1 files changed, 493 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/noder/expr.go b/src/cmd/compile/internal/noder/expr.go
new file mode 100644
index 0000000..4b5ae70
--- /dev/null
+++ b/src/cmd/compile/internal/noder/expr.go
@@ -0,0 +1,493 @@
+// 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 (
+	"fmt"
+
+	"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"
+)
+
+func (g *irgen) expr(expr syntax.Expr) ir.Node {
+	expr = unparen(expr) // skip parens; unneeded after parse+typecheck
+
+	if expr == nil {
+		return nil
+	}
+
+	if expr, ok := expr.(*syntax.Name); ok && expr.Value == "_" {
+		return ir.BlankNode
+	}
+
+	tv, ok := g.info.Types[expr]
+	if !ok {
+		base.FatalfAt(g.pos(expr), "missing type for %v (%T)", expr, expr)
+	}
+	switch {
+	case tv.IsBuiltin():
+		// Qualified builtins, such as unsafe.Add and unsafe.Slice.
+		if expr, ok := expr.(*syntax.SelectorExpr); ok {
+			if name, ok := expr.X.(*syntax.Name); ok {
+				if _, ok := g.info.Uses[name].(*types2.PkgName); ok {
+					return g.use(expr.Sel)
+				}
+			}
+		}
+		return g.use(expr.(*syntax.Name))
+	case tv.IsType():
+		return ir.TypeNode(g.typ(tv.Type))
+	case tv.IsValue(), tv.IsVoid():
+		// ok
+	default:
+		base.FatalfAt(g.pos(expr), "unrecognized type-checker result")
+	}
+
+	base.Assert(g.exprStmtOK)
+
+	// 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.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:
+			base.FatalfAt(g.pos(expr), "unexpected untyped type: %v", basic)
+		}
+	}
+
+	// Constant expression.
+	if tv.Value != nil {
+		typ := g.typ(typ)
+		value := FixValue(typ, tv.Value)
+		return OrigConst(g.pos(expr), typ, value, constExprOp(expr), syntax.String(expr))
+	}
+
+	n := g.expr0(typ, expr)
+	if n.Typecheck() != 1 && n.Typecheck() != 3 {
+		base.FatalfAt(g.pos(expr), "missed typecheck: %+v", n)
+	}
+	if n.Op() != ir.OFUNCINST && !g.match(n.Type(), typ, tv.HasOk()) {
+		base.FatalfAt(g.pos(expr), "expected %L to have type %v", n, typ)
+	}
+	return n
+}
+
+func (g *irgen) expr0(typ types2.Type, expr syntax.Expr) ir.Node {
+	pos := g.pos(expr)
+	assert(pos.IsKnown())
+
+	// Set base.Pos for transformation code that still uses base.Pos, rather than
+	// the pos of the node being converted.
+	base.Pos = pos
+
+	switch expr := expr.(type) {
+	case *syntax.Name:
+		if _, isNil := g.info.Uses[expr].(*types2.Nil); isNil {
+			return Nil(pos, g.typ(typ))
+		}
+		return g.use(expr)
+
+	case *syntax.CompositeLit:
+		return g.compLit(typ, expr)
+
+	case *syntax.FuncLit:
+		return g.funcLit(typ, expr)
+
+	case *syntax.AssertExpr:
+		return Assert(pos, g.expr(expr.X), g.typeExpr(expr.Type))
+
+	case *syntax.CallExpr:
+		fun := g.expr(expr.Fun)
+		return g.callExpr(pos, g.typ(typ), fun, g.exprs(expr.ArgList), expr.HasDots)
+
+	case *syntax.IndexExpr:
+		args := unpackListExpr(expr.Index)
+		if len(args) == 1 {
+			tv, ok := g.info.Types[args[0]]
+			assert(ok)
+			if tv.IsValue() {
+				// This is just a normal index expression
+				n := Index(pos, g.typ(typ), g.expr(expr.X), g.expr(args[0]))
+				if !g.delayTransform() {
+					// transformIndex will modify n.Type() for OINDEXMAP.
+					transformIndex(n)
+				}
+				return n
+			}
+		}
+
+		// expr.Index is a list of type args, so we ignore it, since types2 has
+		// already provided this info with the Info.Instances map.
+		return g.expr(expr.X)
+
+	case *syntax.SelectorExpr:
+		// Qualified identifier.
+		if name, ok := expr.X.(*syntax.Name); ok {
+			if _, ok := g.info.Uses[name].(*types2.PkgName); ok {
+				return g.use(expr.Sel)
+			}
+		}
+		return g.selectorExpr(pos, typ, expr)
+
+	case *syntax.SliceExpr:
+		n := Slice(pos, g.typ(typ), g.expr(expr.X), g.expr(expr.Index[0]), g.expr(expr.Index[1]), g.expr(expr.Index[2]))
+		if !g.delayTransform() {
+			transformSlice(n)
+		}
+		return n
+
+	case *syntax.Operation:
+		if expr.Y == nil {
+			n := Unary(pos, g.typ(typ), g.op(expr.Op, unOps[:]), g.expr(expr.X))
+			if n.Op() == ir.OADDR && !g.delayTransform() {
+				transformAddr(n.(*ir.AddrExpr))
+			}
+			return n
+		}
+		switch op := g.op(expr.Op, binOps[:]); op {
+		case ir.OEQ, ir.ONE, ir.OLT, ir.OLE, ir.OGT, ir.OGE:
+			n := Compare(pos, g.typ(typ), op, g.expr(expr.X), g.expr(expr.Y))
+			if !g.delayTransform() {
+				transformCompare(n)
+			}
+			return n
+		case ir.OANDAND, ir.OOROR:
+			x := g.expr(expr.X)
+			y := g.expr(expr.Y)
+			return typed(x.Type(), ir.NewLogicalExpr(pos, op, x, y))
+		default:
+			n := Binary(pos, op, g.typ(typ), g.expr(expr.X), g.expr(expr.Y))
+			if op == ir.OADD && !g.delayTransform() {
+				return transformAdd(n)
+			}
+			return n
+		}
+
+	default:
+		g.unhandled("expression", expr)
+		panic("unreachable")
+	}
+}
+
+// substType does a normal type substition, but tparams is in the form of a field
+// list, and targs is in terms of a slice of type nodes. substType records any newly
+// instantiated types into g.instTypeList.
+func (g *irgen) substType(typ *types.Type, tparams *types.Type, targs []ir.Node) *types.Type {
+	fields := tparams.FieldSlice()
+	tparams1 := make([]*types.Type, len(fields))
+	for i, f := range fields {
+		tparams1[i] = f.Type
+	}
+	targs1 := make([]*types.Type, len(targs))
+	for i, n := range targs {
+		targs1[i] = n.Type()
+	}
+	ts := typecheck.Tsubster{
+		Tparams: tparams1,
+		Targs:   targs1,
+	}
+	newt := ts.Typ(typ)
+	return newt
+}
+
+// callExpr creates a call expression (which might be a type conversion, built-in
+// call, or a regular call) and does standard transforms, unless we are in a generic
+// function.
+func (g *irgen) callExpr(pos src.XPos, typ *types.Type, fun ir.Node, args []ir.Node, dots bool) ir.Node {
+	n := ir.NewCallExpr(pos, ir.OCALL, fun, args)
+	n.IsDDD = dots
+	typed(typ, n)
+
+	if fun.Op() == ir.OTYPE {
+		// Actually a type conversion, not a function call.
+		if !g.delayTransform() {
+			return transformConvCall(n)
+		}
+		return n
+	}
+
+	if fun, ok := fun.(*ir.Name); ok && fun.BuiltinOp != 0 {
+		if !g.delayTransform() {
+			return transformBuiltin(n)
+		}
+		return n
+	}
+
+	// Add information, now that we know that fun is actually being called.
+	switch fun := fun.(type) {
+	case *ir.SelectorExpr:
+		if fun.Op() == ir.OMETHVALUE {
+			op := ir.ODOTMETH
+			if fun.X.Type().IsInterface() {
+				op = ir.ODOTINTER
+			}
+			fun.SetOp(op)
+			// Set the type to include the receiver, since that's what
+			// later parts of the compiler expect
+			fun.SetType(fun.Selection.Type)
+		}
+	}
+
+	// A function instantiation (even if fully concrete) shouldn't be
+	// transformed yet, because we need to add the dictionary during the
+	// transformation.
+	if fun.Op() != ir.OFUNCINST && !g.delayTransform() {
+		transformCall(n)
+	}
+	return n
+}
+
+// selectorExpr resolves the choice of ODOT, ODOTPTR, OMETHVALUE (eventually
+// ODOTMETH & ODOTINTER), and OMETHEXPR and deals with embedded fields here rather
+// than in typecheck.go.
+func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.SelectorExpr) ir.Node {
+	x := g.expr(expr.X)
+	if x.Type().HasTParam() {
+		// Leave a method call on a type param as an OXDOT, since it can
+		// only be fully transformed once it has an instantiated type.
+		n := ir.NewSelectorExpr(pos, ir.OXDOT, x, typecheck.Lookup(expr.Sel.Value))
+		typed(g.typ(typ), n)
+		return n
+	}
+
+	selinfo := g.info.Selections[expr]
+	// Everything up to the last selection is an implicit embedded field access,
+	// and the last selection is determined by selinfo.Kind().
+	index := selinfo.Index()
+	embeds, last := index[:len(index)-1], index[len(index)-1]
+
+	origx := x
+	for _, ix := range embeds {
+		x = Implicit(DotField(pos, x, ix))
+	}
+
+	kind := selinfo.Kind()
+	if kind == types2.FieldVal {
+		return DotField(pos, x, last)
+	}
+
+	var n ir.Node
+	method2 := selinfo.Obj().(*types2.Func)
+
+	if kind == types2.MethodExpr {
+		// OMETHEXPR is unusual in using directly the node and type of the
+		// original OTYPE node (origx) before passing through embedded
+		// fields, even though the method is selected from the type
+		// (x.Type()) reached after following the embedded fields. We will
+		// actually drop any ODOT nodes we created due to the embedded
+		// fields.
+		n = MethodExpr(pos, origx, x.Type(), last)
+	} else {
+		// Add implicit addr/deref for method values, if needed.
+		if x.Type().IsInterface() {
+			n = DotMethod(pos, x, last)
+		} else {
+			recvType2 := method2.Type().(*types2.Signature).Recv().Type()
+			_, wantPtr := recvType2.(*types2.Pointer)
+			havePtr := x.Type().IsPtr()
+
+			if havePtr != wantPtr {
+				if havePtr {
+					x = Implicit(Deref(pos, x.Type().Elem(), x))
+				} else {
+					x = Implicit(Addr(pos, x))
+				}
+			}
+			recvType2Base := recvType2
+			if wantPtr {
+				recvType2Base = types2.AsPointer(recvType2).Elem()
+			}
+			if recvType2Base.(*types2.Named).TypeParams().Len() > 0 {
+				// recvType2 is the original generic type that is
+				// instantiated for this method call.
+				// selinfo.Recv() is the instantiated type
+				recvType2 = recvType2Base
+				recvTypeSym := g.pkg(method2.Pkg()).Lookup(recvType2.(*types2.Named).Obj().Name())
+				recvType := recvTypeSym.Def.(*ir.Name).Type()
+				// method is the generic method associated with
+				// the base generic type. The instantiated type may not
+				// have method bodies filled in, if it was imported.
+				method := recvType.Methods().Index(last).Nname.(*ir.Name)
+				n = ir.NewSelectorExpr(pos, ir.OMETHVALUE, x, typecheck.Lookup(expr.Sel.Value))
+				n.(*ir.SelectorExpr).Selection = types.NewField(pos, method.Sym(), method.Type())
+				n.(*ir.SelectorExpr).Selection.Nname = method
+				typed(method.Type(), n)
+
+				xt := deref(x.Type())
+				targs := make([]ir.Node, len(xt.RParams()))
+				for i := range targs {
+					targs[i] = ir.TypeNode(xt.RParams()[i])
+				}
+
+				// Create function instantiation with the type
+				// args for the receiver type for the method call.
+				n = ir.NewInstExpr(pos, ir.OFUNCINST, n, targs)
+				typed(g.typ(typ), n)
+				return n
+			}
+
+			if !g.match(x.Type(), recvType2, false) {
+				base.FatalfAt(pos, "expected %L to have type %v", x, recvType2)
+			} else {
+				n = DotMethod(pos, x, last)
+			}
+		}
+	}
+	if have, want := n.Sym(), g.selector(method2); have != want {
+		base.FatalfAt(pos, "bad Sym: have %v, want %v", have, want)
+	}
+	return n
+}
+
+func (g *irgen) exprList(expr syntax.Expr) []ir.Node {
+	return g.exprs(unpackListExpr(expr))
+}
+
+func unpackListExpr(expr syntax.Expr) []syntax.Expr {
+	switch expr := expr.(type) {
+	case nil:
+		return nil
+	case *syntax.ListExpr:
+		return expr.ElemList
+	default:
+		return []syntax.Expr{expr}
+	}
+}
+
+func (g *irgen) exprs(exprs []syntax.Expr) []ir.Node {
+	nodes := make([]ir.Node, len(exprs))
+	for i, expr := range exprs {
+		nodes[i] = g.expr(expr)
+	}
+	return nodes
+}
+
+func (g *irgen) compLit(typ types2.Type, lit *syntax.CompositeLit) ir.Node {
+	if ptr, ok := types2.CoreType(typ).(*types2.Pointer); ok {
+		n := ir.NewAddrExpr(g.pos(lit), g.compLit(ptr.Elem(), lit))
+		n.SetOp(ir.OPTRLIT)
+		return typed(g.typ(typ), n)
+	}
+
+	_, isStruct := types2.CoreType(typ).(*types2.Struct)
+
+	exprs := make([]ir.Node, len(lit.ElemList))
+	for i, elem := range lit.ElemList {
+		switch elem := elem.(type) {
+		case *syntax.KeyValueExpr:
+			var key ir.Node
+			if isStruct {
+				key = ir.NewIdent(g.pos(elem.Key), g.name(elem.Key.(*syntax.Name)))
+			} else {
+				key = g.expr(elem.Key)
+			}
+			value := wrapname(g.pos(elem.Value), g.expr(elem.Value))
+			if value.Op() == ir.OPAREN {
+				// Make sure any PAREN node added by wrapper has a type
+				typed(value.(*ir.ParenExpr).X.Type(), value)
+			}
+			exprs[i] = ir.NewKeyExpr(g.pos(elem), key, value)
+		default:
+			exprs[i] = wrapname(g.pos(elem), g.expr(elem))
+			if exprs[i].Op() == ir.OPAREN {
+				// Make sure any PAREN node added by wrapper has a type
+				typed(exprs[i].(*ir.ParenExpr).X.Type(), exprs[i])
+			}
+		}
+	}
+
+	n := ir.NewCompLitExpr(g.pos(lit), ir.OCOMPLIT, nil, exprs)
+	typed(g.typ(typ), n)
+	var r ir.Node = n
+	if !g.delayTransform() {
+		r = transformCompLit(n)
+	}
+	return r
+}
+
+func (g *irgen) funcLit(typ2 types2.Type, expr *syntax.FuncLit) ir.Node {
+	fn := ir.NewClosureFunc(g.pos(expr), ir.CurFunc != nil)
+	ir.NameClosure(fn.OClosure, ir.CurFunc)
+
+	typ := g.typ(typ2)
+	typed(typ, fn.Nname)
+	typed(typ, fn.OClosure)
+	fn.SetTypecheck(1)
+
+	g.funcBody(fn, nil, expr.Type, expr.Body)
+
+	ir.FinishCaptureNames(fn.Pos(), ir.CurFunc, fn)
+
+	// TODO(mdempsky): ir.CaptureName should probably handle
+	// copying these fields from the canonical variable.
+	for _, cv := range fn.ClosureVars {
+		cv.SetType(cv.Canonical().Type())
+		cv.SetTypecheck(1)
+		cv.SetWalkdef(1)
+	}
+
+	if g.topFuncIsGeneric {
+		// Don't add any closure inside a generic function/method to the
+		// g.target.Decls list, even though it may not be generic itself.
+		// See issue #47514.
+		return ir.UseClosure(fn.OClosure, nil)
+	} else {
+		return ir.UseClosure(fn.OClosure, g.target)
+	}
+}
+
+func (g *irgen) typeExpr(typ syntax.Expr) *types.Type {
+	n := g.expr(typ)
+	if n.Op() != ir.OTYPE {
+		base.FatalfAt(g.pos(typ), "expected type: %L", n)
+	}
+	return n.Type()
+}
+
+// constExprOp returns an ir.Op that represents the outermost
+// operation of the given constant expression. It's intended for use
+// with ir.RawOrigExpr.
+func constExprOp(expr syntax.Expr) ir.Op {
+	switch expr := expr.(type) {
+	default:
+		panic(fmt.Sprintf("%s: unexpected expression: %T", expr.Pos(), expr))
+
+	case *syntax.BasicLit:
+		return ir.OLITERAL
+	case *syntax.Name, *syntax.SelectorExpr:
+		return ir.ONAME
+	case *syntax.CallExpr:
+		return ir.OCALL
+	case *syntax.Operation:
+		if expr.Y == nil {
+			return unOps[expr.Op]
+		}
+		return binOps[expr.Op]
+	}
+}
+
+func unparen(expr syntax.Expr) syntax.Expr {
+	for {
+		paren, ok := expr.(*syntax.ParenExpr)
+		if !ok {
+			return expr
+		}
+		expr = paren.X
+	}
+}