runtime/vm/code_patcher.h

// Copyright (c) 2012, 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.
// Class for patching compiled code.

#ifndef RUNTIME_VM_CODE_PATCHER_H_
#define RUNTIME_VM_CODE_PATCHER_H_

#include "vm/allocation.h"
#include "vm/native_entry.h"

namespace dart {

// Forward declaration.
class Code;
class ICData;
class RawArray;
class RawCode;
class RawFunction;
class RawObject;

// Stack-allocated class to create a scope where the specified region
// [address, address + size] has write access enabled. This is used
// when patching generated code. Access is reset to read-execute in
// the destructor of this scope.
class WritableInstructionsScope : public ValueObject {
 public:
  WritableInstructionsScope(uword address, intptr_t size);
  ~WritableInstructionsScope();

 private:
  const uword address_;
  const intptr_t size_;
};

class CodePatcher : public AllStatic {
 public:
  // Dart static calls have a distinct, machine-dependent code pattern.

  // Patch static call before return_address in given code to the new target.
  static void PatchStaticCallAt(uword return_address,
                                const Code& code,
                                const Code& new_target);

  // Return the target address of the static call before return_address
  // in given code.
  static RawCode* GetStaticCallTargetAt(uword return_address, const Code& code);

  // Get instance call information.  Returns the call target and sets each
  // of the output parameters ic_data and arguments_descriptor if they are
  // non-NULL.
  static RawCode* GetInstanceCallAt(uword return_address,
                                    const Code& code,
                                    ICData* ic_data);

  // Return target of an unoptimized static call and its ICData object
  // (calls target via a stub).
  static RawFunction* GetUnoptimizedStaticCallAt(uword return_address,
                                                 const Code& code,
                                                 ICData* ic_data);

  static void InsertDeoptimizationCallAt(uword start);

  static void PatchPoolPointerCallAt(uword return_address,
                                     const Code& code,
                                     const Code& new_target);

  static void PatchSwitchableCallAt(uword return_address,
                                    const Code& caller_code,
                                    const Object& data,
                                    const Code& target);
  static RawObject* GetSwitchableCallDataAt(uword return_address,
                                            const Code& caller_code);
  static RawCode* GetSwitchableCallTargetAt(uword return_address,
                                            const Code& caller_code);

#if defined(TARGET_ARCH_DBC)
  static NativeFunctionWrapper GetNativeCallAt(uword return_address,
                                               const Code& code,
                                               NativeFunction* target);
#else
  static RawCode* GetNativeCallAt(uword return_address,
                                  const Code& code,
                                  NativeFunction* target);
#endif

#if defined(TARGET_ARCH_DBC)
  static void PatchNativeCallAt(uword return_address,
                                const Code& code,
                                NativeFunction target,
                                NativeFunctionWrapper trampoline);
#else
  static void PatchNativeCallAt(uword return_address,
                                const Code& code,
                                NativeFunction target,
                                const Code& trampoline);
#endif

  static intptr_t GetSubtypeTestCachePoolIndex(uword return_address);
};

// Beginning from [end - size] we compare [size] bytes with [pattern]. All
// [0..255] values in [pattern] have to match, negative values are skipped.
//
// Example pattern: `[0x3d, 0x8b, -1, -1]`.
bool MatchesPattern(uword end, const int16_t* pattern, intptr_t size);

class KBCPatcher : public AllStatic {
 public:
  static NativeFunctionWrapper GetNativeCallAt(uword return_address,
                                               const Bytecode& bytecode,
                                               NativeFunction* function);

  static void PatchNativeCallAt(uword return_address,
                                const Bytecode& bytecode,
                                NativeFunction function,
                                NativeFunctionWrapper trampoline);
};

}  // namespace dart

#endif  // RUNTIME_VM_CODE_PATCHER_H_