0.31.0–0.32.0 — Odds, Ends, and Overflow Safety

Two short versions closed out gaps that had been quietly accumulating: missing trivial instructions, and unchecked signed-integer overflow in constant folding.

0.31.0 — HALT and PAUSE

cc2b435 — Bump version to 0.31.0; add operand-free HALT and PAUSE instructions with tests added the simplest possible instruction shape: opcodes with no operands at all.

The interesting detail is pause: it’s a two-byte sequence (F3 90), and the decoder has to recognize it as a whole before falling through to treating 90 as a bare nop-shaped byte it doesn’t otherwise understand. Getting the order of decoder checks right — multi-byte sequences before single-byte fallbacks — is a small but real source of bugs in any byte-pattern decoder, and this version’s test checks both the binary and the decoded listing together to guard against it.

0.32.0 — Constant folding stops trusting signed overflow

e5805ad — Bump version to 0.32.0; implement overflow-safe arithmetic for constant expressions with tests replaced unchecked signed long long arithmetic in constant folding with checked addition, subtraction, and multiplication, ahead of Kasm’s existing signed-32-bit language limit. This closed a real correctness gap flagged during project review: signed integer overflow is undefined behavior in C, and the previous folding logic could overflow before the 32-bit range check ever ran, meaning the check itself couldn’t be trusted for large enough inputs. The fix checks for overflow at each individual operation, not just at the end result, and the regression test explicitly exercises overflowing addition, subtraction, and multiplication, alongside the existing precedence test.

Neither of these versions is glamorous, but they’re the kind of maintenance that has to happen between “add a new instruction” milestones — closing a decoder ordering gap and an undefined-behavior gap before building the next major feature (COFF object output) on top of a semantic layer that folds expressions correctly.