Add 14 double-cell words to boot.fth: D+, D-, DNEGATE, DABS, D0=, D0<,
D=, D<, D2*, D2/, DMAX, DMIN, M+, DU<.
Phase 3 (SM/REM, FM/MOD, */, */MOD) deferred: these words use DABS which
calls DNEGATE→D+ with return-stack operations. When called from contexts
with 2+ items already on the return stack, the nested >R/>R pattern
causes a silent failure. Root cause needs investigation in the codegen
return-stack handling before these can move to Forth.
All 425 tests pass.
Move to boot.fth: D+, D-, DNEGATE, DABS, D0=, D0<, D=, D<, D2*, D2/,
DMAX, DMIN, M+, DU<.
D+ uses proper carry detection via unsigned comparison after low-cell
addition. All other double-cell words build on D+ and standard Forth
stack operations.
Removed 544 lines of Rust closures. Cumulative: ~1,091 Rust lines removed
across Phases 1-2, replaced by ~80 lines of Forth. All 425 tests pass.
Create boot.fth loaded at startup after IR primitives are compiled.
Forth-compiled WASM with direct calls outperforms host function dispatch
(no call_indirect overhead, Cranelift can inline across word boundaries).
Words moved to Forth: 2OVER, 2ROT, WITHIN, 2@, 2!, FILL, CMOVE, CMOVE>,
MOVE, ERASE, BLANK, /STRING, -TRAILING.
Removed 547 lines of Rust closures, replaced by 48 lines of Forth.
All 425 tests pass.
ok