ftst is always available and faster than fldz+fucom.

The ftst from the other branch cannot be commutative (it only has 1 operand).

(This avoids effects where compilation fails because of an unused
 stackpointer)

We regard them as "constraints" now, so the existing code inserts splits
for these nodes. This simplifies the code as we don't have to check for
already existing Permutations anymore.

Add a phase before coloring thats split all live variables before each instruction that defines a paired value.

- The direct call did not respect the get_opt_constant_folding() flag

the ident module shouldn't have name-mangling policies builtin.

Mangling logic should not be in the ident module, frontends should provide it
(there's also the compilerlib interface for it)

We have to perform the stackframe-type alignment adjustments before we
set the immediates of the Save instruction are adjusted.

(otherwise CSE merges temporary Phi nodes without inputs)

One of the green things on plants is a 'leaf'.
A 'leave', would be a vacation.

For the plural of 'leaf', 'leaves' is more common,
but 'leafs' is also correct and more regular.

This fixes the case where the stackframe size is not a multiple of the
alignment.