src/share/vm/c1/c1_IR.cpp

*** 572,587 ****
  
    if (is_active(cur)) {
      TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
      assert(is_visited(cur), "block must be visisted when block is active");
      assert(parent != NULL, "must have parent");
-     assert(parent->number_of_sux() == 1, "loop end blocks must have one successor (critical edges are split)");
  
      cur->set(BlockBegin::linear_scan_loop_header_flag);
      cur->set(BlockBegin::backward_branch_target_flag);
  
      parent->set(BlockBegin::linear_scan_loop_end_flag);
      _loop_end_blocks.append(parent);
      return;
    }
  
    // increment number of incoming forward branches
--- 572,598 ----
  
    if (is_active(cur)) {
      TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
      assert(is_visited(cur), "block must be visisted when block is active");
      assert(parent != NULL, "must have parent");
  
      cur->set(BlockBegin::linear_scan_loop_header_flag);
      cur->set(BlockBegin::backward_branch_target_flag);
  
      parent->set(BlockBegin::linear_scan_loop_end_flag);
+ 
+     // When a loop header is also the start of an exception handler, then the backward branch is
+     // an exception edge. Because such edges are usually critical edges which cannot be split, the
+     // loop must be excluded here from processing.
+     if (cur->is_set(BlockBegin::exception_entry_flag)) {
+       // Make sure that dominators are correct in this weird situation
+       _iterative_dominators = true;
+       return;
+     }
+     assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
+            "loop end blocks must have one successor (critical edges are split)");
+ 
      _loop_end_blocks.append(parent);
      return;
    }
  
    // increment number of incoming forward branches