cmd/compile: clean up one Node.Etype usage

Whoever Marvin is, we're one step closer to realizing his dream.

Change-Id: I8dece4417d0f9ec234be158d0ee7bc6735342d93
Reviewed-on: https://go-review.googlesource.com/27465
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/inl.go

@@ -365,8 +365,7 @@ func inlnode(n *Node) *Node {
 	case ODEFER, OPROC:
 		switch n.Left.Op {
 		case OCALLFUNC, OCALLMETH:
-			// TODO(marvin): Fix Node.EType type union.
-			n.Left.Etype = EType(n.Op)
+			n.Left.setNoInline(true)
 		}
 		fallthrough
 
@@ -468,8 +467,7 @@ func inlnode(n *Node) *Node {
 	// switch at the top of this function.
 	switch n.Op {
 	case OCALLFUNC, OCALLMETH:
-		// TODO(marvin): Fix Node.EType type union.
-		if n.Etype == EType(OPROC) || n.Etype == EType(ODEFER) {
+		if n.noInline() {
 			return n
 		}
 	}

src/cmd/compile/internal/gc/syntax.go

@@ -80,6 +80,7 @@ const (
 	notLiveAtEnd
 	isClosureVar
 	isOutputParamHeapAddr
+	noInline // used internally by inliner to indicate that a function call should not be inlined; set for OCALLFUNC and OCALLMETH only
 )
 
 func (n *Node) HasBreak() bool {
@@ -112,6 +113,16 @@ func (n *Node) setIsClosureVar(b bool) {
 		n.flags &^= isClosureVar
 	}
 }
+func (n *Node) noInline() bool {
+	return n.flags&noInline != 0
+}
+func (n *Node) setNoInline(b bool) {
+	if b {
+		n.flags |= noInline
+	} else {
+		n.flags &^= noInline
+	}
+}
 
 func (n *Node) IsOutputParamHeapAddr() bool {
 	return n.flags&isOutputParamHeapAddr != 0