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.
