Re: [Iverilog-devel] Crash on invalid indexing of generate block

[Martin W. <mai...@ma...>]

ni...@ly... (Niels Möller) wrote:
> For the attached (broken) code, I get the following error, and a
> segmentation fault. I'm using iverilog compiled from the repo.
>
>    $ iverilog ctz-reduced.vl
>    ctz-reduced.vl:28: error: Scope index expression is not constant: ((n)-(k))-('sd1)
>    ctz-reduced.vl:28: XXXXX: Errors evaluating scope index
>    ctz-reduced.vl:28: error: Scope index expression is not constant: ((n)-(k))-('sd1)
>    ctz-reduced.vl:28: XXXXX: Errors evaluating scope index
>    ctz-reduced.vl:28: error: Unable to bind wire/reg/memory `REDUCE[((n)-(k))-('sd1)].r[('sd2)*(cnt[(n)-('sd1):((n)-(k))+('sd1)])]' in `ctz'
>    Segmentation fault
>
> (I have a working version too, using a second generate block. I wasn't
> sure if that was necessary, but it seems one can't use regular variables
> (i.e., not params or genvar) when indexing generate blocks).
>
Yes, the index must be a constant expression. From the standard:

   hierarchical_identifier ::=
     { identifier [ [ constant_expression ] ] . } identifier

The segfault is poor error recovery, so needs to be fixed.

Martin