Reset front end trees before they make it into the middle end (PR middle-end/97172).

gcc/ChangeLog:

	PR middle-end/97172
	* attribs.c (attr_access::free_lang_data): Define new function.
	* attribs.h (attr_access::free_lang_data): Declare new function.

gcc/c/ChangeLog:

	PR middle-end/97172
	* c-decl.c (free_attr_access_data): New function.
	(c_parse_final_cleanups): Call free_attr_access_data.

gcc/testsuite/ChangeLog:

	PR middle-end/97172
	* gcc.dg/pr97172.c: New test.

1 files changed, 32 insertions, 0 deletions

diff --git a/gcc/attribs.c b/gcc/attribs.c
index 94991fb..81322d4 100644
--- a/gcc/attribs.c
+++ b/gcc/attribs.c
@@ -2238,6 +2238,38 @@ attr_access::vla_bounds (unsigned *nunspec) const
   return list_length (size);
 }
 
+/* Reset front end-specific attribute access data from ATTRS.
+   Called from the free_lang_data pass.  */
+
+/* static */ void
+attr_access::free_lang_data (tree attrs)
+{
+  for (tree acs = attrs; (acs = lookup_attribute ("access", acs));
+       acs = TREE_CHAIN (acs))
+    {
+      tree vblist = TREE_VALUE (acs);
+      vblist = TREE_CHAIN (vblist);
+      if (!vblist)
+	continue;
+
+      vblist = TREE_VALUE (vblist);
+      if (!vblist)
+	continue;
+
+      for (vblist = TREE_VALUE (vblist); vblist; vblist = TREE_CHAIN (vblist))
+	{
+	  tree *pvbnd = &TREE_VALUE (vblist);
+	  if (!*pvbnd || DECL_P (*pvbnd))
+	    continue;
+
+	  /* VLA bounds that are expressions as opposed to DECLs are
+	     only used in the front end.  Reset them to keep front end
+	     trees leaking into the middle end (see pr97172) and to
+	     free up memory.  */
+	  *pvbnd = NULL_TREE;
+	}
+    }
+}
 
 /* Defined in attr_access.  */
 constexpr char attr_access::mode_chars[];