[ARC] Consolidate PIC implementation.

[ARC] Consolidate PIC implementation.

This patch refactors a number of functions and compiler hooks into using a
single function which checks if a rtx is suited for pic or not. Removed
functions are arc_legitimate_pc_offset_p and arc_legitimate_pic_operand_p
beeing replaced by calls to arc_legitimate_pic_addr_p. Thus we have an
unitary way of checking a rtx beeing pic.

gcc/
2017-07-17  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc-protos.h (arc_legitimate_pc_offset_p): Remove
	proto.
	(arc_legitimate_pic_operand_p): Likewise.
	* config/arc/arc.c (arc_legitimate_pic_operand_p): Remove
	function.
	(arc_needs_pcl_p): Likewise.
	(arc_legitimate_pc_offset_p): Likewise.
	(arc_legitimate_pic_addr_p): Remove LABEL_REF case, as this
	function is also used in constrains.md.
	(arc_legitimate_constant_p): Use arc_legitimate_pic_addr_p to
	validate pic constants. Handle CONST_INT, CONST_DOUBLE, MINUS and
	PLUS.  Only return true/false in known cases, otherwise assert.
	(arc_legitimate_address_p): Remove arc_legitimate_pic_addr_p as it
	is already called in arc_legitimate_constant_p.
	* config/arc/arc.h (CONSTANT_ADDRESS_P): Consider also LABEL for
	pic addresses.
	(LEGITIMATE_PIC_OPERAND_P): Use
	arc_raw_symbolic_reference_mentioned_p function.
	* config/arc/constraints.md (Cpc): Use arc_legitimate_pic_addr_p
	function.
	(Cal): Likewise.
	(C32): Likewise.

gcc/testsuite
2017-07-17  Claudiu Zissulescu  <claziss@synopsys.com>

	* gcc.target/arc/pr9000674901.c: New file.
	* gcc.target/arc/pic-1.c: Likewise.
	* gcc.target/arc/pr9001191897.c: Likewise.

From-SVN: r250267