This is required to properly optimize signatures, because these
semantics must be alligned while being packed:
- Array elements.
- The first fields of structs.
- Major vectors of a matrix.
For now this has no effect since semantics are allocated with reg_size
4, but will have effect when optimizing interstage signatures.
The generated pixel shader input signature must be consistent with the
generated vertex shader output signature for the same data type.
Since the interpolation mode affects allocation order, the allocator
needs to know the modifiers for both input and output signature elements.
Similarly to the already done split from
HLSL IR -> d3dbc
to
HLSL IR -> vsir -> d3bc
we now start splitting the
HLSL IR -> tpf
translation into
HLSL IR -> vsir -> tpf
So hlsl_sm4_write is split into two functions, sm4_generate_vsir() and
tpf_compile().
This translation should be completed once tpf_compile() no longer needs
the hlsl_ctx and entry_func parameters.
Currently, if an expression successfully parses according to the bison grammar,
but for one reason or another cannot generate a meaningful IR instruction, we
abort parsing with YYABORT. This includes, for example, an undefined variable or
function, invalid swizzle or field reference, or a constructor with a complex or
non-numeric data type.
Aborting parsing is unfortunate, however, because it means that any further
errors in the program cannot be caught by the programmer, increasing the number
of times they will need to fix errors and recompile.
The idea of this patch is that any such expression will instead generate an IR
node whose data type is of HLSL_CLASS_ERROR. Any further expression which would
consume an "error" typed instruction will instead immediately return an
expression of type "error" (probably the same one) instead of aborting or doing
any other type-checking.
Currently these "error" instructions should not pass the parsing stage, since
hlsl_compile_shader() will immediately notice that compilation has failed and
skip any optimization, lowering, or bytecode-writing.
A further direction to take this is to pre-allocate one "error" expression
immediately when creating the HLSL parser, and return that expression when we
fail to allocate an hlsl_ir_node of any type. This means we do not need to
handle allocation errors when constructing nodes, saving us quite a lot of error
handling (which is not only tedious but currently often broken, if nothing else
by virtue of neglecting cleanup of local variables).
