[gcc r12-965] Fix segfault at run time on strict-alignment platforms

[Eric Botcazou <ebotcazou@gcc.gnu.org>]

https://gcc.gnu.org/g:1e66a9170071aded59dda09ac437757de4223346

commit r12-965-g1e66a9170071aded59dda09ac437757de4223346
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Fri May 21 10:40:41 2021 +0200

    Fix segfault at run time on strict-alignment platforms
    
    This fixes a regression present on the mainline and 11 branch by
    restricting the problematic change dealing with bitfields whose
    nomimal subtype is self-referential to the cases where the size
    is really lower.
    
    gcc/ada/
            * gcc-interface/trans.c (Call_to_gnu): Restrict previous change
            to bitfields whose size is not equal to the type size.
            (gnat_to_gnu): Likewise.

Diff:
---
 gcc/ada/gcc-interface/trans.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c
index 8ce0d8ac9e8..adbbbb11aea 100644
--- a/gcc/ada/gcc-interface/trans.c
+++ b/gcc/ada/gcc-interface/trans.c
@@ -4611,6 +4611,8 @@ Call_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, tree gnu_target,
 	  || (gnu_target
 	      && TREE_CODE (gnu_target) == COMPONENT_REF
 	      && DECL_BIT_FIELD (TREE_OPERAND (gnu_target, 1))
+	      && DECL_SIZE (TREE_OPERAND (gnu_target, 1))
+		 != TYPE_SIZE (TREE_TYPE (gnu_target))
 	      && type_is_padding_self_referential (gnu_result_type))))
     {
       gnu_retval = create_temporary ("R", gnu_result_type);
@@ -8370,7 +8372,9 @@ gnat_to_gnu (Node_Id gnat_node)
 	 much data.  But do not remove it if it is already too small.  */
       if (type_is_padding_self_referential (TREE_TYPE (gnu_result))
 	  && !(TREE_CODE (gnu_result) == COMPONENT_REF
-	       && DECL_BIT_FIELD (TREE_OPERAND (gnu_result, 1))))
+	       && DECL_BIT_FIELD (TREE_OPERAND (gnu_result, 1))
+	       && DECL_SIZE (TREE_OPERAND (gnu_result, 1))
+		  != TYPE_SIZE (TREE_TYPE (gnu_result))))
 	gnu_result = convert (TREE_TYPE (TYPE_FIELDS (TREE_TYPE (gnu_result))),
 			      gnu_result);
     }