The recent fix for case expression width detection causes the width of
the expressions to be queried before they are simplified. Because the
logic supporting module scope identifiers only existed in simplify,
looking them up would fail during width detection. This moves the logic
to a common helper used in both simplify() and detectSignWidthWorker().
- The case expression and case item expressions are extended to the
maximum width among them, and are only interpreted as signed if all of
them are signed
- Add overall width and sign detection for AST_CASE
- Add sign argument to genWidthRTLIL helper
- Coverage for both const and non-const case statements
From IEEE1364-2005, section 7.3 buf and not gates:
> These two logic gates shall have one input and one or more outputs.
> The last terminal in the terminal list shall connect to the input of the
> logic gate, and the other terminals shall connect to the outputs of
> the logic gate.
yosys does not follow this and instead interprets the first argument as
the output, the second as the input and ignores the rest.
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.
- Simplify synthetic localparams for normal calls to update their width
- This step was inadvertently removed alongside `added_mod_children`
- Support redeclaration of constant function arguments
- `eval_const_function` never correctly handled this, but the issue
was not exposed in the existing tests until the recent change to
always attempt constant function evaluation when all-const args
are used
- Check asserts in const_arg_loop and const_func tests
- Add coverage for width mismatch error cases
This adds a mechanism for marking certain portions of elaboration as
occurring within unevaluated ternary branches. To enable elaboration of
the overall ternary, this also adds width detection for these
unelaborated function calls.
Elaboration now attempts constant evaluation of any function call with
only constant arguments, regardless of the context or contents of the
function. This removes the concept of "recommended constant evaluation"
which previously applied to functions with `for` loops or which were
(sometimes erroneously) identified as recursive. Any function call in a
constant context (e.g., `localparam`) or which contains a constant-only
procedural construct (`while` or `repeat`) in its body will fail as
before if constant evaluation does not succeed.
This change set contains a number of bug fixes and improvements related to
scoping and resolution in generate and procedural blocks. While many of the
frontend changes are interdependent, it may be possible bring the techmap
changes in under a separate PR.
Declarations within unnamed generate blocks previously encountered issues
because the data declarations were left un-prefixed, breaking proper scoping.
The LRM outlines behavior for generating names for unnamed generate blocks. The
original goal was to add this implicit labelling, but doing so exposed a number
of issues downstream. Additional testing highlighted other closely related scope
resolution issues, which have been fixed. This change also adds support for
block item declarations within unnamed blocks in SystemVerilog mode.
1. Unlabled generate blocks are now implicitly named according to the LRM in
`label_genblks`, which is invoked at the beginning of module elaboration
2. The Verilog parser no longer wraps explicitly named generate blocks in a
synthetic unnamed generate block to avoid creating extra hierarchy levels
where they should not exist
3. The techmap phase now allows special control identifiers to be used outside
of the topmost scope, which is necessary because such wires and cells often
appear in unlabeled generate blocks, which now prefix the declarations within
4. Some techlibs required modifications because they relied on the previous
invalid scope resolution behavior
5. `expand_genblock` has been simplified, now only expanding the outermost
scope, completely deferring the inspection and elaboration of nested scopes;
names are now resolved by looking in the innermost scope and stepping outward
6. Loop variables now always become localparams during unrolling, allowing them
to be resolved and shadowed like any other identifier
7. Identifiers in synthetic function call scopes are now prefixed and resolved
in largely the same manner as other blocks
before: `$func$\func_01$tests/simple/scopes.blk.v:60$5$\blk\x`
after: `\func_01$func$tests/simple/scopes.v:60$5.blk.x`
8. Support identifiers referencing a local generate scope nested more
than 1 level deep, i.e. `B.C.x` while within generate scope `A`, or using a
prefix of a current or parent scope, i.e. `B.C.D.x` while in `A.B`, `A.B.C`,
or `A.B.C.D`
9. Variables can now be declared within unnamed blocks in SystemVerilog mode
Addresses the following issues: 656, 2423, 2493
The changes in #2476 ensured that function inputs like `input x;`
retained their single-bit size when instantiated with a constant
argument and turned into a localparam. That change did not handle the
possibility for an input to be redeclared later on with an explicit
width, such as `integer x;`.
- expand_genblock defers prefixing of items within named sub-blocks
- Allow partially-qualified references to local scopes
- Handle shadowing within generate blocks
- Resolve generate scope references within tasks and functions
- Apply generate scoping to genvars
- Resolves#2214, resolves#1456
This adds the new rewrite rule. But it's still missing a check that makes
sure the new rewrite rule is actually a valid substitute in the always
block being processed. Therefore the new rewrite rule is just disabled
for now.
Signed-off-by: Claire Wolf <claire@symbioticeda.com>
Before this commit, enum values were serialized as attributes of form
\enum_<width>_<value>
where <value> was a decimal signed integer.
This has multiple drawbacks:
* Enums with large values would be hard to process for downstream
tooling that cannot parse arbitrary precision decimals. (In fact
Yosys also did not correctly process enums with large values,
and would overflow `int`.)
* Enum value attributes were not confined to their own namespace,
making it harder for downstream tooling to enumerate all such
attributes, as opposed to looking up any specific value.
* Enum values could not include x or z, which are explicitly
permitted in the SystemVerilog standard.
After this commit, enum values are serialized as attributes of form
\enum_value_<value>
where <value> is a bit sequence of the appropriate width.
(parameters in systemverilog packages can't actually be overridden, so
allowing parameters in addition to localparams doesn't actually add any
new functionality, but it's useful to be able to use the parameter
keyword also)
Claire Xen
Zachary Snow
Xiretza
Marcelina Kościelnicka
Michael Singer
whitequark
Kamil Rakoczy
clairexen
Udi Finkelstein
Lukasz Dalek
Kazuki Sakamoto
Peter Crozier
Claire Wolf
Eddie Hung
David Shah
Jeff Wang