poly_int: symbolic_number

poly_int: symbolic_number

This patch changes symbol_number::bytepos from a HOST_WIDE_INT
to a poly_int64.  perform_symbolic_merge can cope with symbolic
offsets as long as the difference between the two offsets is
constant.  (This could happen for a constant-sized field that
occurs at a variable offset, for example.)

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

gcc/
	* gimple-ssa-store-merging.c (symbolic_number::bytepos): Change from
	HOST_WIDE_INT to poly_int64_pod.
	(perform_symbolic_merge): Update accordingly.
	(bswap_replace): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r255889