This is the mail archive of the
java@gcc.gnu.org
mailing list for the Java project.
Re: gc problem?
- To: Bryce McKinlay <bryce at waitaki dot otago dot ac dot nz>
- Subject: Re: gc problem?
- From: Jeff Sturm <jsturm at one-point dot com>
- Date: Tue, 23 Oct 2001 23:58:08 -0400 (EDT)
- cc: "Boehm, Hans" <hans_boehm at hp dot com>, "'Anthony Green'" <green at redhat dot com>, "Java at Gcc dot Gnu. Org" <java at gcc dot gnu dot org>
On Wed, 24 Oct 2001, Bryce McKinlay wrote:
> >2) (Harder, may not ever happen.) Teach the compiler to generate descriptors
> >for the stack layout, and the collector to interpret them, so that we can
> >scan the stack (mostly) nonconservatively.
>
> Can't GCC do this already (ie DWARF2)? If that is good enough for the EH
> unwinder and GDB, wouldn't it have enough info for GC as well?
That's an interesting idea. My impression is that it would be a
significant undertaking since neither GCC unwind nor debug info are
sufficient (the former lacks type info, the latter isn't mapped to the
process image). It would require augmenting the unwind info or
introducing a completely new section. (Mapping the debug sections
probably isn't practical due to size.)
The real question is whether any potential gains are worth the effort. I
seldom see any extraordinary heap growth due to blacklisting from
interior pointers on real-world code, even on SPARC (which is somewhat of
a worst case given its sparse stack layout).
Jeff