The choice to store them in an rbtree was made early on. It does not seem likely
that HLSL programs would define many overloads for any of their functions, but I
suspect the idea was rather that intrinsics would be defined as plain
hlsl_ir_function_decl structures [cf. 447463e590]
and that some intrinsics that could operate on any type would therefore need
many overrides.
This is not how we deal with intrinsics, however. When the first intrinsics were
implemented I made the choice disregard this intended design, and instead match
and convert their types manually, in C. Nothing that has happened in the time
since has led me to question that choice, and in fact, the flexibility with
which we must accommodate functions has led me to believe that matching in this
way was definitely the right choice. The main other designs I see would have
been:
* define each intrinsic variant separately using existing HLSL types. Besides
efficiency concerns (i.e. this would take more space in memory, and would take
longer to generate each variant), the normal type-matching rules don't really
apply to intrinsics.
[For example: elementwise intrinsics like abs() return the same type as the
input, including preserving the distinction between float and float1. It is
legal to define separate HLSL overloads taking float and float1, but trying to
invoke these functions yields an "ambiguous function call" error.]
* introduce new (semi-)generic types. This is far more code and ends up acting
like our current scheme (with helpers) in a slightly more complex form.
So I think we can go ahead and rip out this vestige of the original design for
intrinsics.
As for why to change it: rbtrees are simply more complex to deal with, and it
seems unlikely to me that the difference is going to matter. I do not expect any
program to define large quantities of intrinsics; linked list search should be
good enough.
So that they are dumped even if parsing fails, which is a circumstance
in which one likely wants to see the problematic shader.
The downside of that is that for shader types other than HLSL
the profile is not written any more in the filename. This should
not be a big problem, because in those cases the shader describes
its own type.
When dumping an HLSL shader, the id is brought in front of the profile
in the file name, in order to make it more tab-friendly: when dealing
with a directory full of shaders it's likely that the id determines
the profile, but the other way around.
This field is now analogous to vkd3d_shader_register_index.rel_addr.
Also, it makes sense to rename it now because all the constant part of
the offset is now handled to hlsl_deref.const_offset. Consequently, it
may also be NULL now.
This uint will be used for the following:
- Since SM4's relative addressing (the capability of passing a register
as an index to another register) only has whole-register granularity,
we will need to make the offset node express the offset in
whole-registers and specify the register component in this uint,
otherwise we would have to add additional / and % operations in the
output binary.
- If, after we apply constant folding and copy propagation, we determine
that the offset is a single constant node, we can store all the offset
in this uint constant, and remove the offset src.
This allows DCE to remove a good bunch of the nodes previously required
only for the offset constants, which makes the output more liteweight
and readable, and simplifies the implementation of relative addressing
when writing tpf in the following patches.
In dump_deref(), we use "c" to indicate components instead of whole
registers. Since now both the offset node and the offset uint are in
components a lowered deref would look like:
var[@42c + 2c]
But, once we express the offset node in whole registers we will remove
the "c" from the node part:
var[@22 + 3c]
Some functions work with dereferences and need to know if they are
lowered yet.
This can be known checking if deref->offset.node is NULL or
deref->data_type is NULL. I am using the latter since it keeps working
even after the following patches that split deref->offset into
constant and variable parts.
Components only span across a single regset, so instead of expecting the
regset as input for the offset, hlsl_type_get_component_offset() can
actually retrieve it.
We have to distinguish between the "bind count" and the "allocation size"
of variables.
The "allocation size" affects the starting register id for the resource to
be allocated next, while the "bind count" is determined by the last field
actually used. The former may be larger than the latter.
What we are currently calling hlsl_reg.bind_count is actually the
"allocation size", so a rename is in order.
The real "bind count", which will be introduced in following patches,
is important because it is what should be shown in the RDEF table and
some resource allocation rules depend on it.
For instance, for this shader:
texture2D texs[3];
texture2D tex;
float4 main() : sv_target
{
return texs[0].Load(int3(0, 0, 0)) + tex.Load(int3(0, 0, 0));
}
the variable "texs" has a "bind count" of 1, but an "allocation size" of
3:
// Resource Bindings:
//
// Name Type Format Dim HLSL Bind Count
// ------------------------------ ---------- ------- ----------- -------------- ------
// texs texture float4 2d t0 1
// tex texture float4 2d t3 1
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.
