RISC-V: Finish Ada port.

	gcc/
	* config/riscv/riscv.c (TARGET_CUSTOM_FUNCTION_DESCRIPTORS): New.

From-SVN: r262501

gcc/ChangeLog

+2018-07-07  Jim Wilson  <jimw@sifive.com>
+
+	* config/riscv/riscv.c (TARGET_CUSTOM_FUNCTION_DESCRIPTORS): New.
+
 2018-07-07  Tom de Vries  <tdevries@suse.de>
 
 	* tree-dfa.c (dump_enumerated_decls): Handle cfun->cfg == NULL.

gcc/config/riscv/riscv.c

@@ -4786,6 +4786,10 @@ riscv_constant_alignment (const_tree exp, HOST_WIDE_INT align)
 #undef TARGET_WARN_FUNC_RETURN
 #define TARGET_WARN_FUNC_RETURN riscv_warn_func_return
 
+/* The low bit is ignored by jump instructions so is safe to use.  */
+#undef TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+#define TARGET_CUSTOM_FUNCTION_DESCRIPTORS 1
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-riscv.h"