ranger: Add support for float <-> float casts [PR120231]

ranger: Add support for float <-> float casts [PR120231]

I've noticed we don't even support say float -> double and other
scalar floating point to scalar floating point conversions in the
ranger, we just end up with VARYING for those.

The following patch attempts to fix that.
The reverse cast case uses float_binary_op_range_finish e.g. because
if the result isn't infinite, then the source couldn't be infinite
either even if the reverse fold_range would suggest that.
And special cases the case of guaranteed widening cast (where
we have assurance that all the source type values are exactly
representable in the destination type; using ieee_bits for that).

2025-06-04  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/120231
	* range-op-mixed.h (operator_cast::fold_range): Add overload
	with 3 {,const} frange & operands.  Change parameter names and
	add final override keywords for float <-> integer cast overloads.
	(operator_cast::op1_range): Likewise.
	* range-op-float.cc (operator_cast::fold_range): New overload
	with 3 {,const} frange & operands.
	(operator_cast::op1_range): Likewise.

	* gcc.dg/tree-ssa/pr120231-1.c: New test.