[Feature Request] [SPIR-V] `vk::ext_decorate` on return types of Inline SPIR-V Intrinsics or functions In general

[devshgraphicsprogramming]

Is your feature request related to a problem? Please describe.

In SPIR-V certain Result IDs (immediate SSA values) can be OpDecorated with very useful things like:

• Uniform / UniformID , basically the reverse of nonUniformEXT
• SPV_EXT_float_control2 decorations allow decorating expressions

Describe the solution you'd like

I'd like to do this https://godbolt.org/z/a1xnsnord

template<typename T>
[[vk::ext_instruction(/*spv::OpCopyObject*/83)]]
[[vk::ext_decorate(/*spv::DecorationUniform*/26)]]
T decorateExpression(T v);

which should be enough to decorate things like FMul and so on.

But this is not sufficient

template<typename T>
[[vk::ext_decorate(/*spv::DecorationUniform*/26)]]
T decorateExpression(T v)
{
    return v;
}

because certain decorations need to be applied directly to some SPIR-V instruction like mul,add.

Here's the SPIR-V I'd like to arrive at
https://godbolt.org/z/o6z9f6GYc

Describe alternatives you've considered

Ideally I'd love to be able to just decorate a statement.

However I know that even in latest trunk Clang statements cannot have attributes and thats a future C++ proposal
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p3093r0.html