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Re: scheduling cc0


On Wednesday 02 February 2005 12:14, Miles Bader wrote:
> > The "recommended practice" of today is to use a fake hard register for
> > the CC reg, always, instead of cc0.
> > See e.g. "http://gcc.gnu.org/wiki/general backend cleanup", under
> > "Convert md files that use CC0 so they don't anymore."
>
> Hmmm, so that's basically the same method, but defined by the backend.
> Does this mean that any instruction that affects the cpu-flags (e.g.,
> addition) on such a processor has a (clobber (reg:SI CPU_FLAGS)) added to
> it?

A clobber, or it is set to something.  See FLAGS_REG in i386.md for an
example of how this can work (not a very pretty example, but hey! ;-)

> Doesn't this present the same problem with reload?

No.  Many targets work this way.

Gr.
Steven


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