Merge branch 'master' into develop

.gitlab-ci.yml

@@ -10,6 +10,7 @@ stages:
   - build
   - frontend-test
   - backend-test
+  - optimise-test
 
 build-job:
   stage: build
@@ -61,3 +62,14 @@ test-execute-valid:
     paths:
       - log/assembly
       - log/output
+
+test-optimise:
+  stage: optimise-test
+  script:
+    - echo "compile oprimise sample tests and conpair with given .log result file"
+    - ./scripts/constantPropagationTest.sh
+    - ./scripts/extensionValidTest.sh
+  artifacts:
+    paths:
+      - log/assembly
+      - log/output
\ No newline at end of file

antlr_config/WACCParser.g4

@@ -131,8 +131,7 @@ expr : INT_LITER      #IntExpr
      | expr bop=( '+' | '-' ) expr                    #ArithmeticExpr
      | expr bop=( '>' | '>=' | '<' | '<=' ) expr      #CmpExpr
      | expr bop=( '==' | '!=' ) expr                  #EqExpr
-     | expr '&' expr                                  #BitwiseAndExpr
-     | expr '|' expr                                  #BitwiseOrExpr
+     | expr bitop=( '&' | '|' ) expr                    #BitwiseExpr
      | expr '&&' expr                                 #AndExpr
      | expr '||' expr                                 #OrExpr
      | OPEN_PARENTHESES expr CLOSE_PARENTHESES        #ParenExpr

compile

@@ -39,4 +39,5 @@ then
 fi
 
 # compile the given wacc file here
-java -cp ./bin:./lib/antlr-4.9.1-complete.jar Compiler $1 $PARSE_ONLY $PRINT_AST $OPTIMISE "--assembly" $EXECUTE
\ No newline at end of file
+# default as using -o1 optimise and generate assembly
+java -cp ./bin:./lib/antlr-4.9.1-complete.jar Compiler $1 $PARSE_ONLY $PRINT_AST $OPTIMISE "--optimise" "1" "--assembly" $EXECUTE
\ No newline at end of file

scripts/allTest

@@ -8,3 +8,5 @@
 ./scripts/semanticCheckerSemanticErr
 ./scripts/assembleTest.sh
 ./scripts/executeTest.sh
+./scripts/constantPropagation.sh 
+./scripts/extensionValidTest.sh
\ No newline at end of file

scripts/constantEvaluationTest.sh → scripts/constantPropagationTest.sh

 #!/bin/bash
 
-VALID_EXAMPLE_DIR="./src/test/examples/valid/"
 VALID_EXAMPLES=(
-                 "/constantPropagation/evaluation/"
+                 "/propagation"
+                #  "/evaluation"
                 )
 
-VALID_EXAMPLE_LOG="./log/const_eval.log"
-> $VALID_EXAMPLE_LOG
+VALID_EXAMPLES_SRC_DIR="./src/test/custom/valid/constantPropagation"
+ASSEMBLY_OUTPUT_DIR="./log/assembly/constantPropagation"
+
+mkdir log
+mkdir $ASSEMBLY_OUTPUT_DIR
 
-TEST_DIR="$VALID_EXAMPLE_DIR$VALID_EXAMPLES"
 # counters to represent the total number of test files to be processed
-TOTAL_COUNT=$(find "$VALID_EXAMPLE_DIR${VALID_EXAMPLES[@]}" -name "*.wacc" | wc -l)
+TOTAL_COUNT=$(find "${VALID_EXAMPLES[@]/#/${VALID_EXAMPLES_SRC_DIR}}" -name "*.wacc" | wc -l)
 COUNTER=0
 
-for folder in "$VALID_EXAMPLE_DIR${VALID_EXAMPLES[@]}"; do
-  for file in $(find "$folder" -name "*.wacc"); do
+for folder in ${VALID_EXAMPLES[@]}; do
+  ASSEMBLY_OUTPUT_VALID_FOLDER="${ASSEMBLY_OUTPUT_DIR}${folder}"
+  mkdir $ASSEMBLY_OUTPUT_VALID_FOLDER
+  for file in $(find "${VALID_EXAMPLES_SRC_DIR}${folder}" -name "*.wacc")
+  do
     FILE_NAME=$(basename "${file%.*}")
-    ./compile -o1 -t $file 2> $VALID_EXAMPLE_LOG
-    ret=$?
-    echo "exit status: " $ret
-    if [ $ret -ne 0 ]; then
+    EXECUTABLE_FILE_NAME="${ASSEMBLY_OUTPUT_VALID_FOLDER}/${FILE_NAME}"
     echo $file
-      echo "status code incorrect: " $ret
-      exit 1
+    ./compile -t -o1 $file > "${EXECUTABLE_FILE_NAME}.log.txt"
+
+    if diff "${EXECUTABLE_FILE_NAME}.log.txt" "${VALID_EXAMPLES_SRC_DIR}${folder}/${FILE_NAME}.log" -I scope; then
+      (( COUNTER += 1 ))
     fi
 
-    if diff "$TEST_DIR${FILE_NAME}.log" $VALID_EXAMPLE_LOG > temp; then
-      echo $FILE_NAME
-      echo "optimise differ from expected result: "
 
-      exit 1
-    fi
-    (( COUNTER += 1 ))
-    echo "$COUNTER / $(($TOTAL_COUNT)) finished"
-    echo ""
+    echo "$COUNTER / $(($TOTAL_COUNT)) files have been executed"
   done
 
   echo "========================================================================================"

scripts/extensionValidTest.sh

@@ -5,8 +5,8 @@ VALID_EXAMPLES=(
                  "/bitwiseOperation"
                  "/do-while"
                  "/for"
-                 "/import"  # OK
-                 "/jump"    # OK
+                 "/import"
+                 "/jump"
                  "/struct"
                  "/switch"
                 )
@@ -35,6 +35,8 @@ for folder in ${VALID_EXAMPLES[@]}; do
     EXECUTABLE_OUTPUT_FILE="${EXECUTE_OUTPUT_VALID_FOLDER}/${FILE_NAME}"
     echo $file
     ./compile $file 2> "${EXECUTABLE_FILE_NAME}.log.txt"
+    echo "${EXECUTABLE_FILE_NAME}.s"
+    echo "${FILE_NAME}.s"
     mv "${FILE_NAME}.s" "${EXECUTABLE_FILE_NAME}.s"
 
     arm-linux-gnueabi-gcc -o $EXECUTABLE_OUTPUT_FILE -mcpu=arm1176jzf-s -mtune=arm1176jzf-s "${EXECUTABLE_FILE_NAME}.s" > "${EXECUTABLE_OUTPUT_FILE}.log.txt"
@@ -45,11 +47,11 @@ for folder in ${VALID_EXAMPLES[@]}; do
     echo "execution exit status" $ret2
 
     ## altomatically generate output .log file
-    mv "${EXECUTABLE_OUTPUT_FILE}.output.txt" "${VALID_EXAMPLES_SRC_DIR}${folder}/${FILE_NAME}.log"
+    # mv "${EXECUTABLE_OUTPUT_FILE}.output.txt" "${VALID_EXAMPLES_SRC_DIR}${folder}/${FILE_NAME}.log"
 
     if [ "$ret1" -eq 0 ] && [ "$ret2" -eq 0 ]; then 
     ## test if output is same as .log file
-    #   diff "${EXECUTABLE_OUTPUT_FILE}.output.txt" "${VALID_EXAMPLES_SRC_DIR}${folder}/${FILE_NAME}.log"
+       diff "${EXECUTABLE_OUTPUT_FILE}.output.txt" "${VALID_EXAMPLES_SRC_DIR}${folder}/${FILE_NAME}.log"
       (( COUNTER += 1 ))
     fi 
 

src/Compiler.java

@@ -64,13 +64,13 @@ public class Compiler {
 
         int optimise_cmd_index = cmd_ops.indexOf("--optimise");
 
-        /* if not found optimise flag, no optimise */
-        if (optimise_cmd_index == 0) {
+        if (optimise_cmd_index != 0) {
           String optimise_level = cmd_ops.get(optimise_cmd_index + 1);
           switch (optimise_level) {
             case "0":
               break;
             case "1":
+              System.out.println("optimising using const propagate");
               NodeVisitor<Node> constPropOptimiser = new ConstantPropagation();
               program = constPropOptimiser.visit(program);
               break;

src/backend/ARMInstructionGenerator.java

@@ -83,6 +83,9 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
      no need to distinguish function and non function scope, as non function scope does not call return */
   private int funcStackSize;
 
+  /* used when a break/jump occure in a loop statment, accumulated on entering scope */
+  private int loopStackSize;
+
   /* used for mapping type with its print routine function */
   private final Map<Type, RoutineInstruction> typeRoutineMap = Map.of(
     INT_BASIC_TYPE,    PRINT_INT,
@@ -683,16 +686,11 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
 
     /* 1 leave space for variables in stack */
     int stackSize = node.getStackSize();
-    int temp = stackSize;
-    while (temp > 0) {
-      int realStackSize = temp / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : temp;
-      instructions.add(new Sub(SP, SP,
-          new Operand2(realStackSize)));
-      temp = temp - realStackSize;
-    }
+    decStack(stackSize);
 
     /* accumulate function stack size, in case this scope is a function scope and contain return */
     funcStackSize += stackSize;
+    loopStackSize += stackSize;
 
     /* 2 visit statements
      *   set currentSymbolTable here, eliminate all other set symbol table in other statNode */
@@ -704,15 +702,10 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
 
     /* decrease function stack size, as from this point stack is freed by the scope, not by return */
     funcStackSize -= stackSize;
+    loopStackSize -= stackSize;
 
     /* 3 restore stack */
-    temp = stackSize;
-    while (temp > 0) {
-      int realStackSize = temp / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : temp;
-      instructions.add(new Add(SP, SP,
-          new Operand2(realStackSize)));
-      temp = temp - realStackSize;
-    }
+    incStack(stackSize);
 
     return null;
   }
@@ -743,9 +736,16 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
 
     instructions.add(startLabel);
 
+    /* record how much stack parent loop used */
+    int prevLoopSize = loopStackSize;
+    loopStackSize = 0;
+
     /* 3 loop body */
     visit(node.getBody());
     
+    /* restore parent loop stack size */
+    loopStackSize = prevLoopSize;
+
     currBreakJumpToLabel = lastBreakJumpToLabel;
     currContinueJumpToLabel = lastContinueJumpToLabel;
 
@@ -863,51 +863,51 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
   @Override
   public Void visitForNode(ForNode node) {
     /* 1 translate the initiator of the for-loop */
+    currSymbolTable = node.getIncrement().getScope();
+    int stackSize = currSymbolTable.getSize();
+    decStack(stackSize);
+
     visit(node.getInit());
 
     /* 2 create labels and translate for for-loop body */
     Label bodyLabel = branchLabelGenerator.getLabel();
     Label condLabel = branchLabelGenerator.getLabel();
     Label nextLabel = branchLabelGenerator.getLabel();
+    Label incrementLabel = branchLabelGenerator.getLabel();
 
     /* restore the last jump-to label after visiting the for-loop body */
     Label lastBreakJumpToLabel = currBreakJumpToLabel;
     Label lastContinueJumpToLabel = currContinueJumpToLabel;
     currBreakJumpToLabel = nextLabel;
-    currContinueJumpToLabel = condLabel;
+    currContinueJumpToLabel = incrementLabel;
 
     instructions.add(new B(NULL, condLabel.getName()));
 
     instructions.add(bodyLabel);
     currForLoopSymbolTable = node.getBody().getScope();
+
+    /* record now much stack loop body have occupied */
+    int prevLoopSize = loopStackSize;
+    loopStackSize = 0;
+
     visit(node.getBody());
 
-    currBreakJumpToLabel = lastBreakJumpToLabel;
-    currContinueJumpToLabel = lastContinueJumpToLabel;
+    /* restore parent loop stack size */
+    loopStackSize = prevLoopSize;
     
-    /* here we also need to append the for-loop in crement at the end */
+    /* here we also need to append the for-loop increment at the end */
+    instructions.add(incrementLabel);
     visit(node.getIncrement());
 
+    currBreakJumpToLabel = lastBreakJumpToLabel;
+    currContinueJumpToLabel = lastContinueJumpToLabel;
+
     /* 3 add label for condition checking */
     instructions.add(condLabel);
-    currSymbolTable = node.getBody().getScope();
-    /* TODO: better code quality here */
-    int stackSize = currSymbolTable.getSize();
-    int temp = stackSize;
-    while (temp > 0) {
-      int realStackSize = temp / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : temp;
-      instructions.add(new Sub(SP, SP,
-          new Operand2(realStackSize)));
-      temp = temp - realStackSize;
-    }
+
+    currSymbolTable = node.getIncrement().getScope();
     visit(node.getCond());
-    temp = stackSize;
-    while (temp > 0) {
-      int realStackSize = temp / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : temp;
-      instructions.add(new Add(SP, SP,
-          new Operand2(realStackSize)));
-      temp = temp - realStackSize;
-    }
+
     currSymbolTable = currSymbolTable.getParentSymbolTable();
     instructions.add(new Cmp(armRegAllocator.curr(), new Operand2(TRUE)));
     armRegAllocator.free();
@@ -917,32 +917,24 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
     /* 5 add the label for the following instructions after for-loop */
     instructions.add(nextLabel);
     
+    /* loop varient's stack clearing should be after next label, 
+       so that BREAK can add back stack used by varients */
+    incStack(stackSize);
+
     return null;
   }
 
   @Override
   public Void visitJumpNode(JumpNode node) {
-    Instruction addStack = null;
+    List<Instruction> addStack = new ArrayList<>();
     /* this snippet is to deal with for-loop stack difference */
-    if (currForLoopSymbolTable != null && !node.getJumpContext().equals(JumpContext.SWITCH)) {
-      int stackSize = currForLoopSymbolTable.getSize();
-      int temp = stackSize;
-      while (temp > 0) {
-        int realStackSize = temp / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : temp;
-        addStack = new Add(SP, SP,
-            new Operand2(realStackSize));
-        temp = temp - realStackSize;
-      }
+    if (!node.getJumpType().equals(JumpType.BREAK) || !node.getJumpContext().equals(JumpContext.SWITCH)) {
+      incStack(loopStackSize);
     }
 
     if (node.getJumpType().equals(JumpType.BREAK)) {
-      if (addStack != null) instructions.add(addStack);
       instructions.add(new B(NULL, currBreakJumpToLabel.getName()));
     } else if (node.getJumpType().equals(JumpType.CONTINUE)) {
-      /* this snippet is to deal with the for-loop increment */
-      StatNode increment = node.getForIncrement();
-      if (increment != null) visit(increment);
-      if (addStack != null) instructions.add(addStack);
       instructions.add(new B(NULL, currContinueJumpToLabel.getName()));
     }
 
@@ -988,4 +980,22 @@ public class ARMInstructionGenerator implements NodeVisitor<Void> {
     return null;
   }
 
+  private void incStack(int stackSize) {
+    while (stackSize > 0) {
+      int realStackSize = stackSize / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : stackSize;
+      instructions.add(new Add(SP, SP,
+              new Operand2(realStackSize)));
+      stackSize = stackSize - realStackSize;
+    }
+  }
+
+  private void decStack(int stackSize) {
+    while (stackSize > 0) {
+      int realStackSize = stackSize / MAX_STACK_STEP >= 1 ? MAX_STACK_STEP : stackSize;
+      instructions.add(new Sub(SP, SP,
+              new Operand2(realStackSize)));
+      stackSize = stackSize - realStackSize;
+    }
+  }
+
 }

src/frontend/ASTPrinter.java

@@ -328,12 +328,13 @@ public class ASTPrinter implements NodeVisitor<Void> {
       /* body */
       leadingSpace += INDENT_SIZE;
       visit(node.getBody());
+      leadingSpace -= INDENT_SIZE;
 
+      appendLeadingSpace();
       System.out.print("while ");
       visit(node.getCond());
       System.out.println(" :");
 
-      leadingSpace -= INDENT_SIZE;
     } else {
       System.out.print("while ");
       visit(node.getCond());
@@ -384,10 +385,16 @@ public class ASTPrinter implements NodeVisitor<Void> {
     /* for 3 expressions : */
     appendLeadingSpace();
     System.out.print("for ");
+
+    leadingSpace += INDENT_SIZE;
     visit(node.getInit());
+    appendLeadingSpace();
     visit(node.getCond());
     visit(node.getIncrement());
-    System.out.println(" :");
+    leadingSpace -= INDENT_SIZE;
+
+    appendLeadingSpace();
+    System.out.println(":");
 
     /* body */
     leadingSpace += INDENT_SIZE;
@@ -406,15 +413,18 @@ public class ASTPrinter implements NodeVisitor<Void> {
   public Void visitSwitchNode(SwitchNode node) {
     /* switch statement */
     appendLeadingSpace();
-    System.out.println("switch ");
-    System.out.println(node.getExpr());
+    System.out.print("switch ");
+    visit(node.getExpr());
+    System.out.println();
 
     /* switch body */
     leadingSpace += INDENT_SIZE;
 
     for (CaseStat c : node.getCases()) {
-      System.out.println("case ");
+      appendLeadingSpace();
+      System.out.print("case ");
       visit(c.getExpr());
+      System.out.println();
 
       /* case body */
       leadingSpace += INDENT_SIZE;
@@ -422,9 +432,12 @@ public class ASTPrinter implements NodeVisitor<Void> {
       leadingSpace -= INDENT_SIZE;
     }
 
+    appendLeadingSpace();
+    System.out.println("default");
+    leadingSpace += INDENT_SIZE;
     visit(node.getDefault());
 
-    leadingSpace -= INDENT_SIZE;
+    leadingSpace -= 2 * INDENT_SIZE;
 
     return null;
   }

src/frontend/SemanticChecker.java

@@ -11,11 +11,7 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 import frontend.node.FuncNode;
 import frontend.node.Node;
@@ -30,7 +26,6 @@ import frontend.node.expr.BinopNode.Binop;
 import frontend.node.expr.UnopNode.Unop;
 
 import frontend.type.*;
-import java.util.Set;
 
 import org.antlr.v4.runtime.tree.TerminalNode;
 import org.antlr.v4.runtime.CharStream;
@@ -70,10 +65,13 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
   private boolean isMainFunction;
 
   /* used in determining whether branching statement is legal, i.e. break/continue is within a loop/switch */
-  private boolean isBreakAllowed;
-  private boolean isContinueAllowed;
-  private boolean isJumpRepeated;
-  private JumpContext jumpContext;
+  private Stack<Boolean> isBreakAllowed;
+  private Stack<Boolean> isContinueAllowed;
+  private Stack<Boolean> isJumpRepeated;
+  private Stack<JumpContext> jumpContext;
+  /* record the for-loop incrementer so that break and continue know what to do before jumping */
+  private Stack<StatNode> currForLoopIncrementBreak;
+  private Stack<StatNode> currForLoopIncrementContinue;
 
   /* used only in function declare step, to check function has the correct return type */
   private Type expectedFunctionReturn;
@@ -81,15 +79,11 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
   /* record whether a skipable semantic error is found in visiting to support checking of multiple errors */
   private boolean semanticError;
 
-  /* record the for-loop incrementer so that break and continue know what to do before jumping */
-  private StatNode currForLoopIncrementBreak;
-  private StatNode currForLoopIncrementContinue;
-
   /* record which file have already been included, IN the current import chain */
   private Set<String> libraryCollection;
 
   /* record all files that have been imported */
-  private Set<String> allImportCollection = new HashSet<>();
+  private static Set<String> allImportCollection = new HashSet<>();
 
   /* for function overload */
   private Set<String> overloadFuncNames = new HashSet<>();
@@ -101,13 +95,21 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
     globalStructTable = new HashMap<>();
     globalFuncTable = new HashMap<>();
     isMainFunction = false;
-    isBreakAllowed = false;
-    isContinueAllowed = false;
-    jumpContext = null;
-    isJumpRepeated = false;
+
+    isBreakAllowed = new Stack<>();
+    isBreakAllowed.push(false);
+
+    isContinueAllowed = new Stack<>();
+    isContinueAllowed.push(false);
+
+    jumpContext = new Stack<>();
+
+    isJumpRepeated = new Stack<>();
+    isJumpRepeated.push(false);
+
     expectedFunctionReturn = null;
-    currForLoopIncrementBreak = null;
-    currForLoopIncrementContinue = null;
+    currForLoopIncrementBreak = new Stack<>();
+    currForLoopIncrementContinue = new Stack<>();
     this.libraryCollection = libraryCollection;
   }
 
@@ -376,11 +378,11 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
     currSymbolTable = currSymbolTable.getParentSymbolTable();
 
     if (functionBody instanceof ScopeNode) {
-      ((ScopeNode) functionBody).setFuncBody();
+      ((ScopeNode) functionBody).setAvoidSubStack();
       return functionBody;
     }
     ScopeNode enclosedBody = new ScopeNode(functionBody);
-    enclosedBody.setFuncBody();
+    enclosedBody.setAvoidSubStack();
     return enclosedBody;
   }
 
@@ -412,19 +414,26 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
     semanticError |= typeCheck(ctx.expr(), BOOL_BASIC_TYPE, conditionType);
 
     /* both branch are permitted to have/not have jump */
-    boolean permitJump = isJumpRepeated;
+    boolean permitJump = isJumpRepeated.peek();
 
     /* create the StatNode for the if body and gegerate new child scope */
     currSymbolTable = new SymbolTable(currSymbolTable);
     StatNode ifBody = visit(ctx.stat(0)).asStatNode();
     currSymbolTable = currSymbolTable.getParentSymbolTable();
 
-    isJumpRepeated = permitJump;
+    /* restore permit/not permit jump */
+    isJumpRepeated.pop();
+    isJumpRepeated.push(permitJump);
+
     /* create the StatNode for the else body and generate new child scope */
     currSymbolTable = new SymbolTable(currSymbolTable);
     StatNode elseBody = visit(ctx.stat(1)).asStatNode();
     currSymbolTable = currSymbolTable.getParentSymbolTable();
 
+    /* restore permit/not permit jump */
+    isJumpRepeated.pop();
+    isJumpRepeated.push(permitJump);
+
     StatNode node = new IfNode(condition,
             ifBody instanceof ScopeNode ?
                     ifBody :
@@ -448,16 +457,20 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
     /* get the StatNode of the execution body of while loop */
     currSymbolTable = new SymbolTable(currSymbolTable);
 
-    boolean isNestedBreak = isBreakAllowed;
-    boolean isNestedContinue = isContinueAllowed;
-    isBreakAllowed = isContinueAllowed = true;
-    jumpContext = JumpContext.WHILE;
-    isJumpRepeated = false;
+    /* set context for WHILE */
+    isJumpRepeated.push(false);
+    isBreakAllowed.push(true);
+    isContinueAllowed.push(true);
+    jumpContext.push(JumpContext.WHILE);
+
     StatNode body = visit(ctx.stat()).asStatNode();
     currSymbolTable = currSymbolTable.getParentSymbolTable();
 
-    if (!isNestedBreak) isBreakAllowed = false;
-    if (!isNestedContinue) isContinueAllowed = false;
+    /* reset context to parent scope */
+    isJumpRepeated.pop();
+    isBreakAllowed.pop();
+    isContinueAllowed.pop();
+    jumpContext.pop();
 
     StatNode node = (body instanceof ScopeNode) ?
             new WhileNode(condition, body) :
@@ -476,9 +489,21 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
 
     /* get the StatNode of the execution body of while loop */
     currSymbolTable = new SymbolTable(currSymbolTable);
-    isBreakAllowed = isContinueAllowed = true;
+
+    /* set contexts for DOWHILE */
+    isJumpRepeated.push(false);
+    isBreakAllowed.push(true);
+    isContinueAllowed.push(true);
+    jumpContext.push(JumpContext.WHILE);
+
     StatNode body = visit(ctx.stat()).asStatNode();
-    isBreakAllowed = isContinueAllowed = false;
+
+    /* reset context to parent scope */
+    isJumpRepeated.pop();
+    isBreakAllowed.pop();
+    isContinueAllowed.pop();
+    jumpContext.pop();
+
     currSymbolTable = currSymbolTable.getParentSymbolTable();
 
     StatNode node = (body instanceof ScopeNode) ?
@@ -496,31 +521,38 @@ public class SemanticChecker extends WACCParserBaseVisitor<Node> {
     /* visit the initiator */
     StatNode init = visit(ctx.for_stat(0)).asStatNode();
     
-    /* isNestedBreak and isNestedContinue is used for nested/mixed loops/switch statements */
-    boolean isNestedBreak = isBreakAllowed;
-    boolean isNestedContinue = isContinueAllowed;
-    
     ExprNode cond = visit(ctx.expr()).asExprNode();
     StatNode increment = visit(ctx.for_stat(1)).asStatNode();
 
-    /* mark the point where break and continue are allowed to appear */
-    isBreakAllowed = isContinueAllowed = true;
-    /* record the for-loop increment so that when `continue` appear, it still processes the increment in the assembly */