[LLVMdev] VirtRegMap Error

[David Greene]

I just updated from upstream llvm as of about last Thursday and I'm
getting a segfault in VirtRegMap::RemoveMachineInstrFromMaps.
It seems that the particular instruction being removed happens
to reference an object at stack slot 4.  The first spilled register is
assigned stack slot 6 so LowSpillSlot == 6.  Then, when we try to
erase from SpillSlotToUsesMap, we index with a negative number.

The instruction being removed is generated by instruction selection,
so it is part of the original program:

%reg1309<def> = FsMOVLPDrm <fi#4>, 1, %reg0, 0, Mem:LD(8,8) [ZETA + 0]

Since we're hooking up llvm to custom code, I want to check assumptions.
Is there anything in llvm-gcc or the other llvm tools that could generate a
stack slot reference like this before register allocation?  Basically, I'm 
trying to see if only our code could ever do this.  Otherwise, we have a bug
in llvm.  Is everything on the stack assumed to be mem2reg'd and so this
never happens with llvm tools?

Thanks.

                                                -Dave