[gcc(refs/vendors/ARM/heads/arm-struct-reorg-wip)] s390: Fix C++14 vs. C++17 ABI incompatibility on s390{, x} [PR94704]

[Tamar Christina]

https://gcc.gnu.org/g:9612a4833d761e3beda083a3e4dc92feba3b01bc

commit 9612a4833d761e3beda083a3e4dc92feba3b01bc
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Apr 27 09:11:57 2020 +0200

    s390: Fix C++14 vs. C++17 ABI incompatibility on s390{,x} [PR94704]
    
    The following patch fixes the C++14 vs. C++17 ABI passing incompatibility
    on s390x-linux.
    
    Bootstrapped/regtested on s390x-linux without and with the patch, the
    difference being:
    -FAIL: tmpdir-g++.dg-struct-layout-1/t032 cp_compat_x_alt.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t032 cp_compat_x_tst.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t032 cp_compat_x_tst.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t055 cp_compat_x_alt.o-cp_compat_y_alt.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t055 cp_compat_x_alt.o-cp_compat_y_tst.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t055 cp_compat_x_tst.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t055 cp_compat_x_tst.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t056 cp_compat_x_alt.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t056 cp_compat_x_alt.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t056 cp_compat_x_tst.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t056 cp_compat_x_tst.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t057 cp_compat_x_alt.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t057 cp_compat_x_alt.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t057 cp_compat_x_tst.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t057 cp_compat_x_tst.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t058 cp_compat_x_alt.o-cp_compat_y_alt.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t058 cp_compat_x_alt.o-cp_compat_y_tst.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t058 cp_compat_x_tst.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t058 cp_compat_x_tst.o-cp_compat_y_tst.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t059 cp_compat_x_alt.o-cp_compat_y_alt.o execute
     FAIL: tmpdir-g++.dg-struct-layout-1/t059 cp_compat_x_alt.o-cp_compat_y_tst.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t059 cp_compat_x_tst.o-cp_compat_y_alt.o execute
    -FAIL: tmpdir-g++.dg-struct-layout-1/t059 cp_compat_x_tst.o-cp_compat_y_tst.o execute
    when performing ALT_CXX_UNDER_TEST=g++ testing with a system GCC 10 compiler
    from a week ago.  So, the alt vs. alt FAILs are all expected (we know before
    this patch there is an ABI incompatibility) and some alt vs. tst (or tst vs.
    alt) FAILs too - that depends on if the particular x or y test is compiled
    with -std=c++14 or -std=c++17 - if x_tst is compiled with -std=c++14 and
    y_alt is compiled with -std=c++17, then it should FAIL, similarly if x_alt
    is compiled with -std=c++17 and y_tst is compiled with -std=c++14.
    
    2020-04-27  Jakub Jelinek  <jakub@redhat.com>
    
            PR target/94704
            * config/s390/s390.c (s390_function_arg_vector,
            s390_function_arg_float): Ignore cxx17_empty_base_field_p fields.

Diff:
---
 gcc/ChangeLog          | 6 ++++++
 gcc/config/s390/s390.c | 6 ++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 477d2a7163c..ade7418401a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/94704
+	* config/s390/s390.c (s390_function_arg_vector,
+	s390_function_arg_float): Ignore cxx17_empty_base_field_p fields.
+
 2020-04-27  Jiufu Guo   <guojiufu@cn.ibm.com>
 
 	* common/config/rs6000/rs6000-common.c
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index b6bc334796d..e282bb8c666 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -11917,7 +11917,8 @@ s390_function_arg_vector (machine_mode mode, const_tree type)
 
       for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
 	{
-	  if (TREE_CODE (field) != FIELD_DECL)
+	  if (TREE_CODE (field) != FIELD_DECL
+	      || cxx17_empty_base_field_p (field))
 	    continue;
 
 	  if (single == NULL_TREE)
@@ -11967,7 +11968,8 @@ s390_function_arg_float (machine_mode mode, const_tree type)
 
       for (field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
 	{
-	  if (TREE_CODE (field) != FIELD_DECL)
+	  if (TREE_CODE (field) != FIELD_DECL
+	      || cxx17_empty_base_field_p (field))
 	    continue;
 
 	  if (single == NULL_TREE)