Native Matrix Types (OpTypeMatrix)

[newgpudev]

I want to use the native matrix types in spirv and the corresponding instructions (e.g. OpMatrixTimesMatrix) but in C++ there is no way to specify a matrix type like you can for vectors:

from my understanding vectors can be emitted by using the following in C++ code:
typedef float native_vec4 __attribute__((ext_vector_type(4)));

which will generate a LLVM::VectorTypeKind that is lowered to spirv OpTypeVector.

What is the equivalent for matrix types? Can I just use an array of native_vec4?

Similarly, I want to use cooperative matrices - these are a bit different from the native matrix types and are more abstract.

Is there a clean way to support these with stock Clang and shady? I do not want to take the Clang hacking route :(. Thanks a lot!

[Hugobros3]

There is actually a matrix type extension as well: https://clang.llvm.org/docs/LanguageExtensions.html#matrix-types

typedef float mat4 __attribute__((matrix_type(4, 4)));

But these seem to lower to just float arrays, there is no underlying LLVM type for them.

For opaque types such as textures, I have been using an ad-hoc mechanism to declare some types (pointers into unused address spaces). I'd like to eventually move to a more robust system where I can declare arbitrary "foreign" types through SPIR-V "intrinsics", much like how the texture instructions work currently, and that mechanism should cover matrix types too.

It's not super-clear how that looks like yet to me for non-opaque types, given they need to be constructed etc.

[Hugobros3]

See #57