* Support 2D dynamic array initialization (#4700)
- new[] on sub arrays (as per original issue)
- Built-in methods for sub-arrays
- Initialization and literals assignmensts
- Dynamic array as an element for other arrays and queues
For NBAs that might execute a dynamic number of times in a single
evaluation (specifically: those that assign to array elements inside
loops), we introduce a new run-time VlNBACommitQueue data-structure
(currently a vector), which stores all pending updates and the necessary
info to reconstruct the LHS reference of the AstAssignDly at run-time.
All variables needing a commit queue has their corresponding unique
commit queue.
All NBAs to a variable that requires a commit queue go through the
commit queue. This is necessary to preserve update order in sequential
code, e.g.:
a[7] <= 10
for (int i = 1 ; i < 10; ++i) a[i] <= i;
a[2] <= 10
needs to end with array elements 1..9 being 1, 10, 3, 4, 5, 6, 7, 8, 9.
This enables supporting common forms of NBAs to arrays on the left hand
side of <= in non-suspendable/non-fork code. (Suspendable/fork
implementation is unclear to me so I left it unchanged, see #5084).
Any NBA that does not need a commit queue (i.e.: those that were
supported before), use the same scheme as before, and this patch should
have no effect on the generated code for those NBAs.
There is no strong need to re-map LogicMTask IDs and it just adds extra
processing. Instead we just allocate a separate set of ExecMTask IDs as
they are created, which can also be used as the unique profiling ID as
well. The only effect on the output of this is the change in mtask IDs
emitted, which was fairly arbitrary to begin with.
This saves about 5% memory. V3AstUserAllocator is appropriate for most use
cases, performance is marginally up as we are mostly D-cache bound on
large designs.
The typical find/if-not-exists-insert pattern can be achieved with 1
lookup instead of 2 using emplace with a sentinel value. Also maps value
initialize their values when inserted with the [] operator, this is
defined and so there is no need to explicitly insert zeroes for integer
values.
`getCommonClassTypep` and its helper code has been moved to AstNode
class. This is a lot better place for this functionality. Moreover, it
allowed to get rid of the dependency on V3Width from generic AST-related
code.