* lib/target-supports.exp
	(check_effective_target_arm_v8_2a_dotprod_neon_ok_nocache): New.
	(check_effective_target_arm_v8_2a_dotprod_neon_ok): New.
	(add_options_for_arm_v8_2a_dotprod_neon): New.
	(check_effective_target_arm_v8_2a_dotprod_neon_hw): New.
	(check_effective_target_vect_sdot_qi): Add ARM && AArch64.
	(check_effective_target_vect_udot_qi): Likewise.
	* gcc.target/arm/simd/vdot-exec.c: New.
	* gcc.target/aarch64/advsimd-intrinsics/vdot-exec.c: New.
	* gcc/doc/sourcebuild.texi: Document arm_v8_2a_dotprod_neon.

From-SVN: r254100