Reduced memory allocations

src/build/asm/Assembler.go

@@ -13,3 +13,12 @@ func (a *Assembler) Merge(b Assembler) {
 	maps.Copy(a.Data, b.Data)
 	a.Instructions = append(a.Instructions, b.Instructions...)
 }
+
+// SetData sets the data for the given label.
+func (a *Assembler) SetData(label string, data []byte) {
+	if a.Data == nil {
+		a.Data = map[string][]byte{}
+	}
+
+	a.Data[label] = data
+}