cmd/compile: remove isfat from order expr

isfat was removed in walkexpr in CL 32313. For consistency,
remove it from order expr, too.

Change-Id: I0a47e0da13ba0168d6a055d990b8efad26ad790d
Reviewed-on: https://go-review.googlesource.com/c/go/+/179057
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -306,18 +306,6 @@ func ggloblsym(s *obj.LSym, width int32, flags int16) {
 	Ctxt.Globl(s, int64(width), int(flags))
 }
 
-func isfat(t *types.Type) bool {
-	if t != nil {
-		switch t.Etype {
-		case TSTRUCT, TARRAY, TSLICE, TSTRING,
-			TINTER: // maybe remove later
-			return true
-		}
-	}
-
-	return false
-}
-
 func Addrconst(a *obj.Addr, v int64) {
 	a.Sym = nil
 	a.Type = obj.TYPE_CONST

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

@@ -1028,7 +1028,6 @@ func (o *Order) expr(n, lhs *Node) *Node {
 			}
 		}
 
-		// key must be addressable
 	case OINDEXMAP:
 		n.Left = o.expr(n.Left, nil)
 		n.Right = o.expr(n.Right, nil)
@@ -1048,6 +1047,7 @@ func (o *Order) expr(n, lhs *Node) *Node {
 			}
 		}
 
+		// key must be addressable
 		n.Right = o.mapKeyTemp(n.Left.Type, n.Right)
 		if needCopy {
 			n = o.copyExpr(n, n.Type, false)
@@ -1205,10 +1205,7 @@ func (o *Order) expr(n, lhs *Node) *Node {
 
 	case ODOTTYPE, ODOTTYPE2:
 		n.Left = o.expr(n.Left, nil)
-		// TODO(rsc): The isfat is for consistency with componentgen and walkexpr.
-		// It needs to be removed in all three places.
-		// That would allow inlining x.(struct{*int}) the same as x.(*int).
-		if !isdirectiface(n.Type) || isfat(n.Type) || instrumenting {
+		if !isdirectiface(n.Type) || instrumenting {
 			n = o.copyExpr(n, n.Type, true)
 		}
 

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

@@ -1449,3 +1449,15 @@ func liveness(e *ssafn, f *ssa.Func, pp *Progs) LivenessMap {
 
 	return lv.livenessMap
 }
+
+func isfat(t *types.Type) bool {
+	if t != nil {
+		switch t.Etype {
+		case TSTRUCT, TARRAY, TSLICE, TSTRING,
+			TINTER: // maybe remove later
+			return true
+		}
+	}
+
+	return false
+}