This struct is required for handling both whole-variable resources for
SM < 5 and single-component resources for SM 5 in the same way, when
writting the RDEF block and resource declarations within the shader.
After lowering the derefs path to a single offset node, there was no way
of knowing the type of the referenced part of the variable. This little
modification allows to avoid having to pass the data type everywhere and
it is required for supporting instructions that reference objects
components within struct types.
Since deref->data_type allows us to retrieve the type of the deref,
deref->offset_regset is no longer necessary.
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).
A struct declaration with variables is now absorbed into the 'declaration'
rule, like any other variable declaration.
A struct declaration without variables is now reduced to the
'struct_declaration_without_vars' rule.
They both are reduced to a 'declaration_statement' in the end.
In a declaration with multiple variables, the variables must be created
before the initializer of the next variable is parsed. This is required
for initializers such as:
float a = 1, b = a, c = b + 1;
A requisite for this is that the type information is parsed in the same
rule as the first variable (as a variable_def_typed) so it is
immediately available to declare the first variable. Then, the next
untyped variable declaration is parsed, and the type from the first
variable can be used to declare the second, before the third is parsed,
and so on.
Basically, declare_vars() is separated in three functions:
1. check_invalid_in_out_modifiers(), which is to be called once per
declaration and emits an error when in or out modifiers are used for
these non-parameter variables.
2. declare_var(), which now handles one variable at the time and doesn't
free any memory.
3. initialize_vars(), which takes care of preparing the initialization
instructions of several variables and frees their struct
parse_variable_def, using exclusively free_parse_variable_def().
This allows to declare variables individually before the initializer of
the next variable in the same declaration is parsed, which is used in
the following patches.
Also, simplifies memory management.
