1635. gopy intrinsics

What we are porting

Python/intrinsics.c (~400 lines). Two opcodes, CALL_INTRINSIC_1 and CALL_INTRINSIC_2, are emitted by the compiler in places where a runtime helper is cleaner than a dedicated opcode. The oparg selects which helper to call.

This is a small, well-bounded surface. The helper set is closed: about 10 unary intrinsics and 4 binary intrinsics. CPython adds to it sparingly (one or two per release), so a hand-port plus a table is cheaper than codegen.

The unary intrinsic table

CALL_INTRINSIC_1 oparg: pop one value, push one.

ID	Helper
INTRINSIC_1_INVALID	guard; raises if reached
INTRINSIC_PRINT	print expression result (REPL displayhook)
INTRINSIC_IMPORT_STAR	implements from x import *
INTRINSIC_STOPITERATION_ERROR	re-raise StopIteration as RuntimeError
INTRINSIC_ASYNC_GEN_WRAP	wrap value for async generator yield
INTRINSIC_UNARY_POSITIVE	+x (rare; usually inlined)
INTRINSIC_LIST_TO_TUPLE	freeze a list comprehension into a tuple
INTRINSIC_TYPEVAR	PEP 695 TypeVar(...)
INTRINSIC_PARAMSPEC	PEP 695 ParamSpec(...)
INTRINSIC_TYPEVARTUPLE	PEP 695 TypeVarTuple(...)
INTRINSIC_SUBSCRIPT_GENERIC	PEP 695 Generic[T] subscription
INTRINSIC_TYPEALIAS	PEP 695 type X = ...

The binary intrinsic table

CALL_INTRINSIC_2 oparg: pop two, push one.

ID	Helper
INTRINSIC_2_INVALID	guard
INTRINSIC_PREP_RERAISE_STAR	ExceptionGroup re-raise prep
INTRINSIC_TYPEVAR_WITH_BOUND	TypeVar('T', bound=int)
INTRINSIC_TYPEVAR_WITH_CONSTRAINTS	TypeVar('T', int, str)
INTRINSIC_SET_FUNCTION_TYPE_PARAMS	wire generic type params onto a function

(IDs come from Include/internal/pycore_intrinsics.h. Numeric values must match CPython byte-for-byte so emitted bytecode loads the right entry.)

Go shape

// Unary is the CALL_INTRINSIC_1 entry. The eval loop reads
// UnaryTable[oparg] and calls it.
type Unary func(ts *state.Thread, v object.Object) (object.Object, error)

// Binary is the CALL_INTRINSIC_2 entry.
type Binary func(ts *state.Thread, lhs, rhs object.Object) (object.Object, error)

// UnaryTable is the dispatch table for CALL_INTRINSIC_1.
// Indexed by INTRINSIC_* enum value; entries match
// _PyIntrinsics_UnaryFunctions from Python/intrinsics.c.
var UnaryTable = [...]Unary{
    Unary1Invalid,
    UnaryPrint,
    UnaryImportStar,
    UnaryStopIterationError,
    UnaryAsyncGenWrap,
    UnaryUnaryPositive,
    UnaryListToTuple,
    UnaryTypevar,
    UnaryParamspec,
    UnaryTypevartuple,
    UnarySubscriptGeneric,
    UnaryTypealias,
}

// BinaryTable is the dispatch table for CALL_INTRINSIC_2.
var BinaryTable = [...]Binary{
    Binary2Invalid,
    BinaryPrepReraiseStar,
    BinaryTypevarWithBound,
    BinaryTypevarWithConstraints,
    BinarySetFunctionTypeParams,
}

The eval loop dispatch is one indexed call:

case opcode.CALL_INTRINSIC_1:
    v := e.popObject()
    res, err := intrinsics.UnaryTable[oparg](e.ts, v)
    if err != nil {
        return 0, err
    }
    e.pushObject(res)
    return e.advance(1), nil

File mapping

C source	Go target
Python/intrinsics.c (unary table + helpers)	intrinsics/unary.go
Python/intrinsics.c (binary table + helpers)	intrinsics/binary.go
Include/internal/pycore_intrinsics.h (enum)	intrinsics/ids.go

Checklist

Status legend: [x] shipped, [ ] pending, [~] partial / scaffold, [n] deferred / not in scope this phase.

Files

• intrinsics/ids.go: INTRINSIC_* constants matching pycore_intrinsics.h numerically (12 unary, 6 binary, MAX_INTRINSIC_*).
• intrinsics/unary.go: Unary type, UnaryTable, every unary helper (UnaryPrint, UnaryImportStar, ...). Bodies stubbed with notImplementedError pending cross-block prereqs.
• intrinsics/binary.go: Binary type, BinaryTable, every binary helper. Includes BinarySetTypeparamDefault (3.13+).
• intrinsics/intrinsics.go: notImplementedError shared between unary and binary stubs.
• intrinsics/intrinsics_test.go: ID-value pinning, table population, invalid-ID error path, every stub returns notImplementedError.

Unary panel

• [n] UnaryPrint: calls sys.displayhook. Defers to the sys module port (1651). Stub returns notImplementedError.
• [n] UnaryImportStar: walks __all__ and copies into locals. Defers to the import system port (1683). Stub.
• [n] UnaryStopIterationError: wraps StopIteration in a RuntimeError (PEP 479). Defers to the exception module port (1686). Stub.
• [n] UnaryAsyncGenWrap: builds _PyAsyncGenWrappedValue. Defers to the async-generator object (1687). Stub.
• [n] UnaryUnaryPositive: +x via __pos__. Defers to the number-protocol slot dispatch (1684). Stub.
• UnaryListToTuple: freezes a list comprehension into a tuple. Implemented in intrinsics/unary.go; consumed by the LIST_TO_TUPLE lowering in vm/eval_simple.go.
• [n] UnaryTypevar / UnaryParamspec / UnaryTypevartuple / UnarySubscriptGeneric / UnaryTypealias: PEP 695 type runtime objects. Defer to 1689. Stubs.

Binary panel

• [n] BinaryPrepReraiseStar: reconstructs an ExceptionGroup for raise except* re-raise. Defers to the ExceptionGroup type (1686). Stub.
• [n] BinaryTypevarWithBound, BinaryTypevarWithConstraints, BinarySetFunctionTypeParams, BinarySetTypeparamDefault: PEP 695 helpers. Defer to 1689. Stubs.

Surface guarantees

• Numeric IDs match Include/internal/pycore_intrinsics.h byte-for-byte. Pinned by intrinsics_test.go::TestUnaryIDValues and TestBinaryIDValues (every entry plus MaxUnary/MaxBinary).
• Each stubbed helper returns notImplementedError. Pinned by TestStubHelpersReturnNotImplemented (sweeps both tables, skips the implemented UnaryListToTuple).
• [n] PEP 695 helpers (Typevar / Paramspec / Typevartuple / Typealias) build runtime objects whose repr matches CPython's. Defers to 1689; stubs return notImplementedError in v0.6.

Out of scope for v0.6

• Specialized variants: INSTRUMENTED_CALL_INTRINSIC_*. Falls back to base case until 1634 (monitoring) lands at v0.9.

Cross-references

• Eval loop dispatch: 1636.
• PEP 695 type runtime objects: 1689 (typevar, generic alias).
• ExceptionGroup type: 1686.
• sys.displayhook: 1651 (sys module).