Re: [Iverilog-devel] How to get more information when internal errors happen

[Larry D. <ldo...@re...>]

Hi -

To get debug_elaborate turned on without recompiling, do

IVERILOG_ICONFIG=foo.conf iverilog -v -Wall test_tb.v

then add

debug:elaborate

to the resulting foo.conf, and (assuming you don't have any
actual preprocessor activity) rerun the ivl command printed
by the above iverilog -v trace, except ending with test_tb.v
instead of --.  This process is hinted at in the iverilog
man page, in the description of the -v flag.

This particular bug looks like it's in the vvp code generator.
It prints out

L_0x81cde48 .concat [ 4 2 0 0], C4<0000>, L_0x81cdef0;

but the second width (2) should really be 0.
The code that prints the erroneous 2 is in tgt-vvp/vvp_scope.c:1828,
function lpm_concat_inputs().  I didn't trace back width_of_nexus()
yet to see where the bug really is.  The elaborated design itself
looks correct.

   - Larry