[gcc r14-9552] RISC-V: Fix C23 (...) functions returning large aggregates [PR114175]

[Edwin Lu]

https://gcc.gnu.org/g:60586710b0646efdbbd77a7f53b93fb5edb87a61

commit r14-9552-g60586710b0646efdbbd77a7f53b93fb5edb87a61
Author: Edwin Lu <ewlu@rivosinc.com>
Date:   Mon Mar 18 11:43:41 2024 -0700

    RISC-V: Fix C23 (...) functions returning large aggregates [PR114175]
    
    We assume that TYPE_NO_NAMED_ARGS_STDARG_P don't have any named arguments and
    there is nothing to advance, but that is not the case for (...) functions
    returning by hidden reference which have one such artificial argument.
    This causes gcc.dg/c23-stdarg-[68].c to fail
    
    Fix the issue by checking if arg.type is NULL as r14-9503-g218d1749612
    explains
    
    Tested on linux rv64gcv.
    
    gcc/ChangeLog:
    
            PR target/114175
            * config/riscv/riscv.cc (riscv_setup_incoming_varargs): Only skip
            riscv_funciton_arg_advance for TYPE_NO_NAMED_ARGS_STDARG_P functions
            if arg.type is NULL

Diff:
---
 gcc/config/riscv/riscv.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 45015addd1f..02a927f96b4 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -5395,7 +5395,8 @@ riscv_setup_incoming_varargs (cumulative_args_t cum,
      argument.  Advance a local copy of CUM past the last "real" named
      argument, to find out how many registers are left over.  */
   local_cum = *get_cumulative_args (cum);
-  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)
     riscv_function_arg_advance (pack_cumulative_args (&local_cum), arg);
 
   /* Found out how many registers we need to save.  */