Golang Type.Underlying方法代码示例

func (am *algorithmMap) eqalg(t types.Type) llvm.Value {
	t = t.Underlying()
	if st, ok := t.(*types.Struct); ok && st.NumFields() == 1 {
		t = st.Field(0).Type().Underlying()
	}
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String:
			return am.runtime.streqalg.LLVMValue()
		case types.Float32:
			return am.runtime.f32eqalg.LLVMValue()
		case types.Float64:
			return am.runtime.f64eqalg.LLVMValue()
		case types.Complex64:
			return am.runtime.c64eqalg.LLVMValue()
		case types.Complex128:
			return am.runtime.c128eqalg.LLVMValue()
		}
	case *types.Struct:
		// TODO
	}
	// TODO(axw) size-specific memequal cases
	return am.runtime.memequal.LLVMValue()
}

// lockPath returns a typePath describing the location of a lock value
// contained in typ. If there is no contained lock, it returns nil.
func lockPath(tpkg *types.Package, typ types.Type) typePath {
	if typ == nil {
		return nil
	}

	// We're only interested in the case in which the underlying
	// type is a struct. (Interfaces and pointers are safe to copy.)
	styp, ok := typ.Underlying().(*types.Struct)
	if !ok {
		return nil
	}

	// We're looking for cases in which a reference to this type
	// can be locked, but a value cannot. This differentiates
	// embedded interfaces from embedded values.
	if plock := types.NewMethodSet(types.NewPointer(typ)).Lookup(tpkg, "Lock"); plock != nil {
		if lock := types.NewMethodSet(typ).Lookup(tpkg, "Lock"); lock == nil {
			return []types.Type{typ}
		}
	}

	nfields := styp.NumFields()
	for i := 0; i < nfields; i++ {
		ftyp := styp.Field(i).Type()
		subpath := lockPath(tpkg, ftyp)
		if subpath != nil {
			return append(subpath, typ)
		}
	}

	return nil
}

// makeImethodThunk returns a synthetic thunk function permitting a
// method id of interface typ to be called like a standalone function,
// e.g.:
//
//   type I interface { f(x int) R }
//   m := I.f  // thunk
//   var i I
//   m(i, 0)
//
// The thunk is defined as if by:
//
//   func I.f(i I, x int, ...) R {
//     return i.f(x, ...)
//   }
//
// TODO(adonovan): opt: currently the stub is created even when used
// in call position: I.f(i, 0).  Clearly this is suboptimal.
//
// TODO(adonovan): memoize creation of these functions in the Program.
//
func makeImethodThunk(prog *Program, typ types.Type, id Id) *Function {
	if prog.mode&LogSource != 0 {
		defer logStack("makeImethodThunk %s.%s", typ, id)()
	}
	itf := typ.Underlying().(*types.Interface)
	index, meth := methodIndex(itf, id)
	sig := *meth.Type().(*types.Signature) // copy; shared Values
	fn := &Function{
		Name_:     meth.Name(),
		Signature: &sig,
		Prog:      prog,
	}
	fn.startBody()
	fn.addParam("recv", typ)
	createParams(fn)
	var c Call
	c.Call.Method = index
	c.Call.Recv = fn.Params[0]
	for _, arg := range fn.Params[1:] {
		c.Call.Args = append(c.Call.Args, arg)
	}
	emitTailCall(fn, &c)
	fn.finishBody()
	return fn
}

func (tm *llvmTypeMap) makeLLVMType(t types.Type, name string) llvm.Type {
	switch t := t.(type) {
	case *types.Basic:
		return tm.basicLLVMType(t)
	case *types.Array:
		return tm.arrayLLVMType(t)
	case *types.Slice:
		return tm.sliceLLVMType(t, name)
	case *types.Struct:
		return tm.structLLVMType(t, name)
	case *types.Pointer:
		return tm.pointerLLVMType(t)
	case *types.Interface:
		return tm.interfaceLLVMType(t, name)
	case *types.Map:
		return tm.mapLLVMType(t)
	case *types.Chan:
		return tm.chanLLVMType(t)
	case *types.Named:
		// First we set ptrstandin, in case we've got a recursive pointer.
		if _, ok := t.Underlying().(*types.Pointer); ok {
			tm.types.Set(t, tm.ptrstandin)
		}
		return tm.nameLLVMType(t)
	}
	panic(fmt.Errorf("unhandled: %T", t))
}

func (c *compiler) makeInterface(v *LLVMValue, iface types.Type) *LLVMValue {
	llv := v.LLVMValue()
	lltyp := llv.Type()
	i8ptr := llvm.PointerType(llvm.Int8Type(), 0)
	if lltyp.TypeKind() == llvm.PointerTypeKind {
		llv = c.builder.CreateBitCast(llv, i8ptr, "")
	} else {
		// If the value fits exactly in a pointer, then we can just
		// bitcast it. Otherwise we need to malloc.
		if c.target.TypeStoreSize(lltyp) <= uint64(c.target.PointerSize()) {
			bits := c.target.TypeSizeInBits(lltyp)
			if bits > 0 {
				llv = coerce(c.builder, llv, llvm.IntType(int(bits)))
				llv = c.builder.CreateIntToPtr(llv, i8ptr, "")
			} else {
				llv = llvm.ConstNull(i8ptr)
			}
		} else {
			ptr := c.createTypeMalloc(lltyp)
			c.builder.CreateStore(llv, ptr)
			llv = c.builder.CreateBitCast(ptr, i8ptr, "")
		}
	}
	value := llvm.Undef(c.types.ToLLVM(iface))
	rtype := c.types.ToRuntime(v.Type())
	rtype = c.builder.CreateBitCast(rtype, llvm.PointerType(llvm.Int8Type(), 0), "")
	value = c.builder.CreateInsertValue(value, rtype, 0, "")
	value = c.builder.CreateInsertValue(value, llv, 1, "")
	if iface.Underlying().(*types.Interface).NumMethods() > 0 {
		result := c.NewValue(value, types.NewInterface(nil, nil))
		result, _ = result.convertE2I(iface)
		return result
	}
	return c.NewValue(value, iface)
}

// flatten returns a list of directly contained fields in the preorder
// traversal of the type tree of t.  The resulting elements are all
// scalars (basic types or pointerlike types), except for struct/array
// "identity" nodes, whose type is that of the aggregate.
//
// reflect.Value is considered pointerlike, similar to interface{}.
//
// Callers must not mutate the result.
//
func (a *analysis) flatten(t types.Type) []*fieldInfo {
	fl, ok := a.flattenMemo[t]
	if !ok {
		switch t := t.(type) {
		case *types.Named:
			u := t.Underlying()
			if _, ok := u.(*types.Interface); ok {
				// Debuggability hack: don't remove
				// the named type from interfaces as
				// they're very verbose.
				fl = append(fl, &fieldInfo{typ: t})
			} else {
				fl = a.flatten(u)
			}

		case *types.Basic,
			*types.Signature,
			*types.Chan,
			*types.Map,
			*types.Interface,
			*types.Slice,
			*types.Pointer:
			fl = append(fl, &fieldInfo{typ: t})

		case *types.Array:
			fl = append(fl, &fieldInfo{typ: t}) // identity node
			for _, fi := range a.flatten(t.Elem()) {
				fl = append(fl, &fieldInfo{typ: fi.typ, op: true, tail: fi})
			}

		case *types.Struct:
			fl = append(fl, &fieldInfo{typ: t}) // identity node
			for i, n := 0, t.NumFields(); i < n; i++ {
				f := t.Field(i)
				for _, fi := range a.flatten(f.Type()) {
					fl = append(fl, &fieldInfo{typ: fi.typ, op: f, tail: fi})
				}
			}

		case *types.Tuple:
			// No identity node: tuples are never address-taken.
			for i, n := 0, t.Len(); i < n; i++ {
				f := t.At(i)
				for _, fi := range a.flatten(f.Type()) {
					fl = append(fl, &fieldInfo{typ: fi.typ, op: i, tail: fi})
				}
			}

		case *types.Builtin:
			panic("flatten(*types.Builtin)") // not the type of any value

		default:
			panic(t)
		}

		a.flattenMemo[t] = fl
	}

	return fl
}

// makeMapLiteral makes a map with the specified keys and values.
func (c *compiler) makeMapLiteral(typ types.Type, keys, values []Value) *LLVMValue {
	var count, keysptr, valuesptr llvm.Value
	dyntyp := c.types.ToRuntime(typ)
	dyntyp = c.builder.CreatePtrToInt(dyntyp, c.target.IntPtrType(), "")
	if len(keys) == 0 {
		count = llvm.ConstNull(c.types.inttype)
		keysptr = llvm.ConstNull(c.target.IntPtrType())
		valuesptr = keysptr
	} else {
		maptyp := typ.Underlying().(*types.Map)
		keytyp := maptyp.Key()
		valtyp := maptyp.Elem()
		count = llvm.ConstInt(c.types.inttype, uint64(len(keys)), false)
		keysptr = c.builder.CreateArrayAlloca(c.types.ToLLVM(keytyp), count, "")
		valuesptr = c.builder.CreateArrayAlloca(c.types.ToLLVM(valtyp), count, "")
		for i := range keys {
			gepindices := []llvm.Value{llvm.ConstInt(c.types.inttype, uint64(i), false)}
			key := keys[i].Convert(keytyp).LLVMValue()
			ptr := c.builder.CreateGEP(keysptr, gepindices, "")
			c.builder.CreateStore(key, ptr)
			value := values[i].Convert(valtyp).LLVMValue()
			ptr = c.builder.CreateGEP(valuesptr, gepindices, "")
			c.builder.CreateStore(value, ptr)
		}
		keysptr = c.builder.CreatePtrToInt(keysptr, c.target.IntPtrType(), "")
		valuesptr = c.builder.CreatePtrToInt(valuesptr, c.target.IntPtrType(), "")
	}
	f := c.NamedFunction("runtime.makemap", "func(t uintptr, n int, keys, values uintptr) uintptr")
	mapval := c.builder.CreateCall(f, []llvm.Value{dyntyp, count, keysptr, valuesptr}, "")
	return c.NewValue(mapval, typ)
}

// zeroConst returns a new "zero" constant of the specified type,
// which must not be an array or struct type: the zero values of
// aggregates are well-defined but cannot be represented by Const.
//
func zeroConst(t types.Type) *Const {
	switch t := t.(type) {
	case *types.Basic:
		switch {
		case t.Info()&types.IsBoolean != 0:
			return NewConst(exact.MakeBool(false), t)
		case t.Info()&types.IsNumeric != 0:
			return NewConst(exact.MakeInt64(0), t)
		case t.Info()&types.IsString != 0:
			return NewConst(exact.MakeString(""), t)
		case t.Kind() == types.UnsafePointer:
			fallthrough
		case t.Kind() == types.UntypedNil:
			return nilConst(t)
		default:
			panic(fmt.Sprint("zeroConst for unexpected type:", t))
		}
	case *types.Pointer, *types.Slice, *types.Interface, *types.Chan, *types.Map, *types.Signature:
		return nilConst(t)
	case *types.Named:
		return NewConst(zeroConst(t.Underlying()).Value, t)
	case *types.Array, *types.Struct, *types.Tuple:
		panic(fmt.Sprint("zeroConst applied to aggregate:", t))
	}
	panic(fmt.Sprint("zeroConst: unexpected ", t))
}

// emitConv emits to f code to convert Value val to exactly type typ,
// and returns the converted value.  Implicit conversions are required
// by language assignability rules in assignments, parameter passing,
// etc.
//
func emitConv(f *Function, val Value, typ types.Type) Value {
	t_src := val.Type()

	// Identical types?  Conversion is a no-op.
	if types.IsIdentical(t_src, typ) {
		return val
	}

	ut_dst := typ.Underlying()
	ut_src := t_src.Underlying()

	// Just a change of type, but not value or representation?
	if isValuePreserving(ut_src, ut_dst) {
		c := &ChangeType{X: val}
		c.setType(typ)
		return f.emit(c)
	}

	// Conversion to, or construction of a value of, an interface type?
	if _, ok := ut_dst.(*types.Interface); ok {

		// Assignment from one interface type to another?
		if _, ok := ut_src.(*types.Interface); ok {
			return emitTypeAssert(f, val, typ)
		}

		// Untyped nil literal?  Return interface-typed nil literal.
		if ut_src == tUntypedNil {
			return nilLiteral(typ)
		}

		// Convert (non-nil) "untyped" literals to their default type.
		// TODO(gri): expose types.isUntyped().
		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
			val = emitConv(f, val, DefaultType(ut_src))
		}

		mi := &MakeInterface{
			X:       val,
			Methods: f.Prog.MethodSet(t_src),
		}
		mi.setType(typ)
		return f.emit(mi)
	}

	// Conversion of a literal to a non-interface type results in
	// a new literal of the destination type and (initially) the
	// same abstract value.  We don't compute the representation
	// change yet; this defers the point at which the number of
	// possible representations explodes.
	if l, ok := val.(*Literal); ok {
		return newLiteral(l.Value, typ)
	}

	// A representation-changing conversion.
	c := &Convert{X: val}
	c.setType(typ)
	return f.emit(c)
}

func (x array) hash(t types.Type) int {
	h := 0
	tElt := t.Underlying().(*types.Array).Elem()
	for _, xi := range x {
		h += hash(tElt, xi)
	}
	return h
}

func (c *PkgContext) typeCheck(of string, to types.Type) string {
	if in, isInterface := to.Underlying().(*types.Interface); isInterface {
		if in.MethodSet().Len() == 0 {
			return "true"
		}
		return fmt.Sprintf("%s.Go$implementedBy.indexOf(%s) !== -1", c.typeName(to), of)
	}
	return of + " === " + c.typeName(to)
}

func (c *funcContext) typeCheck(of string, to types.Type) string {
	if in, isInterface := to.Underlying().(*types.Interface); isInterface {
		if in.Empty() {
			return "true"
		}
		return fmt.Sprintf("%s.implementedBy.indexOf(%s) !== -1", c.typeName(to), of)
	}
	return of + " === " + c.typeName(to)
}

// underlying returns the underlying type of typ.  Copied from go/types.
func underlyingType(typ types.Type) types.Type {
	if typ, ok := typ.(*types.Named); ok {
		return typ.Underlying() // underlying types are never NamedTypes
	}
	if typ == nil {
		panic("underlying(nil)")
	}
	return typ
}

func (x array) eq(t types.Type, _y interface{}) bool {
	y := _y.(array)
	tElt := t.Underlying().(*types.Array).Elem()
	for i, xi := range x {
		if !equals(tElt, xi, y[i]) {
			return false
		}
	}
	return true
}

// usesBuiltinMap returns true if the built-in hash function and
// equivalence relation for type t are consistent with those of the
// interpreter's representation of type t.  Such types are: all basic
// types (bool, numbers, string), pointers and channels.
//
// usesBuiltinMap returns false for types that require a custom map
// implementation: interfaces, arrays and structs.
//
// Panic ensues if t is an invalid map key type: function, map or slice.
func usesBuiltinMap(t types.Type) bool {
	switch t := t.(type) {
	case *types.Basic, *types.Chan, *types.Pointer:
		return true
	case *types.Named:
		return usesBuiltinMap(t.Underlying())
	case *types.Interface, *types.Array, *types.Struct:
		return false
	}
	panic(fmt.Sprintf("invalid map key type: %T", t))
}