The tests/verilog/*_if_enc.ys scripts instantiate simple encoder
modules, both with and without the SystemVerilog priority/unique/unique0
keywords, and check for consistency between the two for the subset
of inputs where the priority/unique/unique0 "if" result is
well-defined.
These tests vacuously succeed at the moment, since priority/unique
keywords are silently ignored and therefore the generated logic is
trivially identical. But the test cases will be capable of detecting
certain types of unsound optimisation if priority/unique handling is
introduced later.
Add support to the "read_verilog -sv" parser to validate the
"unique", "unique0", and "priority" keywords in contexts where
they're legal according to 1800-2012 12.4.2.
This affects only the grammar accepted; the behaviour of conditionals
is not changed. (But accepting this syntax will provide scope for
possible optimisations as future work.)
Three test cases ("unique_if", "unique_if_else", and
"unique_if_else_begin") verify that the keywords are accepted where
legal and rejected where illegal, as described in the final paragraph
of 12.4.2.
The existing access function isn't useful if we don't have access to the original
names of the input/output/state signals. There may be a better way to do this, but
it might require restructuring the SmtrStruct.
Adds a new pass, `splitlarge`, that recursively divides $add/$sub
cells into smaller cells until each cell's width doesn't exceed a
given max_width (128 by default.) An $add/$sub cell's width for
this purpose is defined as the higher of the widths of its two
inputs.
A test was written in Tcl for it, which tests this matrix:
- cell: $add/$sub
- b: unsigned, signed
- a: unsigned, signed
This is the first test for a Silimate pass in Tcl and thus
`run-test.sh` was modified to include it.
