Assertion failure in register allocation

[vbgl]

The following program does not make much sense but confuses a lot the compiler.

inline fn aux(reg u8 x) -> inline u8 {
  inline u8 r;
  if x == 0 { r = 0; }
  return r;
}

export fn main() -> reg u8 {
  reg u8 t;
  t = aux(0);
  return t;
}

[vbgl]

Compiling this program crashes with an assertion failure in register-allocation. This might be seen as a duplicate of #828: if the compiler ensured that inline variables are gone before register-allocation, this program would be rejected early before the assertion failure can be triggered.