New src/codegen/ir_codegen.rs walks IrProgram and emits 6502 instructions.
This enables optimizer passes to actually affect the output ROM.
Design:
- Each IR temp gets a zero-page slot at $80 + temp_index
- Functions reset the temp counter at entry (temps don't outlive functions)
- Globals map by name to their analyzer-assigned zero-page addresses
- Operands are loaded into A, computed, stored back to the dest slot
Handles all IrOp variants:
- LoadImm, LoadVar, StoreVar (basic loads/stores)
- Add/Sub (CLC+ADC / SEC+SBC)
- Mul (JSR __multiply runtime routine)
- And/Or/Xor (zero-page operands)
- ShiftLeft/ShiftRight (repeated ASL/LSR)
- Negate/Complement (EOR #$FF + optional two's complement)
- CmpEq/Ne/Lt/Gt/LtEq/GtEq (CMP + conditional branch + 0/1)
- ArrayLoad/ArrayStore (TAX + ZeroPageX/AbsoluteX)
- Call (ZP param passing + JSR)
- DrawSprite (OAM slot 0 write, uses sprite_tiles map)
- ReadInput (LDA $01, P1 input)
- WaitFrame (poll frame flag at $00)
All terminators:
- Jump (JMP to block label)
- Branch (LDA temp + BNE true / JMP false)
- Return (optional value in A + RTS)
- Unreachable (BRK)
IR lowering fixes:
- ReadInput now has a destination IrTemp (was a side-effect-only op)
- ButtonRead uses the proper input temp instead of uninitialized register
- Logical AND/OR use new emit_move helper (OR with zero) instead of
bogus raw VarId for path merging
CLI:
- New --use-ir flag on `build` subcommand to opt in to IR codegen
- Default remains AST codegen (for now); IR codegen is experimental
All 7 examples compile through the IR pipeline and produce valid iNES ROMs.
Tests: 266 total (7 new ir_codegen unit + 2 new integration).
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
resolve_sprites() now handles all three AssetSource variants:
- Inline(bytes): use directly (existing behavior)
- Binary(path): read raw bytes from file relative to source_dir
- Chr(path): convert PNG to CHR via png_to_chr()
Missing files are silently skipped rather than erroring, so
declarations can reference assets that haven't been added yet.
This keeps existing tests that use placeholder file paths working.
Updated future-work.md: moved include directive, P2 controller,
sprite resolution, shift-assign, debug statements, warnings, and
asset wiring to the "completed" section. Remaining work is IR codegen,
audio, on_scanline, and language features (structs/enums).
Tests: 257 total (3 new resolve_sprites tests)
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Parser:
- debug.log(expr, ...) and debug.assert(cond) syntax
- parse_debug_statement() handles both methods
- New AST variants: Statement::DebugLog and Statement::DebugAssert
Codegen:
- CodeGen::with_debug(bool) to toggle debug instrumentation
- DebugLog writes each expression to $4800 (Mesen debug port)
- DebugAssert evaluates condition; on false, writes $FF to $4800 + BRK
- Both are stripped entirely when debug_mode = false (release builds)
CLI:
- --debug flag now wired through to CodeGen
- Without --debug, all debug statements produce zero bytes
Analyzer:
- Type-checks DebugAssert condition as bool
- Walks DebugLog args for reads (used_vars tracking)
IR lowering:
- DebugLog/DebugAssert are no-ops (codegen handles them directly)
254 tests (5 new: 3 parser + 2 codegen).
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Parser/preprocess module:
- New src/parser/preprocess.rs handles source-level include inlining
- 'include "path"' at line start splices the target file's content
- Paths resolved relative to the including file's directory
- Circular include detection via visited set (canonicalized paths)
- Non-cycle re-includes allowed (sibling branches can reuse files)
main.rs:
- Both compile() and check() run preprocess_source() before parsing
- Include resolution failures produce a clear error message
Tests: 4 new preprocess unit tests (249 total)
- passthrough, include line parsing, temp-file roundtrip
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Parser:
- p1.button.X and p2.button.X syntax
- Emits Expr::ButtonRead with Some(Player::P1) or Some(Player::P2)
- Plain button.X still works (defaults to P1)
- Removed #[allow(dead_code)] from Player::P1 and Player::P2
Runtime:
- NMI handler now reads both $4016 (JOY1) and $4017 (JOY2) in
the same loop, shifting 8 bits into ZP_INPUT_P1 ($01) and
ZP_INPUT_P2 ($08) simultaneously
- JOY2 register constant added
Codegen:
- Button reads select correct ZP address based on Player variant
- gen_condition and gen_expr both handle P1/P2 dispatching
Tests: 245 (3 new parser tests: p1/p2 button read + shift-assign)
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Sprite/asset pipeline:
- Linker::link_with_assets() places sprite CHR data in ROM at correct tile
- assets::resolve_sprites() walks Program for inline sprite bytes
- CodeGen::with_sprites() maps sprite names to tile indices
- gen_draw() uses correct tile index from sprite declarations
- main.rs wires the full resolution pipeline
Shift-assign operators (<<= and >>=):
- AssignOp::ShiftLeftAssign and ShiftRightAssign variants
- Parser handles in both statement and array index contexts
- Codegen emits ASL A / LSR A
- IR lowering maps to ShiftLeft/ShiftRight ops
Unreachable state warning (W0104):
- BFS from start state finds reachable states via transitions
- States not reached produce W0104 warning
Error polish helpers:
- suggest_var_name() for "did you mean" suggestions
- emit_undefined_var() for E0502 with typo hints
- Used by analyzer for better diagnostics
242 tests pass, clippy clean.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Control flow:
- Break: JMP to break_label from loop_stack
- Continue: JMP to continue_label from loop_stack
- Return: evaluate expr into A (if present), RTS
- Transition: write state index to ZP $03, JMP __main_loop
- Call: evaluate args to ZP param slots, JSR __fn_name
Multi-OAM sprite support:
- next_oam_slot counter (0-63) increments per draw
- Reset to 0 at the start of each frame handler
- Each draw writes to sequential 4-byte OAM entries ($0200+slot*4)
- Silently stops drawing if >64 sprites per frame (OAM full)
All 233 tests pass, clippy clean.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Issues found by systematic review of all compiler modules.
Each fix includes a regression test.
Parser fixes:
- Add EOF checks to function call arg parsing loops (lines 984, 1269)
to prevent infinite loops on unterminated call expressions
- Fix span end positions: use .end instead of .start for 9 declaration
span computations (var, const, fun, state, bank, sprite, palette,
background, block)
- Add missing compound assignment operators (&= |= ^=) to
parse_assign_op() for array element assignments
Codegen fix:
- Fix NOT operator: old code used EOR #$FF + AND #$01 which produced
wrong results for non-boolean inputs (e.g., NOT 0x42 returned 1
instead of 0). New code uses BEQ/branch to properly map any nonzero
value to 0 and zero to 1.
Assembler fixes:
- Add branch offset range validation: assert offset is in -128..127
range instead of silently wrapping on overflow
- Panic on unresolved labels instead of silently leaving placeholder
0x00 bytes in the output
Verified non-issues (reviewer false positives):
- NMI P register: 6502 hardware pushes P automatically on NMI entry;
RTI restores it. PHP/PLP not needed.
- Controller read buffer: 8 iterations of LSR+ROL fully replace all
8 bits, so prior contents don't matter.
- advance() panic: tokens always has at least Eof from lexer.
4 new regression tests, 225 total.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Fuzz targets (cargo +nightly fuzz):
- fuzz_lexer: lexer must never panic on arbitrary input
- fuzz_parser: parser must never panic on arbitrary input
- fuzz_compile: full pipeline (parse → analyze → IR → optimize →
codegen → assemble → link) must never panic
Results: 3.3M iterations across all targets, zero crashes.
Seed corpus from all 7 examples + crafted edge cases.
11 new parser edge case tests:
- draw_followed_by_statement: regression for keyword-arg lookahead bug
- draw_with_frame_followed_by_statement: same with frame: arg
- nested_if_else_chain: 3-deep else-if chain
- deeply_nested_blocks: 4-deep nested if blocks
- empty_function_body: fun noop() {}
- empty_state_handlers: on enter/exit/frame {}
- button_start_in_condition: "start" keyword as button name
- button_select_in_condition: "select" keyword as button name
- multiple_draws_in_sequence: 3 draws followed by assignment
- parser_no_panic_on_garbage: 25 malformed inputs
- lexer_no_panic_on_garbage: 10 malformed inputs
221 tests total, all pre-commit checks pass.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
README: project overview, quick start, feature list, example table
LICENSE: MIT
4 new examples covering all language features:
- arrays_and_functions: arrays, while loops, inline/regular functions
- state_machine: multi-state flow with on enter/exit handlers
- sprites_and_palettes: inline CHR data, palette switching, scroll, cast
- mmc1_banked: MMC1 mapper, bank declarations, software multiply
Parser fix: draw statement keyword-arg parsing now checks for ':'
lookahead before consuming an identifier, preventing it from eating
the next statement as a keyword argument (e.g., `i += 1` after a draw).
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Pipeline:
- main.rs now runs IR lowering and optimization before codegen
- IR is built and optimized but output still uses AST-based codegen
(IR-based codegen is a future improvement)
Coin Cavern example (examples/coin_cavern.ne):
- 3-state game: Title → Playing → GameOver
- Functions (clamp_x), constants, gravity physics, coin collection
- Demonstrates most M2 language features
Integration tests (14 total, 7 new):
- program_with_functions: functions with params and return values
- program_with_while_loop: while loops compile correctly
- program_with_fast_slow_vars: placement hints accepted
- program_with_multi_state_transitions: 3-state cycle
- coin_cavern_compiles: full Coin Cavern example
- ir_pipeline_produces_ir: validates IR lowering + optimizer
- error_test_recursion_detected: E0402 for recursive functions
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Analyzer extensions:
- Call graph construction from function bodies and state handlers
- DFS-based recursion detection (direct and mutual) with E0402 errors
- Max call depth computation per entry point with E0401 enforcement
- Function declarations registered as symbols (E0503 for undefined calls)
- Collects calls from all statement/expression types recursively
Optimizer (new module):
- Constant folding: evaluate known-constant arithmetic at compile time
- Dead code elimination: remove ops with unused destination temps
- Both operate per-basic-block in a single pass
171 tests total (22 new: 6 analyzer + 11 IR lowering + 5 optimizer)
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
- CI: new "Build Examples" job compiles all .ne files and validates
the output ROMs have correct iNES headers
- Examples: add notes explaining that sprite names (Smiley, Ball) are
parsed but not yet resolved — all draws use the built-in CHR tile 0.
Custom sprite declarations come in M3.
- Codegen: explicit `let _ = &draw.sprite_name` to document the
intentional skip, with comment about M2/M3 scope
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
Two example .ne programs with compiled .nes ROMs:
- hello_sprite: d-pad controlled sprite movement
- bouncing_ball: auto-bouncing sprite with edge detection
Includes README with build instructions and emulator setup.
https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3
