VALUE_TYPE_UNDEFINED means that a value is explicitly undefined,
equivalently to what was first represented with is_undefined.
VALUE_TYPE_INVALID will be introduced for values that arise from
invalid programs.
Currently structured TGSM loads are encoded to something like this:
ld_structured sr12 <s:float>, sr1 <s:uint>, l(0) <s:uint>, g0[sr1 <s:uint> + 0] <s:float>
Notice how the TGSM offset, expressed by sr1, is encoded twice in
the instruction. In TPF there is no expectation of two indices
in the resource source, so let's avoid producing it for DXIL as
well. The same instruction will therefore become:
ld_structured sr12 <s:float>, sr1 <s:uint>, l(0) <s:uint>, g0 <s:float>
Rather than an array of pointers to registers. This makes it nicer
to use with registers that are synthesized on the fly, a situation
that already exists and is likely to become more common in future
commits.
The idea is that sm6_value and related structures should not commit
to a specific vsir register representation yet, because at the time
they are created some information might be still unavailable. For
instance, it might be not yet known whether the program is using
native 16-bit types or minimum precision types. vsir registers
should only be synthesized during instruction emission.
Field "reg" in struct sm6_value will be handled in a later commit.
We currently generate our own I/O signatures inside the DXIL parser, but
use the element counts from the DXBC container signatures to allocate
the input_params/output_params/patch_constant_params arrays. That
happens to work for well-behaved inputs, but it's asking for trouble.
