예제 #1
0
static void
CloseLiveIterators(JSContext *cx, const InlineFrameIterator &frame)
{
    JSScript *script = frame.script();
    jsbytecode *pc = frame.pc();

    if (!script->hasTrynotes())
        return;

    JSTryNote *tn = script->trynotes()->vector;
    JSTryNote *tnEnd = tn + script->trynotes()->length;

    uint32 pcOffset = uint32(pc - script->main());
    for (; tn != tnEnd; ++tn) {
        if (pcOffset < tn->start)
            continue;
        if (pcOffset >= tn->start + tn->length)
            continue;

        if (tn->kind != JSTRY_ITER)
            continue;

        JS_ASSERT(JSOp(*(script->main() + tn->start + tn->length)) == JSOP_ENDITER);
        JS_ASSERT(tn->stackDepth > 0);

        uint32 localSlot = tn->stackDepth;
        CloseLiveIterator(cx, frame, localSlot);
    }
}
예제 #2
0
static jsbytecode *
FindExceptionHandler(JSContext *cx)
{
    StackFrame *fp = cx->fp();
    JSScript *script = fp->script();

    if (!script->hasTrynotes())
        return NULL;

  error:
    if (cx->isExceptionPending()) {
        for (TryNoteIter tni(cx->regs()); !tni.done(); ++tni) {
            JSTryNote *tn = *tni;

            UnwindScope(cx, tn->stackDepth);

            /*
             * Set pc to the first bytecode after the the try note to point
             * to the beginning of catch or finally or to [enditer] closing
             * the for-in loop.
             */
            jsbytecode *pc = script->main() + tn->start + tn->length;
            cx->regs().pc = pc;
            cx->regs().sp = fp->base() + tn->stackDepth;

            switch (tn->kind) {
                case JSTRY_CATCH:
                  JS_ASSERT(JSOp(*pc) == JSOP_ENTERBLOCK);

#if JS_HAS_GENERATORS
                  /* Catch cannot intercept the closing of a generator. */
                  if (JS_UNLIKELY(cx->getPendingException().isMagic(JS_GENERATOR_CLOSING)))
                      break;
#endif

                  /*
                   * Don't clear cx->throwing to save cx->exception from GC
                   * until it is pushed to the stack via [exception] in the
                   * catch block.
                   */
                  return pc;

                case JSTRY_FINALLY:
                  /*
                   * Push (true, exception) pair for finally to indicate that
                   * [retsub] should rethrow the exception.
                   */
                  cx->regs().sp[0].setBoolean(true);
                  cx->regs().sp[1] = cx->getPendingException();
                  cx->regs().sp += 2;
                  cx->clearPendingException();
                  return pc;

                case JSTRY_ITER:
                {
                  /*
                   * This is similar to JSOP_ENDITER in the interpreter loop,
                   * except the code now uses the stack slot normally used by
                   * JSOP_NEXTITER, namely regs.sp[-1] before the regs.sp -= 2
                   * adjustment and regs.sp[1] after, to save and restore the
                   * pending exception.
                   */
                  JS_ASSERT(JSOp(*pc) == JSOP_ENDITER);
                  bool ok = UnwindIteratorForException(cx, &cx->regs().sp[-1].toObject());
                  cx->regs().sp -= 1;
                  if (!ok)
                      goto error;
                }
            }
        }
    } else {
        UnwindForUncatchableException(cx, cx->regs());
    }

    return NULL;
}
예제 #3
0
static jsbytecode *
FindExceptionHandler(JSContext *cx)
{
    StackFrame *fp = cx->fp();
    JSScript *script = fp->script();

top:
    if (cx->isExceptionPending() && JSScript::isValidOffset(script->trynotesOffset)) {
        // The PC is updated before every stub call, so we can use it here.
        unsigned offset = cx->regs().pc - script->main();

        JSTryNoteArray *tnarray = script->trynotes();
        for (unsigned i = 0; i < tnarray->length; ++i) {
            JSTryNote *tn = &tnarray->vector[i];

            // The following if condition actually tests two separate conditions:
            //   (1) offset - tn->start >= tn->length
            //       means the PC is not in the range of this try note, so we
            //       should continue searching, after considering:
            //   (2) offset - tn->start == tn->length
            //       means the PC is at the first op of the exception handler
            //       for this try note. This happens when an exception is thrown
            //       during recording: the interpreter sets the PC to the handler
            //       and then exits. In this case, we are in fact at the right
            //       exception handler. 
            //      
            //       Hypothetically, the op we are at might have thrown an
            //       exception, in which case this would not be the right handler.
            //       But the first ops of exception handlers generated by our
            //       bytecode compiler cannot throw, so this is not possible.
            if (offset - tn->start > tn->length)
                continue;
            if (tn->stackDepth > cx->regs().sp - fp->base())
                continue;

            UnwindScope(cx, tn->stackDepth);

            jsbytecode *pc = script->main() + tn->start + tn->length;
            cx->regs().pc = pc;
            cx->regs().sp = fp->base() + tn->stackDepth;

            switch (tn->kind) {
                case JSTRY_CATCH:
                  JS_ASSERT(JSOp(*pc) == JSOP_ENTERBLOCK);

#if JS_HAS_GENERATORS
                  /* Catch cannot intercept the closing of a generator. */
                  if (JS_UNLIKELY(cx->getPendingException().isMagic(JS_GENERATOR_CLOSING)))
                      break;
#endif

                  /*
                   * Don't clear cx->throwing to save cx->exception from GC
                   * until it is pushed to the stack via [exception] in the
                   * catch block.
                   */
                  return pc;

                case JSTRY_FINALLY:
                  /*
                   * Push (true, exception) pair for finally to indicate that
                   * [retsub] should rethrow the exception.
                   */
                  cx->regs().sp[0].setBoolean(true);
                  cx->regs().sp[1] = cx->getPendingException();
                  cx->regs().sp += 2;
                  cx->clearPendingException();
                  return pc;

                case JSTRY_ITER:
                {
                  /*
                   * This is similar to JSOP_ENDITER in the interpreter loop,
                   * except the code now uses the stack slot normally used by
                   * JSOP_NEXTITER, namely regs.sp[-1] before the regs.sp -= 2
                   * adjustment and regs.sp[1] after, to save and restore the
                   * pending exception.
                   */
                  Value v = cx->getPendingException();
                  JS_ASSERT(JSOp(*pc) == JSOP_ENDITER);
                  cx->clearPendingException();
                  bool ok = !!js_CloseIterator(cx, &cx->regs().sp[-1].toObject());
                  cx->regs().sp -= 1;
                  if (!ok)
                      goto top;
                  cx->setPendingException(v);
                }
            }
        }
    }

    return NULL;
}