The unique, unique0, and priority keywords can decorate case statements
to tell the run time (or synthesis) to do extra tests (or make extra
assumptions). These tests are not implemented in the vvp run time, but
now the decorations make it to the code generators.
As discussed on iverilog-devel (2018-03-09), the existing implementation
(using Icarus-specific vpi functions) only worked with assignments to
simple variables, and could not be easily modified to work more generally.
So use the new vvp instructions added in the previous two commits.
The signed version of the power operation in vvp should only be used
if the exponent is signed. Both signed and unsigned versions will
produce the correct result regardless of the type of the base operand,
provided it has been appropriately extended to the result size.
SystemVerilog allows a mixture of procedural and continuous assignments
to be applied to different parts of the same vector. The previous attempt
to make this work for non-blocking assignments was flawed (see preceding
fix for vvp_fun_part_pv::recv_vec4_pv). Instead, handle this case by
converting the non-blocking assignment into a delayed force statement,
which matches the way mixed continuous and blocking assignments are
handled.
If all three rise/fall/decay delay values are constant, we can use
the vvp .delay statement variant that takes three literal numbers.
If not, we have to use the variant that takes three net inputs. If
some of the delay values are constant, we need to create constant
drivers for those delay inputs.
The .scope needs to be aware of return types so that the %call/vec4
function knows how to intialize the return value. We also need to
extend the %ret/vec4 to support writing parts of the return value.
When a binary (in)equality comparison has a constant left operand,
the tgt-vvp code generator swaps the left and right operands to
allow the cmpi instruction to be used. The code for swapping the
operands was incorrect.
Create The %callf/* opcodes to invoke user defined functions in a
more specialized way. This allows for some sanity checking on the
way, and also is a step towards keeping return values on stacks.
Stephen Williams
Nick Brereton
Cary R
Martin Whitaker
Scott Mansell
Maciej Suminski
Michele Castellana
Johann Klammer