lab/sx
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

comptime VM: model .type_value natively (word); harden struct_init vs arrays

Browse Source 
kindOf(.type_value) -> .word; new const_type exec arm -> word = TypeId.index();
regToValue maps a .type_value word back to a .type_tag Value at the legacy
boundary. The VM now runs comptime evals involving Type values instead of
bailing.

This reached a latent VM panic: struct_init assumed a .@"struct" result type and
union-access-panicked on an array literal (EnumVariant.[...]). It is the generic
aggregate-literal op, so it now dispatches on the result kind (struct/array/
tuple) and bails loudly on anything else — never panics (CLAUDE.md no-panic).

697/0 both gates (make_enum type-fns run further on the VM, then bail cleanly at
the define call_builtin -> legacy mints; no mutation before bail). VM unit test
added (const_type -> word -> regToValue -> .type_tag).
This commit is contained in:
agra
2026-06-18 14:05:16 +03:00
parent 94f60c51c0
commit 554871ba0b
3 changed files with 66 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
current/CHECKPOINT-COMPILER-API.md
View File

@@ -335,6 +335,20 @@ when reached (sentinels or accessor fns; see the design doc Risks).
`List` growth; orthogonal, see `current/CHECKPOINT-METATYPE.md`.)
## Log
- **Phase 3 P3.4 step 4 (VM plan) — model `.type_value` natively in the comptime VM (2026-06-18).**
The VM now HANDLES Type values instead of bailing: `kindOf(.type_value)` → `.word`; a new
`const_type` exec arm → the word `TypeId.index()`; `regToValue` maps a `.type_value` word back
to a `.type_tag` Value at the legacy boundary (`valueToReg` already mapped `.type_tag` →
index). Surfaced + fixed a VM PANIC (forbidden): `struct_init` assumed a `.@"struct"` result
type and union-access-panicked on an ARRAY literal (`EnumVariant.[ … ]`, reached now that Type
args no longer bail early) — it's the generic aggregate-literal op, so it now dispatches on the
result kind (struct / array / tuple) and BAILS loudly on anything else, never panics. **697/0
both gates** (the make_enum type-fns now run further on the VM, then bail cleanly at the
`define`/`make_enum` `call_builtin` → legacy mints — no mutation before the bail, parity holds).
VM unit test added (const_type → word → regToValue → `.type_tag`). On `reify`. **Next (the
payoff):** port the WRITE side (declare_type / register_type / pointer_to) into
`Vm.callCompilerFn` + give the lowering-time path a REAL Context (CAllocator thunk func-refs,
not zeroed) → the first HANDLED lowering-time type-fn end-to-end on the VM.
- **Phase 3 P3.4 step 3 (VM plan) — dedicated `Type` builtin TypeId: RESOLVER FLIPPED + `.any` migration (2026-06-18).**
Flipped `type_resolver:64` (`"Type"` → `.type_value`), `module.zig` `constType` (result type
→ `.type_value`), and `emitConstType` (a bare i64 carrying `tid.index()`, NOT a 16-byte Any

23
src/ir/comptime_vm.test.zig
View File

@@ -589,6 +589,29 @@ test "comptime_vm exec: payloadless enum_init + enum_tag" {
try std.testing.expectEqual(@as(i64, 11), toI64(try v.run(&fb.func, &.{})));
}
test "comptime_vm exec: const_type yields a Type-value word; regToValue bridges it to .type_tag" {
const alloc = std.testing.allocator;
var table = types.TypeTable.init(alloc);
defer table.deinit();
// return <Type value u32> → a `.type_value`-typed entry whose word is u32.index()
var fb = Fb.init(alloc, &.{}, .type_value);
defer fb.deinit();
const b0 = fb.block(&.{});
const ct = fb.add(b0, inst(.{ .const_type = .u32 }, .type_value));
_ = fb.add(b0, inst(.{ .ret = .{ .operand = ref(ct) } }, .void));
var v = vm.Vm.init(alloc);
v.table = &table;
defer v.deinit();
const word = try v.run(&fb.func, &.{});
try std.testing.expectEqual(@as(u64, types.TypeId.u32.index()), word);
// The legacy boundary maps the word back to a first-class `.type_tag` Value.
const val = try v.regToValue(alloc, &table, word, .type_value);
try std.testing.expectEqual(types.TypeId.u32, val.type_tag);
}
test "comptime_vm exec: deref a pointer; addr_of passes through a struct address" {
const alloc = std.testing.allocator;
var table = types.TypeTable.init(alloc);

34
src/ir/comptime_vm.zig
View File

@@ -499,6 +499,10 @@ pub const Vm = struct {
.const_bool => |v| return .{ .value = @intFromBool(v) },
.const_float => |v| return .{ .value = @bitCast(v) },
.const_null, .const_undef => return .{ .value = null_addr },
// A `Type` literal: the 8-byte handle is the `TypeId` index in a word
// (the `.type_value` representation). `regToValue` maps it back to a
// `.type_tag` Value at the legacy boundary.
.const_type => |tid| return .{ .value = @as(Reg, tid.index()) },
// ── Arithmetic ──────────────────────────────────────
.add, .sub, .mul, .div, .mod => |b| return .{
@@ -546,12 +550,26 @@ pub const Vm = struct {
.struct_init => |agg| {
const table = try self.requireTable();
const sty = ins.ty;
if (sty.isBuiltin()) return self.failMsg("comptime VM: struct_init at a builtin result type");
const addr = self.machine.allocBytes(table.typeSizeBytes(sty), table.typeAlignBytes(sty));
const fields = table.get(sty).@"struct".fields;
for (fields, 0..) |f, i| {
if (i >= agg.fields.len) break;
const off = fieldOffset(table, sty, @intCast(i));
try self.writeField(table, addr + off, f.ty, frame.get(agg.fields[i].index()));
// `struct_init` is the generic aggregate-literal op — its result
// type may be a struct, an ARRAY (e.g. `EnumVariant.[ … ]`), or a
// tuple. Lay each operand out at the matching offset; bail loudly on
// any other shape (never a `.@"struct"`-union-access panic).
switch (table.get(sty)) {
.@"struct" => |s| for (s.fields, 0..) |f, i| {
if (i >= agg.fields.len) break;
try self.writeField(table, addr + fieldOffset(table, sty, @intCast(i)), f.ty, frame.get(agg.fields[i].index()));
},
.array => |a| {
const esz: Addr = @intCast(table.typeSizeBytes(a.element));
for (agg.fields, 0..) |fr, i| try self.writeField(table, addr + @as(Addr, @intCast(i)) * esz, a.element, frame.get(fr.index()));
},
.tuple => |t| for (t.fields, 0..) |fty, i| {
if (i >= agg.fields.len) break;
try self.writeField(table, addr + tupleFieldOffset(table, sty, @intCast(i)), fty, frame.get(agg.fields[i].index()));
},
else => return self.failMsg("comptime VM: struct_init at a non-aggregate result type"),
}
return .{ .value = addr };
},
@@ -1166,6 +1184,9 @@ pub const Vm = struct {
.word => {
if (isFloat(ty)) return .{ .float = @bitCast(reg) };
if (ty == .bool) return .{ .boolean = reg != 0 };
// A `Type` value word is a `TypeId` index → the first-class
// `.type_tag` Value the legacy interp/host uses for Type values.
if (ty == .type_value) return .{ .type_tag = TypeId.fromIndex(@intCast(reg)) };
// A function-typed word is an encoded func-ref; map it back to
// `.func_ref` (or `.null_val` for the null word) so the host
// serializes it identically to the legacy (e.g. the comptime-global
@@ -1214,6 +1235,9 @@ pub const Vm = struct {
fn kindOf(table: *const types.TypeTable, ty: TypeId) Kind {
switch (ty) {
.bool, .i8, .u8, .i16, .u16, .i32, .u32, .f32, .i64, .u64, .f64, .usize, .isize, .cstring => return .word,
// A comptime `Type` value is an 8-byte handle (a `TypeId` in a word) —
// distinct from the 16-byte boxed `.any`. It rides as a word.
.type_value => return .word,
.string => return .aggregate, // {ptr,len} fat pointer (16B), by-address
else => {},
}