From: Eric Botcazou <ebotcazou@adacore.com>
Date: Thu, 19 Jun 2025 17:15:35 +0000 (+0200)
Subject: ada: Remove strange elaboration code generated for Cluster type in System.Pack_NN
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ccf668274ac66f9692eb0b6775e522ed240890f7;p=thirdparty%2Fgcc.git

ada: Remove strange elaboration code generated for Cluster type in System.Pack_NN

Initialization procedures are turned into functions under the hood and, even
when they are null (empty), the compiler may generate a convoluted sequence
of instructions that return uninitialized data and, therefore, is useless.

gcc/ada/ChangeLog:

	* gcc-interface/trans.cc (Subprogram_Body_to_gnu): Do not generate
	a block-copy out for a null initialization procedure when the _Init
	parameter is not passed in.
---

diff --git a/gcc/ada/gcc-interface/trans.cc b/gcc/ada/gcc-interface/trans.cc
index 520611e7d79..a7254fe036f 100644
--- a/gcc/ada/gcc-interface/trans.cc
+++ b/gcc/ada/gcc-interface/trans.cc
@@ -4172,9 +4172,13 @@ Subprogram_Body_to_gnu (Node_Id gnat_node)
 	    }
 	}
 
-      /* Otherwise, if this is a procedure or a function which does not return
-	 by invisible reference, we can do a direct block-copy out.  */
-      else
+      /* Otherwise, if this is a procedure or a function that does not return
+	 by invisible reference, we can do a direct block-copy out, but we do
+	 not need to do it for a null initialization procedure when the _Init
+	 parameter is not passed in since we would copy uninitialized bits.  */
+      else if (!(Is_Null_Init_Proc (gnat_subprog)
+		 && list_length (gnu_cico_list) == 1
+		 && TREE_CODE (TREE_VALUE (gnu_cico_list)) == VAR_DECL))
 	{
 	  tree gnu_retval;