cfgcleanup: Fix -fcompare-debug issue in outgoing_edges_match [PR100254]

The following testcase fails with -fcompare-debug.  The problem is that
outgoing_edges_match behaves differently between -g0 and -g, if
some load/store with REG_EH_REGION is followed by DEBUG_INSNs, the
REG_EH_REGION check is not done, while when there are no DEBUG_INSNs, it is
done.

We already compute last1 and last2 as BB_END (bb{1,2}) with skipped debug
insns and notes, so this patch just uses those.

2021-04-27  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/100254
	* cfgcleanup.c (outgoing_edges_match): Check REG_EH_REGION on
	last1 and last2 insns rather than BB_END (bb1) and BB_END (bb2) insns.

	* g++.dg/opt/pr100254.C: New test.

2 files changed, 103 insertions, 2 deletions

diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index 8650fb7..260a896 100644
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -1885,8 +1885,8 @@ outgoing_edges_match (int mode, basic_block bb1, basic_block bb2)
 
   /* Ensure the same EH region.  */
   {
-    rtx n1 = find_reg_note (BB_END (bb1), REG_EH_REGION, 0);
-    rtx n2 = find_reg_note (BB_END (bb2), REG_EH_REGION, 0);
+    rtx n1 = find_reg_note (last1, REG_EH_REGION, 0);
+    rtx n2 = find_reg_note (last2, REG_EH_REGION, 0);
 
     if (!n1 && n2)
       return false;
diff --git a/gcc/testsuite/g++.dg/opt/pr100254.C b/gcc/testsuite/g++.dg/opt/pr100254.C
new file mode 100644
index 0000000..dbdac16
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr100254.C
@@ -0,0 +1,101 @@
+// PR rtl-optimization/100254
+// { dg-do compile }
+// { dg-options "-O2 -fno-guess-branch-probability -fipa-pta -fnon-call-exceptions -fcompare-debug" }
+// { dg-additional-options "-mtune=goldmont" { target i?86-*-* x86_64-*-* } }
+
+struct _Rb_tree_node_base {
+  typedef _Rb_tree_node_base *_Base_ptr;
+  typedef _Rb_tree_node_base *_Const_Base_ptr;
+  _Base_ptr _M_left;
+};
+template <typename _Key_compare> struct _Rb_tree_key_compare {
+  _Key_compare _M_key_compare;
+};
+struct _Rb_tree_header {
+  _Rb_tree_node_base _M_header;
+};
+struct _Rb_tree_iterator {
+  _Rb_tree_iterator(_Rb_tree_node_base::_Base_ptr);
+  friend bool operator==(_Rb_tree_iterator, _Rb_tree_iterator);
+};
+template <typename _Tp> struct _Rb_tree_const_iterator {
+  typedef _Rb_tree_const_iterator _Self;
+  _Rb_tree_const_iterator(_Rb_tree_node_base::_Const_Base_ptr) {}
+  _Tp operator*();
+  template <typename _Up>
+  friend bool operator!=(_Rb_tree_const_iterator<_Up>, _Rb_tree_const_iterator<_Up>);
+};
+template <typename _Key, typename _Val, typename _Compare> struct _Rb_tree {
+  template <typename _Key_compare>
+  struct _Rb_tree_impl : _Rb_tree_key_compare<_Key_compare>, _Rb_tree_header {};
+  _Rb_tree_impl<_Compare> _M_impl;
+  _Key _S_key();
+  typedef _Rb_tree_const_iterator<_Val> const_iterator;
+  const_iterator begin() { return _M_impl._M_header._M_left; }
+  _Rb_tree_iterator find(const _Key &);
+};
+template <typename _Key, typename _Val, typename _Compare>
+_Rb_tree_iterator _Rb_tree<_Key, _Val, _Compare>::find(const _Key &__k) {
+  _Rb_tree_iterator __j = 0;
+  return __j == 0 || _M_impl._M_key_compare(__k, _S_key()) ? 0 : __j;
+}
+template <typename _Key, typename _Compare = _Key> struct set {
+  typedef _Key key_type;
+  typedef _Rb_tree<key_type, _Key, _Compare> _Rep_type;
+  _Rep_type _M_t;
+  typedef typename _Rep_type::const_iterator iterator;
+  iterator begin() { return _M_t.begin(); }
+  iterator end();
+  void find(key_type __x) { _M_t.find(__x); }
+};
+struct WindowDesc {
+  WindowDesc(short);
+} _station_view_desc(0);
+struct Window {
+  void IsWidgetLowered();
+  virtual void OnClick(int, int, int);
+};
+int AllocateWindowDescFront_window_number;
+template <typename Wcls> void AllocateWindowDescFront(WindowDesc *desc, bool) {
+  Wcls(desc, AllocateWindowDescFront_window_number);
+}
+class CargoDataEntry;
+struct CargoSorter {
+  bool operator()(const CargoDataEntry *, const CargoDataEntry *) const;
+};
+struct CargoDataEntry {
+  ~CargoDataEntry();
+  char Retrieve_cargo;
+  void Retrieve() {
+    CargoDataEntry t(Retrieve_cargo);
+    children->find(&t);
+  }
+  CargoDataEntry(char);
+  set<CargoDataEntry *, CargoSorter> *children;
+};
+CargoDataEntry::CargoDataEntry(char) : children() {}
+CargoDataEntry::~CargoDataEntry() {
+  if (children)
+    for (set<CargoDataEntry *>::iterator i = children->begin();
+         i != children->end();)
+      delete *i;
+}
+bool CargoSorter::operator()(const CargoDataEntry *,
+                             const CargoDataEntry *) const { return false; }
+struct StationViewWindow : Window {
+  StationViewWindow(WindowDesc *, int);
+  CargoDataEntry HandleCargoWaitingClick_filter;
+  void OnClick(int, int widget, int) {
+    switch (widget) {
+    case 0:
+      HandleCargoWaitingClick_filter.Retrieve();
+      HandleCargoWaitingClick_filter.Retrieve();
+    case 1:
+      IsWidgetLowered();
+    }
+  }
+};
+void ShowStationViewWindow_station() {
+  AllocateWindowDescFront<StationViewWindow>(&_station_view_desc,
+                                             ShowStationViewWindow_station);
+}