On Wed, Apr 22, 2009 at 10:50 AM, Scott Blum <sco...@google.com> wrote:
> On Tue, Apr 21, 2009 at 8:01 PM, <codesite-nore...@google.com> wrote: > >> Don't read stack frames from the input, since they aren't required and are >> incorrect after rewriting > > > Stack frames are incorrect after rewriting? What's the deal with that? > Sorry, it should have been stack maps, not frames, which are used by the 1.6 verifier if present so it doesn't have to build up maps of what is on the stack at each bytecode offset. I was getting errors trying to analyze a rewritten class while trying to track down the IncompatibleClassChangeError in IHM, and javap would throw an exception trying to read beyond the end of the file while ASM would get an IndexOutOfBoundsException trying to parse the included frame data. Our rewriters do nothing to handle changing the stack maps as the code is changed, so they can be incorrect. After talking with Toby, the stack maps are optional, and doing the work at runtime to calculate them is almost certainly slower than just letting the old verifier compute them. If we were to allow our bytecode rewriting to take place outside of hosted mode startup, such as a separate build step, then it might make sense to recompute them. Until then, it is easier to just drop them. -- John A. Tamplin Software Engineer (GWT), Google --~--~---------~--~----~------------~-------~--~----~ http://groups.google.com/group/Google-Web-Toolkit-Contributors -~----------~----~----~----~------~----~------~--~---
