- Attempt to lookup a derived module if it potentially contains a port
connection with elaboration ambiguities
- Mark the cell if module has not yet been derived
- This can be extended to implement automatic hierarchical port
connections in a future change
This code now takes the AST nodes of type AST_BIND and generates a
representation in the RTLIL for them.
This is a little tricky, because a binding of the form:
bind baz foo_t foo_i (.arg (1 + bar));
means "make an instance of foo_t called foo_i, instantiate it inside
baz and connect the port arg to the result of the expression 1+bar".
Of course, 1+bar needs a cell for the addition. Where should that cell
live?
With this patch, the Binding structure that represents the construct
is itself an AST::AstModule module. This lets us put the adder cell
inside it. We'll pull the contents out and plonk them into 'baz' when
we actually do the binding operation as part of the hierarchy pass.
Of course, we don't want RTLIL::Binding to contain an
AST::AstModule (since kernel code shouldn't depend on a frontend), so
we define RTLIL::Binding as an abstract base class and put the
AST-specific code into an AST::Binding subclass. This is analogous to
the AST::AstModule class.
This doesn't do anything useful yet: the patch just adds support for
the syntax to the lexer and parser and adds some tests to check the
syntax parses properly. This generates AST nodes, but doesn't yet
generate RTLIL.
Since our existing hierarchical_identifier parser doesn't allow bit
selects (so you can't do something like foo[1].bar[2].baz), I've also
not added support for a trailing bit select (the "constant_bit_select"
non-terminal in "bind_target_instance" in the spec). If we turn out to
need this in future, we'll want to augment hierarchical_identifier and
its other users too.
Note that you can't easily use the BNF from the spec:
bind_directive ::=
"bind" bind_target_scope [ : bind_target_instance_list]
bind_instantiation ;
| "bind" bind_target_instance bind_instantiation ;
even if you fix the lookahead problem, because code like this matches
both branches in the BNF:
bind a b b_i (.*);
The problem is that 'a' could either be a module name or a degenerate
hierarchical reference. This seems to be a genuine syntactic
ambiguity, which the spec resolves (p739) by saying that we have to
wait until resolution time (the hierarchy pass) and take whatever is
defined, treating 'a' as an instance name if it names both an instance
and a module.
To keep the parser simple, it currently accepts this invalid syntax:
bind a.b : c d e (.*);
This is invalid because we're in the first branch of the BNF above, so
the "a.b" term should match bind_target_scope: a module or interface
identifier, not an arbitrary hierarchical identifier.
This will fail in the hierarchy pass (when it's implemented in a
future patch).
The current_module global is needed so that genRTLIL has somewhere to
put cells and wires that it generates as it makes sense of expressions
that it sees. However, that doesn't actually need to be an AstModule:
the Module base class is enough.
This patch should cause no functional change, but the point is that
it's now possible to call genRTLIL with a module that isn't an
AstModule as "current_module". This will be needed for 'bind' support.
No functional change: just get rid of the explicit iterator and
replace (*it)-> with child->. It's even the same number of characters,
but is hopefully a little easier to read.
Calling log_signal is problematic for several reasons:
- with recent changes, empty string is serialized as { }, which violates
the "no spaces in IdString" rule
- the type (plain / real / signed / string) is dropped, wrongly conflating
functionally different values and potentially introducing a subtle
elaboration bug
Instead, use a custom simple serialization scheme.
This defers the simplification of globals so that globals in one file
may depend on globals in other files. Adds a simplify() call downstream
because globals are appended at the end.
It was previously possible to override global parameters on a
per-instance basis. This could be dangerous when using positional
parameter bindings, hiding oversupplied parameters.
- Modules with a parameter without a default value will be automatically
deferred until the hierarchy pass
- Allows for parameters without defaults as module items, rather than
just int the `parameter_port_list`, despite being forbidden in the LRM
- Check for parameters without defaults that haven't been overriden
- Add location info to parameter/localparam declarations
The $paramod name mangling is not invertible (the \ character, which
separates the module name from the parameters, is valid in the module
name itself), which does not stop people from trying to invert it.
This commit makes it easy to invert the name mangling by storing
the original name explicitly, and fixes the firrtl backend to use
the newly introduced attribute.
- information also useful for strongly-typed enums (not implemented)
- resolves enum values in ilang part of #1594
- still need to output enums to VCD (or better yet FST) files
I tried to keep only the enum-related changes, and minimize the diff. (The
original commit also had a lot of work done to get typedefs working, but yosys
has diverged quite a bit since the 2018-03-09 commit, with a new typedef
implementation.) I did not include the import related changes either.
Original commit:
"Initial implementation of enum, typedef, import. Still a WIP."
881833aa73
Zachary Snow
Rupert Swarbrick
Marcelina Kościelnicka
Claire Xenia Wolf
whitequark
Julius Roob
Udi Finkelstein
Kazuki Sakamoto
Peter Crozier
Claire Wolf
Claire Wolf
David Shah
Eddie Hung
Alberto Gonzalez
Jeff Wang