tree-optimization/93953 - avoid reference into hash-map

When possibly expanding a hash-map avoid keeping a reference to an
entry.

2020-02-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/93953
	* tree-vect-slp.c (slp_copy_subtree): Avoid keeping a reference
	to the hash-map entry.

	* gcc.dg/pr93953.c: New testcase.

gcc/ChangeLog

+2020-02-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/93953
+	* tree-vect-slp.c (slp_copy_subtree): Avoid keeping a reference
+	to the hash-map entry.
+
 2020-02-27  Andrew Stubbs  <ams@codesourcery.com>
 
 	* config/gcn/gcn.md (mov<mode>): Add transformations for BI subregs.

gcc/testsuite/ChangeLog

+2020-02-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/93953
+	* gcc.dg/pr93953.c: New testcase.
+
 2020-02-27  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/93949

gcc/testsuite/gcc.dg/pr93953.c

+/* PR tree-optimization/93953 */
+/* { dg-do compile } */
+/* { dg-options "-O3 --param=ggc-min-expand=0 --param=ggc-min-heapsize=0" } */
+
+int *b, c, e;
+float d, g, f;
+
+void
+foo (int l)
+{
+  for (; l; ++l)
+    {
+      float a = g > l;
+      d += a * b[4 * (l + c * e)];
+      f += a * b[4 * (l + c * e) + 1];
+    }
+}

gcc/tree-vect-slp.c

@@ -1764,11 +1764,12 @@ slp_copy_subtree (slp_tree node, hash_map<slp_tree, slp_tree> &map)
   unsigned i;
 
   bool existed_p;
-  slp_tree &copy = map.get_or_insert (node, &existed_p);
+  slp_tree &copy_ref = map.get_or_insert (node, &existed_p);
   if (existed_p)
-    return copy;
+    return copy_ref;
 
-  copy = XNEW (_slp_tree);
+  copy_ref = XNEW (_slp_tree);
+  slp_tree copy = copy_ref;
   memcpy (copy, node, sizeof (_slp_tree));
   if (SLP_TREE_SCALAR_STMTS (node).exists ())
     {