[ECOS] Question about compiling consideration(GNUPro, GCC for SPARC)? Thanks

[Andrew Lunn]

> Q4. In the ABI docs it says some registers are call-clobbered or
> call-preserved, what's the exact meaning of that?

clobbered is not a commonly used word in written English. The Jargon
file has a nice definition:

>From Jargon File (4.0.0/24 July 1996) [jargon]:

  clobber /vt./  To overwrite, usually unintentionally: "I
     walked off the end of the array and clobbered the stack."  Compare
     {mung}, {scribble}, {trash}, and {smash the stack}.


In the contest of the ABI, it means registers that are call-clobbered
can be overwritten inside a function call. So the caller should not
assume the register have the same value after a function call as
before.

If you want to use a Call-preserved registers inside a function, you
need to save it, and restore the value before the function exits.

     Andrew

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