[PR100066] Check paradoxical subreg when splitting hard reg live range

[PR100066] Check paradoxical subreg when splitting hard reg live range

When splitting live range of a hard reg, LRA actually split multi-register
containing the hard reg.  So we need to check the biggest used mode of the hard reg on
paradoxical subregister when the natural and the biggest
mode are ordered.

gcc/ChangeLog:

	PR rtl-optimization/100066
	* lra-constraints.c (split_reg): Check paradoxical_subreg_p for
	ordered modes when choosing splitting mode for hard reg.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/100066
	* gcc.target/i386/pr100066.c: New.