ARMv8-M Security Extension's cmse_nonsecure_entry: __acle_se label and bxns

ARMv8-M Security Extension's cmse_nonsecure_entry: __acle_se label and bxns
return

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

	* config/arm/arm.c (use_return_insn): Change to return with  bxns
	when cmse_nonsecure_entry.
	(output_return_instruction): Likewise.
	(arm_output_function_prologue): Likewise.
	(thumb_pop): Likewise.
	(thumb_exit): Likewise.
	(thumb2_expand_return): Assert that entry functions always have simple
	returns.
	(arm_expand_epilogue): Handle entry functions.
	(arm_function_ok_for_sibcall): Disable sibcall for entry functions.
	(arm_asm_declare_function_name): New.
	* config/arm/arm-protos.h (arm_asm_declare_function_name): New.
	* config/arm/elf.h (ASM_DECLARE_FUNCTION_NAME): Redefine to
	use arm_asm_declare_function_name.

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

	* gcc.target/arm/cmse/cmse-4.c: New.
	* gcc.target/arm/cmse/cmse-9.c: New.
	* gcc.target/arm/cmse/cmse-10.c: New.

Co-Authored-By: Thomas Preud'homme <thomas.preudhomme@arm.com>
From-SVN: r243189