The 'cache' construct is lowered as marking the acc.loop in ACC MLIR.
This results in any variable references that are not inside of the
acc.loop being invalid. This patch adds a warning to that effect, and
ensures that the variable references won't be added to the AST during
parsing so we don't try to lower them.
This results in loss of instantiation-diagnostics for these, however
that seems like an acceptable consequence to ignoring it.
This statement level construct takes no clauses and has no associated
statement, and simply labels a number of array elements as valid for
caching. The implementation here is pretty simple, but it is a touch of
a special case for parsing, so the parsing code reflects that.
This implementation takes quite a bit from the OMP implementation of
array sections, but only has to enforce the rules as applicable to
OpenACC. Additionally, it does its best to create an AST node (with the
assistance of RecoveryExprs) with as much checking done as soon as
possible in the case of instantiations.
The private clause is the first that takes a 'var-list', thus this has a
lot of additional work to enable the var-list type. A 'var' is a
traditional variable reference, subscript, member-expression, or
array-section, so checking of these is pretty minor.
Note: This ran into some issues with array-sections (aka sub-arrays)
that will be fixed in a follow-up patch.
Currently we just emit a generic 'not implemented' diagnostic for all
OpenACC pragmas. This patch moves the diagnostic to 'Sema' and diagnoses
for a specific clause or construct, in preperation of implementing Sema
for constructs.
The 'cache' directive and various clauses have a 'tag' name that is
optional. This patch cleans up the use of the 'cache' version so that we
get a nicer diagnostic, and enables us to do the same with clauses in
the same situation.
While investigating implementing 'var-list' generically for the variety
of clauses that support this syntax (an extensive list!) I discovered
that it includes 'compound types' and members of compound types, as well
as array sections.
This patch genericizes that function, and implements it in terms of an
assignment expression, and enables a simplified version of OMP Array
Sections for it. OpenACC only supports a startidx + length, so this
patch implements that parsing.
However, it is currently still being represented as an OpenMP Array
Section, which is semantically very similar. It is my intent to come
back and genericize the OMP Array Sections types (or create a similar
expression node) in the future when dealing with Sema.
At the moment, the only obvious problem with it is that the diagnostic
for using it in the 'wrong' place says OpenMP instead of OpenACC, which
I intend to fix when I deal with the AST node changes.
As we've now finished parsing the constructs, we're moving onto
implementing 'clause' parsing. While some are complicated and require
their own patch, the handful added here are simple to parse (that is,
they are a single identifier).
This patch adds the infrastructure to parse these and a clause-list in
its entirety. This adds some complication to how we are diagnosing
parsing errors elsewhere, so a few changes were made to better recover
from errors.
The 'cache' construct takes a list of 'vars', which are array-section
style definitions. This patch implements the parsing, leaving the lower
bound and length of the bound as expressions, so that we can validate
they are the correct 'thing' in sema.
