Interface for IDevice::createShaderProgram

[skallweitNV]

We currently have this descriptor:

struct ShaderProgramDesc
{
    // TODO: Tess doesn't like this but doesn't know what to do about it
    // The linking style of this program.
    LinkingStyle linkingStyle = LinkingStyle::SingleProgram;

    // The global scope or a Slang composite component that represents the entire program.
    slang::IComponentType* slangGlobalScope;

    // An array of Slang entry points. The size of the array must be `slangEntryPointCount`.
    // Each element must define only 1 Slang EntryPoint.
    slang::IComponentType** slangEntryPoints = nullptr;

    // Number of separate entry point components in the `slangEntryPoints` array to link in.
    // If set to 0, then `slangGlobalScope` must contain Slang EntryPoint components.
    // If not 0, then `slangGlobalScope` must not contain any EntryPoint components.
    GfxCount slangEntryPointCount = 0;
};

The linkingSyle allows to select between two styles for linking and we have the following use cases:

• SingleProgram
  • a) we can pass a fully linked program in slangGlobalScope that potentially contains multiple entry-points
  • b) we can pass a global scope + entry point components and let the program be composed
• SeparateEntryPointCompilation
  • c) we pass a global scope + multiple entry points that may contain specializations (type conformances)

Case (b) seems obsolete as we can achieve the same by just passing in a fully composed/linked program.
Case (c) is important for raytracing pipelines.

Is there a better design for handling these use cases?