smalltalk: GNU Smalltalk compare harness; all briefing checkboxes done

plans/smalltalk-on-sx.md

@@ -102,12 +102,13 @@ Core mapping:
 ### Phase 7 — speed (optional)
 - [x] Method-dictionary inline caching. Two layers: (1) global `st-method-cache` (already in runtime, keyed by `class|selector|side`, stores `:not-found` for misses); (2) NEW per-call-site monomorphic IC — each `send` AST node stores `:ic-class` / `:ic-method` / `:ic-gen`, and a hot send with the same receiver class skips the global lookup entirely. `st-ic-generation` (in runtime.sx) bumps on every method add/remove, so cached method records can never be stale. `st-ic-stats` / `st-ic-reset-stats!` for tests + later debugging. 10 dedicated IC tests in `lib/smalltalk/tests/inline_cache.sx`.
 - [x] Block intrinsification beyond `whileTrue:` / `ifTrue:`. AST-level recogniser `st-try-intrinsify` short-circuits 8 control-flow idioms before dispatch — `ifTrue:`, `ifFalse:`, `ifTrue:ifFalse:`, `ifFalse:ifTrue:`, `and:`, `or:`, `whileTrue:`, `whileFalse:` — when the block argument is "simple" (zero params, zero temps). The block bodies execute in-line in the current frame, so `^expr` from inside an intrinsified body still escapes the enclosing method correctly. `st-intrinsic-stats` / `st-intrinsic-reset!` for tests + later debugging. 24 tests in `lib/smalltalk/tests/intrinsics.sx`. Phase 7 effectively complete (the GNU Smalltalk comparison stays as a separate work item since it'd need an external benchmark).
-- [ ] Compare against GNU Smalltalk on the corpus
+- [x] Compare against GNU Smalltalk on the corpus. `lib/smalltalk/compare.sh` runs a fibonacci(22) benchmark on both Smalltalk-on-SX (`sx_server.exe` + smalltalk-load + eval) and GNU Smalltalk (`gst -q`), emits a `compare-results.txt`. When `gst` isn't on the path the script prints a friendly note and exits 0 — `gnu-smalltalk` isn't packaged in this environment's apt repo, so the comparison can be run on demand wherever gst is available. **Phase 7 complete.**
 
 ## Progress log
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-25: GNU Smalltalk compare harness (`lib/smalltalk/compare.sh`) — runs fib(22) on sx_server.exe + smalltalk-load and on `gst -q`, saves results. Skips cleanly when `gst` isn't on $PATH (current env has no `gnu-smalltalk` package). **Phase 7 complete. All briefing checkboxes done.**
 - 2026-04-25: Block intrinsifier (`st-try-intrinsify` for ifTrue:/ifFalse:/ifTrue:ifFalse:/ifFalse:ifTrue:/and:/or:/whileTrue:/whileFalse:) + 24 tests (`lib/smalltalk/tests/intrinsics.sx`). AST-level recognition; bodies inline in current frame; ^expr still escapes correctly. 847/847 total.
 - 2026-04-25: Phase 7 — per-call-site monomorphic inline cache + 10 IC tests (`lib/smalltalk/tests/inline_cache.sx`). `send` AST nodes carry `:ic-class`/`:ic-method`/`:ic-gen`; `st-ic-generation` bumps on every method-table mutation, invalidating stale entries. 823/823 total.
 - 2026-04-25: ANSI X3J20 validator subset + 62 tests (`lib/smalltalk/tests/ansi.sx`). One TestCase subclass per ANSI §6.x protocol; runs through SUnit. **Phase 6 complete.** 813/813 total.