[Bug c/12284] Add feature of preserving processor state in functions written in C

["mkgnu at gmx dot net" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12284



------- Additional Comments From mkgnu at gmx dot net  2003-09-15 17:27 -------
I wasn't aware of this flag, Andrew.

Well, which register do I flag ? Suppose I have a big C function. I have no clue
which registers GCC will decide to use internally  as temporary placeholders
during the computations it does. I want to tell gcc to preserve whatever it will
use, not preserve a particular register. 

Should I run gcc with 6-7(or however many registers they are in an architecture;
well.. i also need to know which registers exist in an architecture)
-fcall-used-<register> arguments ? I need to be able to  specify this for only
one function, NOT the entire source file. Should I be splitting that function in
it's own file for the sake of running gcc against it with 6-7
-fcall-used-<register> arguments ?