arm: CLI for Custom Datapath Extension (CDE)

arm: CLI for Custom Datapath Extension (CDE)

This patch is part of a series that adds support for the Arm Custom
Datapath Extension. It defines the options cdecp0-cdecp7 for CLI to
enable the CDE on corresponding coprocessor 0-7.
It also adds new target supports for CDE feature testsuite.

gcc/ChangeLog:
2020-04-08  Dennis Zhang  <dennis.zhang@arm.com>

	* config.gcc: Add arm_cde.h.
	* config/arm/arm-c.c (arm_cpu_builtins): Define or undefine
	__ARM_FEATURE_CDE and __ARM_FEATURE_CDE_COPROC.
	* config/arm/arm-cpus.in (cdecp0, cdecp1, ..., cdecp7): New options.
	* config/arm/arm.c (arm_option_reconfigure_globals): Configure
	arm_arch_cde and arm_arch_cde_coproc to store the feature bits.
	* config/arm/arm.h (TARGET_CDE): New macro.
	* config/arm/arm_cde.h: New file.
	* doc/invoke.texi: Document CDE options +cdecp[0-7].
	* doc/sourcebuild.texi (arm_v8m_main_cde_ok): Document new target
	supports option.
	(arm_v8m_main_cde_fp, arm_v8_1m_main_cde_mve): Likewise.

gcc/testsuite/ChangeLog:
2020-04-08  Dennis Zhang  <dennis.zhang@arm.com>

	* gcc.target/arm/pragma_cde.c: New test.
	* lib/target-supports.exp (arm_v8m_main_cde_ok): New target support
	option.
	(arm_v8m_main_cde_fp, arm_v8_1m_main_cde_mve): Likewise.