Do jmp condition-suffix mnemonics work?

Tracker: #151 (split from #144) · Marker site: demos/happy-path.a

Question

Appendix B (p.276) of the LCC reference states that jmp uses the same mnemonic suffixes as the branch instructions — implying jmpz, jmpnz, jmpn, jmpp, jmplt, jmpgt, jmpc, jmpb, jmpal, etc. all exist. But the suffixed jmp forms error on assembly in lccjs with Invalid operation. Is that a documentation error, an lccjs gap, or an oracle gap?

Method

Assembled minimal programs using suffixed jmp forms with both lccjs and the reference oracle (cuh63 6.3 lcc, via LCC_ORACLE), e.g.:

        .start main
main:   mvi r0, 5
        jmpz r0
        halt

Result

form	lccjs	oracle (cuh63 6.3)
jmp r0 (plain)	✅ assembles	✅ assembles
jmpz r0	❌ Invalid operation (line 3)	❌ Invalid operation (line 3)
jmpn r0, jmpe r0, …	❌ Invalid operation	❌ Invalid operation

• Identical behaviour: both tools reject every suffixed jmp with the same Invalid operation diagnostic.
• The oracle leaves a 7-byte .e after the errored assembly — that is the documented deviation 10 blank/header-only artifact (OG LCC writes a runnable-looking blank .e even on failed assembly), not a successful assembly of jmpz.
• Static confirmation: src/core/assembler.js recognises jmp (and ret) but has no jmpXX cases — the condition suffixes (z/nz/n/p/lt/gt/c/b/al) belong only to the br family. Any jmpXX token falls through to Invalid operation. Consistent with the ISA: jmp is encoded 1100 000 baser offset6 with no condition-code field (see docs/lcc-isa.md).

Conclusion

Documentation error in Appendix B p.276 — condition-suffixed jmp is not implemented by the LCC architecture as realised in either lccjs or the reference oracle. The conditional-control-flow instruction is br<cc>; jmp is the unconditional register-relative jump.

• Not an lccjs gap: lccjs matches the oracle exactly (both reject identically).
• No assembler change: rejecting jmpXX is correct, parity-preserving behaviour.
• Upstream: worth flagging to the textbook author as a doc erratum, but it does not gate any lccjs work.