cvs diff: Bug fix for SPARCs non-gc grades.

[Fergus Henderson]

Tyson Richard DOWD, you wrote:
> Estimated hours taken: 1.5
> 
> Bug fix for failed tests in non-gc grades on SPARCs.
> 
> Sliding register windows on the SPARC meant that registers were
> being clobbered by C function calls. This bug was foreshadowed
> by Tom, but I hadn't fixed it yet.
> 
> NB: This problem needs to be documented in out C coding standard, and
> possibly the user documentation somewhere.

The C coding standard isn't quite the right place to document it.
After all, it doesn't apply to all the C code we write, just the C code
that happens to be in the Mercury runtime.  The right place to document
memory allocation stuff is in heap.h, IMHO.  (We could put a pointer
to this documentation in the C coding standard, though.)

> library/std_util.m:
> 	- Change arg, expand and functor to save_transient_registers()
> 	  and restore_transient_registers before calling mercury_expand.
> 	- Change mercury_expand to use incr_saved_hp and
> 	  incr_saved_hp_atomic.

That change is fine, except you should mention in the documentation
for mercury_expand() that you need to call save_transient_registers()
and restore_transient_registers() before/after calling mercury_expand().

Please add that little bit of documentation and then commit this change.

Thanks,
	Fergus.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
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