Add Function based profile tree

runtime/vm/instructions_mips.cc

 // 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/constants_mips.h"
 #include "vm/cpu.h"
 #include "vm/instructions.h"
@@ skipping 209 matching lines @@
   Instr* ori = Instr::At(pc_ + (1 * Instr::kInstrSize));
   const int32_t lui_bits = lui->InstructionBits();
   const int32_t ori_bits = ori->InstructionBits();
   const uint16_t target_lo = target_address & 0xffff;
   const uint16_t target_hi = target_address >> 16;
 
   lui->SetInstructionBits((lui_bits & 0xffff0000) | target_hi);
   ori->SetInstructionBits((ori_bits & 0xffff0000) | target_lo);
 }
 
+
+ReturnPattern::ReturnPattern(uword pc)
+    : pc_(pc) {
+}
+
+
+bool ReturnPattern::IsValid() const {
+  Instr* jr = Instr::At(pc_);
+  return (jr->OpcodeField() == SPECIAL) &&
+         (jr->FunctionField() == JR) &&
+         (jr->RsField() == RA);
+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS