First read-only compiler-API reflection readers, bound the same way as the
intern/text_of seed (compiler_lib.bound_fns + Vm.callCompilerFn, native on flat
memory, no marshaling). A type handle is a plain u32 TypeId (like StringId), so
both stay clean scalar host-calls:
find_type(name: StringId) -> TypeId (TypeTable.findByName; unresolved/0 if absent)
type_field_count(t: TypeId) -> i64 (new TypeTable.memberCount; loud-bail, no silent 0)
memberCount is the single source both the legacy handler and the VM read, so the
two paths can't drift. find_type returns a non-optional TypeId using the
unresolved(0) sentinel for not-found rather than ?Type — a Type value is
.any-typed (which the flat-memory VM does not represent) and an optional can't
cross the legacy<->VM eval boundary; unresolved is the project-blessed "no type"
marker.
Example 0628 chains intern -> find_type -> type_field_count (+ a not-found
lookup), folded at #run, VM-HANDLED natively. VM unit test added.
Parity 689/689 (gate OFF and -Dcomptime-flat).
Phase 1.final of the flat-memory comptime VM — wire the host through it,
reach corpus parity, and gate it behind a build flag — plus the first
Phase 3 (compiler-API) step. Default OFF; legacy interpreter unchanged.
Host wiring + hardening:
- Machine accessors return error.OutOfBounds (no debug panic) on bad
addresses; Frame.get/set bounds-check and bail (no panic) on a malformed
operand ref (e.g. a ret Ref.none from an unresolved name).
- tryEval routed at both comptime call sites in emit_llvm — the const-init
fold and the #run side-effect path — with per-eval legacy fallback;
yields .void_val for void/noreturn entries. Both sites sx_trace_clear()
before the legacy fallback so a partial VM run that pushed trace frames
doesn't double-push on re-run.
VM coverage (all corpus const-inits except the inline-asm global):
- Implicit context materialized from the __sx_default_context global; the
full allocator protocol runs on the VM (context.allocator.alloc ->
call_indirect -> CAllocator thunk -> libc_malloc -> native flat malloc).
- Native libc memory builtins (malloc/calloc/free/memcpy/memmove/memset)
on flat memory; f32 stored/loaded as the 4-byte single; signed sub-64-bit
loads sign-extended; global_get (lazy + memoized); func_ref/call_indirect
(func-ref encoded fid+1, 0 reserved for null); string/slice fat-pointer
field access; is_comptime; the failable/error cluster (error_set tuples,
trace_frame + native sx_trace_push/clear -> raise/catch/or + return traces).
Build flag + Phase 3 seed:
- -Dcomptime-flat (build_opts module) OR SX_COMPTIME_FLAT env enables the VM;
zig build test -Dcomptime-flat runs the full corpus on the VM (688/0).
- intern/text_of serviced natively on flat memory via Vm.callCompilerFn
(compiler_welded boundary) — the seed the rest of the compiler-API grows on.
Parity 688/688 gate ON and OFF. Unit tests added throughout. The
lowering-time #insert wiring was explored and reverted (lowering-time IR can
be malformed; full malformed-IR hardening is a prerequisite, deferred).
Phase 1 of the flat-memory comptime VM (current/PLAN-COMPILER-VM.md),
built standalone + unit-tested with the legacy interpreter still live and
the corpus untouched (688 green).
src/ir/comptime_vm.zig:
- Machine: one linear byte memory (comptime stack+heap) with a bump/stack
allocator (mark/reset), scalar readWord/writeWord (1/2/4/8 LE) + byte
views; addr 0 reserved as null_addr. Frame: a Ref-indexed register file
(Reg = raw u64: immediate scalar bits OR an Addr). Target-aware layout
comes from the type table, so cross-compilation stays correct.
- Vm executor over the SAME SSA IR, mirroring the legacy interp's scalar
semantics (i64 wrapping/signed, f64). Ported: constants, arithmetic,
comparison, logical, conversions, control flow (br/cond_br/ret + block
params); structs (alloca/load/store/struct_init/get/gep at target
offsets); tuples; arrays (index_get/gep, length); slices+strings as
{ptr,len} fat pointers (const_string, data_ptr, subslice,
array_to_slice, str_eq/ne, index-through-slice); optionals (pointer and
{T,i1} shapes); payloadless enums; deref/addr_of; direct + recursive
call over the shared flat memory (depth-guarded). The value model: a
word for scalars/pointers, by-address for aggregates (a struct's value
IS its Addr). Any unported op bails loudly (error.Unsupported + detail).
- Reg<->Value boundary bridge (valueToReg / regToValue) + tryEval, the
hybrid-wiring entry point: run a comptime fn on the VM, return a legacy
Value or null to fall back. Transitional, for the legacy interop edge.
Registered in the ir.zig barrel.
