mirror of
https://github.com/imjasonh/nescript
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5 commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Claude
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0600f5b872
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codegen: fuse compare-then-branch to drop boolean materialization
Every NEScript condition (`if x < N`, `while i < end`, etc.) lowers in two IR ops: `CmpX(d, a, b)` materializes a 0/1 boolean into temp `d`, and the block's terminator `Branch(d, t, f)` reads `d` and branches on it. The codegen faithfully emitted both halves — `LDA / CMP / branch-to-true / LDA #0 / JMP done / true: LDA #1 / done:`, then later `LDA d_slot / BNE branch_t / JMP branch_f` — about 14 cycles + 13 bytes per condition. The 6502's natural pattern is one `CMP` + one branch on the flags it just set: 8 cycles, no register-clobber, no temp slot. Detect the canonical pattern in `gen_block` (last op is an 8-bit `CmpX` whose dest temp is what the terminator branches on, with no other uses) and emit the fused form directly via a new `gen_cmp_branch` helper. The temp's allocation, store, load, and the terminator's branch fall away. Bookkeeping subtlety: the source temps `a`/`b` must be retired *after* the fused emit, not before — the original `gen_op` order is "emit body of op, then `retire_op_sources`". Decrementing their use counts before the CMP would free their slots while they were still live; `load_temp(a)` would then re-allocate `a` to whatever stale slot the free list popped next. Got hit by this on the first attempt — the SHA-256 example dutifully returned all-zero hashes until the order was fixed. Updated `ir_codegen_local_label_suffix_is_bank_namespaced`: the test was relying on `if x == 0` to emit `__ir_cmp_*` labels for its bank-namespacing check, which the fusion now collapses into direct branches. Switched the test source to a shift-by-variable pattern (`x = x << n`), which always emits `__ir_shift_loop_*` labels regardless of future cmp/branch optimizations. Cycle savings: ~6 cycles per condition. The SHA-256 rotate loops alone account for ~9K cycles per block. Across all examples the cycle drift shows up as audio-tick phase shifts in five timing-sensitive ROMs (`audio_demo`, `friendly_assets`, `noise_triangle_sfx`, `platformer`, `sfx_pitch_envelope`); the goldens for those are refreshed in this commit, plus `platformer.gif` (the only demo gif whose bytes actually moved). Verified: cargo test/clippy/fmt clean on rustc 1.95.0; emulator harness 34/34; reproducibility diff clean; SHA-256 of "NES" still computes to AE9145DB…4E0D. https://claude.ai/code/session_01FRmSBruVWCufm3LsUVMs8v |
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Claude
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0b5470b054
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codegen: skip parameter-spill prologue for leaf functions
Leaf functions — those that never JSR another routine from inside
their body — don't need to spill the `$04..$07` parameter
transport slots into per-function RAM, because nothing inside the
body clobbers those slots. Detect them in `IrCodeGen::new` via a
linear scan over each function's IR ops, point their parameters
at `$04..$07` directly in `var_addrs` (and in a parallel
`leaf_param_overrides` map for inline-asm `{name}` substitution),
and have `gen_function` skip the spill prologue.
The "leaf" predicate is conservative: any of `IrOp::Call`, `Mul`,
`Div`, `Mod`, `Transition`, or an inline-asm body containing a
`JSR` token disqualifies the function. SetPalette /
LoadBackground / PlaySfx / StartMusic / DebugLog / DebugAssert
were verified by inspection to not emit JSRs.
Per call to a leaf primitive: `LDA $04 / STA <local> / LDA $05 /
STA <local+1>` is now omitted — saves 12 cycles and 12 bytes of
code per call. Across the SHA-256 example's ~5500 leaf-primitive
calls per block, that's ~66K cycles saved per compression — about
2.2 frames at NTSC.
The fix also touches every committed `examples/*.nes` (the leaf
prologue was emitted by every fun with params, not just the SHA
ones), so 9 ROMs and the same three timing-sensitive goldens
(war.png + platformer/pong/war audio hashes) get refreshed; the
two committed gifs that drifted do too.
Verified: cargo test/clippy/fmt clean on rustc 1.95.0; emulator
harness 34/34; reproducibility diff clean; SHA-256 of "NES" still
computes to AE9145DB…4E0D.
https://claude.ai/code/session_01FRmSBruVWCufm3LsUVMs8v
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Claude
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20a244b9e7
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examples: regenerate ROMs, gifs, and goldens after codegen local fix
Commit
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Claude
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76dd8eacb0
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compiler: fix three scoping bugs; war: revert all local/param workarounds
Three related scoping bugs from examples/war/COMPILER_BUGS.md,
all fixed in one pass because they're different layer
manifestations of the same "flat global namespace" problem:
## §3: function-local `var` declarations lived in one namespace
`src/analyzer/mod.rs::register_var` inserted every `var` it
saw — top-level, state-local, AND function-body local — into
the same `self.symbols: HashMap<String, Symbol>`. Two different
functions declaring `var i` collided on E0501, which is why
every local in war/*.ne had a function-prefix like `dfa_card`
or `dwp_px`.
Fix: add a `current_scope_prefix: Option<String>` to the
Analyzer, set it to `Some("<fn_name>")` when checking a
function body (or `Some("Title__frame")` for state handler
bodies), and have `register_var` store the declaration under
an internal key `"__local__{prefix}__{name}"`. New
`resolve_symbol` / `resolve_key` helpers try the
scope-qualified key first and fall back to the bare key for
globals / consts / enum variants / state-level vars / function
names. Every existing `self.symbols.get(name)` inside
body-checking code was swapped over.
Two `var i` declarations inside the SAME function body still
collide with E0501 — we scoped per function body, not per
nested block. Per-block scoping would require live-range
analysis to reuse RAM slots.
## §1b: same-named params across functions shared VarIds
`src/ir/lowering.rs::get_or_create_var` looked up names in a
single global `var_map`, so two functions both with a `card:
u8` parameter resolved to the same `VarId`. Whichever function
was lowered last won the zero-page slot mapping, silently
rerouting the other function's param reads to the wrong slot.
Fix: the IR lowerer now mirrors the analyzer's scope logic.
`LoweringContext` gains a `current_scope_prefix` field that
gets set in `lower_function` / `lower_handler`, and
`get_or_create_var` uses a new `scoped_key` helper that
prepends `"__local__{prefix}__"` when the qualified key exists
in `var_map` or `var_types`. Each function's parameters and
locals therefore get distinct VarIds, and the codegen's
`var_addrs` map naturally has no collisions.
## §2: param transport slots $04-$07 clobbered across nested JSRs
Parameters were passed AND kept in `$04-$07` for the lifetime
of a function. Any nested call overwrote those slots with its
own arguments, so the caller's params were silently corrupted
as soon as it invoked anything. Every war helper that took
params and called other helpers (draw_card_face, push_back_a,
etc) snapshotted its params into fresh locals at the top of
the body.
Fix: in `codegen/ir_codegen.rs::IrCodeGen::new`, every
function-local — including parameters — now gets a dedicated
per-function RAM slot at `$0300+`. Parameters are still passed
via the zero-page transport slots `$04-$07` as the calling
convention, but `gen_function` now emits a **prologue** at
every function entry:
LDA $04
STA <param_0_addr>
LDA $05
STA <param_1_addr>
... etc, up to 4 ...
By the time the body runs, every parameter lives in the
function's dedicated RAM slot, so any nested call can freely
clobber $04-$07 (writing its own arguments there) without
corrupting the caller's saved parameters. Costs 4 LDA/STA
pairs (≈ 20 bytes of ROM, 16 cycles) at every function entry
— worth it to make the calling convention sound.
## War cleanup
With all three fixes in place, every workaround prefix in
`examples/war/*.ne` is gone:
- `card_rank(card)` instead of `card_rank(crk_c)` — bug #1b
- `compare_cards(a, b)` instead of `compare_cards(cmp_a, cmp_b)`
- `push_back_a(card)` instead of `push_back_a(pba_in)` — bug #1b
- `var card: u8 = draw_front_a()` in bury_from_* — bug #3
- `var i: u8 = 0` freely in multiple functions — bug #3
- `fun push_back_a(card)` body no longer snapshots `card` into
`pba_card` before calling wrap52 — bug #2
- `fun draw_card_face` body no longer snapshots x/y/card into
locals before calling card_rank/card_suit — bug #2
- `draw_word_player` steps its own x without needing a
`dwp_px` accumulator to avoid the `x + N` arg compilation
quirk — that quirk was a downstream symptom of bug #2 and
is also gone
The source is now about 300 lines shorter and significantly
more readable.
## Regression tests
Seven new tests nail these bugs down:
- `analyzer::tests::analyze_allows_same_local_name_in_two_functions`
- `analyzer::tests::analyze_allows_same_param_name_in_two_functions`
- `analyzer::tests::analyze_allows_same_local_name_in_two_state_handlers`
- `analyzer::tests::analyze_still_rejects_duplicate_local_in_same_function`
- `codegen::ir_codegen::gen_function_prologue_spills_params_to_local_ram`
Plus the four param-arity tests from the earlier E0506 fix
and the wide_hi-leak regression test from the previous
compiler fix. Total suite: 591 unit tests, all passing.
## Golden drift
The prologue change adds a few cycles to every function entry,
which shifts NMI sampling by a handful of cycles and flips
the audio-hash of any example that plays sfx or music
(platformer, war). `arrays_and_functions.png` also picks up a
1-pixel shift in its enemy positions due to the same timing
drift. All three golden updates are pure "compiler produces
different but functionally-identical output" — no game
behavior changed.
## What's still open in COMPILER_BUGS.md
- §4: 8-sprites-per-scanline hardware limit is invisible to
user code. A static analyzer hint could help; deferred.
- §5: `inline` keyword is silently declined for short
functions that the optimizer's inliner doesn't recognize
(it only removes empty functions). Deferred pending a real
single-return-expression inlining pass.
https://claude.ai/code/session_0143dTgh3UeRrtfHgQwzcv5z
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Claude
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57faf9e36a
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commit built ROMs alongside .ne sources
The compiler is deterministic: rebuilding any example produces a byte-identical ROM, verified across all 22 examples and all four mappers (NROM, MMC1, UxROM, MMC3). That means the .nes files are reproducible artefacts and can live next to their sources without drift. Benefits: - Users can clone the repo and open any example in an emulator without installing a Rust toolchain or running the compiler. - The emulator harness can trust examples/*.nes directly, so its CI job no longer needs a compiler build or a "compile all examples" loop — it just boots jsnes against the committed ROMs and diffs each against its golden. - ROM diffs in PRs are now meaningful: "this compiler change flipped 17 bytes in hello_sprite.nes" is visible review signal, not hidden behind the emulator golden. Guard rails so the ROMs don't drift from their sources: - .gitignore no longer excludes *.nes. - The `examples` CI job rebuilds every .ne into /tmp and fails loudly (with a GitHub error annotation pointing at the exact cargo command to rerun) if any committed ROM differs. - scripts/pre-commit does the same check locally. - CLAUDE.md now states that editing a .ne file requires rebuilding its .nes in the same commit, so future agents won't miss the invariant. Total footprint: 22 ROMs, 624 KB (avg 28 KB each — most are NROM 24 KB; two banked examples are larger). https://claude.ai/code/session_01BcCcHi6FUmTh8jC7UgkA3A |