[vect] PR92317: fix skip_epilogue creation for epilogues

gcc/ChangeLog:
2019-11-06  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	PR tree-optimization/92317
	* tree-vect-loop-manip.c (slpeel_update_phi_nodes_for_guard2): Also
	update phi's with constant phi arguments.

gcc/testsuite/ChangeLog:
2019-11-06  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	PR tree-optimization/92317
	* gcc/testsuite/g++.dg/opt/pr92317.C: New test.

From-SVN: r277877

gcc/ChangeLog

+2019-11-06  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+
+	PR tree-optimization/92317
+	* tree-vect-loop-manip.c (slpeel_update_phi_nodes_for_guard2): Also
+	update phi's with constant phi arguments.
+
 2019-11-06  Eric Botcazou  <ebotcazou@adacore.com>
 	    Alexandre Oliva  <oliva@adacore.com>
 

gcc/testsuite/ChangeLog

+2019-11-06  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+
+	PR tree-optimization/92317
+	* gcc/testsuite/g++.dg/opt/pr92317.C: New test.
+
 2019-11-06  Gergö Barany  <gergo@codesourcery.com>
 	    Frederik Harwath  <frederik@codesourcery.com>
 	    Thomas Schwinge  <thomas@codesourcery.com>

gcc/testsuite/g++.dg/opt/pr92317.C

+// Copied from pr87967.C
+// { dg-do compile { target c++11 } }
+// { dg-options "-O2 -ftree-vectorize -fno-tree-pre --param vect-epilogues-nomask=1" }
+
+void h();
+template <typename b> struct k { using d = b; };
+template <typename b, template <typename> class> using e = k<b>;
+template <typename b, template <typename> class f>
+using g = typename e<b, f>::d;
+struct l {
+  template <typename i> using ab = typename i::j;
+};
+struct n : l {
+  using j = g<char *, ab>;
+};
+class o {
+public:
+  long r();
+};
+char m;
+char s() {
+  if (m)
+    return '0';
+  return 'A';
+}
+class t {
+public:
+  typedef char *ad;
+  ad m_fn2();
+};
+void fn3() {
+  char *a;
+  t b;
+  bool p = false;
+  while (*a) {
+    h();
+    o c;
+    if (*a)
+      a++;
+    if (c.r()) {
+      n::j q;
+      for (t::ad d = b.m_fn2(), e; d != e; d++) {
+        char f = *q;
+        *d = f + s();
+      }
+      p = true;
+    }
+  }
+  if (p)
+    throw;
+}

gcc/tree-vect-loop-manip.c

@@ -2291,12 +2291,14 @@ slpeel_update_phi_nodes_for_guard2 (class loop *loop, class loop *epilog,
     {
       gphi *update_phi = gsi.phi ();
       tree old_arg = PHI_ARG_DEF (update_phi, 0);
-      /* This loop-closed-phi actually doesn't represent a use out of the
-	 loop - the phi arg is a constant.  */
-      if (TREE_CODE (old_arg) != SSA_NAME)
-	continue;
 
-      tree merge_arg = get_current_def (old_arg);
+      tree merge_arg = NULL_TREE;
+
+      /* If the old argument is a SSA_NAME use its current_def.  */
+      if (TREE_CODE (old_arg) == SSA_NAME)
+	merge_arg = get_current_def (old_arg);
+      /* If it's a constant or doesn't have a current_def, just use the old
+	 argument.  */
       if (!merge_arg)
 	merge_arg = old_arg;