diff --git a/src/cmd/compile/internal/gc/builtin.go b/src/cmd/compile/internal/gc/builtin.go
index ec8f1093b6..8051c7d0df 100644
--- a/src/cmd/compile/internal/gc/builtin.go
+++ b/src/cmd/compile/internal/gc/builtin.go
@@ -55,15 +55,15 @@ var runtimeDecls = [...]struct {
 	{"convT2E16", funcTag, 52},
 	{"convT2E32", funcTag, 52},
 	{"convT2E64", funcTag, 52},
-	{"convT2Estring", funcTag, 53},
-	{"convT2Eslice", funcTag, 53},
+	{"convT2Estring", funcTag, 52},
+	{"convT2Eslice", funcTag, 52},
 	{"convT2Enoptr", funcTag, 53},
 	{"convT2I", funcTag, 53},
 	{"convT2I16", funcTag, 52},
 	{"convT2I32", funcTag, 52},
 	{"convT2I64", funcTag, 52},
-	{"convT2Istring", funcTag, 53},
-	{"convT2Islice", funcTag, 53},
+	{"convT2Istring", funcTag, 52},
+	{"convT2Islice", funcTag, 52},
 	{"convT2Inoptr", funcTag, 53},
 	{"assertE2I", funcTag, 52},
 	{"assertE2I2", funcTag, 54},
diff --git a/src/cmd/compile/internal/gc/builtin/runtime.go b/src/cmd/compile/internal/gc/builtin/runtime.go
index 140b7f3b2d..028936b875 100644
--- a/src/cmd/compile/internal/gc/builtin/runtime.go
+++ b/src/cmd/compile/internal/gc/builtin/runtime.go
@@ -68,16 +68,16 @@ func convT2E(typ *byte, elem *any) (ret any)
 func convT2E16(typ *byte, val any) (ret any)
 func convT2E32(typ *byte, val any) (ret any)
 func convT2E64(typ *byte, val any) (ret any)
-func convT2Estring(typ *byte, elem *any) (ret any)
-func convT2Eslice(typ *byte, elem *any) (ret any)
+func convT2Estring(typ *byte, val any) (ret any) // val must be a string
+func convT2Eslice(typ *byte, val any) (ret any)  // val must be a slice
 func convT2Enoptr(typ *byte, elem *any) (ret any)
 
 func convT2I(tab *byte, elem *any) (ret any)
 func convT2I16(tab *byte, val any) (ret any)
 func convT2I32(tab *byte, val any) (ret any)
 func convT2I64(tab *byte, val any) (ret any)
-func convT2Istring(tab *byte, elem *any) (ret any)
-func convT2Islice(tab *byte, elem *any) (ret any)
+func convT2Istring(tab *byte, val any) (ret any) // val must be a string
+func convT2Islice(tab *byte, val any) (ret any)  // val must be a slice
 func convT2Inoptr(tab *byte, elem *any) (ret any)
 
 // interface type assertions x.(T)
diff --git a/src/cmd/compile/internal/gc/order.go b/src/cmd/compile/internal/gc/order.go
index 8afb136515..fbc05b95d2 100644
--- a/src/cmd/compile/internal/gc/order.go
+++ b/src/cmd/compile/internal/gc/order.go
@@ -1042,12 +1042,17 @@ func (o *Order) expr(n, lhs *Node) *Node {
 			n = o.copyExpr(n, n.Type, false)
 		}
 
-	// concrete type (not interface) argument must be addressable
-	// temporary to pass to runtime.
+	// concrete type (not interface) argument might need an addressable
+	// temporary to pass to the runtime conversion routine.
 	case OCONVIFACE:
 		n.Left = o.expr(n.Left, nil)
-
-		if !n.Left.Type.IsInterface() {
+		if n.Left.Type.IsInterface() {
+			break
+		}
+		if _, needsaddr := convFuncName(n.Left.Type, n.Type); needsaddr || consttype(n.Left) > 0 {
+			// Need a temp if we need to pass the address to the conversion function.
+			// We also process constants here, making a named static global whose
+			// address we can put directly in an interface (see OCONVIFACE case in walk).
 			n.Left = o.addrTemp(n.Left)
 		}
 
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index d33674f221..f7676310e9 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -417,9 +417,9 @@ func convFuncName(from, to *types.Type) (fnname string, needsaddr bool) {
 			case from.Size() == 8 && from.Align == types.Types[TUINT64].Align && !types.Haspointers(from):
 				return "convT2E64", false
 			case from.IsString():
-				return "convT2Estring", true
+				return "convT2Estring", false
 			case from.IsSlice():
-				return "convT2Eslice", true
+				return "convT2Eslice", false
 			case !types.Haspointers(from):
 				return "convT2Enoptr", true
 			}
@@ -433,9 +433,9 @@ func convFuncName(from, to *types.Type) (fnname string, needsaddr bool) {
 			case from.Size() == 8 && from.Align == types.Types[TUINT64].Align && !types.Haspointers(from):
 				return "convT2I64", false
 			case from.IsString():
-				return "convT2Istring", true
+				return "convT2Istring", false
 			case from.IsSlice():
-				return "convT2Islice", true
+				return "convT2Islice", false
 			case !types.Haspointers(from):
 				return "convT2Inoptr", true
 			}
diff --git a/src/runtime/iface.go b/src/runtime/iface.go
index 7ab731151e..1ef9825a48 100644
--- a/src/runtime/iface.go
+++ b/src/runtime/iface.go
@@ -329,38 +329,27 @@ func convT2E64(t *_type, val uint64) (e eface) {
 	return
 }
 
-func convT2Estring(t *_type, elem unsafe.Pointer) (e eface) {
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Estring))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
+func convT2Estring(t *_type, val string) (e eface) {
 	var x unsafe.Pointer
-	if *(*string)(elem) == "" {
+	if val == "" {
 		x = unsafe.Pointer(&zeroVal[0])
 	} else {
-		x = mallocgc(t.size, t, true)
-		*(*string)(x) = *(*string)(elem)
+		x = mallocgc(unsafe.Sizeof(val), t, true)
+		*(*string)(x) = val
 	}
 	e._type = t
 	e.data = x
 	return
 }
 
-func convT2Eslice(t *_type, elem unsafe.Pointer) (e eface) {
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Eslice))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
+func convT2Eslice(t *_type, val []byte) (e eface) {
+	// Note: this must work for any element type, not just byte.
 	var x unsafe.Pointer
-	if v := *(*slice)(elem); uintptr(v.array) == 0 {
+	if (*slice)(unsafe.Pointer(&val)).array == nil {
 		x = unsafe.Pointer(&zeroVal[0])
 	} else {
-		x = mallocgc(t.size, t, true)
-		*(*slice)(x) = *(*slice)(elem)
+		x = mallocgc(unsafe.Sizeof(val), t, true)
+		*(*[]byte)(x) = val
 	}
 	e._type = t
 	e.data = x
@@ -438,40 +427,29 @@ func convT2I64(tab *itab, val uint64) (i iface) {
 	return
 }
 
-func convT2Istring(tab *itab, elem unsafe.Pointer) (i iface) {
+func convT2Istring(tab *itab, val string) (i iface) {
 	t := tab._type
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Istring))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
 	var x unsafe.Pointer
-	if *(*string)(elem) == "" {
+	if val == "" {
 		x = unsafe.Pointer(&zeroVal[0])
 	} else {
-		x = mallocgc(t.size, t, true)
-		*(*string)(x) = *(*string)(elem)
+		x = mallocgc(unsafe.Sizeof(val), t, true)
+		*(*string)(x) = val
 	}
 	i.tab = tab
 	i.data = x
 	return
 }
 
-func convT2Islice(tab *itab, elem unsafe.Pointer) (i iface) {
+func convT2Islice(tab *itab, val []byte) (i iface) {
+	// Note: this must work for any element type, not just byte.
 	t := tab._type
-	if raceenabled {
-		raceReadObjectPC(t, elem, getcallerpc(), funcPC(convT2Islice))
-	}
-	if msanenabled {
-		msanread(elem, t.size)
-	}
 	var x unsafe.Pointer
-	if v := *(*slice)(elem); uintptr(v.array) == 0 {
+	if (*slice)(unsafe.Pointer(&val)).array == nil {
 		x = unsafe.Pointer(&zeroVal[0])
 	} else {
-		x = mallocgc(t.size, t, true)
-		*(*slice)(x) = *(*slice)(elem)
+		x = mallocgc(unsafe.Sizeof(val), t, true)
+		*(*[]byte)(x) = val
 	}
 	i.tab = tab
 	i.data = x
diff --git a/test/fixedbugs/issue20250.go b/test/fixedbugs/issue20250.go
index 47879385d2..c190515274 100644
--- a/test/fixedbugs/issue20250.go
+++ b/test/fixedbugs/issue20250.go
@@ -11,13 +11,13 @@
 package p
 
 type T struct {
-	s string
+	s [2]string
 }
 
 func f(a T) { // ERROR "live at entry to f: a"
 	var e interface{} // ERROR "stack object e interface \{\}$"
 	func() {          // ERROR "live at entry to f.func1: a &e"
-		e = a.s // ERROR "live at call to convT2Estring: &e" "stack object a T$"
+		e = a.s // ERROR "live at call to convT2E: &e" "stack object a T$"
 	}()
 	// Before the fix, both a and e were live at the previous line.
 	_ = e
diff --git a/test/live.go b/test/live.go
index 679562d9bf..ba50f5b779 100644
--- a/test/live.go
+++ b/test/live.go
@@ -141,7 +141,7 @@ var i9 interface{}
 func f9() bool {
 	g8()
 	x := i9
-	y := interface{}(str()) // ERROR "live at call to convT2Estring: x.data$" "live at call to str: x.data$" "stack object .autotmp_[0-9]+ string$"
+	y := interface{}(g18()) // ERROR "live at call to convT2E: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
 	i9 = y                  // make y escape so the line above has to call convT2E
 	return x != y
 }
@@ -493,13 +493,13 @@ func f30(b bool) {
 
 func f31(b1, b2, b3 bool) {
 	if b1 {
-		g31(str()) // ERROR "stack object .autotmp_[0-9]+ string$"
+		g31(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	if b2 {
-		h31(str()) // ERROR "live at call to convT2Estring: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$" "stack object .autotmp_[0-9]+ string$"
+		h31(g18()) // ERROR "live at call to convT2E: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$" "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	if b3 {
-		panic(str()) // ERROR "stack object .autotmp_[0-9]+ string$"
+		panic(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
 	}
 	print(b3)
 }