Enable polymorphic inlining of StringBase [] and StringBase codeUnitAt

runtime/vm/flow_graph_optimizer.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLOW_GRAPH_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph.h"
 
@@ skipping 102 matching lines @@
                                      MethodRecognizer::Kind recognized_kind);
   bool TryInlineInt32x4Constructor(StaticCallInstr* call,
                                     MethodRecognizer::Kind recognized_kind);
   bool TryInlineFloat32x4Method(InstanceCallInstr* call,
                                 MethodRecognizer::Kind recognized_kind);
   bool TryInlineInt32x4Method(InstanceCallInstr* call,
                                MethodRecognizer::Kind recognized_kind);
   void ReplaceWithInstanceOf(InstanceCallInstr* instr);
   void ReplaceWithTypeCast(InstanceCallInstr* instr);
 
+  Definition* PrepareInlineStringIndexOp(Instruction* call,
+                                         intptr_t cid,
+                                         Definition* str,
+                                         Definition* index,
+                                         Instruction* cursor);
+
+  bool InlineStringCodeUnitAt(Instruction* call,
+                              intptr_t cid,
+                              TargetEntryInstr** entry,
+                              Definition** last);
+
+  bool InlineStringBaseCharAt(Instruction* call,
+                              intptr_t cid,
+                              TargetEntryInstr** entry,
+                              Definition** last);
+
   LoadIndexedInstr* BuildStringCodeUnitAt(InstanceCallInstr* call,
                                           intptr_t cid);
 
   bool InlineByteArrayViewLoad(Instruction* call,
                                Definition* receiver,
                                intptr_t array_cid,
                                intptr_t view_cid,
                                const ICData& ic_data,
                                TargetEntryInstr** entry,
                                Definition** last);
@@ skipping 256 matching lines @@
 // Optimize spill stores inside try-blocks by identifying values that always
 // contain a single known constant at catch block entry.
 class TryCatchAnalyzer : public AllStatic {
  public:
   static void Optimize(FlowGraph* flow_graph);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_