[27/77] Use is_a <scalar_int_mode> before LOAD_EXTEND_OP

[27/77] Use is_a <scalar_int_mode> before LOAD_EXTEND_OP

This patch adds is_a <scalar_int_mode> checks before load_extend_op/
LOAD_EXTEND_OP calls, if that becomes useful for later patches.
(load_extend_op will return UNKNOWN for any other type of mode.)

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* cse.c (cse_insn): Add is_a <scalar_int_mode> checks.
	* reload.c (push_reload): Likewise.
	(find_reloads): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r251479