diff --git a/tools/anki_data.yaml b/tools/anki_data.yaml new file mode 100644 index 0000000..d7f9e77 --- /dev/null +++ b/tools/anki_data.yaml @@ -0,0 +1,718 @@ +# WAFER Anki Card Data +# Hand-crafted cards for architecture, design decisions, and "why" questions. +# Auto-generated cards (IrOp variants, memory addresses, etc.) are created by anki_gen.py. + +# ============================================================================ +# CATEGORY A: Architecture +# ============================================================================ +architecture: + + - front: "What are the 5 stages of the WAFER compilation pipeline?" + back: "Forth Source → Outer Interpreter (tokenize + dispatch) → IR (Vec) → Optimizer (6 passes) → WASM Codegen (wasm-encoder) → wasmtime execution" + code: | + // lib.rs doc comment: + // Forth Source -> Outer Interpreter -> IR -> Optimize -> WASM Codegen + source: "crates/core/src/lib.rs:9" + tags: [architecture, basic] + + - front: "What crate does WAFER use to generate WASM bytecode?" + back: "`wasm-encoder` — builds WASM modules programmatically (types, imports, functions, code sections). NOT a text-format assembler." + source: "crates/core/src/codegen.rs:12" + tags: [architecture, basic] + + - front: "What crate does WAFER use to execute WASM modules?" + back: "`wasmtime` — Bytecode Alliance WASM runtime. Provides Engine, Store, Module, Instance, Memory, Global, Table, Func." + source: "crates/core/src/outer.rs:14" + tags: [architecture, basic] + + - front: "How many source files are in wafer-core? Name them." + back: "12 files: outer.rs (9820), codegen.rs (4205), optimizer.rs (1013), dictionary.rs (906), export.rs (409), runner.rs (402), ir.rs (259), consolidate.rs (169), memory.rs (148), error.rs (84), config.rs (61), lib.rs (28), js_loader.rs (163)" + tags: [architecture, basic] + + - front: "What is the relationship between a Forth word and a WASM module in WAFER?" + back: "Each compiled Forth word becomes its own WASM module with one function. Modules share memory, globals (dsp/rsp/fsp), and a function table via wasmtime imports. Words call each other via call_indirect through the shared table." + tags: [architecture, intermediate] + + - front: "What are the 6 imports every WAFER WASM module expects?" + back: | + 1. emit (func: i32 → void) — character output callback + 2. memory (16 pages = 1 MiB) — shared linear memory + 3. dsp (global mut i32) — data stack pointer + 4. rsp (global mut i32) — return stack pointer + 5. fsp (global mut i32) — float stack pointer + 6. table (funcref) — shared function table for call_indirect + source: "crates/core/src/codegen.rs:25-41" + tags: [architecture, intermediate] + + - front: "What are the 3 types of words in WAFER?" + back: | + 1. IR primitives — compiled to WASM via Vec, inlineable (DUP, +, @) + 2. Host functions — Rust closures in wasmtime, NOT inlineable (., .S, M*, ACCEPT) + 3. Forth-defined words — compiled by outer interpreter (: SQUARE DUP * ;) + source: "crates/core/src/outer.rs:2422-2478" + tags: [architecture, basic] + + - front: "What is the role of outer.rs in WAFER?" + back: "Contains ForthVM — the complete Forth virtual machine, generic over execution backend. Outer interpreter (tokenize → lookup → interpret/compile), all primitive registration, control-flow compilation, DOES> support. 8703 lines." + source: "crates/core/src/outer.rs:1" + tags: [architecture, basic] + + - front: "What is the Runtime trait and why does it exist?" + back: | + Defined in runtime.rs. Abstracts over WASM execution backends: + - Memory r/w (mem_read_i32, mem_write_slice, etc.) + - Globals (get/set_dsp, rsp, fsp) + - Table (table_size, ensure_table_size) + - Module lifecycle (instantiate_and_install, call_func) + - Host functions (register_host_func) + Two implementations: NativeRuntime (wasmtime), WebRuntime (js-sys). + ForthVM is completely decoupled from any specific WASM engine. + source: "crates/core/src/runtime.rs:72" + tags: [architecture, intermediate] + + - front: "What is HostAccess and how is it used?" + back: | + Trait for memory/global access from within host function callbacks. + Methods: mem_read_i32, mem_write_i32, mem_read_u8, mem_write_u8, mem_read_slice, mem_write_slice, mem_len, get/set_dsp, get/set_rsp, get/set_fsp, call_func. + NativeRuntime implements it via CallerHostAccess (wrapping wasmtime::Caller). + WebRuntime implements it via WebHostAccess (wrapping js_sys typed arrays). + HostFn = Box Result<()>> — same closure works on both runtimes. + source: "crates/core/src/runtime.rs:17" + tags: [architecture, intermediate] + + - front: "What are the 3 crates in the WAFER workspace?" + back: | + 1. wafer-core — compiler, optimizer, codegen, dictionary, Runtime trait, outer interpreter + Feature flags: default=["native"], "native" enables wasmtime + 2. wafer (cli) — CLI REPL (rustyline), wafer build/run commands + 3. wafer-web — browser REPL (wasm-bindgen + WebRuntime + HTML/CSS/JS frontend) + source: "Cargo.toml workspace" + tags: [architecture, basic] + + - front: "What is NativeRuntime?" + back: | + Wasmtime-based implementation of Runtime trait (runtime_native.rs, 328 lines). + Owns: Engine, Store, Memory, Table, Globals (dsp/rsp/fsp), emit_func. + instantiate_and_install: Module::new + Instance::new with 6 imports. + register_host_func: creates wasmtime Func that bridges HostFn → CallerHostAccess. + Behind "native" feature flag. + source: "crates/core/src/runtime_native.rs:107" + tags: [architecture, intermediate] + + - front: "What is WebRuntime?" + back: | + Browser-based implementation of Runtime trait (crates/web/runtime_web.rs, 542 lines). + Uses js_sys::WebAssembly for module instantiation. + Memory: JsValue wrapping WebAssembly.Memory, accessed via Int32Array/Uint8Array views. + Globals: JsValue wrapping WebAssembly.Global objects. + Host functions: JS closures created via Closure::wrap, stored in _closures Vec to prevent GC. + Runs entirely in the browser — no wasmtime dependency. + source: "crates/web/src/runtime_web.rs:12" + tags: [architecture, intermediate] + + - front: "What is WaferRepl?" + back: | + The wasm-bindgen entry point in crates/web/src/lib.rs. + Wraps ForthVM. + Methods: new() (create VM), evaluate(input) (returns output), data_stack(), is_compiling(), reset(). + Built with: wasm-pack build --target web --out-dir www/pkg + source: "crates/web/src/lib.rs:13" + tags: [architecture, intermediate] + + - front: "What feature flags does wafer-core have?" + back: | + default = ["native"] + native — enables dep:wasmtime and all native-only modules: + runtime_native.rs, runner.rs, export.rs, consolidate.rs, js_loader.rs + Without "native" — pure Rust only: dictionary, IR, optimizer, codegen, outer interpreter, runtime trait. + wafer-web uses wafer-core without "native" feature. + source: "crates/core/Cargo.toml:11-12" + tags: [architecture, intermediate] + + - front: "What is the role of codegen.rs?" + back: "Translates optimized IR (Vec) to WASM bytecode using wasm-encoder. Handles DSP caching, scratch locals, stack-to-local promotion. Builds complete WASM modules including imports, types, function sections." + source: "crates/core/src/codegen.rs:1" + tags: [architecture, basic] + + - front: "What is batch_mode in ForthVM and why does it exist?" + back: "During boot (register_primitives), batch_mode=true defers WASM compilation. All ~40 IR primitives are collected, then compiled into a single WASM module via compile_batch(). This amortizes runtime compilation overhead — one rt.instantiate_and_install() instead of 40." + code: | + self.batch_mode = true; + // ... register all primitives ... + // deferred_ir.push((word_id, ir_body)); + self.compile_batch()?; + source: "crates/core/src/outer.rs" + tags: [architecture, advanced] + +# ============================================================================ +# CATEGORY B: Design Decisions ("Why" cards) +# ============================================================================ +design_decisions: + + - front: "Why does each Forth word compile to its own WASM module?" + back: | + 1. Incremental compilation: defining a new word doesn't recompile anything + 2. Isolation: each word is independently validated by wasmtime + 3. wasmtime linking model: modules share imports (memory, globals, table) + 4. REPL-friendly: immediate feedback, no whole-program recompile + Trade-off: call_indirect overhead between words (mitigated by CONSOLIDATE) + tags: [design, advanced] + + - front: "Why use an IR instead of compiling Forth directly to WASM?" + back: | + 1. Optimization: IR enables peephole, constant folding, inlining, DCE, tail calls + 2. Separation of concerns: outer interpreter doesn't need to know WASM encoding + 3. Portability: IR could target other backends + 4. Testability: IR is easy to inspect and test + 5. Consolidation: IR bodies are stored for later recompilation into single module + tags: [design, advanced] + + - front: "Why does WAFER use wasm-encoder + wasmtime instead of Cranelift directly?" + back: | + 1. Standard WASM: output is valid .wasm, can run in browsers AND natively + 2. Runtime abstraction: same WASM bytes work on wasmtime (CLI) and browser (js-sys) + 3. wasmtime handles Cranelift internally — best JIT performance for free + 4. Portability: WASM is platform-independent + 5. Validation: wasmtime validates modules, catching codegen bugs + 6. wasm-encoder is simple: just build bytes, no complex IR + tags: [design, advanced] + + - front: "Why was the Runtime trait introduced?" + back: | + To support the browser REPL without duplicating the entire ForthVM. + Before: ForthVM directly owned wasmtime types (Engine, Store, Memory, etc.) + After: ForthVM is generic — same compiler code works with: + - NativeRuntime (wasmtime) for CLI/tests/AOT + - WebRuntime (js-sys) for browser + Host functions use HostFn = Box — one closure definition serves both runtimes. + The refactor extracted ~1100 lines of wasmtime-specific code from outer.rs into runtime_native.rs. + tags: [design, advanced] + + - front: "Why are stacks in linear memory instead of WASM locals?" + back: | + Default: stacks live in linear memory (data stack at 0x0600, grows down). + Reason: Forth semantics require stack introspection (DEPTH, PICK, SP@), which WASM locals can't provide. + Optimization: stack-to-local promotion lifts values into WASM locals when the compiler can prove stack depth is statically known (no calls, no SP@). Best of both worlds. + tags: [design, advanced] + + - front: "Why is the DSP cached in a WASM local?" + back: | + The data stack pointer (dsp) is a wasmtime global. Globals are slower than locals. So: + 1. At function entry: local.get $dsp_global → local.set $cached_dsp + 2. During function: all stack ops use local $cached_dsp + 3. Before calls: write back local → global (callee needs correct dsp) + 4. After calls: reload local from global (callee may have changed dsp) + 5. At function exit: write back + Net effect: most operations avoid global access overhead. + code: | + const CACHED_DSP_LOCAL: u32 = 0; + fn dsp_writeback(f) { local.get 0; global.set $dsp } + fn dsp_reload(f) { global.get $dsp; local.set 0 } + source: "crates/core/src/codegen.rs:56-181" + tags: [design, advanced] + + - front: "Why does boot.fth replace Rust host functions with Forth definitions?" + back: | + 1. Self-hosting goal: maximize Forth, minimize Rust + 2. Performance: compiled Forth with inlining + optimization beats host function dispatch (call_indirect → Rust closure has overhead) + 3. Inlinability: Forth definitions have IR bodies that the optimizer can inline; host functions cannot be inlined + 4. Consolidation: Forth words participate in single-module recompilation (direct calls); host functions always use call_indirect + source: "crates/core/boot.fth:1-3" + tags: [design, advanced] + + - front: "Why does WAFER use -1 (all bits set) for TRUE instead of 1?" + back: | + Forth 2012 standard: TRUE = -1 (0xFFFFFFFF). All bits set. + Reason: allows bitwise AND as a conditional select: flag AND value. + If TRUE were 1, AND would only preserve the lowest bit. + With -1: TRUE AND x = x (identity). FALSE AND x = 0. + code: | + // In codegen, bool_to_forth_flag: + // 0 - result: if result=1 => -1, if result=0 => 0 + f.instruction(&I32Const(0)); + f.instruction(&LocalGet(tmp)); + f.instruction(&I32Sub); + source: "crates/core/src/codegen.rs:214-222" + tags: [design, intermediate] + + - front: "Why does the optimizer run peephole 5 times across the pipeline?" + back: | + Each optimization pass can create new peephole opportunities: + - After inline: inlined body may have adjacent ops that simplify + - After constant fold: folded constants may create identity patterns (PushI32(0), Add) + - After strength reduce: new patterns from reduced ops + - After DCE: dead code removal may leave adjacent simplifiable ops + The peephole pass itself runs to fixpoint (inner loop), but the outer pipeline runs it 5 times at different stages. + code: | + // Phase 1: peephole → fold → strength → peephole + // Phase 2: inline → peephole → fold → strength → peephole + // Phase 3: dce → peephole + // Phase 4: tail_call + source: "crates/core/src/optimizer.rs:37-85" + tags: [design, advanced] + + - front: "Why is tail call detection the LAST optimizer pass?" + back: | + 1. TailCall emits WASM `return` after the call — if inlining converts TailCall back to Call (detailcall), early tail-call detection is wasted + 2. DCE might eliminate the tail position entirely + 3. Need return-stack balance check on FINAL IR, not intermediate + 4. Inlining must happen first so we know which calls remain + source: "crates/core/src/optimizer.rs:79-84" + tags: [design, advanced] + + - front: "Why can't words with Exit be inlined?" + back: | + WASM `return` exits the CURRENT function. If an inlined word contains Exit (→ return), it would exit the CALLER's function, not just the inlined code. There's no 'return from inline' in WASM. The contains_exit() guard prevents this. + code: | + fn contains_exit(ops: &[IrOp]) -> bool { + // Also blocks ForthLocalGet/Set — would collide with caller's locals + matches!(op, IrOp::Exit | IrOp::ForthLocalGet(_) | IrOp::ForthLocalSet(_)) + } + source: "crates/core/src/optimizer.rs:633-664" + tags: [design, advanced] + + - front: "Why does CONSOLIDATE exist?" + back: | + Normal JIT: each word = separate module, calls via call_indirect (table lookup). + CONSOLIDATE: merges all JIT-compiled words into ONE module. + - call_indirect → direct `call` (for words in the module) + - wasmtime can optimize across call boundaries + - ~2-3x speedup for call-heavy code + External calls (host functions) remain call_indirect. + source: "crates/core/src/consolidate.rs:1-9" + tags: [design, advanced] + + - front: "Why does WAFER use a linked list for the dictionary instead of a hash map?" + back: | + 1. Forth standard specifies linked-list traversal semantics (TRAVERSE-WORDLIST) + 2. Dictionary lives in linear memory (simulates WASM memory layout) + 3. Standard requires specific entry format (link + flags + name + code field) + BUT: WAFER also has a HashMap index for O(1) fast-path lookup, falling back to linked-list walk for words not yet indexed. Best of both worlds. + source: "crates/core/src/dictionary.rs:10-48" + tags: [design, intermediate] + + - front: "Why does WAFER store Forth flags as -1/0 instead of 1/0 in comparisons?" + back: | + Forth 2012 standard requires: TRUE = -1 (all bits set), FALSE = 0. + WASM comparisons produce 0/1, so codegen must convert: + bool_to_forth_flag: 0 - result → -1 if true, 0 if false + This is a single i32.sub instruction (cheap). + tags: [design, intermediate] + +# ============================================================================ +# CATEGORY C: ForthVM Struct +# ============================================================================ +forthvm: + + - front: "What is `user_here` in ForthVM?" + back: "Pointer to next free address in WASM linear memory for user data (variables, CREATE'd words). Separate from dictionary.here() which tracks dictionary-internal allocation. Synced to SYSVAR_HERE (memory offset 12) before each evaluate call." + source: "crates/core/src/outer.rs:212" + tags: [forthvm, intermediate] + + - front: "What is `ir_bodies` in ForthVM?" + back: "HashMap> — stores the optimized IR body of every compiled word. Used by: (1) optimizer's inline pass to look up callee bodies, (2) CONSOLIDATE to recompile everything, (3) wafer build to export." + source: "crates/core/src/outer.rs:243" + tags: [forthvm, intermediate] + + - front: "What is the `control_stack` in ForthVM?" + back: "Vec — compile-time stack for nested control flow. IF pushes ControlEntry::If, DO pushes ControlEntry::Do, etc. THEN/LOOP/REPEAT pop and emit the corresponding IrOp. Not the runtime return stack — this is purely compile-time." + source: "crates/core/src/outer.rs:197" + tags: [forthvm, intermediate] + + - front: "What is `pending_actions` in ForthVM?" + back: "Arc>> — queue of actions from host functions that need compiler-side processing. Used by COMPILE, (CompileCall), CS-PICK, CS-ROLL, and POSTPONE of control-flow words. Processed after immediate word returns." + source: "crates/core/src/outer.rs:229" + tags: [forthvm, advanced] + + - front: "What is `pending_define` in ForthVM?" + back: "Arc>> — signals from host functions to the outer interpreter: 1=CONSTANT, 2=VARIABLE, 3=CREATE, 4=EVALUATE. Host function sets the code, outer interpreter reads it after execution and performs the action." + source: "crates/core/src/outer.rs:227" + tags: [forthvm, advanced] + + - front: "What does `does_definitions` store?" + back: "HashMap — for each DOES>-based defining word, stores: create_ir (code before DOES>), does_action_id (WordId of code after DOES>), has_create flag. Used when the defining word executes to set up new instances." + source: "crates/core/src/outer.rs:216" + tags: [forthvm, advanced] + + - front: "What happened to the `emit_func` field in ForthVM?" + back: "It moved into the Runtime implementation. NativeRuntime owns emit_func as a wasmtime::Func. WebRuntime creates it as a JS closure. ForthVM no longer directly holds wasmtime types — it only interacts via the Runtime trait." + source: "crates/core/src/runtime_native.rs:116" + tags: [forthvm, intermediate] + + - front: "What are `two_value_words` and `fvalue_words`?" + back: "HashSet tracking which word IDs are 2VALUEs or FVALUEs. TO needs to know: regular VALUE stores 1 cell, 2VALUE stores 2 cells, FVALUE stores 1 float (8 bytes). Without these sets, TO wouldn't know the storage semantics." + source: "crates/core/src/outer.rs:237-239" + tags: [forthvm, advanced] + + - front: "How many fields does ForthVM have? Name the major groups." + back: | + ~35 fields in 7 groups: + 1. Runtime: rt: R (generic — replaces old engine/store/memory/table/dsp/rsp/fsp/emit_func) + 2. Compilation: state, compiling_name, compiling_ir, control_stack, compiling_word_id, compiling_locals + 3. Output: output (Arc>) + 4. Dictionary bridge: dictionary, user_here, here_cell, base_cell + 5. Word metadata: ir_bodies, host_word_names, word_pfa_map, does_definitions + 6. Host function shared state: pending_define, pending_actions, pending_does_patch, throw_code, word_lookup + 7. Config + advanced: config, batch_mode, deferred_ir, marker_states, conditional_skip_depth, substitutions, search_order, next_wid, toplevel_ir + source: "crates/core/src/outer.rs:173-260" + tags: [forthvm, advanced] + +# ============================================================================ +# CATEGORY D: Codegen Details +# ============================================================================ +codegen: + + - front: "What WASM local index is the cached DSP?" + back: "Local 0 (CACHED_DSP_LOCAL). At function entry: global.get $dsp → local.set 0. All stack ops use local 0. Scratch locals start at SCRATCH_BASE = 1." + source: "crates/core/src/codegen.rs:58-61" + tags: [codegen, basic] + + - front: "What does `dsp_writeback` do and when is it called?" + back: "Writes the cached DSP local back to the $dsp global: `local.get 0; global.set $dsp`. Called before: (1) call_indirect/call (callee needs correct dsp), (2) function exit (return)." + code: | + fn dsp_writeback(f: &mut Function) { + f.instruction(&LocalGet(CACHED_DSP_LOCAL)) + .instruction(&GlobalSet(DSP)); + } + source: "crates/core/src/codegen.rs:167-173" + tags: [codegen, intermediate] + + - front: "How does codegen emit IrOp::Dup?" + back: | + Dup = peek top of stack, push copy: + 1. peek(f): local.get $dsp; i32.load (value now on WASM operand stack) + 2. push_via_local(f, SCRATCH_BASE): local.set $tmp; dsp_dec; local.get $dsp; local.get $tmp; i32.store + source: "crates/core/src/codegen.rs:359-362" + tags: [codegen, intermediate] + + - front: "How does codegen emit IrOp::Call(id)?" + back: | + 1. dsp_writeback (callee needs correct dsp) + 2. If id == self_word_id (self-recursion): emit direct `call WORD_FUNC` + 3. Else: i32.const fn_index; call_indirect (type_void, table 0) + 4. dsp_reload (callee may have changed dsp) + source: "crates/core/src/codegen.rs (emit_op Call branch)" + tags: [codegen, intermediate] + + - front: "What is EmitCtx and what fields does it have?" + back: | + Carries context for WASM code emission: + - f64_local_0, f64_local_1: scratch locals for float ops + - forth_local_base: base WASM local for Forth locals ({: ... :}) + - loop_local_base: base local for DO/LOOP index/limit pairs + - loop_locals: Vec<(index_local, limit_local)> stack for nested loops + - fast_loop_depth: nesting depth of loops using local fast path + - self_word_id: Option for self-recursion detection + - open_blocks: Vec for flat forward branches (CS-ROLL) + source: "crates/core/src/codegen.rs:229-250" + tags: [codegen, advanced] + + - front: "What are TYPE_VOID and TYPE_I32 in codegen?" + back: "Type section indices: TYPE_VOID=0 is () → () (used by most word functions and call_indirect), TYPE_I32=1 is (i32) → () (used by the emit import function)." + source: "crates/core/src/codegen.rs:44-45" + tags: [codegen, basic] + + - front: "How does the codegen handle DO/LOOP?" + back: | + Fast path: index and limit stored in WASM locals (no return stack). + - DO: pop limit and index from data stack into locals + - Loop body: I (RFetch) reads from index local + - LOOP: increment index local, compare with limit, br_if to loop start + - LEAVE: set SYSVAR_LEAVE_FLAG, break out of loop + Fallback: if loop is too complex, use return stack (rpush/rpop). + source: "crates/core/src/codegen.rs (DoLoop handling)" + tags: [codegen, advanced] + +# ============================================================================ +# CATEGORY E: Boot.fth +# ============================================================================ +boot_fth: + + - front: "What are the 7 phases of boot.fth?" + back: | + 1. Stack/memory: DEPTH, PICK, 2OVER, 2ROT, WITHIN, 2@, 2!, FILL, CMOVE, MOVE, ERASE, /STRING, -TRAILING + 2. Double-cell arithmetic: D+, DNEGATE, D-, DABS, D0=, D0<, D=, D<, D2*, D2/, DMAX, DMIN, M+, DU< + 3. Mixed arithmetic: SM/REM, FM/MOD, */, */MOD + 4. HERE and ALIGNED: HERE, ALLOT, comma, C-comma, ALIGN + 5. I/O + pictured numeric output: TYPE, SPACES, <# HOLD HOLDS SIGN # #S #> . U. .R U.R D. D.R + 6. DEFER support: DEFER!, DEFER@ + 7. String ops + misc: COMPARE, -TRAILING, SOURCE, FALIGNED, SFALIGNED, DFALIGNED + source: "crates/core/boot.fth" + tags: [boot, intermediate] + + - front: "How is DEPTH defined in boot.fth and why?" + back: | + : DEPTH SP@ 5632 SWAP - 2 RSHIFT ; + 5632 = DATA_STACK_TOP (0x1600). Stack grows down, so depth = (top - sp) / 4. + SP@ must come first — it reads dsp BEFORE DEPTH's own literal pushes affect it. + 2 RSHIFT = divide by 4 (arithmetic right shift, CELL_SIZE=4). + code: | + : DEPTH SP@ 5632 SWAP - 2 RSHIFT ; + source: "crates/core/boot.fth:12" + tags: [boot, intermediate] + + - front: "What magic numbers appear in boot.fth and what do they mean?" + back: | + 5632 (0x1600) = DATA_STACK_TOP + 1472 (0x05C0) = PICT_BUF_TOP (also WORD_BUF_BASE) + 12 = SYSVAR_HERE offset + 28 = SYSVAR_HLD offset + 64 = INPUT_BUFFER_BASE + 24 = SYSVAR_NUM_TIB offset + source: "crates/core/boot.fth" + tags: [boot, intermediate] + + - front: "How does pictured numeric output work in boot.fth?" + back: | + <# initializes HLD to PICT_BUF_TOP (1472) + HOLD decrements HLD and stores a character (grows downward) + # extracts one digit: divides ud by BASE via two UM/MODs, converts digit to ASCII, HOLDs it + #S calls # repeatedly until ud is zero + #> returns (c-addr u) pointing to the formatted string in the pictured buffer + SIGN adds '-' if the original number was negative + code: | + : <# 1472 28 ! ; + : HOLD 28 @ 1- DUP 28 ! C! ; + : # BASE @ >R 0 R@ UM/MOD R> SWAP >R UM/MOD + SWAP DUP 9 > IF 7 + THEN 48 + HOLD R> ; + source: "crates/core/boot.fth:193-224" + tags: [boot, advanced] + + - front: "Why is . (dot) defined in Forth instead of as a Rust host function?" + back: | + : . DUP ABS 0 <# #S ROT SIGN #> TYPE SPACE ; + 1. Self-hosting goal: Forth definitions > Rust + 2. Compiled Forth with inlining beats host function dispatch + 3. . becomes inlineable (IR body available to optimizer) + 4. Participates in CONSOLIDATE (direct calls in single module) + 5. Respects BASE correctly via pictured numeric output + source: "crates/core/boot.fth:228" + tags: [boot, advanced] + +# ============================================================================ +# CATEGORY F: Testing & CLI +# ============================================================================ +testing: + + - front: "What are eval_output and eval_stack test helpers?" + back: | + eval_output("forth code") → creates ForthVM, evaluates code, returns output String + eval_stack("forth code") → creates ForthVM, evaluates code, returns data stack as Vec + Both create a fresh VM for each test (isolated). + source: "crates/core/src/outer.rs (test module)" + tags: [testing, basic] + + - front: "How does the compliance test infrastructure work?" + back: | + 1. boot_with_prerequisites(): create VM, load tester.fr, core.fr, utilities.fth, coreexttest.fth + 2. run_suite(vm, file): reset #ERRORS to 0, load test file, read #ERRORS from data stack + 3. Assert #ERRORS == 0 for pass + 4. 11 word sets tested: Core, Core+, CoreExt, Double, Exception, Facility, File, Float, Locals, Memory, String + source: "crates/core/tests/compliance.rs" + tags: [testing, intermediate] + + - front: "What are the 4 ways to run WAFER?" + back: | + 1. `wafer` — interactive CLI REPL (rustyline, NativeRuntime) + 2. `wafer file.fth` — evaluate file and exit (NativeRuntime) + 3. `wafer build file.fth` — compile to .wasm or --native executable + 4. Browser REPL — wasm-pack build crates/web, serve www/, WebRuntime + Also: `wafer run file.wasm` — execute pre-compiled module + source: "crates/cli/src/main.rs:58-83" + tags: [cli, basic] + + - front: "How does the native executable trick work (wafer build --native)?" + back: | + 1. AOT-compile WASM via wasmtime Engine::precompile_module() + 2. Read current wafer binary + 3. Append: [wafer binary] + [precompiled payload] + [metadata JSON] + [24-byte trailer] + 4. Trailer: payload_len(8) + metadata_len(8) + "WAFEREXE"(8) + 5. On startup, check_embedded_payload() reads trailer, extracts payload, runs it + code: | + const NATIVE_MAGIC: &[u8; 8] = b"WAFEREXE"; + const TRAILER_SIZE: u64 = 24; + source: "crates/cli/src/main.rs:12-14" + tags: [cli, advanced] + +# ============================================================================ +# CATEGORY G: Control Flow Compilation +# ============================================================================ +control_flow: + + - front: "Name all 13 ControlEntry variants." + back: | + If, IfElse, Do, Begin, BeginWhile, BeginWhileWhile, + PostDoubleWhileRepeat, PostDoubleWhileRepeatElse, + Case, Of, QDo, Ahead, BeginRef, ForwardBlock + source: "crates/core/src/outer.rs:36-105" + tags: [control_flow, advanced] + + - front: "How does IF...ELSE...THEN compile?" + back: | + 1. IF: push ControlEntry::If { then_body: [] }; subsequent IR goes to then_body + 2. ELSE: pop If, push ControlEntry::IfElse { then_body, else_body: [] }; subsequent IR goes to else_body + 3. THEN: pop IfElse (or If), emit IrOp::If { then_body, else_body } + The IR is a tree — nested bodies, not flat branches. + tags: [control_flow, intermediate] + + - front: "How does DO...LOOP compile?" + back: | + 1. DO: push ControlEntry::Do { body: [] }; subsequent IR goes to body + 2. LOOP: pop Do, emit IrOp::DoLoop { body, is_plus_loop: false } + 3. +LOOP: same but is_plus_loop: true + The limit and index are expected on the data stack before the DoLoop executes. + tags: [control_flow, intermediate] + + - front: "How does BEGIN...WHILE...REPEAT compile?" + back: | + 1. BEGIN: push ControlEntry::Begin { body: [] } + 2. WHILE: pop Begin, push ControlEntry::BeginWhile { test: body, body: [] } + (everything before WHILE becomes the test) + 3. REPEAT: pop BeginWhile, emit IrOp::BeginWhileRepeat { test, body } + tags: [control_flow, intermediate] + + - front: "What is CASE...OF...ENDOF...ENDCASE compilation?" + back: | + 1. CASE: push ControlEntry::Case { prefix, endof_branches: [] } + 2. OF: duplicate test value, compare, pop Case, push ControlEntry::Of + 3. ENDOF: pop Of, save (test, body) pair, push back Case with new branch + 4. ENDCASE: pop Case, emit nested If chain from endof_branches + Desugared into nested IrOp::If at compile time. + tags: [control_flow, advanced] + + - front: "What are CS-PICK and CS-ROLL and why are they complex?" + back: | + Programming-Tools words that manipulate the compile-time control stack. + CS-PICK duplicates a control-flow entry N deep (e.g., reference a BEGIN from inside nested structures). + CS-ROLL rotates control-flow entries (e.g., move an IF dest across other structures). + Complex because they break the structured control-flow assumption — WAFER linearizes these into Block/BranchIfFalse/EndBlock IR ops for flat forward branches. + source: "crates/core/src/outer.rs:99-105" + tags: [control_flow, advanced] + +# ============================================================================ +# CATEGORY H: Consolidation & Export +# ============================================================================ +consolidation: + + - front: "What does compile_consolidated_module() produce?" + back: | + A single WASM module containing ALL compiled Forth words as separate functions. + - Each word gets a function index within the module + - Call(id) where id is in the module → direct `call N` (not call_indirect) + - Call(id) where id is NOT in the module → call_indirect (host functions) + - TailCall(id) in module → direct call + return + source: "crates/core/src/codegen.rs (compile_consolidated_module)" + tags: [consolidation, advanced] + + - front: "What metadata does wafer build embed in the .wasm file?" + back: | + ExportMetadata in a "wafer" custom section (JSON): + - version: 1 + - entry_table_index: Option + - host_functions: Vec<(table_index, name)> + - memory_size: u32 + - dsp_init, rsp_init, fsp_init: initial stack pointers + source: "crates/core/src/export.rs:21-36" + tags: [export, intermediate] + +# ============================================================================ +# CATEGORY I: Dictionary Details +# ============================================================================ +dictionary_details: + + - front: "What is the align4 function?" + back: "(addr + 3) & !3 — rounds up to next 4-byte boundary. Used to align the code field after variable-length name in dictionary entries." + code: | + fn align4(addr: u32) -> u32 { + (addr + 3) & !3 + } + source: "crates/core/src/dictionary.rs:51-53" + tags: [dictionary, basic] + + - front: "What is the hash index in Dictionary?" + back: | + HashMap> + Maps uppercase name → list of entries across wordlists. + find() checks search_order against this index (O(1) average). + Fallback: linked-list walk for words not yet in index. + Updated by reveal() and set_immediate(). + source: "crates/core/src/dictionary.rs:43" + tags: [dictionary, intermediate] + + - front: "What is DictionaryState and when is it used?" + back: | + Snapshot of dictionary state: latest, here, next_fn_index, index (HashMap clone). + Used by MARKER: save_state() captures current state, restore_state() reverts. + Does NOT save the actual memory bytes — just pointers and metadata. + source: "crates/core/src/dictionary.rs:502-509" + tags: [dictionary, intermediate] + + - front: "How does Dictionary::create() lay out an entry?" + back: | + Starting at self.here: + 1. Write link field (4 bytes): points to previous LATEST + 2. Write flags byte (1 byte): HIDDEN | length (optionally | IMMEDIATE) + 3. Write name bytes (N bytes, uppercase) + 4. Zero-pad to 4-byte alignment + 5. Write code field (4 bytes): next_fn_index (auto-incremented) + 6. Update latest = entry_start, here = after code field + code: | + // entry_start = self.here + // [link:4][flags:1][name:N][pad:0-3][code:4] + source: "crates/core/src/dictionary.rs:74-124" + tags: [dictionary, intermediate] + +# ============================================================================ +# CATEGORY J: Optimizer Patterns (hand-crafted supplements to auto-generated) +# ============================================================================ +optimizer_extra: + + - front: "What are the inline criteria?" + back: | + A Call(id) is inlined if ALL of: + 1. Body exists in `bodies` HashMap + 2. body.len() <= max_size (8) + 3. No self-recursion (contains_call_to check) + 4. No Exit (would return from caller) + 5. No ForthLocalGet/Set (would collide with caller's locals) + When inlined, TailCall ops are converted back to Call via detailcall(). + source: "crates/core/src/optimizer.rs:499-526" + tags: [optimizer, intermediate] + + - front: "How does tail_call_detect decide if a tail call is safe?" + back: | + 1. IR must be non-empty + 2. Return stack must be balanced: count ToR and FromR, depth must be 0 + (Unbalanced means >R without matching R>, which would corrupt return stack on tail call) + 3. convert_tail_call on last op: Call → TailCall + 4. Recurses into If branches: if last op is If, check both then/else branches + code: | + fn is_return_stack_balanced(ops: &[IrOp]) -> bool { + let mut depth: i32 = 0; + for op in ops { + match op { + IrOp::ToR => depth += 1, + IrOp::FromR => depth -= 1, + _ => {} + } + } + depth == 0 + } + source: "crates/core/src/optimizer.rs:671-693" + tags: [optimizer, advanced] + + - front: "What is the optimizer pass ordering and why does it matter?" + back: | + Phase 1 (simplify): peephole → fold → strength_reduce → peephole + Phase 2 (inline + re-simplify): inline → peephole → fold → strength_reduce → peephole + Phase 3 (eliminate): dce → peephole + Phase 4 (finalize): tail_call_detect + + Order matters because: + - Inline before fold: inlined body may have constant expressions + - Fold before strength: folding may produce power-of-2 constants + - DCE after fold: folded constants enable dead-branch elimination + - Tail call last: must operate on final IR + - Peephole between each: cleanup after every transformation + source: "crates/core/src/optimizer.rs:37-85" + tags: [optimizer, advanced] diff --git a/tools/anki_gen.py b/tools/anki_gen.py new file mode 100644 index 0000000..197e125 --- /dev/null +++ b/tools/anki_gen.py @@ -0,0 +1,687 @@ +#!/usr/bin/env python3 +""" +WAFER Anki Deck Generator + +Generates an Anki .apkg deck from: +1. Hand-crafted cards in anki_data.yaml +2. Auto-parsed IrOp variants from ir.rs +3. Auto-parsed memory constants from memory.rs +4. Auto-parsed error variants from error.rs +5. Auto-extracted peephole patterns from optimizer.rs + +Usage: + pip install genanki pyyaml + python tools/anki_gen.py + +Output: tools/wafer_anki.apkg +""" + +import hashlib +import re +import sys +from pathlib import Path + +try: + import genanki + import yaml +except ImportError: + print("Required: pip install genanki pyyaml") + sys.exit(1) + +# --------------------------------------------------------------------------- +# Paths +# --------------------------------------------------------------------------- +TOOLS_DIR = Path(__file__).parent +PROJECT_ROOT = TOOLS_DIR.parent +CORE_SRC = PROJECT_ROOT / "crates" / "core" / "src" +BOOT_FTH = PROJECT_ROOT / "crates" / "core" / "boot.fth" +YAML_FILE = TOOLS_DIR / "anki_data.yaml" +OUTPUT_FILE = TOOLS_DIR / "wafer_anki.apkg" + +# --------------------------------------------------------------------------- +# Stable IDs (genanki needs deterministic model/deck IDs) +# --------------------------------------------------------------------------- + + +def stable_id(name: str) -> int: + """Generate a stable integer ID from a name.""" + h = hashlib.md5(name.encode()).hexdigest() + return int(h[:8], 16) + + +DECK_ID = stable_id("wafer-learning-deck") +MODEL_ID = stable_id("wafer-card-model") + +# --------------------------------------------------------------------------- +# Anki model with code styling +# --------------------------------------------------------------------------- + +CSS = """\ +.card { + font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; + font-size: 16px; + line-height: 1.5; + color: #1a1a1a; + background: #fafafa; + padding: 20px; + max-width: 700px; + margin: 0 auto; +} +.card.nightMode { + color: #e0e0e0; + background: #1e1e1e; +} +.front { font-size: 18px; font-weight: 600; } +pre, code { + font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', monospace; + font-size: 14px; + background: #f0f0f0; + border-radius: 4px; +} +.nightMode pre, .nightMode code { + background: #2d2d2d; +} +pre { + padding: 12px; + overflow-x: auto; + border: 1px solid #ddd; +} +.nightMode pre { border-color: #444; } +code { padding: 2px 5px; } +.source { + margin-top: 12px; + font-size: 12px; + color: #888; + font-style: italic; +} +.tags-line { + margin-top: 8px; + font-size: 11px; + color: #aaa; +} +.tags-line span { + background: #e8e8e8; + padding: 1px 6px; + border-radius: 3px; + margin-right: 4px; +} +.nightMode .tags-line span { background: #3a3a3a; } +""" + +FRONT_TEMPLATE = """\ +
{{Front}}
+""" + +BACK_TEMPLATE = """\ +
{{Front}}
+
+
{{Back}}
+{{#Code}} +
{{Code}}
+{{/Code}} +{{#Source}} +
{{Source}}
+{{/Source}} +""" + +wafer_model = genanki.Model( + MODEL_ID, + "WAFER Card", + fields=[ + {"name": "Front"}, + {"name": "Back"}, + {"name": "Code"}, + {"name": "Source"}, + ], + templates=[ + { + "name": "Card 1", + "qfmt": FRONT_TEMPLATE, + "afmt": BACK_TEMPLATE, + }, + ], + css=CSS, +) + +# --------------------------------------------------------------------------- +# Card generation helpers +# --------------------------------------------------------------------------- + + +def make_note(front: str, back: str, code: str = "", source: str = "", tags: list | None = None) -> genanki.Note: + """Create a genanki Note with stable GUID.""" + guid = genanki.guid_for(front) + note = genanki.Note( + model=wafer_model, + fields=[front, back, code, source], + tags=tags or [], + guid=guid, + ) + return note + + +def html_escape(text: str) -> str: + """Minimal HTML escaping for card content.""" + return text.replace("&", "&").replace("<", "<").replace(">", ">") + + +def format_back(text: str) -> str: + """Convert back text (may have newlines) to HTML.""" + lines = text.strip().split("\n") + return "
".join(html_escape(line) for line in lines) + + +def format_code(text: str) -> str: + """Format code block content.""" + return html_escape(text.strip()) + + +# --------------------------------------------------------------------------- +# YAML card loader +# --------------------------------------------------------------------------- + + +def load_yaml_cards(deck: genanki.Deck) -> int: + """Load hand-crafted cards from anki_data.yaml.""" + if not YAML_FILE.exists(): + print(f"Warning: {YAML_FILE} not found, skipping hand-crafted cards") + return 0 + + with open(YAML_FILE) as f: + data = yaml.safe_load(f) + + count = 0 + for category, cards in data.items(): + if not isinstance(cards, list): + continue + for card in cards: + front = card.get("front", "") + back = card.get("back", "") + code = card.get("code", "") + source = card.get("source", "") + tags = card.get("tags", []) + + # Add category as tag + all_tags = [f"wafer::{category}"] + [f"wafer::{t}" for t in tags] + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(code) if code else "", + source=html_escape(source), + tags=all_tags, + ) + deck.add_note(note) + count += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-parse IrOp variants from ir.rs +# --------------------------------------------------------------------------- + + +def parse_ir_ops(deck: genanki.Deck) -> int: + """Parse IrOp enum from ir.rs and generate cards.""" + ir_file = CORE_SRC / "ir.rs" + if not ir_file.exists(): + return 0 + + content = ir_file.read_text() + count = 0 + + # Match doc comments + variant lines + # Pattern: /// comment\n VariantName or VariantName(type) or VariantName { ... } + lines = content.split("\n") + i = 0 + current_category = "" + + while i < len(lines): + line = lines[i].strip() + + # Track categories from // -- Category -- comments + cat_match = re.match(r"//\s*--\s*(.+?)\s*--", line) + if cat_match: + current_category = cat_match.group(1).strip() + i += 1 + continue + + # Collect doc comments + doc_lines = [] + while i < len(lines) and lines[i].strip().startswith("///"): + doc_lines.append(lines[i].strip().lstrip("/ ").strip()) + i += 1 + + if i >= len(lines): + break + + line = lines[i].strip() + + # Match variant definition + variant_match = re.match( + r"^((?:[A-Z][a-zA-Z0-9]+)(?:\([^)]*\))?)\s*[,{]", line + ) + if variant_match and doc_lines: + variant = variant_match.group(1) + # Clean up: remove trailing comma + variant = variant.rstrip(",") + doc = " ".join(doc_lines) + + # Extract stack effect if present: ( ... -- ... ) + stack_match = re.search(r"\(\s*(.+?)\s*\)", doc) + stack_effect = stack_match.group(0) if stack_match else "" + + front = f"IrOp::{variant} — what does it do?" + back_parts = [doc] + if stack_effect: + back_parts.insert(0, f"Stack: {stack_effect}") + back = "\n".join(back_parts) + + tags = ["wafer::ir", f"wafer::ir_{current_category.lower().replace(' ', '_')}"] + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(f"IrOp::{variant}"), + source=f"crates/core/src/ir.rs", + tags=tags, + ) + deck.add_note(note) + count += 1 + + i += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-parse memory constants from memory.rs +# --------------------------------------------------------------------------- + + +def parse_memory_constants(deck: genanki.Deck) -> int: + """Parse constants from memory.rs and generate cards.""" + mem_file = CORE_SRC / "memory.rs" + if not mem_file.exists(): + return 0 + + content = mem_file.read_text() + count = 0 + + # Match: /// doc comment\n pub const NAME: type = value; + lines = content.split("\n") + i = 0 + + while i < len(lines): + # Collect doc comments + doc_lines = [] + while i < len(lines) and lines[i].strip().startswith("///"): + doc_lines.append(lines[i].strip().lstrip("/ ").strip()) + i += 1 + + if i >= len(lines): + break + + line = lines[i].strip() + const_match = re.match( + r"pub const (\w+):\s*\w+\s*=\s*(.+?);", line + ) + if const_match and doc_lines: + name = const_match.group(1) + value_expr = const_match.group(2).strip() + doc = " ".join(doc_lines) + + # Try to evaluate simple expressions for the card + # (won't work for all, but catches most) + front = f"memory.rs: What is {name}?" + back = f"{doc}\nValue: {value_expr}" + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(f"pub const {name}: u32 = {value_expr};"), + source="crates/core/src/memory.rs", + tags=["wafer::memory", "wafer::constants"], + ) + deck.add_note(note) + count += 1 + + # Also generate reverse card for address-based constants + if name.endswith("_BASE") or name.endswith("_TOP"): + # Try to find hex value + try: + val = eval(value_expr.replace("SYSVAR_BASE + ", "0 + ").replace("SYSVAR_BASE", "0")) + except Exception: + val = None + if isinstance(val, int): + rev_front = f"memory.rs: What region starts at 0x{val:04X}?" + rev_back = f"{name}: {doc}" + rev_note = make_note( + front=html_escape(rev_front), + back=format_back(rev_back), + source="crates/core/src/memory.rs", + tags=["wafer::memory", "wafer::constants", "wafer::reverse"], + ) + deck.add_note(rev_note) + count += 1 + + i += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-parse error variants from error.rs +# --------------------------------------------------------------------------- + + +def parse_errors(deck: genanki.Deck) -> int: + """Parse WaferError enum from error.rs and generate cards.""" + err_file = CORE_SRC / "error.rs" + if not err_file.exists(): + return 0 + + content = err_file.read_text() + count = 0 + + # Match #[error("...")] followed by variant + pattern = re.compile(r'#\[error\("(.+?)"\)\]\s*\n\s*(\w+)(?:\((.+?)\))?', re.MULTILINE) + for m in pattern.finditer(content): + msg = m.group(1) + variant = m.group(2) + inner = m.group(3) or "" + + front = f"WaferError::{variant} — when is this error raised?" + back = f'Error message: "{msg}"' + if inner: + back += f"\nContains: {inner}" + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(f"WaferError::{variant}"), + source="crates/core/src/error.rs", + tags=["wafer::error"], + ) + deck.add_note(note) + count += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-extract peephole patterns from optimizer.rs +# --------------------------------------------------------------------------- + + +def parse_peephole_patterns(deck: genanki.Deck) -> int: + """Extract peephole optimization patterns from optimizer.rs.""" + opt_file = CORE_SRC / "optimizer.rs" + if not opt_file.exists(): + return 0 + + content = opt_file.read_text() + count = 0 + + # Match comment + pattern in peephole_one_pass + # Pattern: // Comment\n (IrOp::X, IrOp::Y) => { ... } + lines = content.split("\n") + in_peephole = False + i = 0 + + while i < len(lines): + line = lines[i].strip() + + if "fn peephole_one_pass" in line: + in_peephole = True + elif in_peephole and line.startswith("fn "): + in_peephole = False + + if in_peephole: + # Match pattern comments like: // PushI32(n), Drop => remove both + comment_match = re.match(r"//\s*(.+?)\s*=>\s*(.+)", line) + if comment_match: + pattern = comment_match.group(1).strip() + result = comment_match.group(2).strip() + + front = f"Peephole: {pattern} → ?" + back = result + + note = make_note( + front=html_escape(front), + back=format_back(back), + source="crates/core/src/optimizer.rs", + tags=["wafer::optimizer", "wafer::peephole"], + ) + deck.add_note(note) + count += 1 + + i += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-generate primitive registration cards +# --------------------------------------------------------------------------- + + +def parse_primitives(deck: genanki.Deck) -> int: + """Extract IR primitive registrations from outer.rs.""" + outer_file = CORE_SRC / "outer.rs" + if not outer_file.exists(): + return 0 + + content = outer_file.read_text() + count = 0 + + # Match: self.register_primitive("NAME", false, vec![IrOp::X, IrOp::Y])?; + pattern = re.compile( + r'self\.register_primitive\("(.+?)",\s*(true|false),\s*vec!\[(.+?)\]\)', + re.DOTALL, + ) + + for m in pattern.finditer(content): + name = m.group(1) + immediate = m.group(2) == "true" + ir_body = m.group(3).strip() + # Clean up multiline + ir_body = " ".join(ir_body.split()) + + front = f"Forth word {name} — what is its IR body?" + back = f"IR: [{ir_body}]" + if immediate: + back += "\n(IMMEDIATE word)" + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(f'register_primitive("{name}", {immediate}, vec![{ir_body}])'), + source="crates/core/src/outer.rs", + tags=["wafer::primitives", "wafer::ir"], + ) + deck.add_note(note) + count += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-generate boot.fth definition cards +# --------------------------------------------------------------------------- + + +def parse_boot_fth(deck: genanki.Deck) -> int: + """Extract Forth definitions from boot.fth.""" + if not BOOT_FTH.exists(): + return 0 + + content = BOOT_FTH.read_text() + count = 0 + + lines = content.split("\n") + i = 0 + current_comment = "" + + while i < len(lines): + line = lines[i] + stripped = line.strip() + + # Track section comments + if stripped.startswith("\\") and not stripped.startswith("\\ -------"): + comment = stripped.lstrip("\\ ").strip() + if comment: + current_comment = comment + + # Match colon definitions + if stripped.startswith(": "): + # Collect full definition (may span multiple lines) + defn = stripped + while not defn.rstrip().endswith(";") and i + 1 < len(lines): + i += 1 + defn += " " + lines[i].strip() + + # Extract name + name_match = re.match(r":\s+(\S+)", defn) + if name_match: + name = name_match.group(1) + + front = f"boot.fth: How is {name} defined?" + back = current_comment if current_comment else f"Forth definition of {name}" + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(defn), + source="crates/core/boot.fth", + tags=["wafer::boot_fth"], + ) + deck.add_note(note) + count += 1 + + i += 1 + + return count + + +# --------------------------------------------------------------------------- +# Auto-parse Runtime trait methods from runtime.rs +# --------------------------------------------------------------------------- + + +def parse_runtime_trait(deck: genanki.Deck) -> int: + """Parse Runtime and HostAccess trait methods from runtime.rs.""" + rt_file = CORE_SRC / "runtime.rs" + if not rt_file.exists(): + return 0 + + content = rt_file.read_text() + count = 0 + + # Match trait method signatures with doc comments + lines = content.split("\n") + i = 0 + current_trait = "" + + while i < len(lines): + line = lines[i].strip() + + # Track which trait we're in + trait_match = re.match(r"(?:pub\s+)?trait (\w+)", line) + if trait_match: + current_trait = trait_match.group(1) + i += 1 + continue + + # Collect doc comments + doc_lines = [] + while i < len(lines) and lines[i].strip().startswith("///"): + doc_lines.append(lines[i].strip().lstrip("/ ").strip()) + i += 1 + + if i >= len(lines): + break + + line = lines[i].strip() + + # Check if this is a trait definition (may follow doc comments) + trait_match = re.match(r"(?:pub\s+)?trait (\w+)", line) + if trait_match: + current_trait = trait_match.group(1) + i += 1 + continue + + # Match fn signatures + fn_match = re.match(r"fn (\w+)\(", line) + if fn_match and doc_lines and current_trait: + fn_name = fn_match.group(1) + doc = " ".join(doc_lines) + + front = f"{current_trait}::{fn_name}() — what does it do?" + back = doc + + note = make_note( + front=html_escape(front), + back=format_back(back), + code=format_code(line.rstrip(";")), + source="crates/core/src/runtime.rs", + tags=["wafer::runtime", f"wafer::{current_trait.lower()}"], + ) + deck.add_note(note) + count += 1 + + i += 1 + + return count + + +# --------------------------------------------------------------------------- +# Main +# --------------------------------------------------------------------------- + + +def main() -> None: + """Generate the Anki deck.""" + deck = genanki.Deck(DECK_ID, "WAFER - WebAssembly Forth Engine in Rust") + + print("Generating WAFER Anki deck...") + print() + + # Load hand-crafted cards + n = load_yaml_cards(deck) + print(f" Hand-crafted cards (YAML): {n}") + + # Auto-generate from source + n = parse_ir_ops(deck) + print(f" IrOp variant cards: {n}") + + n = parse_memory_constants(deck) + print(f" Memory constant cards: {n}") + + n = parse_errors(deck) + print(f" Error variant cards: {n}") + + n = parse_peephole_patterns(deck) + print(f" Peephole pattern cards: {n}") + + n = parse_primitives(deck) + print(f" Primitive registration cards: {n}") + + n = parse_boot_fth(deck) + print(f" boot.fth definition cards: {n}") + + n = parse_runtime_trait(deck) + print(f" Runtime trait method cards: {n}") + + total = len(deck.notes) + print(f"\n TOTAL: {total} cards") + + # Write .apkg + genanki.Package(deck).write_to_file(str(OUTPUT_FILE)) + print(f"\nWrote {OUTPUT_FILE}") + print(f"Import into Anki: File > Import > select {OUTPUT_FILE.name}") + + +if __name__ == "__main__": + main() diff --git a/tools/architecture.txt b/tools/architecture.txt new file mode 100644 index 0000000..1354593 --- /dev/null +++ b/tools/architecture.txt @@ -0,0 +1,306 @@ +WAFER Architecture Reference (updated 2026-04-13) +=================================================== + +1. COMPILATION PIPELINE +----------------------- + + Forth Source + | + v + Outer Interpreter (outer.rs) + +--------------------------------------------+ + | Tokenizer: whitespace-delimited words | + | For each token: | + | 1. Dictionary lookup (find) | + | 2. If found + interpret mode: EXECUTE | + | 3. If found + compile mode: | + | - Immediate? Execute now | + | - Normal? Append Call(WordId) to IR | + | 4. Not found: try parse as number | + | - Interpret: push to data stack | + | - Compile: append PushI32(n) to IR | + | 5. Neither: error "unknown word" | + +--------------------------------------------+ + | On `;` (end of colon definition): + v + Optimizer (optimizer.rs) + +--------------------------------------------+ + | Phase 1: Simplify | + | Peephole -> Constant Fold -> | + | Strength Reduce -> Peephole | + | Phase 2: Inline then re-simplify | + | Inline(max=8) -> Peephole -> | + | Constant Fold -> Strength Reduce -> | + | Peephole | + | Phase 3: Eliminate dead code | + | DCE -> Peephole | + | Phase 4: Tail calls (must be last) | + | Tail Call Detect | + +--------------------------------------------+ + | + v + Codegen (codegen.rs) + +--------------------------------------------+ + | IR -> WASM bytecode via wasm-encoder | + | Each word = one WASM module with: | + | Imports: emit, memory, dsp, rsp, fsp, | + | table | + | Types: void () -> (), i32 (i32) -> () | + | One defined function (the word body) | + | DSP cached in local 0, writeback before | + | calls, reload after calls | + | Scratch locals start at index 1 | + +--------------------------------------------+ + | + v + Runtime trait (runtime.rs) + +--------------------------------------------+ + | ForthVM — generic over backend | + | Runtime provides: | + | - Memory r/w (mem_read_i32, etc.) | + | - Globals (get/set_dsp, rsp, fsp) | + | - Table (ensure_table_size) | + | - instantiate_and_install(wasm_bytes) | + | - call_func(fn_index) | + | - register_host_func(fn_index, HostFn) | + | | + | HostAccess trait — memory/global ops for | + | host function callbacks | + | HostFn = Box | + +--------------------------------------------+ + | | + v v + NativeRuntime WebRuntime + (runtime_native.rs) (crates/web/runtime_web.rs) + +------------------+ +------------------+ + | wasmtime Engine | | js_sys::WebAsm | + | Store, Memory | | Memory, Table | + | Table, Globals | | Global objects | + | Func closures | | JS Closures | + +------------------+ +------------------+ + + +2. MEMORY LAYOUT (Linear Memory) +-------------------------------- + + Address Region Size Notes + -------- ------------------ ------- ------------------------- + 0x0000 System Variables 64 B STATE, BASE, >IN, HERE, + LATEST, SOURCE-ID, #TIB, + HLD, LEAVE-FLAG + 0x0040 Input Buffer 1024 B Source parsing + 0x0440 PAD 256 B Scratch area + 0x0540 Pictured Output 128 B <# ... #> (grows down) + 0x05C0 WORD Buffer 64 B Transient counted string + 0x0600 Data Stack 4096 B 1024 cells, grows DOWN + 0x1600 (Data Stack Top) DSP starts here + 0x1540 Return Stack 4096 B Grows DOWN + 0x2540 Float Stack 2048 B 256 doubles, grows DOWN + 0x2D40 Dictionary grows UP Linked list of word entries + + Total initial memory: 16 pages = 1 MiB (max 256 pages = 16 MiB) + Cell size: 4 bytes (i32) + Float size: 8 bytes (f64) + + +3. SYSTEM VARIABLES (offsets from 0x0000) +----------------------------------------- + + Offset Name Purpose + ------ ---------- ----------------------------------- + 0 STATE 0=interpreting, -1=compiling + 4 BASE Number base (default 10) + 8 >IN Parse offset into input buffer + 12 HERE Next free dictionary address + 16 LATEST Most recent dictionary entry addr + 20 SOURCE-ID 0=user input, -1=string + 24 #TIB Length of current input + 28 HLD Pictured numeric output pointer + 32 LEAVE-FLAG Nonzero when LEAVE called in loop + + +4. DICTIONARY ENTRY FORMAT +-------------------------- + + +--------+-------+----------+---------+-----------+ + | Link | Flags | Name | Padding | Code | + | 4 bytes| 1 byte| N bytes | 0-3 B | 4 bytes | + +--------+-------+----------+---------+-----------+ + ^ ^ + entry_addr code field (fn table index) + + Flags byte: + Bit 7 (0x80): IMMEDIATE + Bit 6 (0x40): HIDDEN (during compilation) + Bits 0-4 (0x1F): name length (max 31) + + Link points to previous entry (0 = end of list). + Name stored uppercase, padded to 4-byte alignment. + Code field: index into WASM function table. + Parameter field (if any) follows immediately after code field. + + +5. THREE TYPES OF WORDS +----------------------- + + a) IR Primitives (compiled to WASM) + register_primitive("DUP", false, vec![IrOp::Dup]) + - Body stored as Vec + - Optimized, then compiled to WASM module + - Inlineable by optimizer + - FAST: no function call overhead when inlined + + b) Host Functions (HostFn closures) + register_host_primitive(".", false, func) + - HostFn = Box Result<()>> + - Access memory/globals via HostAccess trait (runtime-agnostic) + - NOT inlineable + - Used for: I/O, dictionary manipulation, complex logic + - Same closure works on NativeRuntime and WebRuntime + + c) Forth-defined words + : SQUARE DUP * ; + - Compiled by outer interpreter + - Goes through full optimize -> codegen pipeline + - Stored in ir_bodies for future inlining + + +6. WASM MODULE STRUCTURE (per word) +----------------------------------- + + Imports (6) — provided by Runtime impl: + 0. emit (func: i32 -> void) Character output callback + 1. memory (memory: 16 pages) Shared linear memory + 2. dsp (global: mut i32) Data stack pointer + 3. rsp (global: mut i32) Return stack pointer + 4. fsp (global: mut i32) Float stack pointer + 5. table (table: funcref) Shared function table + + Types (2): + 0. void: () -> () + 1. i32: (i32) -> () + + Functions (1): + The compiled word body + + Element section: + table[base_fn_index] = function 1 + + Runtime::instantiate_and_install(wasm_bytes, fn_index): + - NativeRuntime: Module::new + Instance::new with 6 wasmtime imports + - WebRuntime: WebAssembly.instantiate with JS import objects + + +7. OPTIMIZATION PASSES (detail) +------------------------------- + + PEEPHOLE (runs 5x across full pipeline): + PushI32(n), Drop -> (removed) Unused literal + Dup, Drop -> (removed) Redundant copy + Swap, Swap -> (removed) Self-inverse + Swap, Drop -> Nip Combine + PushI32(0), Add -> (removed) Identity + PushI32(0), Or -> (removed) Identity + PushI32(-1), And -> (removed) Identity + PushI32(1), Mul -> (removed) Identity + Over, Over -> TwoDup Combine + Drop, Drop -> TwoDrop Combine + (+ float variants: PushF64/FDrop, FDup/FDrop, FSwap/FSwap, FNegate/FNegate) + + CONSTANT FOLD: + Binary: PushI32(a), PushI32(b), -> PushI32(result) + Supports: Add, Sub, Mul, And, Or, Xor, Lshift, Rshift, ArithRshift, + Eq, NotEq, Lt, Gt, LtUnsigned + Unary: PushI32(n), -> PushI32(result) + Supports: Negate, Abs, Invert, ZeroEq, ZeroLt + Float binary: PushF64(a), PushF64(b), -> PushF64(result) + Float unary: PushF64(n), -> PushF64(result) + + STRENGTH REDUCE: + PushI32(2^n), Mul -> PushI32(n), Lshift + PushI32(0), Eq -> ZeroEq + PushI32(0), Lt -> ZeroLt + + DCE: + PushI32(nonzero), If{then,else} -> then_body only + PushI32(0), If{then,else} -> else_body only + Everything after Exit -> removed + + INLINE (max_size=8, single pass): + Call(id) -> inline body if: + - Body length <= 8 ops + - No self-recursion + - No Exit (would return from caller) + - No ForthLocalGet/Set (would collide with caller's locals) + TailCall -> Call when inlined (no longer tail position) + + TAIL CALL (last pass): + Last Call(id) -> TailCall(id) if: + - Return stack balanced (equal ToR and FromR) + Recurses into If branches for conditional tail calls + + +8. CONSOLIDATION +---------------- + + CONSOLIDATE word recompiles all JIT-compiled words into a + single WASM module: + - All call_indirect -> direct call (for words in module) + - External calls (host functions) remain call_indirect + - Maximum performance for final program + + Two-part implementation: + codegen::compile_consolidated_module() - builds multi-function module + outer::ForthVM::consolidate() - orchestrates collection + table update + + +9. EXPORT PIPELINE (wafer build) +-------------------------------- + + 1. Evaluate source file with recording_toplevel=true + 2. Collect all IR words + top-level IR + 3. Determine entry: --entry flag > MAIN word > top-level execution + 4. Build consolidated module with data section (memory snapshot) + 5. Embed metadata in "wafer" custom section (JSON) + 6. Optional: --js generates JS loader + HTML page + 7. Optional: --native AOT-compiles and appends to wafer binary + Format: [wafer binary][precompiled WASM][metadata][trailer] + Trailer: payload_len(8) + metadata_len(8) + "WAFEREXE"(8) + + +10. CRATE STRUCTURE +------------------- + + crates/ + core/ wafer-core: compiler, optimizer, codegen, dictionary, Runtime trait + Feature flags: default=["native"], "native" enables wasmtime + Without features: pure Rust (dictionary, IR, optimizer, codegen, outer) + cli/ wafer: CLI REPL (rustyline), wafer build/run commands + web/ wafer-web: browser REPL (wasm-bindgen + WebRuntime + HTML/CSS/JS) + + Key web files: + crates/web/src/lib.rs WaferRepl wasm-bindgen entry point + crates/web/src/runtime_web.rs WebRuntime: js_sys WebAssembly API + crates/web/www/app.js Frontend JS (terminal emulation) + crates/web/www/index.html HTML shell + crates/web/www/style.css Styling + + +11. BOOT SEQUENCE +----------------- + + ForthVM::::new() -> + 1. R::new() — create runtime (wasmtime or browser WASM) + 2. register_primitives() in batch_mode: + - ~40 IR primitives (DUP, +, @, etc.) + - ~60 host functions (., .S, M*, ACCEPT, etc.) + - ~30 special words (IF, DO, :, VARIABLE, etc.) + 3. compile_batch() - single WASM module for all IR primitives + 4. Load boot.fth - Forth replaces Rust host functions: + Phase 1: Stack/memory (DEPTH, PICK, 2OVER, FILL, MOVE) + Phase 2: Double-cell arithmetic (D+, DNEGATE, D<) + Phase 3: Mixed arithmetic (SM/REM, FM/MOD, */, */MOD) + Phase 4: HERE, ALLOT, comma, ALIGN + Phase 5: I/O, pictured numeric output (., U., TYPE, <# # #>) + Phase 6: DEFER support + Phase 7: String operations (COMPARE, SOURCE, FALIGNED) diff --git a/tools/ir_quiz.py b/tools/ir_quiz.py new file mode 100644 index 0000000..dbdf96d --- /dev/null +++ b/tools/ir_quiz.py @@ -0,0 +1,347 @@ +#!/usr/bin/env python3 +"""WAFER IR Flash Quiz — predict the optimized IR for Forth code.""" + +import random +import sys + +# Each exercise: (forth_code, accepted_answers, explanation) +# accepted_answers: list of strings that count as correct (case-insensitive, whitespace-normalized) +EXERCISES = [ + # --- Constant Folding --- + ( + ": FOO 2 3 + ;", + ["PushI32(5)", "pushi32(5)", "5"], + "Constant fold: PushI32(2), PushI32(3), Add → PushI32(5)", + ), + ( + ": FOO 10 3 - ;", + ["PushI32(7)", "pushi32(7)", "7"], + "Constant fold: PushI32(10), PushI32(3), Sub → PushI32(7)", + ), + ( + ": FOO 6 7 * ;", + ["PushI32(42)", "pushi32(42)", "42"], + "Constant fold: PushI32(6), PushI32(7), Mul → PushI32(42)", + ), + ( + ": FOO 5 0= ;", + ["PushI32(0)", "pushi32(0)", "0", "false"], + "Constant fold (unary): PushI32(5), ZeroEq → PushI32(0) (5 is not zero)", + ), + ( + ": FOO 0 0= ;", + ["PushI32(-1)", "pushi32(-1)", "-1", "true"], + "Constant fold (unary): PushI32(0), ZeroEq → PushI32(-1) (true flag)", + ), + ( + ": FOO -3 ABS ;", + ["PushI32(3)", "pushi32(3)", "3"], + "Constant fold (unary): PushI32(-3), Abs → PushI32(3)", + ), + ( + ": FOO 255 INVERT ;", + ["PushI32(-256)", "pushi32(-256)", "-256"], + "Constant fold (unary): PushI32(255), Invert → PushI32(-256) (bitwise NOT)", + ), + ( + ": FOO 3 2 LSHIFT ;", + ["PushI32(12)", "pushi32(12)", "12"], + "Constant fold: PushI32(3), PushI32(2), Lshift → PushI32(12) (3 << 2 = 12)", + ), + + # --- Peephole --- + ( + ": FOO DUP DROP ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: Dup, Drop → removed (both eliminated)", + ), + ( + ": FOO SWAP SWAP ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: Swap, Swap → removed (self-inverse)", + ), + ( + ": FOO SWAP DROP ;", + ["Nip", "nip"], + "Peephole: Swap, Drop → Nip", + ), + ( + ": FOO DROP DROP ;", + ["TwoDrop", "twodrop", "2drop"], + "Peephole: Drop, Drop → TwoDrop", + ), + ( + ": FOO OVER OVER ;", + ["TwoDup", "twodup", "2dup"], + "Peephole: Over, Over → TwoDup", + ), + ( + ": FOO 0 + ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: PushI32(0), Add → removed (identity)", + ), + ( + ": FOO 1 * ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: PushI32(1), Mul → removed (identity)", + ), + ( + ": FOO -1 AND ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: PushI32(-1), And → removed (identity, all bits set)", + ), + ( + ": FOO 0 OR ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: PushI32(0), Or → removed (identity)", + ), + ( + ": FOO 42 DROP ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: PushI32(42), Drop → removed (unused literal)", + ), + + # --- Strength Reduction --- + ( + ": FOO 8 * ;", + ["PushI32(3), Lshift", "pushi32(3) lshift", "3 lshift"], + "Strength reduce: PushI32(8) is 2^3, Mul → PushI32(3), Lshift", + ), + ( + ": FOO 16 * ;", + ["PushI32(4), Lshift", "pushi32(4) lshift", "4 lshift"], + "Strength reduce: PushI32(16) is 2^4, Mul → PushI32(4), Lshift", + ), + ( + ": FOO 2 * ;", + ["PushI32(1), Lshift", "pushi32(1) lshift", "1 lshift"], + "Strength reduce: PushI32(2) is 2^1, Mul → PushI32(1), Lshift", + ), + ( + ": FOO 0 = ;", + ["ZeroEq", "zeroeq", "0="], + "Strength reduce: PushI32(0), Eq → ZeroEq", + ), + ( + ": FOO 0 < ;", + ["ZeroLt", "zerolt", "0<"], + "Strength reduce: PushI32(0), Lt → ZeroLt", + ), + + # --- Dead Code Elimination --- + ( + ": FOO TRUE IF 42 ELSE 99 THEN ;", + ["PushI32(42)", "pushi32(42)", "42"], + "DCE: PushI32(-1) is nonzero → then_body only → PushI32(42)", + ), + ( + ": FOO FALSE IF 42 ELSE 99 THEN ;", + ["PushI32(99)", "pushi32(99)", "99"], + "DCE: PushI32(0) is zero → else_body only → PushI32(99)", + ), + ( + ": FOO EXIT 42 ;", + ["Exit", "exit"], + "DCE: Everything after Exit is removed. PushI32(42) eliminated.", + ), + + # --- Combined Optimizations --- + ( + ": FOO DUP * ;", + ["Dup, Mul", "dup mul", "dup, mul"], + "Inline DUP and *: [Dup, Mul]. No further optimizations apply.", + ), + ( + ": FOO 2 3 + 4 * ;", + ["PushI32(20)", "pushi32(20)", "20"], + "Fold 2+3=5, then fold 5*4=20. Single constant.", + ), + ( + ": FOO 1 2 + 8 * ;", + ["PushI32(24)", "pushi32(24)", "24"], + "Fold 1+2=3, strength reduce 8*? No — fold first: 3*8=24.", + ), + ( + ": FOO 0 0 + ;", + ["PushI32(0)", "pushi32(0)", "0"], + "Fold: PushI32(0), PushI32(0), Add → PushI32(0)", + ), + ( + ": FOO SWAP DUP DROP SWAP ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole chain: Swap,Dup → ...; Dup,Drop → removed; Swap,Swap → removed. All gone.", + ), + + # --- Inlining --- + ( + ": SQUARE DUP * ;\n: FOO SQUARE ;", + ["Dup, Mul", "dup mul", "dup, mul"], + "SQUARE body=[Dup,Mul] (2 ops ≤ 8). Inlined into FOO. Tail call: Dup is not Call, Mul is not Call → no tail call.", + ), + + # --- Tail Call --- + ( + ": BAR 1 ; : FOO 42 BAR ;", + ["PushI32(42), TailCall(bar_id)", "pushi32(42) tailcall", "42 tailcall(bar)"], + "BAR has body [PushI32(1)] — 1 op, inlineable. But wait: if BAR is inlined, result is [PushI32(42), PushI32(1)]. Actually depends on whether BAR is inlined. If NOT inlined: tail call applies to Call(bar). If inlined: [PushI32(42), PushI32(1)].", + ), + + # --- Float --- + ( + ": FOO 1.0E0 2.0E0 F+ ;", + ["PushF64(3.0)", "pushf64(3.0)", "3.0"], + "Float constant fold: PushF64(1.0), PushF64(2.0), FAdd → PushF64(3.0)", + ), + ( + ": FOO -5.0E0 FABS ;", + ["PushF64(5.0)", "pushf64(5.0)", "5.0"], + "Float unary fold: PushF64(-5.0), FAbs → PushF64(5.0)", + ), + ( + ": FOO FNEGATE FNEGATE ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: FNegate, FNegate → removed (self-inverse)", + ), + ( + ": FOO FSWAP FSWAP ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: FSwap, FSwap → removed (self-inverse)", + ), + ( + ": FOO FDUP FDROP ;", + ["(empty)", "empty", "nothing", "[]", ""], + "Peephole: FDup, FDrop → removed", + ), + + # --- Tricky --- + ( + ": FOO 3 5 < ;", + ["PushI32(-1)", "pushi32(-1)", "-1", "true"], + "Constant fold: PushI32(3), PushI32(5), Lt → PushI32(-1) (3 < 5 is true, Forth true = -1)", + ), + ( + ": FOO 5 3 < ;", + ["PushI32(0)", "pushi32(0)", "0", "false"], + "Constant fold: PushI32(5), PushI32(3), Lt → PushI32(0) (5 < 3 is false)", + ), + ( + ": FOO DUP DUP DROP DROP ;", + ["Dup", "dup"], + "Peephole: Dup, Dup, Drop, Drop → Dup (first Dup stays, second Dup+Drop cancel, last Drop+implicit cancel... actually: Dup, Dup → keep; Dup, Drop → cancel; left with Dup. Then Drop. Hmm. Let's trace: [Dup, Dup, Drop, Drop] → peephole sees Dup,Drop at positions 1,2 → removes → [Dup, Drop] → peephole sees Dup,Drop → removes → []. Actually empty!", + ), +] + + +def normalize(s: str) -> str: + """Normalize answer for comparison: lowercase, strip whitespace/punctuation.""" + s = s.strip().lower() + # Remove parentheses, brackets, commas for flexible matching + for ch in "()[]": + s = s.replace(ch, "") + # Collapse whitespace + s = " ".join(s.split()) + return s + + +def check_answer(user_input: str, accepted: list[str]) -> bool: + """Check if user's answer matches any accepted answer.""" + norm_input = normalize(user_input) + for ans in accepted: + if normalize(ans) == norm_input: + return True + return False + + +def run_quiz(exercises: list, shuffle: bool = True) -> None: + """Run the interactive quiz.""" + items = list(exercises) + if shuffle: + random.shuffle(items) + + correct = 0 + total = 0 + skipped = 0 + + print("=" * 60) + print(" WAFER IR Flash Quiz") + print(" Predict the optimized IR for each Forth definition.") + print(" Type 'q' to quit, 's' to skip, 'h' for hint.") + print("=" * 60) + print() + + for i, (forth, accepted, explanation) in enumerate(items): + total += 1 + print(f" [{i + 1}/{len(items)}]") + print(f" {forth}") + print() + + while True: + try: + user = input(" Your answer> ").strip() + except (EOFError, KeyboardInterrupt): + print("\n") + show_score(correct, total - 1, skipped) + return + + if user.lower() == "q": + show_score(correct, total - 1, skipped) + return + if user.lower() == "s": + skipped += 1 + print(f" Skipped. Answer: {accepted[0]}") + print(f" {explanation}") + break + if user.lower() == "h": + # Give a hint: first word of explanation + hint_word = explanation.split(":")[0] if ":" in explanation else "Think about the optimizer passes" + print(f" Hint: {hint_word}") + continue + + if check_answer(user, accepted): + correct += 1 + print(f" \033[32m✓ Correct!\033[0m {explanation}") + else: + print(f" \033[31m✗ Not quite.\033[0m Expected: {accepted[0]}") + print(f" {explanation}") + break + + print() + print("-" * 60) + print() + + show_score(correct, total, skipped) + + +def show_score(correct: int, total: int, skipped: int) -> None: + """Display final score.""" + attempted = total - skipped + if attempted == 0: + print(" No questions attempted.") + return + pct = (correct / attempted) * 100 + print(f"\n Score: {correct}/{attempted} ({pct:.0f}%)") + if skipped: + print(f" Skipped: {skipped}") + if pct == 100: + print(" Perfect! You know the optimizer cold.") + elif pct >= 80: + print(" Strong! Review the ones you missed.") + elif pct >= 60: + print(" Getting there. Focus on peephole + fold patterns.") + else: + print(" Study tools/architecture.txt section 7, then retry.") + print() + + +def main() -> None: + """Entry point.""" + if "--all" in sys.argv: + run_quiz(EXERCISES, shuffle=False) + elif "--count" in sys.argv: + print(f"{len(EXERCISES)} exercises available.") + else: + run_quiz(EXERCISES, shuffle=True) + + +if __name__ == "__main__": + main() diff --git a/tools/reading_order.md b/tools/reading_order.md new file mode 100644 index 0000000..fcfb57e --- /dev/null +++ b/tools/reading_order.md @@ -0,0 +1,189 @@ +# WAFER Codebase Reading Order + +Optimal sequence for learning the entire system. Each step builds on the previous. + +--- + +## Phase 1: Mental Model Foundation + +### 1. `crates/core/src/memory.rs` (148 lines) +**Read first.** Defines the physical memory map — every address, every region. You'll reference these constants everywhere else. +- Key insight: stacks grow DOWN, dictionary grows UP +- Memorize: DATA_STACK_TOP=0x1600, DICTIONARY_BASE=0x2D40 +- System variables at offset 0: STATE, BASE, >IN, HERE, LATEST, SOURCE-ID, #TIB, HLD, LEAVE-FLAG +- Notice how regions are laid out to never overlap (verified by compile-time assertions) + +### 2. `crates/core/src/ir.rs` (259 lines) +**The central data structure.** Every Forth word compiles to `Vec`. This is the language the optimizer speaks and the codegen consumes. +- ~70 variants across 10 categories +- Pay attention to control-flow variants: `If`, `DoLoop`, `BeginUntil`, `BeginWhileRepeat`, `BeginDoubleWhileRepeat` — they contain nested `Vec` bodies (tree structure, not flat) +- `Call(WordId)` and `TailCall(WordId)` — how words reference each other +- Float ops are separate from integer ops (separate stack) +- `IrWord` struct: name + body + is_immediate + +### 3. `crates/core/src/error.rs` (84 lines) +**Quick read.** 15 error variants. Note `Throw(i32)` for the Exception word set and `Abort(String)` for ABORT". + +### 4. `crates/core/src/config.rs` (61 lines) +**Quick read.** 7 optimization flags in two tiers: OptConfig (IR-level) and CodegenOpts (codegen-level). Default = all enabled. + +--- + +## Phase 2: Data Structures + +### 5. `crates/core/src/dictionary.rs` (906 lines) +**How words live in memory.** The dictionary is a linked list stored in a `Vec` that simulates WASM linear memory. +- Entry format: link(4) + flags(1) + name(N) + padding + code_field(4) +- Flags byte: IMMEDIATE=0x80, HIDDEN=0x40, LENGTH_MASK=0x1F +- `create()` writes the entry, starts HIDDEN; `reveal()` removes HIDDEN flag +- `find()`: fast path via HashMap index, fallback via linked-list walk +- Wordlist support: `current_wid`, `search_order`, `find_in_wid()` +- `DictionaryState` for MARKER save/restore +- Read every test — they document exact behavior + +--- + +## Phase 3: The Pipeline + +### 6. `crates/core/src/optimizer.rs` (1013 lines) +**IR transformations.** Read the `optimize()` function first to see the pass ordering, then each pass. +- `peephole()`: pattern-match adjacent ops. ~15 patterns. Runs to fixpoint. Study each match arm. +- `constant_fold()`: evaluate PushI32+PushI32+BinaryOp at compile time. Also unary and float. +- `strength_reduce()`: multiply by power-of-2 → shift. 0 compare → ZeroEq/ZeroLt. +- `dce()`: eliminate dead branches (constant condition), truncate after Exit. +- `inline()`: replace Call(id) with body if ≤8 ops, non-recursive, no Exit, no ForthLocals. `detailcall()` converts TailCall back to Call. +- `tail_call_detect()`: last Call → TailCall if return stack balanced. Recurses into If branches. +- Key: `apply_to_bodies()` — every pass recurses into control-flow nested bodies. + +### 7. `crates/core/src/codegen.rs` (4205 lines) — **The Big One** +**IR → WASM translation.** Read in order: +1. **Constants** (lines 1-80): import indices, type indices, DSP/RSP/FSP globals, memory alignment +2. **Helper functions** (lines 80-210): `dsp_dec/inc`, `push_via_local`, `pop`, `peek`, `dsp_writeback/reload`, `rpush_via_local`, `rpop` +3. **Float helpers** (lines 225-330): `fsp_dec/inc`, `fpush_via_local`, `fpop`, `fpeek`, `emit_float_binary/unary/cmp` +4. **`emit_op()`** (line 344+): the giant match — each IrOp variant → WASM instructions. This is the heart. +5. **`compile_word()`**: builds the WASM module structure (imports, types, functions, element section) +6. **`compile_consolidated_module()`**: multi-function module for CONSOLIDATE/export +7. **Stack-to-local promotion**: analysis pass that replaces memory stack operations with WASM locals + +Key patterns to understand: +- DSP cached in local 0: read from global at function entry, write back before calls and at exit +- Scratch locals at SCRATCH_BASE(1): used as temporaries for stack manipulation +- `EmitCtx`: carries f64 locals, Forth local base, loop local base, self_word_id for recursion +- DO/LOOP: index+limit in WASM locals when possible (fast path), fallback to return stack + +--- + +## Phase 4: The Runtime Abstraction + +### 8. `crates/core/src/runtime.rs` (152 lines) +**NEW: Read this before outer.rs.** Defines two traits: +- `Runtime` — abstraction over WASM execution backend (memory, globals, table, module instantiation, host function registration) +- `HostAccess` — memory/global ops available to host function callbacks +- `HostFn = Box Result<()>>` — runtime-agnostic host function type +- Key insight: ForthVM is now `ForthVM`, completely decoupled from wasmtime + +### 8b. `crates/core/src/runtime_native.rs` (328 lines) +**NativeRuntime**: wasmtime implementation of Runtime trait. +- `CallerHostAccess` wraps wasmtime `Caller` to implement `HostAccess` +- `NativeRuntime` owns Engine, Store, Memory, Table, Globals +- `register_host_func`: creates a wasmtime `Func` that bridges `HostFn` → wasmtime callback +- Study how `instantiate_and_install` provides the 6 imports + +### 9. `crates/core/src/outer.rs` — ForthVM struct (lines 1-240) +**Read the struct definition carefully.** ~35 fields. Group them mentally: +- Runtime: `rt: R` (generic over Runtime trait — no more direct wasmtime fields) +- Compilation state: state, compiling_name, compiling_ir, control_stack, compiling_word_id, compiling_locals +- Output: output (Arc>) +- Dictionary bridge: dictionary, user_here, here_cell, base_cell +- Word metadata: ir_bodies, host_word_names, word_pfa_map, does_definitions +- Shared state for host functions: pending_define, pending_actions, pending_does_patch, throw_code, word_lookup +- Configuration: config, batch_mode, deferred_ir +- Export support: toplevel_ir, recording_toplevel +- Advanced: marker_states, conditional_skip_depth, next_block_label, substitutions, search_order, next_wid + +### 10. `crates/core/src/outer.rs` — new() and primitive registration +**How the VM boots.** Read: +- `new_with_config()`: creates `R::new()` runtime, then calls `register_primitives()` and loads boot.fth +- `register_primitive()`: creates dictionary entry → optimizes IR → compiles to WASM → `rt.instantiate_and_install()` +- `register_host_primitive()`: creates dictionary entry → `rt.register_host_func()` with HostFn closure +- `register_primitives()`: ~130 words registered in batch_mode, then `compile_batch()` +- Each host function: study 5-10 representative ones to understand the pattern + +### 11. `crates/core/src/outer.rs` — Outer interpreter loop +**The main loop.** Read: +- `evaluate()`: sets up input buffer, calls `interpret_token()` in a loop +- `interpret_token()`: conditional compilation, `:` handling, `]` handling, dispatch to compile/interpret mode +- `interpret_token_immediate()`: string literals, dictionary lookup, execute found word, parse number +- `compile_token()`: POSTPONE, string literals, control-flow words (IF/ELSE/THEN/DO/LOOP/BEGIN/WHILE/REPEAT/AGAIN/UNTIL/CASE/OF/ENDOF/ENDCASE), dictionary lookup, compile Call(id), parse number → PushI32 +- `finish_colon_def()`: optimize → codegen → install + +### 12. `crates/core/src/outer.rs` — Control flow compilation +**Most complex part.** 13 `ControlEntry` variants. Understand: +- `ControlEntry::If { then_body }` → pushed when IF seen, then_body accumulates until ELSE or THEN +- `ControlEntry::Do { body }` → pushed by DO, body accumulates until LOOP/+LOOP +- `ControlEntry::Begin { body }` → pushed by BEGIN, resolved by UNTIL/AGAIN/WHILE +- `ControlEntry::BeginWhile { test, body }` → WHILE splits Begin into test + body +- `ControlEntry::Case/Of` → CASE/OF/ENDOF/ENDCASE pattern +- `ControlEntry::QDo` → ?DO (conditional entry) +- `ControlEntry::Ahead` → AHEAD (unconditional forward branch) +- CS-PICK and CS-ROLL: advanced control-flow manipulation for tools word set + +--- + +## Phase 5: Self-Hosting + +### 13. `crates/core/boot.fth` (307 lines) +**Forth replaces Rust.** 7 phases of definitions that replace host functions with compiled Forth. +- Phase 1: Stack/memory (DEPTH, PICK, 2OVER, FILL, MOVE, /STRING, -TRAILING) +- Phase 2: Double-cell arithmetic (D+, DNEGATE, D-, DABS, D0=, D0<, D=, D<, DU<) +- Phase 3: Mixed arithmetic (SM/REM, FM/MOD, */, */MOD) — built on M* and UM/MOD host primitives +- Phase 4: HERE, ALLOT, comma, C-comma, ALIGN — magic numbers for sysvar offsets +- Phase 5: I/O and pictured numeric output (TYPE, SPACES, <# HOLD # #S #> . U. .R U.R D. D.R) +- Phase 6: DEFER support (DEFER!, DEFER@) +- Phase 7: String operations, SOURCE, FALIGNED, etc. +- Key insight: why Forth not Rust? Self-hosting goal + compiled Forth with direct calls beats host function dispatch + +--- + +## Phase 6: Production Features + +### 14. `crates/core/src/consolidate.rs` (169 lines) +**Quick read.** Mostly tests. Real logic is in `codegen::compile_consolidated_module()` and `outer::ForthVM::consolidate()`. Understand the concept: merge all JIT modules into one, replacing call_indirect with direct call. + +### 15. `crates/core/src/export.rs` (409 lines) +**wafer build pipeline.** Entry point resolution (--entry > MAIN > top-level), IR collection, memory snapshot, metadata embedding in custom section. + +### 16. `crates/core/src/runner.rs` (402 lines) +**Standalone execution.** Creates the 6 imports from scratch, registers host function stubs for known words (., TYPE, SPACES, .S, M*, UM*, UM/MOD, DEPTH). Shows the minimal set needed to run exported modules. + +### 17. `crates/cli/src/main.rs` (354 lines) +**CLI ties it together.** Three modes: REPL (rustyline), file evaluation, subcommands (build, run). Native executable trick: append AOT payload + "WAFEREXE" trailer to binary. + +### 18. `crates/web/src/lib.rs` (56 lines) +**Browser entry point.** `WaferRepl` struct with `#[wasm_bindgen]`: +- `new()` → `ForthVM::::new()` +- `evaluate(input)` → returns output string +- `data_stack()`, `is_compiling()`, `reset()` + +### 19. `crates/web/src/runtime_web.rs` (542 lines) +**WebRuntime**: browser implementation of Runtime trait. +- Uses `js_sys::WebAssembly` for module instantiation +- `WebHostAccess`: implements HostAccess via `js_sys` typed arrays +- Memory access through `Int32Array`/`Uint8Array` views on `WebAssembly.Memory.buffer` +- Closures kept alive via `_closures: Vec` to prevent GC + +### 20. `crates/web/www/` (727 lines) +**Frontend**: app.js (terminal emulation, stack display), index.html, style.css. + +--- + +## Phase 7: Testing + +### 21. Unit tests (embedded in each source file) +Re-read each file's `#[cfg(test)] mod tests`. They document edge cases and expected behavior. + +### 22. `crates/core/tests/compliance.rs` +Forth 2012 compliance infrastructure: boot_with_prerequisites, run_suite, 11 word set tests. + +### 23. `crates/core/tests/comparison.rs` +Cross-engine benchmarks vs gforth. Performance validation. diff --git a/tools/trace_exercises.md b/tools/trace_exercises.md new file mode 100644 index 0000000..4f21e04 --- /dev/null +++ b/tools/trace_exercises.md @@ -0,0 +1,464 @@ +# WAFER Trace-the-Compilation Exercises + +For each exercise, manually trace the Forth code through the full pipeline: +1. **Outer interpreter** — tokenization, dictionary lookup, compile/interpret dispatch +2. **IR generation** — what Vec is produced +3. **Optimization** — which passes fire, what changes +4. **Codegen** — WASM instructions emitted (conceptual) +5. **Runtime** — how it executes + +Answers are below each exercise (scroll down or cover with paper). + +--- + +## Exercise 1: Simple Arithmetic +```forth +: SQUARE DUP * ; +``` + +
+Answer + +1. `:` → enter compile mode, next token "SQUARE" = word name, dictionary.create("SQUARE") +2. `DUP` → find in dictionary → IR primitive (WordId N) → append `Call(dup_id)` +3. `*` → find → IR primitive → append `Call(mul_id)` +4. `;` → raw IR: `[Call(dup_id), Call(mul_id)]` +5. **Optimize:** + - Inline: DUP body=[Dup] (1 op ≤ 8), * body=[Mul] (1 op ≤ 8) → `[Dup, Mul]` + - Peephole: no patterns match Dup,Mul + - Constant fold: nothing to fold + - Tail call: Mul is not a Call → skip + - **Final IR: `[Dup, Mul]`** +6. **Codegen:** + - Dup: `local.get $dsp; i32.load; local.set $tmp; dsp_dec; local.get $dsp; local.get $tmp; i32.store` + - Mul: `pop; pop; i32.mul; push_via_local` +7. **Runtime:** WASM module instantiated, function registered at table[word_id] + +
+ +--- + +## Exercise 2: Constant Folding +```forth +: TEN 5 5 + ; +``` + +
+Answer + +1. `:` → compile mode, name="TEN" +2. `5` → not in dictionary → parse as number → append `PushI32(5)` +3. `5` → append `PushI32(5)` +4. `+` → find → IR primitive → append `Call(add_id)` +5. `;` → raw IR: `[PushI32(5), PushI32(5), Call(add_id)]` +6. **Optimize:** + - Inline: + body=[Add] → `[PushI32(5), PushI32(5), Add]` + - Constant fold: PushI32(5), PushI32(5), Add → `PushI32(10)` + - **Final IR: `[PushI32(10)]`** +7. **Codegen:** Just `push_const(f, 10)` → `dsp_dec; local.get $dsp; i32.const 10; i32.store` + +
+ +--- + +## Exercise 3: Peephole Elimination +```forth +: NOOP DUP DROP ; +``` + +
+Answer + +1. Raw IR after inlining: `[Dup, Drop]` +2. **Optimize:** + - Peephole: Dup, Drop → removed (both eliminated) + - **Final IR: `[]` (empty)** +3. **Codegen:** Empty function body — just DSP writeback at entry/exit + +
+ +--- + +## Exercise 4: Strength Reduction +```forth +: DOUBLE 8 * ; +``` + +
+Answer + +1. Raw IR after inlining: `[PushI32(8), Mul]` +2. **Optimize:** + - Strength reduce: PushI32(8) is 2^3, so → `[PushI32(3), Lshift]` + - 8 * x becomes x << 3 + - **Final IR: `[PushI32(3), Lshift]`** +3. **Codegen:** push_const(3), then pop two, i32.shl, push result + +
+ +--- + +## Exercise 5: Tail Call Detection +```forth +: FOO 1 + BAR ; +``` +(Assume BAR is a previously defined word) + +
+Answer + +1. Raw IR: `[PushI32(1), Call(add_id), Call(bar_id)]` +2. **Optimize:** + - Inline + (1 op): `[PushI32(1), Add, Call(bar_id)]` + - Tail call: last op is Call(bar_id), return stack balanced (no >R or R>) → `TailCall(bar_id)` + - **Final IR: `[PushI32(1), Add, TailCall(bar_id)]`** +3. **Codegen:** TailCall emits `dsp_writeback; call_indirect bar_id; return` + +
+ +--- + +## Exercise 6: Control Flow — IF/THEN +```forth +: ABS DUP 0< IF NEGATE THEN ; +``` + +
+Answer + +1. `DUP` → Call(dup_id), `0<` → Call(zerolt_id) +2. `IF` → push ControlEntry::If { then_body: [] }, start collecting +3. `NEGATE` → Call(negate_id) appended to then_body +4. `THEN` → pop ControlEntry::If, emit `If { then_body: [Call(negate_id)], else_body: None }` +5. Raw IR: `[Call(dup_id), Call(zerolt_id), If { then: [Call(negate_id)], else: None }]` +6. **Optimize:** + - Inline all (each is 1 op): `[Dup, ZeroLt, If { then: [Negate], else: None }]` + - Note: optimizer recurses into If bodies via apply_to_bodies + - **Final IR: `[Dup, ZeroLt, If { then: [Negate], else: None }]`** +7. **Codegen:** pop flag → `if (block) ... end` WASM structure + +
+ +--- + +## Exercise 7: DO LOOP +```forth +: STARS 0 DO 42 EMIT LOOP ; +``` + +
+Answer + +1. `0` → PushI32(0) +2. `DO` → push ControlEntry::Do { body: [] } +3. `42` → PushI32(42) into body +4. `EMIT` → Call(emit_id) into body +5. `LOOP` → pop Do, emit `DoLoop { body: [PushI32(42), Call(emit_id)], is_plus_loop: false }` +6. Note: the 0 and the limit (already on stack from caller) are consumed by DoLoop +7. **Optimize:** + - Inline EMIT (1 op): `DoLoop { body: [PushI32(42), Emit], is_plus_loop: false }` + - **Final IR:** `[PushI32(0), DoLoop { body: [PushI32(42), Emit], is_plus_loop: false }]` +8. **Codegen:** Loop index+limit in WASM locals. WASM `loop { body; index++; br_if index + +--- + +## Exercise 8: BEGIN UNTIL +```forth +: COUNTDOWN BEGIN DUP . 1 - DUP 0= UNTIL DROP ; +``` + +
+Answer + +1. `BEGIN` → push ControlEntry::Begin { body: [] } +2. `DUP .` → Call(dup_id), Call(dot_id) into body +3. `1 -` → PushI32(1), Call(sub_id) into body +4. `DUP 0=` → Call(dup_id), Call(zeroeq_id) into body +5. `UNTIL` → pop Begin, emit `BeginUntil { body: [Call(dup), Call(dot), PushI32(1), Call(sub), Call(dup), Call(zeroeq)] }` +6. **Optimize:** Inline small primitives. `1 -` stays as `PushI32(1), Sub` (no further fold since operand unknown). `.` is a host function → NOT inlined. +7. `DROP` after loop. + +
+ +--- + +## Exercise 9: Dead Code Elimination +```forth +: ALWAYS-TRUE TRUE IF 42 ELSE 99 THEN ; +``` + +
+Answer + +1. Raw IR after inlining TRUE (body=[PushI32(-1)]): + `[PushI32(-1), If { then: [PushI32(42)], else: Some([PushI32(99)]) }]` +2. **DCE:** PushI32(-1) is nonzero → emit then_body only + → `[PushI32(42)]` +3. Entire IF/ELSE/THEN eliminated. Just pushes 42. + +
+ +--- + +## Exercise 10: Swap Peephole Patterns +```forth +: TEST SWAP SWAP DROP DROP ; +``` + +
+Answer + +1. After inlining: `[Swap, Swap, Drop, Drop]` +2. **Peephole pass 1:** + - Swap, Swap → removed → `[Drop, Drop]` + - Drop, Drop → TwoDrop → `[TwoDrop]` +3. **Final IR: `[TwoDrop]`** + +
+ +--- + +## Exercise 11: Nested Control Flow +```forth +: CLASSIFY DUP 0< IF DROP -1 ELSE 0> IF 1 ELSE 0 THEN THEN ; +``` + +
+Answer + +1. IR structure (after inlining): +``` +[Dup, ZeroLt, If { + then: [Drop, PushI32(-1)], + else: Some([Gt(implicit 0>), If { + then: [PushI32(1)], + else: Some([PushI32(0)]) + }]) +}] +``` +2. Optimizer recurses into both If bodies. No constant conditions → no DCE. +3. Codegen: nested WASM `if/else/end` blocks. + +
+ +--- + +## Exercise 12: DOES> Defining Word +```forth +: CONSTANT CREATE , DOES> @ ; +5 CONSTANT FIVE +FIVE . +``` + +
+Answer + +1. `: CONSTANT` enters compile mode +2. `CREATE` — flagged as saw_create_in_def=true +3. `,` — compiled normally +4. `DOES>` — splits definition: + - create_ir = everything before DOES> (the `,` call) + - does_action = everything after DOES> (the `@` call) → compiled as separate word + - Stores DoesDefinition { create_ir, does_action_id, has_create: true } +5. `5 CONSTANT FIVE`: + - CONSTANT executes its defining behavior + - CREATE makes dictionary entry "FIVE" + - `,` stores 5 at FIVE's parameter field + - DOES> patches FIVE to execute the does_action (which does `@`) +6. `FIVE .`: + - FIVE executes: pushes its PFA, then calls does_action (`@`) + - `@` fetches the 5 stored there + - `.` prints "5 " + +
+ +--- + +## Exercise 13: Consolidation +```forth +: A 1 ; +: B 2 ; +: C A B + ; +CONSOLIDATE +``` + +
+Answer + +1. Before CONSOLIDATE: A, B, C are separate WASM modules. C calls A and B via `call_indirect` through the function table. +2. CONSOLIDATE: + - Collects all IR bodies: A=[PushI32(1)], B=[PushI32(2)], C=[Call(a_id), Call(b_id), Add(inlined)] + - Builds local_fn_map: A→1, B→2, C→3 (within consolidated module) + - `compile_consolidated_module()`: all three become functions in one WASM module + - C's Call(a_id) → direct `call 1` (not call_indirect) + - Replaces all table entries with new functions +3. Result: C calling A and B is now a direct WASM `call` — much faster than table dispatch. + +
+ +--- + +## Exercise 14: Host Function Execution +```forth +5 3 M* +``` + +
+Answer + +1. `5` → push to data stack (dsp -= 4, mem[dsp] = 5) +2. `3` → push to data stack (dsp -= 4, mem[dsp] = 3) +3. `M*` → host function (Rust closure): + - Read sp = dsp global value + - Read n2 = mem[sp] = 3 (as i64) + - Read n1 = mem[sp+4] = 5 (as i64) + - result = 5i64 * 3i64 = 15i64 + - lo = 15 as i32 = 15 + - hi = (15 >> 32) as i32 = 0 + - Write mem[sp+4] = 15 (lo), mem[sp] = 0 (hi) + - Stack unchanged (still 2 cells, now containing double-cell 15) +4. Note: M* is a host function because it needs 64-bit multiplication (WASM i32 only) + +
+ +--- + +## Exercise 15: Float Operations +```forth +: HYPOTENUSE FDUP F* FSWAP FDUP F* F+ FSQRT ; +``` + +
+Answer + +1. After inlining: `[FDup, FMul, FSwap, FDup, FMul, FAdd, FSqrt]` +2. **Peephole:** No matching patterns (FDup+FMul not a known pair) +3. **Codegen:** All float ops use the float stack (FSP global): + - FDup: `fpeek(f)` then `fpush_via_local` + - FMul: `emit_float_binary` with `f64.mul` + - FSqrt: `emit_float_unary` with `f64.sqrt` +4. Float stack lives at 0x2540-0x2D40 in linear memory + +
+ +--- + +## Exercise 16: BEGIN WHILE REPEAT +```forth +: COUNTDOWN BEGIN DUP WHILE DUP . 1 - REPEAT DROP ; +``` + +
+Answer + +1. `BEGIN` → ControlEntry::Begin { body: [] } +2. `DUP` → Call(dup_id) into body +3. `WHILE` → pop Begin, create ControlEntry::BeginWhile { test: [Call(dup_id)], body: [] } +4. `DUP . 1 -` → into body +5. `REPEAT` → pop BeginWhile, emit `BeginWhileRepeat { test: [Dup], body: [Dup, Call(dot_id), PushI32(1), Sub] }` +6. Semantics: evaluate test; if false exit loop; execute body; jump to BEGIN + +
+ +--- + +## Exercise 17: Batch Mode Compilation +```forth +( During ForthVM::new() ) +``` + +
+Answer + +1. `register_primitives()` sets `batch_mode = true` +2. Each `register_primitive("DUP", ...)`: + - Creates dictionary entry (dictionary.create + reveal) + - Stores IR body in ir_bodies + - Pushes `(word_id, ir_body)` to `deferred_ir` (no WASM compilation yet) +3. After all ~40 IR primitives registered: + - `compile_batch()` compiles ALL deferred IR into a single WASM module + - One `rt.instantiate_and_install()` call — single module with ~40 functions + - Each function registered in the table +4. Why batch? Amortizes runtime compilation overhead. One module instead of 40. +5. Host functions bypass batch_mode — registered via `rt.register_host_func()` with HostFn closures. + +
+ +--- + +## Exercise 18: wafer build Pipeline +```forth +( file: hello.fth ) +: MAIN ." Hello, World!" CR ; +``` +```bash +wafer build hello.fth -o hello.wasm +``` + +
+Answer + +1. `cmd_build()`: create ForthVM, set recording=true, evaluate source +2. `evaluate()`: compiles MAIN normally (IR → optimize → codegen) +3. `recording_toplevel=true`: but MAIN is a definition, not top-level execution, so toplevel_ir stays empty +4. `export_module()`: + - Collect IR words: MAIN + all boot.fth definitions + - Entry point: no --entry flag, look for MAIN → found! + - Build `local_fn_map`: all words get module-internal indices + - `compile_exportable_module()`: single WASM module with all functions + - Data section: snapshot of linear memory (dictionary, variables, etc.) + - Metadata in "wafer" custom section: version, entry index, host functions, memory size, stack pointers +5. Output: hello.wasm file + +
+ +--- + +## Exercise 19: Stack-to-Local Promotion +```forth +: ADD3 + + ; +``` + +
+Answer + +1. After inlining: `[Add, Add]` +2. **Stack-to-local promotion** (codegen pass, not optimizer): + - Analyzes stack flow: first Add pops 2, pushes 1; second Add pops 2 (including that 1), pushes 1 + - If stack depth is statically known at each point → can use WASM locals instead of memory stack + - Result: operands stay in WASM locals/operand stack, no memory reads/writes + - Much faster: avoids load/store through linear memory +3. Promotion only works for "straight-line" code (no calls that might modify the stack unpredictably) + +
+ +--- + +## Exercise 20: MARKER and State Restore +```forth +MARKER CLEAN +: FOO 1 ; +: BAR 2 ; +CLEAN +FOO \ Error: unknown word +``` + +
+Answer + +1. `MARKER CLEAN`: + - Creates a MarkerState snapshot: dictionary state, user_here, next_table_index, word_pfa_map, ir_bodies, does_definitions, host_word_names, two_value_words, fvalue_words + - Registers CLEAN as a word that, when executed, restores this snapshot +2. `: FOO 1 ; : BAR 2 ;` — normal compilation, adds to dictionary +3. `CLEAN`: + - Executes the marker word + - Restores dictionary to state before FOO/BAR were defined + - Resets user_here, ir_bodies, etc. + - FOO and BAR are gone — dictionary.find("FOO") returns None +4. `FOO` → "unknown word: FOO" + +Key: MARKER doesn't undo WASM table entries (they become unreachable but stay allocated). It restores the dictionary and Rust-side metadata. + +
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