Optimize AOT's switchable calls for the monomorphic case.

runtime/vm/instructions_arm64.h

 // Copyright (c) 2014, 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.
 // Classes that describe assembly patterns as used by inline caches.
 
 #ifndef VM_INSTRUCTIONS_ARM64_H_
 #define VM_INSTRUCTIONS_ARM64_H_
 
 #ifndef VM_INSTRUCTIONS_H_
 #error Do not include instructions_arm64.h directly; use instructions.h instead.
@@ skipping 88 matching lines @@
   const ObjectPool& object_pool_;
 
   uword end_;
   intptr_t native_function_pool_index_;
   intptr_t target_code_pool_index_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeCallPattern);
 };
 
 
-// Instance call that can switch from an IC call to a megamorphic call
-//   load ICData             load MegamorphicCache
-//   call ICLookup stub  ->  call MegamorphicLookup stub
-//   call target             call target
+// Instance call that can switch between a direct monomorphic call, an IC call,
+// and a megamorphic call.
+//   load guarded cid            load ICData             load MegamorphicCache
+//   load monomorphic target <-> load ICLookup stub  ->  load MMLookup stub
+//   call target.entry           call stub.entry         call stub.entry
 class SwitchableCallPattern : public ValueObject {
  public:
   SwitchableCallPattern(uword pc, const Code& code);
 
-  RawObject* cache() const;
-  void SetCache(const MegamorphicCache& cache) const;
-  void SetLookupStub(const Code& stub) const;
+  RawObject* data() const;
+  RawCode* target() const;
+  void SetData(const Object& data) const;
+  void SetTarget(const Code& target) const;
 
  private:
   const ObjectPool& object_pool_;
-  intptr_t cache_pool_index_;
-  intptr_t stub_pool_index_;
+  intptr_t data_pool_index_;
+  intptr_t target_pool_index_;
 
   DISALLOW_COPY_AND_ASSIGN(SwitchableCallPattern);
 };
 
 
 class ReturnPattern : public ValueObject {
  public:
   explicit ReturnPattern(uword pc);
 
   // bx_lr = 1.
   static const int kLengthInBytes = 1 * Instr::kInstrSize;
 
   int pattern_length_in_bytes() const {
     return kLengthInBytes;
   }
 
   bool IsValid() const;
 
  private:
   const uword pc_;
 };
 
 }  // namespace dart
 
 #endif  // VM_INSTRUCTIONS_ARM64_H_