libgcc: strange optimization

[Ian Lance Taylor]

Richard Guenther <richard.guenther@gmail.com> writes:

> Or go one step further and deprecate local register variables alltogether
> (they IMHO don't make much sense, and rather the targets should provide
> a way to properly constrain asm inputs and outputs).

No, local register variables are documented as working and many programs
rely on them.  They are a straightforward way to get an asm argument in
a specific register, and I don't see any reason to break that.

> I suggest to amend the documentation for local call-clobbered register
> variables to say that the only valid sequence using them is from a
> non-inlinable function that contains only direct initializations of the
> register variables from constants or parameters.

Let's just implement those requirements in the compiler itself.

Ian