Added support for copied parameters to the SSA compiler.

runtime/vm/flow_graph_allocator.cc

Index: runtime/vm/flow_graph_allocator.cc
diff --git a/runtime/vm/flow_graph_allocator.cc b/runtime/vm/flow_graph_allocator.cc
index 36a9306eca9db9ff41e9b87371aef4ffdee28e13..25b07e5d64ab2420de327a129061621f172f352a 100644
--- a/runtime/vm/flow_graph_allocator.cc
+++ b/runtime/vm/flow_graph_allocator.cc
@@ -448,6 +448,8 @@ void FlowGraphAllocator::BuildLiveRanges() {
     ConnectIncomingPhiMoves(block);
   }
 
+  const bool copied = builder_->parsed_function().copied_parameter_count() > 0;
+
   // Process incoming parameters.
   const intptr_t fixed_parameters_count =
       builder_->parsed_function().function().num_fixed_parameters();
@@ -462,8 +464,13 @@ void FlowGraphAllocator::BuildLiveRanges() {
       range->AddUseInterval(graph_entry->start_pos(), graph_entry->end_pos());
       range->DefineAt(graph_entry->start_pos());
 
-      // Slot index for the rightmost parameter is -1.
-      const intptr_t slot_index = param->index() - fixed_parameters_count;
+      // Slot index for the leftmost copied parameter is 0.
+      intptr_t slot_index = param->index();
+      if (!copied) {
+        // Slot index for the rightmost fixed parameter is -1.
+        slot_index -= fixed_parameters_count;
+      }
+
       range->set_assigned_location(Location::StackSlot(slot_index));
       range->set_spill_slot(Location::StackSlot(slot_index));
 
@@ -477,6 +484,11 @@ void FlowGraphAllocator::BuildLiveRanges() {
         AddToUnallocated(tail);
       }
       ConvertAllUses(range);
+
+      if (copied) {
+        ASSERT(spill_slots_.length() == slot_index);
+        spill_slots_.Add(range->End());
+      }
     }
   }
 }