gimple-low.c (lower_gimple_bind): Clear DECL_CHAIN of vars in gimple_bind_vars…

gimple-low.c (lower_gimple_bind): Clear DECL_CHAIN of vars in gimple_bind_vars but not in BLOCK_VARS.

2016-10-07  Richard Biener  <rguenther@suse.de>

	* gimple-low.c (lower_gimple_bind): Clear DECL_CHAIN of
	vars in gimple_bind_vars but not in BLOCK_VARS.

From-SVN: r240855

gcc/ChangeLog

 2016-10-07  Richard Biener  <rguenther@suse.de>
 
+	* gimple-low.c (lower_gimple_bind): Clear DECL_CHAIN of
+	vars in gimple_bind_vars but not in BLOCK_VARS.
+
+2016-10-07  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/77879
 	* tree-ssa-structalias.c (handle_const_call): Properly handle
 	NRV return slots.

gcc/gimple-low.c

@@ -416,6 +416,23 @@ lower_gimple_bind (gimple_stmt_iterator *gsi, struct lower_data *data)
     }
 
   record_vars (gimple_bind_vars (stmt));
+
+  /* Scrap DECL_CHAIN up to BLOCK_VARS to ease GC after we no longer
+     need gimple_bind_vars.  */
+  tree next;
+  tree end = NULL_TREE;
+  if (gimple_bind_block (stmt))
+    end = BLOCK_VARS (gimple_bind_block (stmt));
+  for (tree var = gimple_bind_vars (stmt); var != end; var = next)
+    {
+      /* Ugh, something is violating the constraint that BLOCK_VARS
+         is a sub-chain of gimple_bind_vars.  */
+      if (! var)
+	break;
+      next = DECL_CHAIN (var);
+      DECL_CHAIN (var) = NULL_TREE;
+    }
+
   lower_sequence (gimple_bind_body_ptr (stmt), data);
 
   if (new_block)