All 4 of the 'data' constructs have a requirement that at least 1 of a
small list of clauses must appear on the construct. This patch
implements that restriction, and updates all of the tests it takes to
do so.
These constructs are all very similar and closely related, so this patch
creates the AST nodes for them, serialization, printing/etc.
Additionally the restrictions are all added as tests/todos in the tests,
as those will have to be implemented once we get those clauses implemented.
OpenACC restricts the contents of a 'for' loop affected by a 'loop'
construct without a 'seq'. The loop variable must be integer, pointer,
or random-access-iterator, it must monotonically increase/decrease, and
the trip count must be computable at runtime before the function.
This patch tries to implement some of these limitations to the best of
our ability, though it causes us to be perhaps overly restrictive at the
moment. I expect we'll revisit some of these rules/add additional
supported forms of loop-variable and 'monotonically increasing' here,
but the currently enforced rules are heavily inspired by the OMP
implementation here.
OpenACC Spec requires that each loop associated with a 'collapse' have
exactly 1 loop/nest. This is implemented in 2 parts: 1- diagnosing when
we see a 2nd loop at any level with an applicable 'collapse'
2- Diagnosing if we didn't see enough 'depth' of loops.
Other loops (non-for) are diagnosed by a previous patch, and other
intervening code will be diagnosed in a followup.
'collapse' makes the 'loop' construct apply to the next N nested loops,
and 'loop' requires all associated loops be 'for' loops (or range-for).
This patch adds this restriction, plus adds a number of infrastructure
changes to permit some of the other restrictions in the future to be
implemented.
'collapse' also requires that there is not any calls to other directives
inside of the collapse region, so this also implements that limitation.
The 'collapse' clause on a 'loop' construct is used to specify how many
nested loops are associated with the 'loop' construct. It takes an
optional 'force' tag, and an integer constant expression as arguments.
There are many other restrictions based on the contents of the loop/etc,
but those are implemented in followup patches, for now, this patch just
adds the AST node and does basic argument checking on the loop-count.
