Handling ARMv8-M Security Extension's cmse_nonsecure_entry attribute

Handling ARMv8-M Security Extension's cmse_nonsecure_entry attribute

    gcc/ChangeLog:
    2016-12-02  Andre Vieira  <andre.simoesdiasvieira@arm.com>
	    Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config/arm/arm.c (arm_handle_cmse_nonsecure_entry): New.
	(arm_attribute_table): Added cmse_nonsecure_entry
	(arm_compute_func_type): Handle cmse_nonsecure_entry.
	(cmse_func_args_or_return_in_stack): New.
	(arm_handle_cmse_nonsecure_entry): New.
	* config/arm/arm.h (ARM_FT_CMSE_ENTRY): New macro define.
	(IS_CMSE_ENTRY): Likewise.
	* doc/extend.texi (ARM ARMv8-M Security Extensions): New attribute.

    gcc/testsuite/ChangeLog:
    2016-12-02  Andre Vieira  <andre.simoesdiasvieira@arm.com>
	    Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* gcc.target/arm/cmse/cmse-3.c: New.

Co-Authored-By: Thomas Preud'homme <thomas.preudhomme@arm.com>
From-SVN: r243188