cmd/compile/internal/typecheck: add NewMethodExpr helper

This CL refactors the common pattern for constructing OMETHEXPR nodes,
which is the most common use of ir.TypeNode currently.

Change-Id: I446a21af97ab5a4bc2f04bbd581c1ede8a5ede60
Reviewed-on: https://go-review.googlesource.com/c/go/+/520978
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

3 files changed, 14 insertions, 7 deletions

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 08d731637f..adba0b961f 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -1404,8 +1404,7 @@ func (pr *pkgReader) dictNameOf(dict *readerDict) *ir.Name {
 	assertOffset("type param method exprs", dict.typeParamMethodExprsOffset())
 	for _, info := range dict.typeParamMethodExprs {
 		typeParam := dict.targs[info.typeParamIdx]
-		method := typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, ir.TypeNode(typeParam), info.method)).(*ir.SelectorExpr)
-		assert(method.Op() == ir.OMETHEXPR)
+		method := typecheck.NewMethodExpr(pos, typeParam, info.method)
 
 		rsym := method.FuncName().Linksym()
 		assert(rsym.ABI() == obj.ABIInternal) // must be ABIInternal; see ir.OCFUNC in ssagen/ssa.go
@@ -2274,7 +2273,7 @@ func (r *reader) expr() (res ir.Node) {
 		// expression (OMETHEXPR) and the receiver type is unshaped, then
 		// we can rely on a statically generated wrapper being available.
 		if method, ok := wrapperFn.(*ir.SelectorExpr); ok && method.Op() == ir.OMETHEXPR && !recv.HasShape() {
-			return typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, ir.TypeNode(recv), method.Sel)).(*ir.SelectorExpr)
+			return typecheck.NewMethodExpr(pos, recv, method.Sel)
 		}
 
 		return r.methodExprWrap(origPos, recv, implicits, deref, addr, baseFn, dictPtr)
@@ -2891,7 +2890,7 @@ func (r *reader) methodExpr() (wrapperFn, baseFn, dictPtr ir.Node) {
 		// For statically known instantiations, we can take advantage of
 		// the stenciled wrapper.
 		base.AssertfAt(!recv.HasShape(), pos, "shaped receiver %v", recv)
-		wrapperFn := typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, ir.TypeNode(recv), sym)).(*ir.SelectorExpr)
+		wrapperFn := typecheck.NewMethodExpr(pos, recv, sym)
 		base.AssertfAt(types.Identical(sig, wrapperFn.Type()), pos, "wrapper %L does not have type %v", wrapperFn, sig)
 
 		return wrapperFn, shapedFn, dictPtr
@@ -2899,7 +2898,7 @@ func (r *reader) methodExpr() (wrapperFn, baseFn, dictPtr ir.Node) {
 
 	// Simple method expression; no dictionary needed.
 	base.AssertfAt(!recv.HasShape() || recv.IsInterface(), pos, "shaped receiver %v", recv)
-	fn := typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, ir.TypeNode(recv), sym)).(*ir.SelectorExpr)
+	fn := typecheck.NewMethodExpr(pos, recv, sym)
 	return fn, fn, nil
 }
 
@@ -2924,7 +2923,7 @@ func shapedMethodExpr(pos src.XPos, obj *ir.Name, sym *types.Sym) *ir.SelectorEx
 
 	// Construct an OMETHEXPR node.
 	recv := method.Type.Recv().Type
-	return typecheck.Expr(ir.NewSelectorExpr(pos, ir.OXDOT, ir.TypeNode(recv), sym)).(*ir.SelectorExpr)
+	return typecheck.NewMethodExpr(pos, recv, sym)
 }
 
 func (r *reader) multiExpr() []ir.Node {
diff --git a/src/cmd/compile/internal/typecheck/func.go b/src/cmd/compile/internal/typecheck/func.go
index b727150596..5400fbee0b 100644
--- a/src/cmd/compile/internal/typecheck/func.go
+++ b/src/cmd/compile/internal/typecheck/func.go
@@ -62,7 +62,7 @@ func FixMethodCall(call *ir.CallExpr) {
 
 	dot := call.X.(*ir.SelectorExpr)
 
-	fn := Expr(ir.NewSelectorExpr(dot.Pos(), ir.OXDOT, ir.TypeNode(dot.X.Type()), dot.Selection.Sym))
+	fn := NewMethodExpr(dot.Pos(), dot.X.Type(), dot.Selection.Sym)
 
 	args := make([]ir.Node, 1+len(call.Args))
 	args[0] = dot.X
diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/src/cmd/compile/internal/typecheck/typecheck.go
index 92a907fec9..3bd384a0a7 100644
--- a/src/cmd/compile/internal/typecheck/typecheck.go
+++ b/src/cmd/compile/internal/typecheck/typecheck.go
@@ -843,6 +843,14 @@ func Lookdot1(errnode ir.Node, s *types.Sym, t *types.Type, fs *types.Fields, do
 	return r
 }
 
+// NewMethodExpr returns an OMETHEXPR node representing method
+// expression "recv.sym".
+func NewMethodExpr(pos src.XPos, recv *types.Type, sym *types.Sym) *ir.SelectorExpr {
+	n := Expr(ir.NewSelectorExpr(pos, ir.OXDOT, ir.TypeNode(recv), sym)).(*ir.SelectorExpr)
+	base.Assert(n.Op() == ir.OMETHEXPR)
+	return n
+}
+
 // typecheckMethodExpr checks selector expressions (ODOT) where the
 // base expression is a type expression (OTYPE).
 func typecheckMethodExpr(n *ir.SelectorExpr) (res ir.Node) {