Researching in prep of doing the implementation for lowering, I found
that the source of the valid identifiers list from flang is in the
frontend. This patch adds the same list to the frontend, but does it as
a sema diagnostic, so we still parse it as an identifier/identifier-like
thing, but then diagnose it as invalid later.
This is the last item of the OpenACC 3.3 spec. It includes the
implicit-name version of 'routine', plus significant refactorings to
make the two work together. The implicit name version is represented as
an attribute on the function call. This patch also implements the
clauses for the implicit-name version, as well as the A.3.4 warning.
The 'bind' clause allows the renaming of a function during code
generation. There are a few rules about when this can/cannot happen,
and it takes either a string or identifier (previously mis-implemetned
as ID-expression) argument.
Note there are additional rules to this in the implicit-function routine
case, but that isn't implemented in this patch, as implicit-function
routine is not yet implemented either.
There is a slightly different list for routine on which clauses are
permitted after it (like the rest of the constructs), but this
implements and tests them to make sure we get them right.
'nohost' is only valid on routine, and states that the compiler
shouldn't compile this routine for the host. It has no arguments, so no
checking is required besides putting it in the AST.
These 4 clauses are mutually exclusive, AND require at least one of
them. Additionally, gang has some additional restrictions in that only
the 'dim' specifier is permitted. This patch implements all of this, and
ends up refactoring the handling of each of these clauses for
readabililty.
The 'routine' construct has two forms, one which takes the name of a
function that it applies to, and another where it implicitly figures it
out based on the next declaration. This patch implements the former with
the required restrictions on the name and the function-static-variables
as specified.
What has not been implemented is any clauses for this, any of the A.3.4
warnings, or the other form.
