AArch64: Add SVE support for simd clones [PR96342]

AArch64: Add SVE support for simd clones [PR96342]

This patch finalizes adding support for the generation of SVE simd clones when
no simdlen is provided, following the ABI rules where the widest data type
determines the minimum amount of elements in a length agnostic vector.

gcc/ChangeLog:

	PR target/96342
	* config/aarch64/aarch64-protos.h (add_sve_type_attribute): Declare.
	* config/aarch64/aarch64-sve-builtins.cc (add_sve_type_attribute): Make
	visibility global and support use for non_acle types.
	* config/aarch64/aarch64.cc
	(aarch64_simd_clone_compute_vecsize_and_simdlen): Create VLA simd clone
	when no simdlen is provided, according to ABI rules.
	(simd_clone_adjust_sve_vector_type): New helper function.
	(aarch64_simd_clone_adjust): Add '+sve' attribute to SVE simd clones
	and modify types to use SVE types.
	* omp-simd-clone.cc (simd_clone_mangle): Print 'x' for VLA simdlen.
	(simd_clone_adjust): Adapt safelen check to be compatible with VLA
	simdlen.

gcc/testsuite/ChangeLog:

	PR target/96342
	* gcc.target/aarch64/declare-simd-2.c: Add SVE clone scan.
	* gcc.target/aarch64/vect-simd-clone-1.c: New test.
	* g++.target/aarch64/vect-simd-clone-1.C: New test.

Co-authored-by: Victor Do Nascimento <victor.donascimento@arm.com>
Co-authored-by: Tamar Christina <tamar.christina@arm.com>