cmd/compile/internal/noder: explicit receiver expression handling

This CL adds a helper expression code for receiver addressing; i.e.,
the implicit addressing, dereferencing, and field selections involved
in changing the `x` in `x.M()` into an appropriate expression to pass
as an argument to the method.

Change-Id: I9be933e2a38c8f94f6a85d95b54f34164e5efb0a
Reviewed-on: https://go-review.googlesource.com/c/go/+/421820
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 8c80c78c0b..3ab11399a5 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -1914,6 +1914,19 @@ func (r *reader) expr() (res ir.Node) {
 		}
 		return typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
 
+	case exprRecv:
+		x := r.expr()
+		pos := r.pos()
+		for i, n := 0, r.Len(); i < n; i++ {
+			x = Implicit(DotField(pos, x, r.Len()))
+		}
+		if r.Bool() { // needs deref
+			x = Implicit(Deref(pos, x.Type().Elem(), x))
+		} else if r.Bool() { // needs addr
+			x = Implicit(Addr(pos, x))
+		}
+		return x
+
 	case exprCall:
 		fun := r.expr()
 		if r.Bool() { // method call