Implement rewind: drop one or more frames from the debugger.

runtime/vm/stub_code.h

 // Copyright (c) 2011, 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 RUNTIME_VM_STUB_CODE_H_
 #define RUNTIME_VM_STUB_CODE_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 
 namespace dart {
 
 // Forward declarations.
 class Code;
 class Isolate;
 class ObjectPointerVisitor;
 class RawCode;
 class SnapshotReader;
 class SnapshotWriter;
 class Serializer;
 class Deserializer;
 
 // List of stubs created in the VM isolate, these stubs are shared by different
 // isolates running in this dart process.
 #if !defined(TARGET_ARCH_DBC)
 #define VM_STUB_CODE_LIST(V)                                                   \
   V(GetStackPointer)                                                           \
   V(JumpToFrame)                                                               \
   V(RunExceptionHandler)                                                       \
+  V(DeoptForRewind)                                                            \
   V(UpdateStoreBuffer)                                                         \
   V(PrintStopMessage)                                                          \
   V(CallToRuntime)                                                             \
   V(LazyCompile)                                                               \
   V(CallBootstrapCFunction)                                                    \
   V(CallNativeCFunction)                                                       \
   V(FixCallersTarget)                                                          \
   V(CallStaticFunction)                                                        \
   V(OptimizeFunction)                                                          \
   V(InvokeDartCode)                                                            \
@@ skipping 28 matching lines @@
   V(Subtype2TestCache)                                                         \
   V(Subtype3TestCache)                                                         \
   V(CallClosureNoSuchMethod)                                                   \
   V(FrameAwaitingMaterialization)
 
 #else
 #define VM_STUB_CODE_LIST(V)                                                   \
   V(LazyCompile)                                                               \
   V(OptimizeFunction)                                                          \
   V(RunExceptionHandler)                                                       \
+  V(DeoptForRewind)                                                            \
   V(FixCallersTarget)                                                          \
   V(Deoptimize)                                                                \
   V(DeoptimizeLazyFromReturn)                                                  \
   V(DeoptimizeLazyFromThrow)                                                   \
   V(FrameAwaitingMaterialization)
 
 #endif  // !defined(TARGET_ARCH_DBC)
 
 // Is it permitted for the stubs above to refer to Object::null(), which is
 // allocated in the VM isolate and shared across all isolates.
@@ skipping 100 matching lines @@
       Token::Kind kind,
       bool optimized = false);
   static void GenerateUsageCounterIncrement(Assembler* assembler,
                                             Register temp_reg);
   static void GenerateOptimizedUsageCounterIncrement(Assembler* assembler);
 };
 
 
 enum DeoptStubKind { kLazyDeoptFromReturn, kLazyDeoptFromThrow, kEagerDeopt };
 
+// Zap value used to indicate unused CODE_REG in deopt.
+static const int64_t kZapCodeReg = 0xf1f1f1f1;
+
+// Zap value used to indicate unused return address in deopt.
+static const int64_t kZapReturnAddress = 0xe1e1e1e1;
+
 }  // namespace dart
 
 #endif  // RUNTIME_VM_STUB_CODE_H_