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[COMMITTED,6/6] ada: Add bypass for internal fields on strict-alignment platforms

Message ID 20240905081056.2402112-6-poulhies@adacore.com
State New
Headers show
Series [COMMITTED,1/6] ada: Tweak assertions in Inline.Cannot_Inline | expand

Commit Message

Marc Poulhiès Sept. 5, 2024, 8:10 a.m. UTC 
From: Eric Botcazou <ebotcazou@adacore.com>

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.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/gcc-interface/trans.cc | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
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Patch

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));