This patch generalises create_integer_operand so that it accepts
poly_int64s rather than HOST_WIDE_INTs.

2017-12-20  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* optabs.h (expand_operand): Add an int_value field.
	(create_expand_operand): Add an int_value parameter and use it
	to initialize the new expand_operand field.
	(create_integer_operand): Replace with a declaration of a function
	that accepts poly_int64s.  Move the implementation to...
	* optabs.c (create_integer_operand): ...here.
	(maybe_legitimize_operand): For EXPAND_INTEGER, check whether
	the mode preserves the value of int_value, instead of calling
	const_int_operand on the rtx.  Use gen_int_mode to generate
	the new rtx.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r255865