trans.c (Case_Statement_to_gnu): Do not push a binding level for each branch if...

	* gcc-interface/trans.c (Case_Statement_to_gnu): Do not push a binding
	level for each branch if this is a case expression in Ada 2012.
	(gnat_to_gnu) <case N_Expression_With_Actions>: Adjust comment.

From-SVN: r205662

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index f1f73169933d6fa6529fa29f4cfea529be98fff9..504f358a782944cbb7ec7f9c378a1f09ee32d08a 100644 (file)
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,9 @@
+2013-12-04  Eric Botcazou  <ebotcazou@adacore.com>
+
+       * gcc-interface/trans.c (Case_Statement_to_gnu): Do not push a binding
+       level for each branch if this is a case expression in Ada 2012.
+       (gnat_to_gnu) <case N_Expression_With_Actions>: Adjust comment.
+
 2013-11-29  Eric Botcazou  <ebotcazou@adacore.com>
 
        PR ada/54040

diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c
index e533de6dcbf7a33caabf4cdcbb859704fe4d12df..2eae39976d86613410e7b7343676b093ece987c1 100644 (file)
--- a/gcc/ada/gcc-interface/trans.c
+++ b/gcc/ada/gcc-interface/trans.c
@@ -2348,12 +2348,17 @@ Case_Statement_to_gnu (Node_Id gnat_node)
            }
        }
 
-      /* Push a binding level here in case variables are declared as we want
-        them to be local to this set of statements instead of to the block
-        containing the Case statement.  */
+      /* This construct doesn't define a scope so we shouldn't push a binding
+        level around the statement list.  Except that we have always done so
+        historically and this makes it possible to reduce stack usage.  As a
+        compromise, we keep doing it for case statements, for which this has
+        never been problematic, but not for case expressions in Ada 2012.  */
       if (choices_added_p)
        {
-         tree group = build_stmt_group (Statements (gnat_when), true);
+         const bool is_case_expression
+           = (Nkind (Parent (gnat_node)) == N_Expression_With_Actions);
+         tree group
+           = build_stmt_group (Statements (gnat_when), !is_case_expression);
          bool group_may_fallthru = block_may_fallthru (group);
          add_stmt (group);
          if (group_may_fallthru)
@@ -7002,8 +7007,8 @@ gnat_to_gnu (Node_Id gnat_node)
     /****************/
 
     case N_Expression_With_Actions:
-      /* This construct doesn't define a scope so we don't wrap the statement
-        list in a BIND_EXPR; however, we wrap it in a SAVE_EXPR to protect it
+      /* This construct doesn't define a scope so we don't push a binding level
+        around the statement list; but we wrap it in a SAVE_EXPR to protect it
         from unsharing.  */
       gnu_result = build_stmt_group (Actions (gnat_node), false);
       gnu_result = build1 (SAVE_EXPR, void_type_node, gnu_result);