Pattern match on generated code to find edge counters.

runtime/vm/instructions_arm.h

 // Copyright (c) 2013, 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_ARM_H_
 #define VM_INSTRUCTIONS_ARM_H_
 
 #ifndef VM_INSTRUCTIONS_H_
 #error Do not include instructions_arm.h directly; use instructions.h instead.
 #endif
 
 #include "vm/constants_arm.h"
 #include "vm/object.h"
 
 namespace dart {
 
+class InstructionPattern : public AllStatic {
+ public:
+  // Decodes a load sequence ending at 'end' (the last instruction of the
+  // load sequence is the instruction before the one at end).  Returns the
+  // address of the first instruction in the sequence.  Returns the register
+  // being loaded and the loaded object in the output parameters 'reg' and
+  // 'obj' respectively.
+  static uword DecodeLoadObject(uword end,
+                                const Array& object_pool,
+                                Register* reg,
+                                Object* obj);
+
+  // Decodes a load sequence ending at 'end' (the last instruction of the
+  // load sequence is the instruction before the one at end).  Returns the
+  // address of the first instruction in the sequence.  Returns the register
+  // being loaded and the loaded immediate value in the output parameters
+  // 'reg' and 'value' respectively.
+  static uword DecodeLoadWordImmediate(uword end,
+                                       Register* reg,
+                                       intptr_t* value);
+
+  // Decodes a load sequence ending at 'end' (the last instruction of the
+  // load sequence is the instruction before the one at end).  Returns the
+  // address of the first instruction in the sequence.  Returns the register
+  // being loaded and the index in the pool being read from in the output
+  // parameters 'reg' and 'index' respectively.
+  static uword DecodeLoadWordFromPool(uword end,
+                                      Register* reg,
+                                      intptr_t* index);
+};
+
+
 class CallPattern : public ValueObject {
  public:
   CallPattern(uword pc, const Code& code);
 
   RawICData* IcData();
   RawArray* ClosureArgumentsDescriptor();
 
   uword TargetAddress() const;
   void SetTargetAddress(uword target_address) const;
 
   // This constant length is only valid for inserted call patterns used for
   // lazy deoptimization. Regular call pattern may vary in length.
   static const int kFixedLengthInBytes = 3 * Instr::kInstrSize;
 
   static void InsertAt(uword pc, uword target_address);
 
  private:
-  uword Back(int n) const;
-  int DecodeLoadObject(int end, Register* reg, Object* obj);
-  int DecodeLoadWordImmediate(int end, Register* reg, int* value);
-  int DecodeLoadWordFromPool(int end, Register* reg, int* index);
-  const uword* end_;
-  int target_address_pool_index_;
-  int args_desc_load_end_;
+  const Array& object_pool_;
+
+  uword end_;
+  uword args_desc_load_end_;
+  uword ic_data_load_end_;
+
+  intptr_t target_address_pool_index_;
   Array& args_desc_;
-  int ic_data_load_end_;
   ICData& ic_data_;
-  const Array& object_pool_;
 
   DISALLOW_COPY_AND_ASSIGN(CallPattern);
 };
 
 
 class JumpPattern : public ValueObject {
  public:
   JumpPattern(uword pc, const Code& code);
 
   static const int kLengthInBytes = 3 * Instr::kInstrSize;
 
   int pattern_length_in_bytes() const {
     return kLengthInBytes;
   }
 
   bool IsValid() const;
   uword TargetAddress() const;
   void SetTargetAddress(uword target_address) const;
 
  private:
   const uword pc_;
 
   DISALLOW_COPY_AND_ASSIGN(JumpPattern);
 };
 
 }  // namespace dart
 
 #endif  // VM_INSTRUCTIONS_ARM_H_
-