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[COMMITTED,28/35] ada: Fix fallout of change in parameter passing out of aliasing considerations

Message ID 20241025091107.485741-28-poulhies@adacore.com
State New
Headers show
Series [COMMITTED,01/35] ada: Pass parameters of full access unconstrained array types by copy in calls | expand

Commit Message

Marc Poulhiès Oct. 25, 2024, 9:10 a.m. UTC 
From: Eric Botcazou <ebotcazou@adacore.com>

If an actual parameter that is a type conversion is passed by reference but
not addressable, the temporary that is created and whose address is passed
instead may need to be in the target type of the conversion to fulfill the
requirements of strict aliasing.

gcc/ada/ChangeLog:

	* gcc-interface/trans.cc (Call_to_gnu): If the formal is passed by
	reference and the actual is a type conversion but not addressable,
	create the temporary in the target type of the conversion if this
	is needed to enforce strict aliasing.

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

---
 gcc/ada/gcc-interface/trans.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
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Patch

diff --git a/gcc/ada/gcc-interface/trans.cc b/gcc/ada/gcc-interface/trans.cc
index 93f67404ddb..5f8a18eebb7 100644
--- a/gcc/ada/gcc-interface/trans.cc
+++ b/gcc/ada/gcc-interface/trans.cc
@@ -5010,9 +5010,12 @@  Call_to_gnu (Node_Id gnat_node, tree *gnu_result_type_p, tree gnu_target,
 					       TREE_TYPE (gnu_name))))
 	    gnu_name = convert (gnu_name_type, gnu_name);
 
-	  /* If the temporary is created  because of aliasing considerations,
+	  /* If the temporary is created because of aliasing considerations,
+	     or would have been so created if the actual was addressable,
 	     it must be in the target type of the (unchecked) conversion.  */
-	  if (aliasing)
+	  if (aliasing
+	      || (node_is_type_conversion (gnat_actual)
+		  && !aliasable_p (gnu_name, gnu_actual_type)))
 	    {
 	      if (Nkind (gnat_actual) == N_Unchecked_Type_Conversion)
 		gnu_name = unchecked_convert (gnu_actual_type, gnu_name,