[25/77] Use is_a <scalar_int_mode> for bitmask optimisations

[25/77] Use is_a <scalar_int_mode> for bitmask optimisations

Explicitly check for scalar_int_mode in code that maps arithmetic
to full-mode bit operations.  These operations wouldn't work correctly
for vector modes, for example.  In many cases this is enforced also by
checking whether an operand is CONST_INT_P, but there were other cases
where the condition is more indirect.

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

gcc/
	* combine.c (combine_simplify_rtx): Add checks for
	is_a <scalar_int_mode>.
	(simplify_if_then_else): Likewise.
	(make_field_assignment): Likewise.
	(simplify_comparison): Likewise.
	* ifcvt.c (noce_try_bitop): Likewise.
	* loop-invariant.c (canonicalize_address_mult): Likewise.
	* simplify-rtx.c (simplify_unary_operation_1): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r251477