Non-constant vector indexing is not solved with relative addressing
in the register indexes because this indexation cannot be at the level
of register-components.
Mathematical operations must be used instead.
Currently, the compiler requires that dereferences be HLSL_IR_CONSTANT, so that
it can compute the offset at compile time. However, scenarios such as this test
will produce a dereference with HLSL_IR_EXPR, which will generate an error.
Passing this test in particular will require adding support for SM4 relative
addressing, as well as support for non-constant indexing in general.
Signed-off-by: Ethan Lee <flibitijibibo@gmail.com>
