Hi! Like in the r14-9503 change on x86-64, I think Alpha also needs to function_arg_advance after the hidden return pointer argument if any. At least, the following patch changes the assembly of s1-s6 functions on the https://gcc.gnu.org/pipermail/gcc-patches/2024-March/647956.html c23-stdarg-9.c testcase, and eyeballing the assembly for int f8 (...) the ... args are passed in 16..21 registers and then on the stack, while for struct S s8 (...) have hidden return pointer passed in 16 register and ... args in 17..21 registers and then on the stack, and seems without this patch the incoming varargs setup does the wrong thing (but I can't test on alpha easily).
Many targets seem to be unaffected, e.g. aarch64, arm, s390*, so I'm not trying to change all targets together because such a change clearly isn't needed e.g. for targets which use special register for the hidden return pointer. Ok for trunk? 2024-03-18 Jakub Jelinek <ja...@redhat.com> PR target/114175 * config/alpha/alpha.cc (alpha_setup_incoming_varargs): Only skip function_arg_advance for TYPE_NO_NAMED_ARGS_STDARG_P functions if arg.type is NULL. --- gcc/config/alpha/alpha.cc.jj 2024-01-05 15:22:21.762686175 +0100 +++ gcc/config/alpha/alpha.cc 2024-03-18 16:12:14.594761619 +0100 @@ -6090,7 +6090,8 @@ alpha_setup_incoming_varargs (cumulative { CUMULATIVE_ARGS cum = *get_cumulative_args (pcum); - if (!TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (current_function_decl))) + if (!TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (current_function_decl)) + || arg.type != NULL_TREE) /* Skip the current argument. */ targetm.calls.function_arg_advance (pack_cumulative_args (&cum), arg); Jakub