Hi All,

On passing +cdecp[0-7] extension to the -march string in command line options,
multilib linking is failing as mentioned in PR100856. This patch fixes this issue by
generating a separate canonical string by removing compiler options which are not
required for multilib linking from march string and assign the new string to mlibarch
option. This mlibarch string is used for multilib comparison.

Regression tested on arm-none-eabi and found no regressions.

Ok for master?

Regards,
Srinath.

gcc/ChangeLog:

2021-06-10  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	PR target/100856
	* common/config/arm/arm-common.c (arm_canon_arch_option): Define
	function to call arm_canon_arch_option_1 with flase boolean argument to
	generate canonical string for march option.
	(arm_canon_arch_option_1): Rename arm_canon_arch_option to
	arm_canon_arch_option_1 and add a boolean argument.
	(arm_canon_arch_multilib_option): Define function to call
	arm_canon_arch_option_1 with true boolean argument to generate canonical
	string for mlibarch option.
	* config/arm/arm-cpus.in (IGNORE_FOR_MULTILIB): Define fgroup with cde
	feature bits.
	* config/arm/arm.h (arm_canon_arch_option_1): Function declaration.
	(arm_canon_arch_multilib_option): Function declaration.
	(CANON_ARCH_MULTILIB_SPEC_FUNCTION): Define new macro.
	(MULTILIB_ARCH_CANONICAL_SPECS): Define new macro.
	(DRIVER_SELF_SPECS): Add MULTILIB_ARCH_CANONICAL_SPECS entry.
	* config/arm/arm.opt (mlibarch): Add new option which is supported by
	DriverOnly.
	* config/arm/t-rmprofile (MULTILIB_MATCHES): march on right hand side of
	equal to is replaced with mlibarch for multilib comparison.

gcc/testsuite/ChangeLog:

2021-06-10  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	PR target/100856
	* gcc.target/arm/acle/pr100856.c: New test.
	* gcc.target/arm/multilib.exp: Add cde compiler option entries.