Linking Programs Compiled from Source with Programs Compiled from IL

Creating this issue from a discussion in a SPIRV-LLVM-Translator PR review:

https://github.com/KhronosGroup/SPIRV-LLVM-Translator/pull/1149#discussion_r707579538

Is it possible to link one program object created from source with another program object created from IL?

Discussion "for":

> The program object created from source or IL must be compiled (via clCompileProgram) before it can be linked, which transitions the state of the program object from BINARY_TYPE_NONE to BINARY_TYPE_COMPILED_OBJECT. After the program object has been compiled I can't think of any reason to differentiate between program objects that originated from source and program objects that originate from IL, so the linking should "just work". Is there a detail I'm missing here?

Discussion "against":

> C++ compilers have similar problems here, where a "compiled object" from one version of a compiler doesn't necessarily have the same ABI as a "compiled object" from another version of a compiler, and therefore the two objects can't necessarily be linked. This is similar, if we treat an IL program as an object from one version of a compiler, which might not be the same as the platform's source compiler.

Start with the linked SPIRV-LLVM-Translator PR #1149 discussion and the OpenCL program-object rules around clCompileProgram and linking. Determine whether compiled program objects originating from source and IL may be linked, including any compatibility or ABI constraint; done means the specification gives an unambiguous answer.

Written by the indexing model from the issue text.