Add Function based profile tree

runtime/vm/instructions_arm.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_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/constants_arm.h"
 #include "vm/cpu.h"
@@ skipping 326 matching lines @@
         0xe300c000 | ((target_lo >> 12) << 16) | (target_lo & 0xfff);
     const uword movt_ip =
         0xe340c000 | ((target_hi >> 12) << 16) | (target_hi & 0xfff);
 
     *reinterpret_cast<uword*>(pc_ + (0 * Instr::kInstrSize)) = movw_ip;
     *reinterpret_cast<uword*>(pc_ + (1 * Instr::kInstrSize)) = movt_ip;
     CPU::FlushICache(pc_, 2 * Instr::kInstrSize);
   }
 }
 
+
+ReturnPattern::ReturnPattern(uword pc)
+    : pc_(pc) {
+}
+
+
+bool ReturnPattern::IsValid() const {
+  Instr* bx_lr = Instr::At(pc_);
+  const int32_t B4 = 1 << 4;
+  const int32_t B21 = 1 << 21;
+  const int32_t B24 = 1 << 24;
+  int32_t instruction = (static_cast<int32_t>(AL) << kConditionShift) |
+                         B24 | B21 | (0xfff << 8) | B4 |
+                        (static_cast<int32_t>(LR) << kRmShift);
+  const ARMVersion version = TargetCPUFeatures::arm_version();
+  if ((version == ARMv5TE) || (version == ARMv6)) {
+    return bx_lr->InstructionBits() == instruction;
+  } else {
+    ASSERT(version == ARMv7);
+    return bx_lr->InstructionBits() == instruction;
+  }
+  return false;
+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM