Pushed: [PATCH v2] LoongArch: Fix C23 (...) functions returning large aggregates [PR114175]

[Xi Ruoyao <xry111@xry111.site>]

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On Tue, 2024-03-19 at 11:19 +0800, chenglulu wrote:
> 
> 在 2024/3/18 下午5:34, Xi Ruoyao 写道:
> > 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.
> > ---
> > 
> > Bootstrapped and regtested on loongarch64-linux-gnu.  Ok for trunk?
> > 
> >   gcc/config/loongarch/loongarch.cc | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/gcc/config/loongarch/loongarch.cc
> > b/gcc/config/loongarch/loongarch.cc
> > index 70e31bb831c..57de8ef7d20 100644
> > --- a/gcc/config/loongarch/loongarch.cc
> > +++ b/gcc/config/loongarch/loongarch.cc
> > @@ -767,7 +767,8 @@ 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);
> I think it's important to add annotation information here:
>      /* where there is no hidden return argument passed, arg.type
> 
>       is always NULL.  */
> 
> Others LTGM.
> 
> Thanks!

Pushed v2 with a comment added as attached.

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

[-- Attachment #2: v2-0001-LoongArch-Fix-C23-.-functions-returning-large-agg.patch --]
[-- Type: text/x-patch, Size: 1940 bytes --]

From c1fd4589c2bf9fd8409d51b94df219cb75107762 Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <xry111@xry111.site>
Date: Mon, 18 Mar 2024 17:18:34 +0800
Subject: [PATCH v2] 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 | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index 70e31bb831c..5344f2a6987 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -767,7 +767,13 @@ 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);
-  if (!TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (current_function_decl)))
+
+  /* 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.  */
-- 
2.44.0