re PR target/16458 (PowerPC - redundant compare)

re PR target/16458 (PowerPC - redundant compare)

gcc/
	PR target/16458
	* rtlanal.c (unsigned_reg_p): New function.
	Update copyright notice dates.
	* rtl.h (unsigned_reg_p): Prototype it.
	Update copyright notice dates.
	* config/rs6000/rs6000.c (rs6000_generate_compare): Use it.
	Update comment.
	* expr.c (expand_expr_real_1): Set register attributes.
	* stmt.c (expand_case): Likewise.

gcc/testsuite/
	PR target/16458
	* gcc.target/powerpc/pr16458-1.c: New test.
	* gcc.target/powerpc/pr16458-2.c: Likewise.
	* gcc.target/powerpc/pr16458-3.c: Likewise.
	* gcc.target/powerpc/pr16458-4.c: Likewise.

Co-Authored-By: Michael Matz <matz@suse.de>
From-SVN: r186312