[LLVMdev] LiveInterval Questions

[dag at cray.com]

<dag at cray.com> writes:

> - Why are there any phi defs at all given that the register is only ever
>   defined once at the top level of the function?  No defs of vreg637
>   appear anywhere else.

I looked back through the debug trace and indeed %vreg637 is defined by
multiple COPY instructions, presumably artifacts of phi elimination.
Coalescing eliminates the copies.  I would have expected coalescing to
join the live ranges.  Any idea why the live ranges would not be merged?

                             -David