Initial idea was to remodel AssignW as Assign under Alway. Trying that
uncovered some issues, the most difficult of them was that a delay
attached to a continuous assignment behaves differently from a delay
attached to a blocking assignment statement, so we need to keep the
knowledge of which flavour an assignment was until V3Timing.
So instead of removing AstAssignW, we always wrap it in an AstAlways,
with a special `keyword()` type. This makes it into a proper procedural
statement, which is almost equivalent to AstAssign, except for the case
when they contain a delay. We still gain the benefits of #6280 and can
simplify some code. Every AstNodeStmt should now be under an
AstNodeProcedure - which we should rename to AstProcess, or an
AstNodeFTask). As a result, V3Table can now handle AssignW for free.
Also uncovered and fixed a bug in handling intra-assignment delays if
a function is present on the RHS of an AssignW.
There is more work to be done towards #6280, and potentially simplifying
AssignW handing, but this is the minimal change required to tick it off
the TODO list for #6280.
1. Move class V3ParseGrammar into V3ParseGrammar.h so editors understand
it as c++ code
2. Fix #line directives in the bison output file
This together enables us to gdb through V3ParseGrammar, verilog.y, and
the bison generated C code step by step, with all source annotations in
the debug info pointing to the right place (e.g.: you will step to the
right place in verilog.y, then step back to the bison generated switch
statement/loop, and then step into calls in V3ParseGrammar as kind of
expected.
Geza Lore
Wilson Snyder