void
LiveSavedFrameCache::find(JSContext* cx, FrameIter& frameIter, MutableHandleSavedFrame frame) const
{
MOZ_ASSERT(initialized());
MOZ_ASSERT(!frameIter.done());
MOZ_ASSERT(frameIter.hasCachedSavedFrame());
Maybe<FramePtr> maybeFramePtr = getFramePtr(frameIter);
MOZ_ASSERT(maybeFramePtr.isSome());
FramePtr framePtr(*maybeFramePtr);
jsbytecode* pc = frameIter.pc();
size_t numberStillValid = 0;
frame.set(nullptr);
for (auto* p = frames->begin(); p < frames->end(); p++) {
numberStillValid++;
if (framePtr == p->framePtr && pc == p->pc) {
frame.set(p->savedFrame);
break;
}
}
if (!frame) {
frames->clear();
return;
}
MOZ_ASSERT(0 < numberStillValid && numberStillValid <= frames->length());
if (frame->compartment() != cx->compartment()) {
frame.set(nullptr);
numberStillValid--;
}
// Everything after the cached SavedFrame are stale younger frames we have
// since popped.
frames->shrinkBy(frames->length() - numberStillValid);
}
bool
SavedStacks::insertFrames(JSContext *cx, FrameIter &iter, MutableHandleSavedFrame frame,
unsigned maxFrameCount)
{
// In order to lookup a cached SavedFrame object, we need to have its parent
// SavedFrame, which means we need to walk the stack from oldest frame to
// youngest. However, FrameIter walks the stack from youngest frame to
// oldest. The solution is to append stack frames to a vector as we walk the
// stack with FrameIter, and then do a second pass through that vector in
// reverse order after the traversal has completed and get or create the
// SavedFrame objects at that time.
//
// To avoid making many copies of FrameIter (whose copy constructor is
// relatively slow), we save the subset of FrameIter's data that is relevant
// to our needs in a FrameState object, and maintain a vector of FrameState
// objects instead of a vector of FrameIter objects.
// Accumulate the vector of FrameState objects in |stackState|.
AutoFrameStateVector stackState(cx);
while (!iter.done()) {
AutoLocationValueRooter location(cx);
{
AutoCompartment ac(cx, iter.compartment());
if (!cx->compartment()->savedStacks().getLocation(cx, iter, &location))
return false;
}
{
FrameState frameState(iter);
frameState.location = location.get();
if (!stackState->append(frameState))
return false;
}
++iter;
if (maxFrameCount == 0) {
// If maxFrameCount is zero, then there's no limit on the number of
// frames.
continue;
} else if (maxFrameCount == 1) {
// Since we were only asked to save one frame, do not continue
// walking the stack and saving frame state.
break;
} else {
maxFrameCount--;
}
}
// Iterate through |stackState| in reverse order and get or create the
// actual SavedFrame instances.
RootedSavedFrame parentFrame(cx, nullptr);
for (size_t i = stackState->length(); i != 0; i--) {
SavedFrame::AutoLookupRooter lookup(cx,
stackState[i-1].location.source,
stackState[i-1].location.line,
stackState[i-1].location.column,
stackState[i-1].name,
parentFrame,
stackState[i-1].principals);
parentFrame.set(getOrCreateSavedFrame(cx, lookup));
if (!parentFrame)
return false;
}
frame.set(parentFrame);
return true;
}
bool
SavedStacks::insertFrames(JSContext *cx, FrameIter &iter, MutableHandleSavedFrame frame,
unsigned maxFrameCount)
{
if (iter.done()) {
frame.set(nullptr);
return true;
}
// Don't report the over-recursion error because if we are blowing the stack
// here, we already blew the stack in JS, reported it, and we are creating
// the saved stack for the over-recursion error object. We do this check
// here, rather than inside saveCurrentStack, because in some cases we will
// pass the check there, despite later failing the check here (for example,
// in js/src/jit-test/tests/saved-stacks/bug-1006876-too-much-recursion.js).
JS_CHECK_RECURSION_DONT_REPORT(cx, return false);
JSPrincipals* principals = iter.compartment()->principals;
RootedAtom name(cx, iter.isNonEvalFunctionFrame() ? iter.functionDisplayAtom() : nullptr);
// When we have a |JSScript| for this frame, use |getLocation| to get a
// potentially memoized location result and copy it into |location|. When we
// do not have a |JSScript| for this frame (asm.js frames), we take a slow
// path that doesn't employ memoization, and update |location|'s slots
// directly.
AutoLocationValueRooter location(cx);
if (iter.hasScript()) {
JSScript *script = iter.script();
jsbytecode *pc = iter.pc();
{
AutoCompartment ac(cx, iter.compartment());
if (!cx->compartment()->savedStacks().getLocation(cx, script, pc, &location))
return false;
}
} else {
const char *filename = iter.scriptFilename();
if (!filename)
filename = "";
location.get().source = Atomize(cx, filename, strlen(filename));
if (!location.get().source)
return false;
uint32_t column;
location.get().line = iter.computeLine(&column);
location.get().column = column;
}
RootedSavedFrame parentFrame(cx);
// If maxFrameCount is zero, then there's no limit on the number of frames.
if (maxFrameCount == 0) {
if (!insertFrames(cx, ++iter, &parentFrame, 0))
return false;
} else if (maxFrameCount == 1) {
// Since we were only asked to save one frame, the SavedFrame we're
// building here should have no parent, even if there are older frames
// on the stack.
parentFrame = nullptr;
} else {
if (!insertFrames(cx, ++iter, &parentFrame, maxFrameCount - 1))
return false;
}
SavedFrame::AutoLookupRooter lookup(cx,
location.get().source,
location.get().line,
location.get().column,
name,
parentFrame,
principals);
frame.set(getOrCreateSavedFrame(cx, lookup));
return frame.get() != nullptr;
}