIT-compiler
in Windows.


So I was wondering if anyone had any clue why the new PointerIntPair
implementation might fail. It doesn't seem very safe to me to store other
data into a pointer to begin with, but surely the lower bits must be a safer
location than the upper bits?


The actual crash I'm seeing is preceded by an assert in
X86InstrInfo::sizeOfImm: "Immediate size not set!". Tracing backward, I'm
seeing a MachineInstr with opcode MOV32rm and NumOperands equal to 6 (which
is 5 in earlier revisions). I'm not sure if this actually helps explain the
bug but it's one of the weird things that happen with revision 67979 and
subsequent revisions.


All help appreciated.



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