This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]

Re: robustness vs. conservative GC

On 15-Aug-2001, Joern Rennecke <> wrote:
> [someone, I think it was Hans Boehm, wrote:]
> > For one, you basically can no longer use callee-save registers or stacked
> > registers for pointers across procedure calls.  You need to spill everything
> It should be safe if the GC uses setjmp to get a copy of the calee-saved
> registers.

I don't understand what you're talking about here.  What should be safe? 

We were talking about doing (type-)accurate GC, not conservative GC.  With the
scheme for doing accurate GC that I was describing, the GC *doesn't need* to
use setjmp to get a copy of the callee-saved registers, since the back-end
will never store any pointers in callee-saved registers across calls.

If you have some other scheme for doing type-accurate GC, which uses setjmp
to get a copy of the callee-saved registers, then you'd need to explain it
in more detail -- I haven't the foggiest idea of what you have in mind.
But I doubt that any such scheme could work without a high degree
of back-end cooperation.

Fergus Henderson <>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <>  |     -- the last words of T. S. Garp.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]