[52/77] Use scalar_int_mode in extract/store_bit_field

After a certain point, extract_bit_field and store_bit_field
ensure that they're dealing with integer modes or BLKmode MEMs.
This patch uses scalar_int_mode and opt_scalar_int_mode for
those parts.

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

gcc/
	* expmed.c (store_bit_field_using_insv): Add op0_mode and
	value_mode arguments.  Use scalar_int_mode internally.
	(store_bit_field_1): Rename the new integer mode from imode
	to op0_mode and use it instead of GET_MODE (op0).  Update calls
	to store_split_bit_field, store_bit_field_using_insv and
	store_fixed_bit_field.
	(store_fixed_bit_field): Add op0_mode and value_mode arguments.
	Use scalar_int_mode internally.  Use a bit count rather than a mode
	when calculating the largest bit size for get_best_mode.
	Update calls to store_split_bit_field and store_fixed_bit_field_1.
	(store_fixed_bit_field_1): Add mode and value_mode arguments.
	Remove assertion that OP0 has a scalar integer mode.
	(store_split_bit_field): Add op0_mode and value_mode arguments.
	Update calls to extract_fixed_bit_field.
	(extract_bit_field_using_extv): Add an op0_mode argument.
	Use scalar_int_mode internally.
	(extract_bit_field_1): Rename the new integer mode from imode to
	op0_mode and use it instead of GET_MODE (op0).  Update calls to
	extract_split_bit_field, extract_bit_field_using_extv and
	extract_fixed_bit_field.
	(extract_fixed_bit_field): Add an op0_mode argument.  Update calls
	to extract_split_bit_field and extract_fixed_bit_field_1.
	(extract_fixed_bit_field_1): Add a mode argument.  Remove assertion
	that OP0 has a scalar integer mode.  Use as_a <scalar_int_mode>
	on the target mode.
	(extract_split_bit_field): Add an op0_mode argument.  Update call
	to extract_fixed_bit_field.

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

From-SVN: r251504