update

src/main/java/chocopy/pa3/CodeGenImpl.java

@@ -724,7 +724,13 @@ public class CodeGenImpl extends CodeGenBase
             }
             else if(node.left.getInferredType().equals(Type.STR_TYPE) && node.right.getInferredType().equals(Type.STR_TYPE))
             {
-                
+                incSp(2);
+                backend.emitSW(node.left.dispatch(this), FP, (1 - sp_off) *wordSize, "Push argument 0 from last.");
+                backend.emitSW(node.right.dispatch(this), FP, ( - sp_off) *wordSize, "Push argument 1 from last.");
+                backend.emitADDI(SP, FP, -sp_off * wordSize, "Set SP to last argument.");
+                backend.emitJAL(streqlLablel, "Invoke method:streql");
+                sp_off -= 2;
+                backend.emitADDI(SP, FP, -sp_off*wordSize, "restore sp");
             }
             else
             {
@@ -768,7 +774,7 @@ public class CodeGenImpl extends CodeGenBase
 //                int loc = offsetMap.get(svi);
 //                backend.emitLW(Register.A0, Register.FP, -loc*4, "Load local variable: "+svi.getVarName());
             }
-            return null;
+            return A0;
         }
         
         @Override