This moves the sema checking of the entrypoint sensitive HLSL
attributes all into one place. This ended up being kind of large for a
couple of reasons:
- I had to move the call to CheckHLSLEntryPoint later in
ActOnFunctionDeclarator so that we do this after redeclarations and
have access to all of the attributes.
- We need to transfer the target shader stage onto the specified entry
point before doing the checking.
- I removed "library" from the HLSLShader attribute value enum and
just go through a string to convert from the triple - the other way
was confusing and brittle.
Differential Revision: https://reviews.llvm.org/D158803
ef2b1700f4