diff --git a/src/cmd/compile/internal/gc/order.go b/src/cmd/compile/internal/gc/order.go
index 616945685c..4913e3c11a 100644
--- a/src/cmd/compile/internal/gc/order.go
+++ b/src/cmd/compile/internal/gc/order.go
@@ -183,7 +183,23 @@ func isaddrokay(n *Node) bool {
 // Orderaddrtemp ensures that n is okay to pass by address to runtime routines.
 // If the original argument n is not okay, orderaddrtemp creates a tmp, emits
 // tmp = n, and then returns tmp.
+// The result of orderaddrtemp MUST be assigned back to n, e.g.
+// 	n.Left = orderaddrtemp(n.Left, order)
 func orderaddrtemp(n *Node, order *Order) *Node {
+	if consttype(n) >= 0 {
+		// TODO: expand this to all static composite literal nodes?
+		n = defaultlit(n, nil)
+		dowidth(n.Type)
+		vstat := staticname(n.Type)
+		vstat.Name.Readonly = true
+		var out []*Node
+		staticassign(vstat, n, &out)
+		if out != nil {
+			Fatalf("staticassign of const generated code: %+v", n)
+		}
+		vstat = typecheck(vstat, Erv)
+		return vstat
+	}
 	if isaddrokay(n) {
 		return n
 	}
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index d5da170119..ba4b1af4ff 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -889,20 +889,29 @@ opswitch:
 			n = l
 			break
 		}
-		// Optimize convT2{E,I} when T is not pointer-shaped.
-		// We make the interface by initializing a stack temporary to
-		// the value we want to put in the interface, then using the address of
-		// that stack temporary for the interface data word.
-		if !n.Left.Type.IsInterface() && n.Esc == EscNone && n.Left.Type.Width <= 1024 {
-			tmp := temp(n.Left.Type)
-			init.Append(typecheck(nod(OAS, tmp, n.Left), Etop))
+
+		// Optimize convT2{E,I} when T is not pointer-shaped,
+		// but the value does not escape or is a readonly global.
+		var value *Node
+		switch {
+		case !n.Left.Type.IsInterface() && n.Esc == EscNone && n.Left.Type.Width <= 1024:
+			// Initializing a stack temporary to the value we want to put in the interface,
+			// then using the address of that stack temporary for the interface data word.
+			value = temp(n.Left.Type)
+			init.Append(typecheck(nod(OAS, value, n.Left), Etop))
+		case n.Left.Class == PEXTERN && n.Left.Name != nil && n.Left.Name.Readonly:
+			// readonly global; use directly.
+			value = n.Left
+		}
+
+		if value != nil {
 			var t *Node
 			if n.Type.IsEmptyInterface() {
 				t = typename(n.Left.Type)
 			} else {
 				t = itabname(n.Left.Type, n.Type)
 			}
-			l := nod(OEFACE, t, typecheck(nod(OADDR, tmp, nil), Erv))
+			l := nod(OEFACE, t, typecheck(nod(OADDR, value, nil), Erv))
 			l.Type = n.Type
 			l.Typecheck = n.Typecheck
 			n = l
diff --git a/src/cmd/internal/obj/data.go b/src/cmd/internal/obj/data.go
index d5565f24dc..114841dedb 100644
--- a/src/cmd/internal/obj/data.go
+++ b/src/cmd/internal/obj/data.go
@@ -70,7 +70,7 @@ func (s *LSym) GrowCap(c int64) {
 // prepwrite prepares to write data of size siz into s at offset off.
 func (s *LSym) prepwrite(ctxt *Link, off int64, siz int) {
 	if off < 0 || siz < 0 || off >= 1<<30 {
-		log.Fatalf("prepwrite: bad off=%d siz=%d", off, siz)
+		log.Fatalf("prepwrite: bad off=%d siz=%d s=%v", off, siz, s)
 	}
 	if s.Type == SBSS || s.Type == STLSBSS {
 		ctxt.Diag("cannot supply data for BSS var")
diff --git a/test/live.go b/test/live.go
index b23e1509e0..462f3ef12e 100644
--- a/test/live.go
+++ b/test/live.go
@@ -141,7 +141,7 @@ var i9 interface{}
 func f9() bool {
 	g8()
 	x := i9
-	y := interface{}(99.0i) // ERROR "live at call to convT2E: x.data x.type$"
+	y := interface{}(str()) // ERROR "live at call to convT2E: .autotmp_[0-9]+ x.data x.type$" "live at call to str: x.data x.type$"
 	i9 = y                  // make y escape so the line above has to call convT2E
 	return x != y
 }
@@ -256,12 +256,15 @@ func g15() string
 
 var m map[string]int
 
+// str is used to ensure that a temp is required for runtime calls below.
+func str() string
+
 func f16() {
 	if b {
-		delete(m, "hi") // ERROR "live at call to mapdelete: .autotmp_[0-9]+$"
+		delete(m, str()) // ERROR "live at call to mapdelete: .autotmp_[0-9]+$"
 	}
-	delete(m, "hi") // ERROR "live at call to mapdelete: .autotmp_[0-9]+$"
-	delete(m, "hi") // ERROR "live at call to mapdelete: .autotmp_[0-9]+$"
+	delete(m, str()) // ERROR "live at call to mapdelete: .autotmp_[0-9]+$"
+	delete(m, str()) // ERROR "live at call to mapdelete: .autotmp_[0-9]+$"
 }
 
 var m2s map[string]*byte
@@ -280,19 +283,19 @@ func f17a(p *byte) { // ERROR "live at entry to f17a: p$"
 func f17b(p *byte) { // ERROR "live at entry to f17b: p$"
 	// key temporary
 	if b {
-		m2s["x"] = p // ERROR "live at call to mapassign: p .autotmp_[0-9]+$"
+		m2s[str()] = p // ERROR "live at call to mapassign: p .autotmp_[0-9]+$" "live at call to str: p$"
 	}
-	m2s["x"] = p // ERROR "live at call to mapassign: p .autotmp_[0-9]+$"
-	m2s["x"] = p // ERROR "live at call to mapassign: p .autotmp_[0-9]+$"
+	m2s[str()] = p // ERROR "live at call to mapassign: p .autotmp_[0-9]+$" "live at call to str: p$"
+	m2s[str()] = p // ERROR "live at call to mapassign: p .autotmp_[0-9]+$" "live at call to str: p$"
 }
 
 func f17c() {
 	// key and value temporaries
 	if b {
-		m2s["x"] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign: .autotmp_[0-9]+ .autotmp_[0-9]+$"
+		m2s[str()] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign: .autotmp_[0-9]+ .autotmp_[0-9]+$"
 	}
-	m2s["x"] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign: .autotmp_[0-9]+ .autotmp_[0-9]+$"
-	m2s["x"] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign: .autotmp_[0-9]+ .autotmp_[0-9]+$"
+	m2s[str()] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign: .autotmp_[0-9]+ .autotmp_[0-9]+$"
+	m2s[str()] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign: .autotmp_[0-9]+ .autotmp_[0-9]+$"
 }
 
 func f17d() *byte
@@ -313,6 +316,9 @@ func f18() {
 
 var ch chan *byte
 
+// byteptr is used to ensure that a temp is required for runtime calls below.
+func byteptr() *byte
+
 func f19() {
 	// dest temporary for channel receive.
 	var z *byte
@@ -328,10 +334,10 @@ func f19() {
 func f20() {
 	// src temporary for channel send
 	if b {
-		ch <- nil // ERROR "live at call to chansend1: .autotmp_[0-9]+$"
+		ch <- byteptr() // ERROR "live at call to chansend1: .autotmp_[0-9]+$"
 	}
-	ch <- nil // ERROR "live at call to chansend1: .autotmp_[0-9]+$"
-	ch <- nil // ERROR "live at call to chansend1: .autotmp_[0-9]+$"
+	ch <- byteptr() // ERROR "live at call to chansend1: .autotmp_[0-9]+$"
+	ch <- byteptr() // ERROR "live at call to chansend1: .autotmp_[0-9]+$"
 }
 
 func f21() {
@@ -488,13 +494,13 @@ func f30(b bool) {
 
 func f31(b1, b2, b3 bool) {
 	if b1 {
-		g31("a") // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to g31: .autotmp_[0-9]+$"
+		g31(str()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to g31: .autotmp_[0-9]+$"
 	}
 	if b2 {
-		h31("b") // ERROR "live at call to convT2E: .autotmp_[0-9]+ .autotmp_[0-9]+$" "live at call to h31: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
+		h31(str()) // ERROR "live at call to convT2E: .autotmp_[0-9]+ .autotmp_[0-9]+$" "live at call to h31: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
 	}
 	if b3 {
-		panic("asdf") // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to gopanic: .autotmp_[0-9]+$"
+		panic(str()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to gopanic: .autotmp_[0-9]+$"
 	}
 	print(b3)
 }
@@ -529,7 +535,7 @@ func call32(func())
 var m33 map[interface{}]int
 
 func f33() {
-	if m33[nil] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
+	if m33[byteptr()] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
 		printnl()
 		return
 	} else {
@@ -539,7 +545,7 @@ func f33() {
 }
 
 func f34() {
-	if m33[nil] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
+	if m33[byteptr()] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
 		printnl()
 		return
 	}
@@ -547,7 +553,7 @@ func f34() {
 }
 
 func f35() {
-	if m33[nil] == 0 && m33[nil] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
+	if m33[byteptr()] == 0 && m33[byteptr()] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
 		printnl()
 		return
 	}
@@ -555,7 +561,7 @@ func f35() {
 }
 
 func f36() {
-	if m33[nil] == 0 || m33[nil] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
+	if m33[byteptr()] == 0 || m33[byteptr()] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
 		printnl()
 		return
 	}
@@ -563,7 +569,7 @@ func f36() {
 }
 
 func f37() {
-	if (m33[nil] == 0 || m33[nil] == 0) && m33[nil] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
+	if (m33[byteptr()] == 0 || m33[byteptr()] == 0) && m33[byteptr()] == 0 { // ERROR "live at call to mapaccess1: .autotmp_[0-9]+$"
 		printnl()
 		return
 	}