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Work in progress on http://bugzilla.mozilla.org/show_bug.cgi?id=213231 :
Replacing try stack by static table of exception handlers
This commit is contained in:
igor%mir2.org
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7625f8b519
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@ -58,12 +58,11 @@ public class Interpreter {
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RETURN_UNDEF_ICODE = TokenStream.LAST_TOKEN + 5,
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// Exception handling implementation
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ENDTRY = TokenStream.LAST_TOKEN + 6,
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GOSUB = TokenStream.LAST_TOKEN + 7,
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RETSUB = TokenStream.LAST_TOKEN + 8,
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GOSUB = TokenStream.LAST_TOKEN + 6,
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RETSUB = TokenStream.LAST_TOKEN + 7,
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// Last icode
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END_ICODE = TokenStream.LAST_TOKEN + 9;
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END_ICODE = TokenStream.LAST_TOKEN + 8;
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public IRFactory createIRFactory(Context cx, TokenStream ts)
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@ -227,13 +226,20 @@ public class Interpreter {
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itsDoubleTableTop);
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itsData.itsDoubleTable = tmp;
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}
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if (itsExceptionTableTop != 0
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&& itsData.itsExceptionTable.length != itsExceptionTableTop)
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{
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int[] tmp = new int[itsExceptionTableTop];
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System.arraycopy(itsData.itsExceptionTable, 0, tmp, 0,
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itsExceptionTableTop);
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itsData.itsExceptionTable = tmp;
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}
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itsData.itsMaxVars = scriptOrFn.getParamAndVarCount();
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// itsMaxFrameArray: interpret method needs this amount for its
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// stack and sDbl arrays
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itsData.itsMaxFrameArray = itsData.itsMaxVars
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+ itsData.itsMaxLocals
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+ itsData.itsMaxTryDepth
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+ itsData.itsMaxStack;
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itsData.argNames = scriptOrFn.getParamAndVarNames();
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@ -502,12 +508,6 @@ public class Interpreter {
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case TokenStream.JSR : {
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Node target = (Node)(node.getProp(Node.TARGET_PROP));
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// Bug 115717 is due to adding a GOSUB here before
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// we insert an ENDTRY. I'm not sure of the best way
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// to fix this; perhaps we need to maintain a stack
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// of pending trys and have some knowledge of how
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// many trys we need to close when we perform a
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// GOTO or GOSUB.
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iCodeTop = addGoto(target, GOSUB, iCodeTop);
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break;
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}
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@ -829,9 +829,6 @@ public class Interpreter {
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break;
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case TokenStream.TRY : {
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itsTryDepth++;
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if (itsTryDepth > itsData.itsMaxTryDepth)
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itsData.itsMaxTryDepth = itsTryDepth;
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Node catchTarget = (Node)node.getProp(Node.TARGET_PROP);
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Node finallyTarget = (Node)node.getProp(Node.FINALLY_PROP);
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@ -841,30 +838,17 @@ public class Interpreter {
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iCodeTop = addShort(0, iCodeTop); // placeholder for finally pc
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iCodeTop = addIndex(itsWithDepth, iCodeTop);
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boolean insertedEndTry = false;
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int tryEnd = -1;
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while (child != null) {
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/*
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When the following child is the catchTarget
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(or the finallyTarget if there are no catches),
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the current child is the goto at the end of
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the try statemets, we need to emit the endtry
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before that goto.
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*/
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Node nextSibling = child.getNext();
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if (!insertedEndTry && nextSibling != null &&
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(nextSibling == catchTarget ||
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nextSibling == finallyTarget))
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{
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iCodeTop = addByte(ENDTRY, iCodeTop);
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insertedEndTry = true;
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}
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boolean generated = false;
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if (child == catchTarget) {
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if (child.getType() != TokenStream.TARGET)
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Context.codeBug();
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if (tryEnd >= 0) Context.codeBug();
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tryEnd = iCodeTop;
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int catchOffset = iCodeTop - tryStart;
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recordJumpOffset(tryStart + 1, catchOffset);
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@ -875,11 +859,15 @@ public class Interpreter {
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itsStackDepth = 1;
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if (itsStackDepth > itsData.itsMaxStack)
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itsData.itsMaxStack = itsStackDepth;
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}
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if (child == finallyTarget) {
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} else if (child == finallyTarget) {
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if (child.getType() != TokenStream.TARGET)
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Context.codeBug();
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if (tryEnd < 0) {
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tryEnd = iCodeTop;
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}
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int finallyOffset = iCodeTop - tryStart;
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recordJumpOffset(tryStart + 3, finallyOffset);
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@ -899,10 +887,18 @@ public class Interpreter {
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if (!generated) {
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iCodeTop = generateICode(child, iCodeTop);
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}
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child = nextSibling;
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child = child.getNext();
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}
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itsStackDepth = 0;
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itsTryDepth--;
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// [tryStart, tryEnd) contains GOSUB to call finally when it
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// presents at the end of try code and before return, break
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// continue that transfer control outside try.
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// After finally is executed the control will be
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// transfered back into [tryStart, tryEnd) and exception
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// handling assumes that the only code executed after
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// finally returns will be a jump outside try which could not
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// trigger exceptions.
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addExceptionHandler(tryStart, tryEnd);
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break;
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}
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@ -1147,6 +1143,23 @@ public class Interpreter {
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return iCodeTop;
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}
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private void addExceptionHandler(int icodeStart, int icodeEnd)
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{
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int[] table = itsData.itsExceptionTable;
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if (table == null) {
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if (itsExceptionTableTop != 0) Context.codeBug();
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table = new int[EXCEPTION_SLOT_SIZE * 2];
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itsData.itsExceptionTable = table;
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} else if (table.length == itsExceptionTableTop) {
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table = new int[table.length * 2];
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System.arraycopy(itsData.itsExceptionTable, 0, table, 0,
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itsExceptionTableTop);
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itsData.itsExceptionTable = table;
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}
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table[itsExceptionTableTop++] = icodeStart;
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table[itsExceptionTableTop++] = icodeEnd;
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}
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private byte[] increaseICodeCapasity(int iCodeTop, int extraSize) {
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int capacity = itsData.itsICode.length;
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if (iCodeTop + extraSize <= capacity) Context.codeBug();
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@ -1178,6 +1191,27 @@ public class Interpreter {
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return pc - 1 + displacement;
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}
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private static int getExceptionHandler(int[] exceptionTable, int pc)
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{
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// OPT: use binary search
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if (exceptionTable == null) { return -1; }
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int best = -1, bestStart = 0, bestEnd = 0;
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for (int i = 0; i != exceptionTable.length; i += EXCEPTION_SLOT_SIZE) {
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int start = exceptionTable[i];
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int end = exceptionTable[i + 1];
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if (start <= pc && pc < end) {
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if (best < 0 || bestStart <= start) {
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// Check handlers are nested
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if (best >= 0 && bestEnd < end) Context.codeBug();
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best = i;
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bestStart = start;
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bestEnd = end;
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}
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}
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}
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return best;
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}
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static PrintWriter out;
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static {
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if (Context.printICode) {
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@ -1201,7 +1235,6 @@ public class Interpreter {
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case SHORTNUMBER_ICODE: return "shortnumber";
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case INTNUMBER_ICODE: return "intnumber";
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case RETURN_UNDEF_ICODE: return "return_undef";
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case ENDTRY: return "endtry";
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case GOSUB: return "gosub";
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case RETSUB: return "retsub";
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case END_ICODE: return "end";
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@ -1370,7 +1403,6 @@ public class Interpreter {
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case TokenStream.ENTERWITH :
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case TokenStream.LEAVEWITH :
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case TokenStream.RETURN :
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case ENDTRY :
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case TokenStream.CATCH:
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case TokenStream.THROW :
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case TokenStream.GETTHIS :
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@ -1578,16 +1610,13 @@ public class Interpreter {
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final int VAR_SHFT = 0;
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final int maxVars = idata.itsMaxVars;
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final int LOCAL_SHFT = VAR_SHFT + maxVars;
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final int TRY_STACK_SHFT = LOCAL_SHFT + idata.itsMaxLocals;
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final int STACK_SHFT = TRY_STACK_SHFT + idata.itsMaxTryDepth;
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final int STACK_SHFT = LOCAL_SHFT + idata.itsMaxLocals;
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// stack[VAR_SHFT <= i < LOCAL_SHFT]: variables
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// stack[LOCAL_SHFT <= i < TRY_STACK_SHFT]: used for newtemp/usetemp
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// stack[TRY_STACK_SHFT <= i < STACK_SHFT]: stack of try scopes
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// stack[STACK_SHFT <= i < STACK_SHFT + idata.itsMaxStack]: stack data
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// sDbl[TRY_STACK_SHFT <= i < STACK_SHFT]: stack of try block pc, stored as doubles
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// sDbl[any other i]: if stack[i] is DBL_MRK, sDbl[i] holds the number value
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// sDbl[i]: if stack[i] is DBL_MRK, sDbl[i] holds the number value
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int maxFrameArray = idata.itsMaxFrameArray;
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if (maxFrameArray != STACK_SHFT + idata.itsMaxStack)
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@ -1597,7 +1626,6 @@ public class Interpreter {
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double[] sDbl = new double[maxFrameArray];
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int stackTop = STACK_SHFT - 1;
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int tryStackTop = 0; // add TRY_STACK_SHFT to get real index
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int withDepth = 0;
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@ -1674,6 +1702,7 @@ public class Interpreter {
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// If javaException != null on exit, it will be throw instead of
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// normal return
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Throwable javaException = null;
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int exceptionPC = -1;
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byte[] iCode = idata.itsICode;
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String[] strings = idata.itsStringTable;
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@ -1693,12 +1722,7 @@ public class Interpreter {
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switch (iCode[pc] & 0xff) {
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// Back indent to ease imlementation reading
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case ENDTRY :
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tryStackTop--;
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break;
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case TokenStream.TRY :
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sDbl[TRY_STACK_SHFT + tryStackTop] = (double)pc;
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++tryStackTop;
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// Skip starting pc of catch/finally blocks and with depth
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pc += 6;
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break;
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@ -1711,11 +1735,10 @@ public class Interpreter {
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int pcTry = -1;
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int pcNew = -1;
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boolean doCatch = false;
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if (tryStackTop > 0) {
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// Decrease tryStackTop even if catch or finally would not
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// be processed to properly deal with exceptions thrown
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// by debuggerFrame.onExceptionThrown or cx.observeInstructionCount
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--tryStackTop;
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int handlerOffset = getExceptionHandler(idata.itsExceptionTable,
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exceptionPC);
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if (handlerOffset >= 0) {
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final int SCRIPT_CAN_CATCH = 0, ONLY_FINALLY = 1, OTHER = 2;
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int exType;
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@ -1737,7 +1760,7 @@ public class Interpreter {
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// Do not allow for JS to interfere with Error instances
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// (exType == OTHER), as they can be used to terminate
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// long running script
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pcTry = (int)sDbl[TRY_STACK_SHFT + tryStackTop];
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pcTry = idata.itsExceptionTable[handlerOffset];
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if (exType == SCRIPT_CAN_CATCH) {
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// Allow JS to catch only JavaScriptException and
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// EcmaError
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@ -1808,6 +1831,7 @@ public class Interpreter {
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--stackTop;
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javaException = new JavaScriptException(value);
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exceptionPC = pc;
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if (instructionThreshold != 0) {
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instructionCount += pc + 1 - pcPrevBranch;
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@ -2007,6 +2031,7 @@ public class Interpreter {
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if (value != DBL_MRK) {
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// Invocation from exception handler, restore object to rethrow
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javaException = (Throwable)value;
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exceptionPC = pc;
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newPC = getJavaCatchPC(iCode);
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} else {
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// Normal return from GOSUB
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@ -2635,8 +2660,9 @@ public class Interpreter {
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}
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}
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pc = getJavaCatchPC(iCode);
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javaException = ex;
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exceptionPC = pc;
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pc = getJavaCatchPC(iCode);
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continue Loop;
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}
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}
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@ -2973,7 +2999,6 @@ public class Interpreter {
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private InterpreterData itsData;
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private ScriptOrFnNode scriptOrFn;
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private int itsTryDepth = 0;
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private int itsStackDepth = 0;
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private int itsWithDepth = 0;
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private String itsSourceFile;
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@ -2983,6 +3008,9 @@ public class Interpreter {
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private ObjToIntMap itsStrings = new ObjToIntMap(20);
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private String lastAddString;
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private int itsExceptionTableTop = 0;
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private static final int EXCEPTION_SLOT_SIZE = 2;
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private int version;
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private boolean inLineStepMode;
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private String debugSource;
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@ -72,10 +72,11 @@ final class InterpreterData implements Serializable, DebuggableScript {
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byte[] itsICode;
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int itsICodeTop;
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int[] itsExceptionTable;
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int itsMaxVars;
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int itsMaxLocals;
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int itsMaxTryDepth;
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int itsMaxStack;
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int itsMaxFrameArray;
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