C1 crash in LinearScan::eliminate_spill_moves

[Eirik Bjørsnøs]

>
> # A fatal error has been detected by the Java Runtime Environment:
> #
> #  Internal Error ([..]/jdk/src/hotspot/share/c1/c1_LIR.hpp:732),
> pid=5366, tid=23811
> #  assert(res->vreg_number() == index) failed: conversion check
>

FWIW, I added some print statements to see what  res->vreg_number() and
index are when this assertion fails:

CONVERSION CHECK FAILED
vreg_number: -131071
index: 131073

Does a negative vreg_number make any sense here?

Eirik.