Improve code generation for pdp11 target.

Improve code generation for pdp11 target.

	* config/pdp11/pdp11.c (pdp11_addr_cost): New function.
	(pdp11_insn_cost): New function.
	(pdp11_md_asm_adjust): New function.
	(TARGET_INVALID_WITHIN_DOLOOP): Define.
	(pdp11_rtx_costs): Update to match machine better.
	(output_addr_const_pdp11): Correct format mismatch warnings.
	* config/pdp11/pdp11.h (SLOW_BYTE_ACCESS): Correct definition.
	* config/pdp11/pdp11.md: General change to add base_cost and/or
	length attributes for use by new pdp11_insn_cost function.
	(MIN_BRANCH): Correct definition.
	(MIN_SOB): Ditto.
	(doloop_end): Use standard pattern name for looping pattern.
	(doloop_end_nocc): New.
	(movsf): Add another constraint alternative.
	(zero_extendqihi2): Add constraint alternatives for not in place
	extend.
	(zero_extendhisi2): Remove.
	(shift patterns): Add CC handling variants.
	(bswaphi2): New.
	(bswapsi2): New.
	(rothi3): New.
	(define_peephole2): New peephole to recognize mov that sets CC for
	subsequent test.

From-SVN: r262519