From 3ed698858f0ebb12a99ed1cc12c038b533f64b2c Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <xry111@xry111.site>
Date: Fri, 25 Oct 2024 06:15:21 +0000
Subject: [PATCH 150/188] LoongArch: Fix C23 (...) functions returning large
 aggregates  [PR114175]

We were assuming 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 is causing gcc.dg/c23-stdarg-6.c and
gcc.dg/c23-stdarg-8.c to fail.

Fix the issue by checking if arg.type is NULL, as r14-9503 explains.

gcc/ChangeLog:

        PR target/114175
        * config/loongarch/loongarch.cc
        (loongarch_setup_incoming_varargs): Only skip
        loongarch_function_arg_advance for TYPE_NO_NAMED_ARGS_STDARG_P
        functions if arg.type is NULL.
---
 gcc/config/loongarch/loongarch.cc | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index c1dc30b61..1e3981e19 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -767,7 +767,14 @@ loongarch_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);
-  loongarch_function_arg_advance (pack_cumulative_args (&local_cum), arg);
+
+  /* For a C23 variadic function w/o any named argument, and w/o an
+     artifical argument for large return value, skip advancing args.
+     There is such an artifical argument iff. arg.type is non-NULL
+     (PR 114175).  */
+  if (!TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (current_function_decl))
+      || arg.type != NULL_TREE)
+    loongarch_function_arg_advance (pack_cumulative_args (&local_cum), arg);
 
   /* Found out how many registers we need to save.  */
   gp_saved = MAX_ARGS_IN_REGISTERS - local_cum.num_gprs;
-- 
2.43.0