This patch makes SpiderMonkey respect resumption values returned by
Debugger onEnterFrame handler functions, as documented.
In Debugger, we change fireEnterFrame to collect a resumption value from
the hook, and change onEnterFrame and slowPathOnEnterFrame to propagate
them out. These now need an 'rval' argument, so that they can return forced
return values and exceptions.
ScriptDebugPrologue now accepts a JSTrapStatus from Debugger::onEnterFrame,
takes care of placing the return value or exception where it belongs, and
returns a JSTrapStatus.
Calls to ScriptDebugPrologue now handle the JSTrapStatus:
- at the head of js::Interpret;
- in the JSOP_NEW/JSOP_CALL/JSOP_FUNCALL/JSOP_FUNAPPLY case;
- in stubs::ScriptDebugPrologue, which JM epilogues call; and
- in the REJOIN_THIS_PROTOTYPE case in js_InternalInterpret (you must add a
JS_GC call to ic::GetPropNoCache for Debugger-onEnterFrame-resumption-05.js to
hit this reliably).
We also rearrange the js_InternalThrow JSTrapStatus-handling switch statement to
have an explicit default case that raises a JS_NOT_REACHED assertion, instead of
just omitting JSTRAP_CONTINUE.
Explanation in the comments.
Fixing bug 699196 properly entails replacing the assertion this patch adds
with real code to call ScriptDebugPrologue. If this patch lands, hopefully
the person fixing 669196 will notice that and write tests that reach the
assertion/new code, but just to make sure we should probably add a note to
that bug about it.
At the moment, ScriptDebugPrologue is called (conditionally) from within
ScriptPrologue. For onEnterFrame handlers to be able to return a resumption
value, we need ScriptDebugPrologue to return a JSTrapStatus value, but it
is (non-debug) ScriptPrologue's callers that would need to handle those
values.
It seems strange to have ScriptPrologue return a JSTrapStatus. So this
patch brings ScriptDebugPrologue out of ScriptPrologue (and
ScriptPrologueOrGeneratorResume), and has ScriptPrologue's callers call
ScriptDebugPrologue explicitly.
For symmetry, we do the same with ScriptEpilogue,
ScriptEpilogueOrGeneratorYield, and ScriptDebugEpilogue.
Actually adding and processing the JSTrapStatus values comes in a later
patch. This is just meant to be a behavior-preserving rearrangement.
