runtime: fix map len and chan len/cap

ssa/datastruct.go

@@ -145,18 +145,6 @@ func (b Builder) SliceCap(x Expr) Expr {
 	return Expr{ptr, b.Prog.Int()}
 }
 
-func (b Builder) MapLen(x Expr) Expr {
-	if debugInstr {
-		log.Printf("MapLen %v\n", x.impl)
-	}
-	prog := b.Prog
-	if x.impl.IsNull() {
-		return prog.Val(0)
-	}
-	x.Type = prog.Pointer(prog.Int())
-	return b.Load(x)
-}
-
 // -----------------------------------------------------------------------------
 
 // The IndexAddr instruction yields the address of the element at

ssa/expr.go

@@ -1083,7 +1083,7 @@ func (b Builder) BuiltinCall(fn string, args ...Expr) (ret Expr) {
 			case vkChan:
 				return b.InlineCall(b.Pkg.rtFunc("ChanLen"), arg)
 			case vkMap:
-				return b.MapLen(arg)
+				return b.InlineCall(b.Pkg.rtFunc("MapLen"), arg)
 			}
 		}
 	case "cap":