AArch64: Migrate calls and returns to ISLE. (#4788)

cranelift/codegen/src/isa/aarch64/lower.isle

@@ -2016,3 +2016,17 @@
 
 (rule (lower (get_return_address))
       (aarch64_link))
+
+;;;; Rules for calls ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(rule (lower (call (func_ref_data sig_ref extname dist) inputs))
+      (gen_call sig_ref extname dist inputs))
+
+(rule (lower (call_indirect sig_ref val inputs))
+      (gen_call_indirect sig_ref val inputs))
+
+;;;; Rules for `return` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;; N.B.: the Ret itself is generated by the ABI.
+(rule (lower (return args))
+      (lower_return (range 0 (value_slice_len args)) args))