This patch makes the mode size assumptions in expand_ifn_atomic_compare_exchange_into_call a bit more explicit, so that a later patch can add a to_constant () call.
2017-10-23 Richard Sandiford <richard.sandif...@linaro.org> Alan Hayward <alan.hayw...@arm.com> David Sherwood <david.sherw...@arm.com> gcc/ * builtins.c (expand_ifn_atomic_compare_exchange_into_call): Assert that the mode size is in the set {1, 2, 4, 8, 16}. Index: gcc/builtins.c =================================================================== --- gcc/builtins.c 2017-10-23 17:22:18.226824652 +0100 +++ gcc/builtins.c 2017-10-23 17:25:41.647742640 +0100 @@ -5838,9 +5838,12 @@ expand_ifn_atomic_compare_exchange_into_ /* Skip the boolean weak parameter. */ for (z = 4; z < 6; z++) vec->quick_push (gimple_call_arg (call, z)); + /* At present we only have BUILT_IN_ATOMIC_COMPARE_EXCHANGE_{1,2,4,8,16}. */ + unsigned int bytes_log2 = exact_log2 (GET_MODE_SIZE (mode)); + gcc_assert (bytes_log2 < 5); built_in_function fncode = (built_in_function) ((int) BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1 - + exact_log2 (GET_MODE_SIZE (mode))); + + bytes_log2); tree fndecl = builtin_decl_explicit (fncode); tree fn = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fndecl)), fndecl);