We want to be able to remap input signatures based on the signature index, but
signature normalization both reorders the signature, and requires the old
register index, so add a new field for this.
Store it in the shader_desc, and declare temps from that when compiling SPIR-V,
instead of parsing dcl_instructions.
As part of this change, we declare a single, global temps array (with Private
scope instead of Function) which is as large as the maximum of all dcl_temps
instructions. It is not clear to me whether this will improve, hurt, or have no
significant effect on the lower-level compiler. An alternative is to still
redeclare a new temps array every time (although still with a smaller size).
In Shader Model 6 each signature element can span a range of register
indices, or 'rows', and system values do not share a register index with
non-system values. Inputs and outputs are referenced by element index
instead of register index. This patch merges multiple signature elements
into a single element under the following conditions:
- The register index in a load or store is specified dynamically by
including a relative address parameter with a base register index. The
dcl_index_range instruction is used to identify these.
- A register declaration is split across multiple elements which declare
different components of the register.
- A patch constant function writes tessellation factors. These are an
array in SPIR-V, but in SM 5.x each factor is declared as a separate
register, and these are dynamically indexed by the fork/join instance
id. Elimination of multiple fork/join phases converts the indices to
constants, but merging the signature elements into a single arrayed
element matches the SPIR-V output.
All references to input/output register indices are converted to element
indices. If a relative address is present, the element index is moved up
a slot so it cannot be confused with a constant offset. Existing code
only handles register index relative addressing for tessellation factors.
This patch adds generic support for it.
The SPIR-V backend will emit a default control point phase. Inserting
inputs into the IR allows handling of declarations via the usual path
instead of an ad hoc implementation which may not match later changes
to input handling.
In SPIR-V the address must include the invocation id, but in TPF it
is implicit. Move the register index up one slot and insert an
OUTPOINTID relative address.
The practical effect this has is that we avoid potential trailing padding at
the end of DXBC blobs. Unfortunately this also means we need to be more
careful about using bytecode_get_size() to find the offset where subsequent
data would get written, although in many cases this follows a put_u32() call.
