[AArch64] Implement workaround for ARM Cortex-A53 erratum 835769

	Backport from mainline
	2014-10-10  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
	            Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>

	* config/aarch64/aarch64.h (FINAL_PRESCAN_INSN): Define.
	(ADJUST_INSN_LENGTH): Define.
	* config/aarch64/aarch64.opt (mfix-cortex-a53-835769): New option.
	* config/aarch64/aarch64.c (is_mem_p): New function.
	(is_memory_op): Likewise.
	(aarch64_prev_real_insn): Likewise.
	(is_madd_op): Likewise.
	(dep_between_memop_and_curr): Likewise.
	(aarch64_madd_needs_nop): Likewise.
	(aarch64_final_prescan_insn): Likewise.
	* doc/invoke.texi (AArch64 Options): Document -mfix-cortex-a53-835769
	and -mno-fix-cortex-a53-835769 options.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@216077 138bc75d-0d04-0410-961f-82ee72b054a4
[AArch64] Add --enable-fix-cortex-a53-835769 configure-time option

	Backport from mainline
	2014-10-10  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* configure.ac: Add --enable-fix-cortex-a53-835769 option.
	* configure: Regenerate.
	* config/aarch64/aarch64.c (aarch64_override_options): Handle
	TARGET_FIX_ERR_A53_835769_DEFAULT.
	* config/aarch64/aarch64.opt (mfix-cortex-a53-835769): Set Init
	value to 2.
	* doc/install.texi (aarch64*-*-*): Document new
	--enable-fix-cortex-a53-835769 option.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@216079 138bc75d-0d04-0410-961f-82ee72b054a4