packu instruction not decoded as illegal when extension RV32B=RV32BBalanced

[esdatmisarian]

Observed Behavior

packu instruction(encoding with 32'h4822c433) is part of Zbp extension.
When excluding Zbp extension RV32B= RV32BBalanced, we expected packu instruction to be flagged as illegal in decoder
It is not the case from what is coded in ibex_decoder module:
...
{7'b010_0100, 3'b100}, // packu
{7'b000_0100, 3'b111}, // packh
// RV32B zbs
{7'b010_0100, 3'b001}, // bclr
{7'b001_0100, 3'b001}, // bset
{7'b011_0100, 3'b001}, // binv
{7'b010_0100, 3'b101}, // bext
// RV32B zbf
{7'b010_0100, 3'b111}: illegal_insn = (RV32B != RV32BNone) ? 1'b0 : 1'b1; // bfp
...

Version of the Ibex source code:

[kliuMsft]

Acknowledged. @marnovandermaas, any comments?

[marnovandermaas]

I think this observation is correct based on the current B ISA extension. This may have been a change since B was added to Ibex, which was before the 1.0 release. We may want to fix this when we review the B-extension in Ibex in the future. @GregAC any further comments on this?