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Wilson Snyder 2021-04-05 20:04:41 -04:00
parent a29ac44af9
commit efc116323b
1 changed files with 12 additions and 0 deletions
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@ -4507,6 +4507,11 @@ likely all of them are oscillating. It may also be that e.g. "a" may be
oscillating, then "a" feeds signal "c" which then is also reported as oscillating, then "a" feeds signal "c" which then is also reported as
oscillating. oscillating.
One way DIDNOTCONVERGE may occur is flops are built out of gate primitives.
error. Verilator does not support building flops or latches out of gate
primitives, and any such code must change to use behavioral constructs
(e.g. always_ff and always_latch).
Finally, rare, more difficult cases can be debugged like a "C" program; Finally, rare, more difficult cases can be debugged like a "C" program;
either enter GDB and use its tracing facilities, or edit the generated C++ either enter GDB and use its tracing facilities, or edit the generated C++
code to add appropriate prints to see what is going on. code to add appropriate prints to see what is going on.
@ -5012,6 +5017,13 @@ being generated from an always statement that consumed high bits of the
same bus processed by another series of always blocks. The fix is the same bus processed by another series of always blocks. The fix is the
same; split it into two separate signals generated from each block. same; split it into two separate signals generated from each block.
Occasionally UNOPTFLAT may be indicated when there is a true circulation.
e.g. if trying to implement a flop or latch using individual gate
primitives. If UNOPTFLAT is suppressed the code may get a DIDNOTCONVERGE
error. Verilator does not support building flops or latches out of gate
primitives, and any such code must change to use behavioral constructs
(e.g. always_ff and always_latch).
Another way to resolve this warning is to add a C<split_var> metacomment Another way to resolve this warning is to add a C<split_var> metacomment
described above. This will cause the variable to be split internally, described above. This will cause the variable to be split internally,
potentially resolving the conflict. If you run with --report-unoptflat potentially resolving the conflict. If you run with --report-unoptflat