From: Eric Botcazou <ebotcazou@adacore.com>
Date: Mon, 26 Aug 2024 09:16:41 +0000 (+0200)
Subject: ada: Add bypass for internal fields on strict-alignment platforms
X-Git-Tag: basepoints/gcc-16~6080
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=65186cab1d3c9b0dad17dc0536586bec634b93f3;p=thirdparty%2Fgcc.git

ada: Add bypass for internal fields on strict-alignment platforms

This is required to support misalignment of tagged types in legacy code.

gcc/ada/

	* gcc-interface/trans.cc (addressable_p) <COMPONENT_REF>: Add bypass
	for internal fields on strict-alignment platforms.
---

diff --git a/gcc/ada/gcc-interface/trans.cc b/gcc/ada/gcc-interface/trans.cc
index 9e9f5f8dcba..92e000686fb 100644
--- a/gcc/ada/gcc-interface/trans.cc
+++ b/gcc/ada/gcc-interface/trans.cc
@@ -10295,9 +10295,14 @@ addressable_p (tree gnu_expr, tree gnu_type)
 		   is guaranteed to be not smaller than that of its most
 		   aligned field that is not a bit-field.  However, we need
 		   to cope with quirks of ABIs that may misalign fields.  */
-		&& DECL_ALIGN (TREE_OPERAND (gnu_expr, 1))
-		   >= default_field_alignment (TREE_OPERAND (gnu_expr, 1),
-					       TREE_TYPE (gnu_expr)))
+		&& (DECL_ALIGN (TREE_OPERAND (gnu_expr, 1))
+		    >= default_field_alignment (TREE_OPERAND (gnu_expr, 1),
+						TREE_TYPE (gnu_expr))
+		    /* We do not enforce this on strict-alignment platforms for
+		       internal fields in order to keep supporting misalignment
+		       of tagged types in legacy code.  */
+		    || (!STRICT_ALIGNMENT
+			&& DECL_INTERNAL_P (TREE_OPERAND (gnu_expr, 1)))))
 	       /* The field of a padding record is always addressable.  */
 	       || TYPE_IS_PADDING_P (TREE_TYPE (TREE_OPERAND (gnu_expr, 0))))
 	      && addressable_p (TREE_OPERAND (gnu_expr, 0), NULL_TREE));