[LLVMdev] Expected behavior of eliminateFrameIndex() on dbg_value machine instructions

[Jakob Stoklund Olesen]

On Oct 10, 2011, at 10:26 AM, Richard Osborne wrote:

> I'm investigating a bug associated with debug information that manifests 
> itself in the XCore backend (PR11105). I'd like to understand what the 
> expected behavior of eliminateFrameIndex() is when it is called on a 
> dbg_value machine instruction.

That is up to the target.

The TII::emitFrameIndexDebugValue() hook is called to insert DBG_VALUE instructions referring to values on the stack.

The target's eliminateFrameIndex() should be able to handle any DBG_VALUE instructions created by this hook.

If you don't implement the hook, you will get DBG_VALUE instructions with just a FrameIndex operand followed by the mandatory Offset and Metadata operands.

/jakob