This is the mail archive of the
mailing list for the GCC project.
Re: Build failure with 3.1 CVS on sparc-sun-solaris2.8
- From: Jeff Sturm <jsturm at one-point dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 7 Feb 2002 13:01:38 -0500 (EST)
- Subject: Re: Build failure with 3.1 CVS on sparc-sun-solaris2.8
On Thu, 7 Feb 2002, Jakub Jelinek wrote:
> > To satisfy my curiosity, does anybody know why v9 has a stack bias?
> Sparc load/store instruction addresses are either reg + reg or reg + 13 bit
> signed immediate. This is +-4KB. In most functions, the region accessed
> above frame pointer is quite small (function arguments) while below it is
> much larger. So, the stack bias makes these areas 2KB above and 6KB below.
I see. Thanks for the enlightenment.
> Register windows aren't brain damaged as you think, it means that typical
> programs pass all arguments/return values in registers all the time without
> need for their saving.
Yes, that's the theory. I suppose it depends on the code whether that
savings is offset by the overhead of overflow/underflow trap handlers. In
particular, deep recursion must be bad on sparc.
And sparc stack frames are large and sloppy, creating a nuisance for
conservative garbage collectors e.g. the Boehm GC used by gcj.