Generation support for CLOBBER_HIGH

Generation support for CLOBBER_HIGH

Ensure clobber high is a register expression.
Info is passed through for the error case.

gcc/
	* emit-rtl.c (verify_rtx_sharing): Check for CLOBBER_HIGH.
	(copy_insn_1): Likewise.
	(gen_hard_reg_clobber_high): New gen function.
	* genconfig.c (walk_insn_part): Check for CLOBBER_HIGH.
	* genemit.c (gen_exp): Likewise.
	(gen_emit_seq): Pass through info.
	(gen_insn): Check for CLOBBER_HIGH.
	(gen_expand): Pass through info.
	(gen_split): Likewise.
	(output_add_clobbers): Likewise.
	* genrecog.c (validate_pattern): Check for CLOBBER_HIGH.
	(remove_clobbers): Likewise.
	* rtl.h (gen_hard_reg_clobber_high): New declaration.

From-SVN: r263327