mirror of
https://github.com/mozilla/gecko-dev.git
synced 2025-02-04 13:07:52 +00:00
The code to deal with caught Java exceptions and transfer control to script finally/catch is transfered to CATCH bytecode which is now always added to the and of script bytecode. In this way if Context.observeInstructionCount throws an exception, a proper cleanup to restore Interpreter runtime will still be carried out. It also allowed to transfer control directly to catch/finally code when script call throw instead of throwing Java exception just to capture it immediately.
This special CATCH bytecode is a simple way to workaround lack of goto in Java which makes writing interpreters more complex then necessary...
This commit is contained in:
igor%mir2.org
parent
387b707f61
commit
0ca2f9239b
@ -189,6 +189,10 @@ public class Interpreter {
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if (itsData.itsFunctionType == 0) {
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theICodeTop = addByte(END_ICODE, theICodeTop);
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}
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// Add special CATCH to simplify Interpreter.interpret logic
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// and workaround lack of goto in Java
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theICodeTop = addByte(TokenStream.CATCH, theICodeTop);
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itsData.itsICodeTop = theICodeTop;
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if (itsData.itsICode.length != theICodeTop) {
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@ -869,7 +873,6 @@ public class Interpreter {
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if (child == catchTarget) {
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int catchOffset = iCodeTop - tryStart;
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recordJumpOffset(tryStart + 1, catchOffset);
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iCodeTop = addByte(TokenStream.CATCH, iCodeTop);
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}
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iCodeTop = generateICode(child, iCodeTop);
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lastChild = child;
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@ -1660,6 +1663,9 @@ public class Interpreter {
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}
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Object result = undefined;
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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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byte[] iCode = idata.itsICode;
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String[] strings = idata.itsStringTable;
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@ -1674,13 +1680,14 @@ public class Interpreter {
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// other functions
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final int INVOCATION_COST = 100;
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Loop: while (true) {
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Loop: for (;;) {
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try {
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switch (iCode[pc] & 0xff) {
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// Back indent to ease imlementation reading
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case TokenStream.ENDTRY :
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tryStackTop--;
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stack[TRY_STACK_SHFT + tryStackTop] = null;
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break;
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case TokenStream.TRY :
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stack[TRY_STACK_SHFT + tryStackTop] = scope;
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@ -1690,28 +1697,123 @@ public class Interpreter {
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pc += 4;
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break;
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case TokenStream.CATCH: {
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Throwable ex = (Throwable)stack[stackTop];
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Object catchObj;
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for (;;) {
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if (ex instanceof JavaScriptException) {
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catchObj = ScriptRuntime.unwrapJavaScriptException(
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(JavaScriptException)ex);
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} else if (ex instanceof EcmaError) {
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// an offical ECMA error object,
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catchObj = ((EcmaError)ex).getErrorObject();
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} else if (ex instanceof WrappedException) {
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WrappedException wex = (WrappedException)ex;
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ex = wex.getWrappedException();
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continue;
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} else {
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// catch can not be called with any other exceptions
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Context.codeBug();
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catchObj = null;
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// See comments in generateICodeFromTree: the following code should
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// be executed inside try/catch inside main loop, not in the loop catch
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// block itself
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if (javaException == null) Context.codeBug();
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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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final int SCRIPT_CAN_CATCH = 0, ONLY_FINALLY = 1, OTHER = 2;
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int exType;
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for (;;) {
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if (javaException instanceof JavaScriptException) {
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exType = SCRIPT_CAN_CATCH;
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} else if (javaException instanceof EcmaError) {
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// an offical ECMA error object,
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exType = SCRIPT_CAN_CATCH;
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} else if (javaException instanceof WrappedException) {
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WrappedException wex = (WrappedException)javaException;
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javaException = wex.getWrappedException();
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continue;
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} else if (javaException instanceof RuntimeException) {
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exType = ONLY_FINALLY;
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} else {
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// Error instance
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exType = OTHER;
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}
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break;
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}
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if (exType != OTHER) {
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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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int pcTry = (int)sDbl[TRY_STACK_SHFT + tryStackTop];
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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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int catch_offset = getShort(iCode, pcTry + 1);
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if (catch_offset != 0) {
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// Has catch block
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doCatch = true;
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pcNew = pcTry + catch_offset;
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}
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}
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if (pcNew < 0) {
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int finally_offset = getShort(iCode, pcTry + 3);
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if (finally_offset != 0) {
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// has finally block
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pcNew = pcTry + finally_offset;
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}
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}
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}
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break;
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}
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stack[stackTop] = catchObj;
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break;
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if (debuggerFrame != null && !(javaException instanceof Error)) {
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debuggerFrame.onExceptionThrown(cx, javaException);
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}
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if (pcNew < 0) {
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break Loop;
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}
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// We caught an exception,
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// restore scope at try point
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scope = (Scriptable)stack[TRY_STACK_SHFT + tryStackTop];
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stack[TRY_STACK_SHFT + tryStackTop] = null;
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// make stack to contain single exception object
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stackTop = STACK_SHFT;
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if (doCatch) {
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stack[stackTop] = ScriptRuntime.getCatchObject(cx, scope,
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javaException);
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} else {
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stack[stackTop] = javaException;
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}
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// clear exception
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javaException = null;
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// Notify instruction observer if necessary
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// and point pc and pcPrevBranch to start of catch/finally block
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if (instructionThreshold != 0) {
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if (instructionCount > instructionThreshold) {
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// Note: this can throw Error
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cx.observeInstructionCount(instructionCount);
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instructionCount = 0;
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}
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}
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pcPrevBranch = pc = pcNew;
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continue Loop;
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}
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case TokenStream.THROW:
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case TokenStream.JTHROW: {
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if ((iCode[pc] & 0xff) == TokenStream.THROW) {
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Object value = stack[stackTop];
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if (value == DBL_MRK) value = doubleWrap(sDbl[stackTop]);
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javaException = new JavaScriptException(value);
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} else {
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// No need to check for DBL_MRK: stack[stackTop] must be Throwable
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javaException = (Throwable)stack[stackTop];
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}
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--stackTop;
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if (instructionThreshold != 0) {
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instructionCount += pc + 1 - pcPrevBranch;
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if (instructionCount > instructionThreshold) {
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cx.observeInstructionCount(instructionCount);
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instructionCount = 0;
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}
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}
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pcPrevBranch = pc = getJavaCatchPC(iCode);
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continue Loop;
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}
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case TokenStream.GE : {
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--stackTop;
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@ -1836,7 +1938,7 @@ public class Interpreter {
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}
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}
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pcPrevBranch = pc = getTarget(iCode, pc + 1);
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continue;
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continue Loop;
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}
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pc += 2;
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break;
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@ -1860,7 +1962,7 @@ public class Interpreter {
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}
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}
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pcPrevBranch = pc = getTarget(iCode, pc + 1);
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continue;
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continue Loop;
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}
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pc += 2;
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break;
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@ -1874,7 +1976,7 @@ public class Interpreter {
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}
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}
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pcPrevBranch = pc = getTarget(iCode, pc + 1);
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continue;
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continue Loop;
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case TokenStream.GOSUB :
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sDbl[++stackTop] = pc + 3;
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if (instructionThreshold != 0) {
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@ -1884,7 +1986,7 @@ public class Interpreter {
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instructionCount = 0;
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}
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}
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pcPrevBranch = pc = getTarget(iCode, pc + 1); continue;
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pcPrevBranch = pc = getTarget(iCode, pc + 1); continue Loop;
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case TokenStream.RETSUB : {
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int slot = (iCode[pc + 1] & 0xFF);
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if (instructionThreshold != 0) {
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@ -1895,9 +1997,10 @@ public class Interpreter {
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}
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}
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pcPrevBranch = pc = (int)sDbl[LOCAL_SHFT + slot];
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continue;
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continue Loop;
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}
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case TokenStream.POP :
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stack[stackTop] = null;
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stackTop--;
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break;
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case TokenStream.DUP :
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@ -1908,6 +2011,7 @@ public class Interpreter {
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case TokenStream.POPV :
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result = stack[stackTop];
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if (result == DBL_MRK) result = doubleWrap(sDbl[stackTop]);
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stack[stackTop] = null;
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--stackTop;
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break;
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case TokenStream.RETURN :
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@ -2399,19 +2503,6 @@ public class Interpreter {
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case TokenStream.UNDEFINED :
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stack[++stackTop] = Undefined.instance;
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break;
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case TokenStream.THROW : {
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Object exception = stack[stackTop];
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if (exception == DBL_MRK) exception = doubleWrap(sDbl[stackTop]);
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--stackTop;
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throw new JavaScriptException(exception);
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}
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case TokenStream.JTHROW : {
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// No need to check for DBL_MRK: stack[stackTop] must be Throwable
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Throwable ex = (Throwable)stack[stackTop];
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--stackTop;
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throwJavaOrJSException(ex);
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break; // unreachable
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}
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case TokenStream.ENTERWITH : {
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Object lhs = stack[stackTop];
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if (lhs == DBL_MRK) lhs = doubleWrap(sDbl[stackTop]);
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@ -2526,92 +2617,18 @@ public class Interpreter {
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}
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}
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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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for (;;) {
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if (ex instanceof JavaScriptException) {
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exType = SCRIPT_CAN_CATCH;
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} else if (ex instanceof EcmaError) {
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// an offical ECMA error object,
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exType = SCRIPT_CAN_CATCH;
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} else if (ex instanceof WrappedException) {
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WrappedException wex = (WrappedException)ex;
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ex = wex.getWrappedException();
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continue;
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} else if (ex instanceof RuntimeException) {
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exType = ONLY_FINALLY;
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} else {
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// Error instance
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exType = OTHER;
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}
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break;
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}
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if (exType != OTHER && debuggerFrame != null) {
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debuggerFrame.onExceptionThrown(cx, ex);
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}
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boolean rethrow = true;
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if (exType != OTHER && tryStackTop > 0) {
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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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--tryStackTop;
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int try_pc = (int)sDbl[TRY_STACK_SHFT + tryStackTop];
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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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int catch_offset = getShort(iCode, try_pc + 1);
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if (catch_offset != 0) {
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// Has catch block
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rethrow = false;
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pc = try_pc + catch_offset;
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stackTop = STACK_SHFT;
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stack[stackTop] = ex;
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}
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}
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if (rethrow) {
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int finally_offset = getShort(iCode, try_pc + 3);
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if (finally_offset != 0) {
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// has finally block
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rethrow = false;
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pc = try_pc + finally_offset;
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stackTop = STACK_SHFT;
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stack[stackTop] = ex;
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}
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}
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}
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if (rethrow) {
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if (debuggerFrame != null) {
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debuggerFrame.onExit(cx, true, ex);
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}
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if (idata.itsNeedsActivation) {
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ScriptRuntime.popActivation(cx);
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}
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throwJavaOrJSException(ex);
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}
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// We caught an exception,
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// Notify instruction observer if necessary
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// and point pcPrevBranch to start of catch/finally block
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if (instructionThreshold != 0) {
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if (instructionCount > instructionThreshold) {
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// Note: this can throw Error
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cx.observeInstructionCount(instructionCount);
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instructionCount = 0;
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}
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}
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pcPrevBranch = pc;
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// restore scope at try point
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scope = (Scriptable)stack[TRY_STACK_SHFT + tryStackTop];
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pc = getJavaCatchPC(iCode);
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javaException = ex;
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continue Loop;
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}
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}
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if (debuggerFrame != null) {
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debuggerFrame.onExit(cx, false, result);
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if (javaException != null) {
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debuggerFrame.onExit(cx, true, javaException);
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} else {
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debuggerFrame.onExit(cx, false, result);
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}
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}
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if (idata.itsNeedsActivation) {
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ScriptRuntime.popActivation(cx);
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@ -2624,6 +2641,17 @@ public class Interpreter {
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}
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cx.instructionCount = instructionCount;
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}
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if (javaException != null) {
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if (javaException instanceof JavaScriptException) {
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throw (JavaScriptException)javaException;
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} else if (javaException instanceof RuntimeException) {
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throw (RuntimeException)javaException;
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} else {
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// Must be instance of Error or code bug
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throw (Error)javaException;
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}
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}
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return result;
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}
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@ -2911,25 +2939,18 @@ public class Interpreter {
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try {
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return cx.getSecurityController().
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execWithDomain(cx, scope, code, idata.securityDomain);
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}finally {
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} finally {
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cx.interpreterSecurityDomain = savedDomain;
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}
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}
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private static void throwJavaOrJSException(Throwable ex)
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throws JavaScriptException
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private static int getJavaCatchPC(byte[] iCode)
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{
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if (ex instanceof JavaScriptException) {
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throw (JavaScriptException)ex;
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} else if (ex instanceof RuntimeException) {
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throw (RuntimeException)ex;
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} else {
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// Must be instance of Error or code bug
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throw (Error)ex;
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}
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int pc = iCode.length - 1;
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if ((iCode[pc] & 0xFF) != TokenStream.CATCH) Context.codeBug();
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return pc;
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}
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private boolean itsInFunctionFlag;
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private InterpreterData itsData;
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@ -2943,7 +2964,6 @@ 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 version;
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private boolean inLineStepMode;
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private String debugSource;
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