1 files changed, 284 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/noder/helpers.go b/src/cmd/compile/internal/noder/helpers.go
new file mode 100644
index 0000000..4ef46a4
--- /dev/null
+++ b/src/cmd/compile/internal/noder/helpers.go
@@ -0,0 +1,284 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package noder
+
+import (
+	"go/constant"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/syntax"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/compile/internal/types2"
+	"cmd/internal/src"
+)
+
+// Helpers for constructing typed IR nodes.
+//
+// TODO(mdempsky): Move into their own package so they can be easily
+// reused by iimport and frontend optimizations.
+
+type ImplicitNode interface {
+	ir.Node
+	SetImplicit(x bool)
+}
+
+// Implicit returns n after marking it as Implicit.
+func Implicit(n ImplicitNode) ImplicitNode {
+	n.SetImplicit(true)
+	return n
+}
+
+// typed returns n after setting its type to typ.
+func typed(typ *types.Type, n ir.Node) ir.Node {
+	n.SetType(typ)
+	n.SetTypecheck(1)
+	return n
+}
+
+// Values
+
+func OrigConst(pos src.XPos, typ *types.Type, val constant.Value, op ir.Op, raw string) ir.Node {
+	orig := ir.NewRawOrigExpr(pos, op, raw)
+	return ir.NewConstExpr(val, typed(typ, orig))
+}
+
+// FixValue returns val after converting and truncating it as
+// appropriate for typ.
+func FixValue(typ *types.Type, val constant.Value) constant.Value {
+	assert(typ.Kind() != types.TFORW)
+	switch {
+	case typ.IsInteger():
+		val = constant.ToInt(val)
+	case typ.IsFloat():
+		val = constant.ToFloat(val)
+	case typ.IsComplex():
+		val = constant.ToComplex(val)
+	}
+	if !typ.IsUntyped() {
+		val = typecheck.DefaultLit(ir.NewBasicLit(src.NoXPos, val), typ).Val()
+	}
+	if !typ.IsTypeParam() {
+		ir.AssertValidTypeForConst(typ, val)
+	}
+	return val
+}
+
+func Nil(pos src.XPos, typ *types.Type) ir.Node {
+	return typed(typ, ir.NewNilExpr(pos))
+}
+
+// Expressions
+
+func Addr(pos src.XPos, x ir.Node) *ir.AddrExpr {
+	n := typecheck.NodAddrAt(pos, x)
+	typed(types.NewPtr(x.Type()), n)
+	return n
+}
+
+func Assert(pos src.XPos, x ir.Node, typ *types.Type) ir.Node {
+	return typed(typ, ir.NewTypeAssertExpr(pos, x, nil))
+}
+
+func Binary(pos src.XPos, op ir.Op, typ *types.Type, x, y ir.Node) *ir.BinaryExpr {
+	switch op {
+	case ir.OADD:
+		n := ir.NewBinaryExpr(pos, op, x, y)
+		typed(typ, n)
+		return n
+	default:
+		n := ir.NewBinaryExpr(pos, op, x, y)
+		typed(x.Type(), n)
+		return n
+	}
+}
+
+func Compare(pos src.XPos, typ *types.Type, op ir.Op, x, y ir.Node) *ir.BinaryExpr {
+	n := ir.NewBinaryExpr(pos, op, x, y)
+	typed(typ, n)
+	return n
+}
+
+func Deref(pos src.XPos, typ *types.Type, x ir.Node) *ir.StarExpr {
+	n := ir.NewStarExpr(pos, x)
+	typed(typ, n)
+	return n
+}
+
+func DotField(pos src.XPos, x ir.Node, index int) *ir.SelectorExpr {
+	op, typ := ir.ODOT, x.Type()
+	if typ.IsPtr() {
+		op, typ = ir.ODOTPTR, typ.Elem()
+	}
+	if !typ.IsStruct() {
+		base.FatalfAt(pos, "DotField of non-struct: %L", x)
+	}
+
+	// TODO(mdempsky): This is the backend's responsibility.
+	types.CalcSize(typ)
+
+	field := typ.Field(index)
+	return dot(pos, field.Type, op, x, field)
+}
+
+func DotMethod(pos src.XPos, x ir.Node, index int) *ir.SelectorExpr {
+	method := method(x.Type(), index)
+
+	// Method value.
+	typ := typecheck.NewMethodType(method.Type, nil)
+	return dot(pos, typ, ir.OMETHVALUE, x, method)
+}
+
+// MethodExpr returns a OMETHEXPR node with the indicated index into the methods
+// of typ. The receiver type is set from recv, which is different from typ if the
+// method was accessed via embedded fields. Similarly, the X value of the
+// ir.SelectorExpr is recv, the original OTYPE node before passing through the
+// embedded fields.
+func MethodExpr(pos src.XPos, recv ir.Node, embed *types.Type, index int) *ir.SelectorExpr {
+	method := method(embed, index)
+	typ := typecheck.NewMethodType(method.Type, recv.Type())
+	// The method expression T.m requires a wrapper when T
+	// is different from m's declared receiver type. We
+	// normally generate these wrappers while writing out
+	// runtime type descriptors, which is always done for
+	// types declared at package scope. However, we need
+	// to make sure to generate wrappers for anonymous
+	// receiver types too.
+	if recv.Sym() == nil {
+		typecheck.NeedRuntimeType(recv.Type())
+	}
+	return dot(pos, typ, ir.OMETHEXPR, recv, method)
+}
+
+func dot(pos src.XPos, typ *types.Type, op ir.Op, x ir.Node, selection *types.Field) *ir.SelectorExpr {
+	n := ir.NewSelectorExpr(pos, op, x, selection.Sym)
+	n.Selection = selection
+	typed(typ, n)
+	return n
+}
+
+// TODO(mdempsky): Move to package types.
+func method(typ *types.Type, index int) *types.Field {
+	if typ.IsInterface() {
+		return typ.AllMethods().Index(index)
+	}
+	return types.ReceiverBaseType(typ).Methods().Index(index)
+}
+
+func Index(pos src.XPos, typ *types.Type, x, index ir.Node) *ir.IndexExpr {
+	n := ir.NewIndexExpr(pos, x, index)
+	typed(typ, n)
+	return n
+}
+
+func Slice(pos src.XPos, typ *types.Type, x, low, high, max ir.Node) *ir.SliceExpr {
+	op := ir.OSLICE
+	if max != nil {
+		op = ir.OSLICE3
+	}
+	n := ir.NewSliceExpr(pos, op, x, low, high, max)
+	typed(typ, n)
+	return n
+}
+
+func Unary(pos src.XPos, typ *types.Type, op ir.Op, x ir.Node) ir.Node {
+	switch op {
+	case ir.OADDR:
+		return Addr(pos, x)
+	case ir.ODEREF:
+		return Deref(pos, typ, x)
+	}
+
+	if op == ir.ORECV {
+		if typ.IsFuncArgStruct() && typ.NumFields() == 2 {
+			// Remove the second boolean type (if provided by type2),
+			// since that works better with the rest of the compiler
+			// (which will add it back in later).
+			assert(typ.Field(1).Type.Kind() == types.TBOOL)
+			typ = typ.Field(0).Type
+		}
+	}
+	return typed(typ, ir.NewUnaryExpr(pos, op, x))
+}
+
+// Statements
+
+var one = constant.MakeInt64(1)
+
+func IncDec(pos src.XPos, op ir.Op, x ir.Node) *ir.AssignOpStmt {
+	assert(x.Type() != nil)
+	bl := ir.NewBasicLit(pos, one)
+	if x.Type().HasTParam() {
+		// If the operand is generic, then types2 will have proved it must be
+		// a type that fits with increment/decrement, so just set the type of
+		// "one" to n.Type(). This works even for types that are eventually
+		// float or complex.
+		typed(x.Type(), bl)
+	} else {
+		bl = typecheck.DefaultLit(bl, x.Type())
+	}
+	return ir.NewAssignOpStmt(pos, op, x, bl)
+}
+
+func idealType(tv syntax.TypeAndValue) types2.Type {
+	// The gc backend expects all expressions to have a concrete type, and
+	// types2 mostly satisfies this expectation already. But there are a few
+	// cases where the Go spec doesn't require converting to concrete type,
+	// and so types2 leaves them untyped. So we need to fix those up here.
+	typ := tv.Type
+	if basic, ok := typ.(*types2.Basic); ok && basic.Info()&types2.IsUntyped != 0 {
+		switch basic.Kind() {
+		case types2.UntypedNil:
+			// ok; can appear in type switch case clauses
+			// TODO(mdempsky): Handle as part of type switches instead?
+		case types2.UntypedInt, types2.UntypedFloat, types2.UntypedComplex:
+			// Untyped rhs of non-constant shift, e.g. x << 1.0.
+			// If we have a constant value, it must be an int >= 0.
+			if tv.Value != nil {
+				s := constant.ToInt(tv.Value)
+				assert(s.Kind() == constant.Int && constant.Sign(s) >= 0)
+			}
+			typ = types2.Typ[types2.Uint]
+		case types2.UntypedBool:
+			typ = types2.Typ[types2.Bool] // expression in "if" or "for" condition
+		case types2.UntypedString:
+			typ = types2.Typ[types2.String] // argument to "append" or "copy" calls
+		default:
+			return nil
+		}
+	}
+	return typ
+}
+
+func isTypeParam(t types2.Type) bool {
+	_, ok := t.(*types2.TypeParam)
+	return ok
+}
+
+// isNotInHeap reports whether typ is or contains an element of type
+// runtime/internal/sys.NotInHeap.
+func isNotInHeap(typ types2.Type) bool {
+	if named, ok := typ.(*types2.Named); ok {
+		if obj := named.Obj(); obj.Name() == "nih" && obj.Pkg().Path() == "runtime/internal/sys" {
+			return true
+		}
+		typ = named.Underlying()
+	}
+
+	switch typ := typ.(type) {
+	case *types2.Array:
+		return isNotInHeap(typ.Elem())
+	case *types2.Struct:
+		for i := 0; i < typ.NumFields(); i++ {
+			if isNotInHeap(typ.Field(i).Type()) {
+				return true
+			}
+		}
+		return false
+	default:
+		return false
+	}
+}