b38babb7d6
feat: implement Phase 4d const-fold transform for select AST
...
Adds sel_const_fold_pass() — a single-pass bottom-up const-fold that
runs after the Phase 4c flatten loop in parse_select():
4d-1 EQ/NE with either operand SEL_ANY → SEL_TRUE / SEL_FALSE
(checks both child slots — commutativity sort makes SEL_ANY
position non-deterministic after makeSelectNode interning)
4d-2 Identity laws: TRUE&&X→X, X&&TRUE→X, FALSE||X→X, X||FALSE→X
4d-3 Annihilation laws: FALSE&&X→FALSE, TRUE||X→TRUE (symmetric)
4d-4 Complement laws: !TRUE→FALSE, !FALSE→TRUE
Memory semantics:
level==0 (API server): frees orphaned nodes via free_select_node /
sel_free_tree; OOM from makeSelectNode returns original node safely
level>0 (CSE/scheduler): never manually frees; annihilation folds
return the already-interned left/right singleton directly (no
redundant makeSelectNode call); OOM guard unconditional so CSE
mode also degrades gracefully instead of returning NULL
9 new TDD tests added to test_select.c (RED→GREEN verified).
All 166 tests pass (157 prior + 9 Phase 4d).
2026-04-29 08:24:04 +00:00
