Core VM changes:
- Add VmClosure value variant — inner closures created by OP_CLOSURE are
first-class VM values, not NativeFn wrappers around call_closure
- Convert `run` from recursive to while-loop — zero OCaml stack growth,
true TCO for VmClosure tail calls
- vm_call handles VmClosure by pushing frame on current VM (no new VM
allocation per call)
- Forward ref _vm_call_closure_ref for cross-boundary calls (CEK/primitives)
Compiler (spec/compiler.sx):
- Define hoisting in compile-begin: pre-allocate local slots for all
define forms before compiling any values. Fixes forward references
between inner functions (e.g. read-expr referencing skip-ws in sx-parse)
- scope-define-local made idempotent (skip if slot already exists)
Server (sx_server.ml):
- JIT fail-once sentinel: mark l_compiled as failed after first VM runtime
error. Eliminates thousands of retry attempts per page render.
- HTML tag bindings: register all HTML tags as pass-through NativeFns so
eval-expr can handle (div ...) etc. in island component bodies.
- Log VM FAIL errors with function name before disabling JIT.
SSR fixes:
- adapter-html.sx letrec handler: evaluate bindings in proper letrec scope
(pre-bind nil, then evaluate), render body with render-to-html instead of
eval-expr. Fixes island SSR for components using letrec.
- Add `init` primitive to OCaml kernel (all-but-last of list).
- VmClosure handling in sx_runtime.ml sx_call dispatch.
Tests: 971/971 OCaml (+19 new), 0 failures.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The compiler was treating letrec as let — binding values sequentially.
This meant mutually recursive functions (like sx-parse's read-list
calling read-expr and vice versa) couldn't reference each other.
compile-letrec uses two phases:
1. Define all local slots initialized to nil
2. Compile and assign values — all names already in scope
This fixes sx-parse producing wrong ASTs (nested instead of sibling
lists) when JIT-compiled, which caused the stepper's step count to
be 2 instead of 16.
Also: skip JIT for lambdas with closure bindings (inner functions
like read-list-loop) — the closure merging into vm_env_ref produces
incorrect variable resolution.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Fix infinite recursion in VM JIT: restore sentinel pre-mark in vm_call
and pre-compile loop so recursive compiler functions don't trigger
unbounded compilation cascades. Runtime VM errors fall back to CEK;
compile errors surface visibly (not silently swallowed).
New: compile-quasiquote emits inline code instead of delegating to
qq-expand-runtime. Closure-captured variables merged into VM globals
so compiled closures resolve outer bindings via GLOBAL_GET.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
compile-quasiquote, compile-defcomp, compile-defmacro were hardcoding
CALL_PRIM for runtime functions (qq-expand-runtime, eval-defcomp,
eval-defmacro) that aren't in the primitives table. Changed to
GLOBAL_GET + CALL so the VM resolves them from env.bindings at runtime.
The compile-call function already checks (primitive? name) before
emitting CALL_PRIM — only the three special-case compilers were wrong.
Also: register scope-push!/pop! as primitives, add scope-peek/emit!
to OCaml transpiler name mapping, fix sx_runtime.ml scope wrappers
to route through prim_call "scope-push!" etc.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Compiler fixes:
- Upvalue re-lookup returns own position (uv-index), not parent slot
- Spec: cek-call uses (make-env) not (dict) — OCaml Dict≠Env
- Bootstrap post-processes transpiler Dict→Env for cek_call
VM runtime fixes:
- compile_adapter evaluates constant defines (SPECIAL_FORM_NAMES etc.)
via execute_module instead of wrapping as NativeFn closures
- Native primitives: map-indexed, some, every?
- Nil-safe HO forms: map/filter/for-each/some/every? accept nil as empty
- expand-components? set in kernel env (not just VM globals)
- unwrap_env diagnostic: reports actual type received
sx-page-full command:
- Single OCaml call: aser-slot body + render-to-html shell
- Eliminates two pipe round-trips (was: aser-slot→Python→shell render)
- Shell statics (component_defs, CSS, pages_sx) cached in Python,
injected into kernel once, referenced by symbol in per-request command
- Large blobs use placeholder tokens — Python splices post-render,
pipe transfers ~51KB instead of 2MB
Performance (warm):
- Server total: 0.55s (was ~2s)
- aser-slot VM: 0.3s, shell render: 0.01s, pipe: 0.06s
- kwargs computation: 0.000s (cached)
SX_STANDALONE mode for sx_docs dev (skips fragment fetches).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Fixed compile-define to skip :effects/:as keyword annotations between
the name and body. (define name :effects [render] (fn ...)) now
correctly compiles the fn body, not the :effects keyword.
Result: adapter-sx.sx compiles to 25 code objects, 4044 bytes of
bytecode. All 12 aser functions (aser, aser-call, aser-list,
aser-fragment, aser-expand-component, etc.) compile successfully.
40/40 VM tests pass.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Added vm-compile command: iterates env, compiles lambdas to bytecode,
replaces with NativeFn VM wrappers (with CEK fallback on error).
Tested: 3/109 compile, reduces CEK steps 23%.
Disabled auto-compile in production — the compiler doesn't handle
closures with upvalues yet, and compiled functions that reference
dynamic env vars crash. Infrastructure stays for when compiler
handles all SX features.
Also: added set-nth! and mutable-list primitives (needed by
compiler.sx for bytecode patching). Fixed compiler.sx to use
mutable lists on OCaml (ListRef for append!/set-nth! mutation).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
End-to-end pipeline working:
Python compiler.sx → bytecode → OCaml VM → result
Verified: (+ (* 3 4) 2) → 14 ✓
(+ 0 1 2 ... 49) → 1225 ✓
Benchmark (500 iterations, 50 additions each):
CEK machine: 327ms
Bytecode VM: 145ms
Speedup: 2.2x
VM handles: constants, local variables, global variables,
primitive calls, jumps, conditionals, closures (via NativeFn
wrapper), define, return.
Protocol: (vm-exec {:bytecode (...) :constants (...)})
- Compiler outputs clean format (no internal index dict)
- VM converts bytecode list to int array, constants to value array
- Stack-based execution with direct opcode dispatch
The 2.2x speedup is for pure arithmetic. For aser (the real
target), the speedup will be larger because aser involves:
- String building (no CEK frame allocation in VM)
- Map/filter iterations (no frame-per-iteration in VM)
- Closure calls (no thunk/trampoline in VM)
Next: compile and run the aser adapter on the VM.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Three new files forming the bytecode compilation pipeline:
spec/bytecode.sx — opcode definitions (~65 ops):
- Stack/constant ops (CONST, NIL, TRUE, POP, DUP)
- Lexical variable access (LOCAL_GET/SET, UPVALUE_GET/SET, GLOBAL_GET/SET)
- Jump-based control flow (JUMP, JUMP_IF_FALSE/TRUE)
- Function ops (CALL, TAIL_CALL, RETURN, CLOSURE, CALL_PRIM)
- HO form ops (ITER_INIT/NEXT, MAP_OPEN/APPEND/CLOSE)
- Scope/continuation ops (SCOPE_PUSH/POP, RESET, SHIFT)
- Aser specialization (ASER_TAG, ASER_FRAG)
spec/compiler.sx — SX-to-bytecode compiler (SX code, portable):
- Scope analysis: resolve variables to local/upvalue/global at compile time
- Tail position detection for TCO
- Code generation for: if, when, and, or, let, begin, lambda,
define, set!, quote, function calls, primitive calls
- Constant pool with deduplication
- Jump patching for forward references
hosts/ocaml/lib/sx_vm.ml — bytecode interpreter (OCaml):
- Stack-based VM with array-backed operand stack
- Call frames with base pointer for locals
- Direct opcode dispatch via pattern match
- Zero allocation per step (unlike CEK machine's dict-per-step)
- Handles: constants, variables, jumps, calls, primitives,
collections, string concat, define
Architecture: compiler.sx is spec (SX, portable). VM is platform
(OCaml-native). Same bytecode runs on JS/WASM VMs.
Also includes: CekFrame record optimization in transpiler.sx
(29 frame types as records instead of Hashtbl).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
