re PR target/63910 (ICE: simplify_immed_subreg, at simplify-rtx.c:5519 with -mstringop-strategy=vector_loop -mavx512f)

	PR target/63910
	* simplify-rtx.c (simplify_immed_subreg): Return NULL for integer
	modes wider than MAX_BITSIZE_MODE_ANY_INT.  If not using
	CONST_WIDE_INT, make sure r fits into CONST_DOUBLE.

	* gcc.target/i386/pr63910.c: New test.

From-SVN: r217908