added return null cmp int, 17 pass

Makefile

 CLEAN=mvn clean package
 TEST=java -cp "chocopy-ref.jar:target/assignment.jar" chocopy.ChocoPy --pass=..s --run --dir src/test/data/pa3/sample/ --test
-FILE=
+FILE=op_cmp_int
 clean:
 	$(CLEAN)
 test:

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

@@ -548,6 +548,7 @@ public class CodeGenImpl extends CodeGenBase {
                         backend.emitXOR(T0, T0, T1, "== operator on BOOL/INT");
                         backend.emitSEQZ(T0, T0, "Set to 1 if XOR results in 0, they were equal");
                         backend.emitSW(T0, SP, 0, "Push result onto stack");
+                        return null;
                     }
 
                 case "!=":
@@ -566,6 +567,7 @@ public class CodeGenImpl extends CodeGenBase {
                         // Don't think we need to do the SEQZ/SNEZ instructions here because XOR will already result in 1
                         // if they are not equal, which is the desired result.
                         backend.emitSW(T0, SP, 0, "Push result onto stack");
+                        return null;
                     }
                 case "<=":
                     if (binaryExpr.left.getInferredType().equals(SymbolType.INT_TYPE)) {
@@ -583,7 +585,7 @@ public class CodeGenImpl extends CodeGenBase {
                         backend.emitSLLI(T1, T1, 4, "Compute offset to correct object");
                         backend.emitADD(T0, T0, T1, "Add offset to curr ptr");
                         backend.emitSW(T0, SP, 0, "Push result onto stack");
-
+                        return null;
                     }
                 case ">=":
                     if (binaryExpr.left.getInferredType().equals(SymbolType.INT_TYPE)) {
@@ -601,6 +603,7 @@ public class CodeGenImpl extends CodeGenBase {
                         backend.emitSLLI(T1, T1, 4, "Compute offset to correct object");
                         backend.emitADD(T0, T0, T1, "Add offset to curr ptr");
                         backend.emitSW(T0, SP, 0, "Push result onto stack");
+                        return null;
                     }
                 case "<":
                     if (binaryExpr.left.getInferredType().equals(SymbolType.INT_TYPE)) {
@@ -617,7 +620,7 @@ public class CodeGenImpl extends CodeGenBase {
                         backend.emitSLLI(T1, T1, 4, "Compute offset to correct object");
                         backend.emitADD(T0, T0, T1, "Add offset to curr ptr");
                         backend.emitSW(T0, SP, 0, "Push result onto stack");
-
+                        return null;
                     }
                 case ">":
                     if (binaryExpr.left.getInferredType().equals(SymbolType.INT_TYPE)) {
@@ -634,6 +637,7 @@ public class CodeGenImpl extends CodeGenBase {
                         backend.emitSLLI(T1, T1, 4, "Compute offset to correct object");
                         backend.emitADD(T0, T0, T1, "Add offset to curr ptr");
                         backend.emitSW(T0, SP, 0, "Push result onto stack");
+                        return null;
                     }
                 case "and":
                     if (binaryExpr.getInferredType().equals(SymbolType.INT_TYPE)) {