- Add explicitly handling of A_WIDTH=1 for completeness
- mux2 uses one LUT3 instead of a hard mux (which did use LUTs anyway)
- mux4 uses one LUT4 instead of hard muxes (which did use LUTs anyway)
- mux8 uses only bottom half of a slice
- Add a mux12 for intermediate variant between mux8 and mux16
- For sizes larger than 16 inputs, instantiate the right mux size
- More comments about implementation choices
- More tests including with -widemux and -abc9, and more comments
* verilog: fix string literal regular expression.
A backslash was improperly quoted, causing string literal matching
to fail when the final token before a closing quote was an escaped
backslash.
* verilog: add regression test for string literal regex bug.
Test for bug triggered by escaped backslash immediately before
closing quote (introduced in ca7d94af and fixed by 40aa7eaf).
This is @KrystalDelusion's suggestion in PR #5141 to verify
sensible implementation of all 4 possible full_case/parallel_case
combinations.
(Also including two similar tests to check the Verilog frontend
applies the correct attributes when given SystemVerilog
priority/unique case and if statements.)
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.
