Garbage collect unused bit-flag org.eclipse.jdt.internal.compiler.codegen.BranchLabel.USED (eclipse-jdt#3408)

* Fixes eclipse-jdt#3407

Author: srikanth-sankaran

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ConditionalExpression.java

@@ -290,7 +290,6 @@ public void generateCode(
 
 		// Generate code for the condition
 		falseLabel = new BranchLabel(codeStream);
-		falseLabel.tagBits |= BranchLabel.USED;
 		this.condition.generateOptimizedBoolean(
 			currentScope,
 			codeStream,

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/DoStatement.java

@@ -172,7 +172,6 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 
 	// labels management
 	BranchLabel actionLabel = new BranchLabel(codeStream);
-	if (this.action != null) actionLabel.tagBits |= BranchLabel.USED;
 	actionLabel.place();
 	this.breakLabel.initialize(codeStream);
 	boolean hasContinueLabel = this.continueLabel != null;

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ForStatement.java

@@ -288,7 +288,6 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 
 		// label management
 		BranchLabel actionLabel = new BranchLabel(codeStream);
-		actionLabel.tagBits |= BranchLabel.USED;
 		BranchLabel conditionLabel = new BranchLabel(codeStream);
 		this.breakLabel.initialize(codeStream);
 		if (this.continueLabel == null || conditionInjectsBindings) {
@@ -305,7 +304,6 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 			if ((this.condition != null)
 				&& (this.condition.constant == Constant.NotAConstant)
 				&& !((this.action == null || this.action.isEmptyBlock()) && (this.increments == null))) {
-				conditionLabel.tagBits |= BranchLabel.USED;
 				int jumpPC = codeStream.position;
 				codeStream.goto_(conditionLabel);
 				codeStream.recordPositionsFrom(jumpPC, this.condition.sourceStart);

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/ForeachStatement.java

@@ -265,9 +265,7 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 		}
 		// label management
 		BranchLabel actionLabel = new BranchLabel(codeStream);
-		actionLabel.tagBits |= BranchLabel.USED;
 		BranchLabel conditionLabel = new BranchLabel(codeStream);
-		conditionLabel.tagBits |= BranchLabel.USED;
 		this.breakLabel.initialize(codeStream);
 		if (this.continueLabel == null) {
 			// generate the condition (swapped for optimizing)
@@ -290,7 +288,6 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 			codeStream.recordPositionsFrom(conditionPC, this.elementVariable.sourceStart);
 		} else {
 			this.continueLabel.initialize(codeStream);
-			this.continueLabel.tagBits |= BranchLabel.USED;
 			// jump over the actionBlock
 			codeStream.goto_(conditionLabel);
 		}

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/SwitchStatement.java

@@ -540,7 +540,6 @@ public String toString() {
 				String literal = this.labelExpressions[i].constant.stringValue();
 				stringCases[i] = new StringSwitchCase(literal.hashCode(), literal, sourceCaseLabels[i]);
 				hashCodeCaseLabels[i] = new CaseLabel(codeStream);
-				hashCodeCaseLabels[i].tagBits |= BranchLabel.USED;
 			}
 			Arrays.sort(stringCases);
 
@@ -563,13 +562,11 @@ public String toString() {
 			}
 
 			CaseLabel defaultCaseLabel = new CaseLabel(codeStream);
-			defaultCaseLabel.tagBits |= BranchLabel.USED;
 
 			// prepare the labels and constants
 			this.breakLabel.initialize(codeStream);
 
 			BranchLabel defaultBranchLabel = new BranchLabel(codeStream);
-			if (hasCases) defaultBranchLabel.tagBits |= BranchLabel.USED;
 			if (this.defaultCase != null) {
 				this.defaultCase.targetLabel = defaultBranchLabel;
 			}
@@ -649,10 +646,9 @@ private <T extends BranchLabel>T[] gatherLabels(CodeStream codeStream, T[] caseL
 			for (int k = 0; k < length; ++k) {
 				Expression e = peeledLabelExpressions[k];
 				if (e instanceof FakeDefaultLiteral) continue;
-				targetLabels[count++] = (caseLabels[j] = newLabel.apply(codeStream));
+				targetLabels[count++] = (caseLabels[j++] = newLabel.apply(codeStream));
 				if (e == this.totalPattern)
 					this.defaultCase = stmt;
-				caseLabels[j++].tagBits |= BranchLabel.USED;
 			}
 			System.arraycopy(targetLabels, 0, stmt.targetLabels = new BranchLabel[count], 0, count);
 		}
@@ -682,7 +678,6 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 
 			CaseLabel defaultLabel = new CaseLabel(codeStream);
 			final boolean hasCases = this.caseCount > 1 || (this.caseCount == 1 && this.defaultCase == null);
-			if (hasCases) defaultLabel.tagBits |= BranchLabel.USED;
 			if (this.defaultCase != null) {
 				this.defaultCase.targetLabel = defaultLabel;
 			}

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/WhileStatement.java

@@ -242,7 +242,6 @@ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
 		// generate the action
 		BranchLabel actionLabel = new BranchLabel(codeStream);
 		if (this.action != null) {
-			actionLabel.tagBits |= BranchLabel.USED;
 			// Required to fix 1PR0XVS: LFRE:WINNT - Compiler: variable table for method appears incorrect
 			if (this.condIfTrueInitStateIndex != -1) {
 				// insert all locals initialized inside the condition into the action generated prior to the condition

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/codegen/BranchLabel.java

@@ -30,8 +30,7 @@ public class BranchLabel extends Label {
 	public int tagBits;
 	protected int targetStackDepth = -1;
 	public final static int WIDE = 1;
-	public final static int USED = 2;
-	public final static int VALIDATE = 4;
+	public final static int VALIDATE = 2;
 	private OperandStack operandStack;
 
 
@@ -194,7 +193,6 @@ protected void trackStackDepth(boolean branch) {
 * Put down  a reference to the array at the location in the codestream.
 */
 void branch() {
-	this.tagBits |= BranchLabel.USED;
 	if (this.delegate != null) {
 		this.delegate.branch();
 		return;
@@ -217,7 +215,6 @@ void branch() {
 * No support for wide branches yet
 */
 void branchWide() {
-	this.tagBits |= BranchLabel.USED;
 	if (this.delegate != null) {
 		this.delegate.branchWide();
 		return;

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/codegen/CaseLabel.java

@@ -66,11 +66,7 @@ public boolean isStandardLabel(){
 */
 @Override
 public void place() {
-	if ((this.tagBits & USED) != 0) {
-		this.position = this.codeStream.getPosition();
-	} else {
-		this.position = this.codeStream.position;
-	}
+	this.position = this.codeStream.position;
 	if (this.instructionPosition != POS_NOT_SET) {
 		int offset = this.position - this.instructionPosition;
 		int[] forwardRefs = forwardReferences();

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/codegen/CodeStream.java

@@ -3690,9 +3690,6 @@ public static TypeBinding getConstantPoolDeclaringClass(Scope currentScope, Meth
 	}
 	return constantPoolDeclaringClass;
 }
-protected int getPosition() {
-	return this.position;
-}
 
 public void getClass(TypeBinding baseType) {
 	this.countLabels = 0;

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/codegen/ExceptionLabel.java

@@ -46,7 +46,7 @@ public int getCount() {
 public void place() {
 	// register the handler inside the codeStream then normal place
 	this.codeStream.registerExceptionHandler(this);
-	this.position = this.codeStream.getPosition();
+	this.position = this.codeStream.position;
 	this.codeStream.stackDepth = 1;
 }