[arm] early split most DImode comparison operations.

[arm] early split most DImode comparison operations.

This patch does most of the work for early splitting the DImode
comparisons.  We now handle EQ, NE, LT, GE, LTU and GEU during early
expansion, in addition to EQ and NE, for which the expansion has now
been reworked to use a standard conditional-compare pattern already in
the back-end.

To handle this we introduce two new condition flag modes that are used
when comparing the upper words of decomposed DImode values: one for
signed, and one for unsigned comparisons.  CC_Bmode (B for Borrow) is
essentially the inverse of CC_Cmode and is used when the carry flag is
set by a subtraction of unsigned values.

	* config/arm/arm-modes.def (CC_NV, CC_B): New CC modes.
	* config/arm/arm.c (arm_select_cc_mode): Recognize constructs that
	need these modes.
	(arm_gen_dicompare_reg): New code to early expand the sub-operations
	of EQ, NE, LT, GE, LTU and GEU.
	* config/arm/iterators.md (CC_EXTEND): New code attribute.
	* config/arm/predicates.md (arm_adcimm_operand): New predicate..
	* config/arm/arm.md (cmpsi3_carryin_<CC_EXTEND>out): New pattern.
	(cmpsi3_imm_carryin_<CC_EXTEND>out): Likewise.
	(cmpsi3_0_carryin_<CC_EXTEND>out): Likewise.

From-SVN: r277179