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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ART_RUNTIME_MANAGED_STACK_H_
     18 #define ART_RUNTIME_MANAGED_STACK_H_
     19 
     20 #include <cstring>
     21 #include <stdint.h>
     22 #include <string>
     23 
     24 #include "base/logging.h"
     25 #include "base/macros.h"
     26 #include "base/mutex.h"
     27 
     28 namespace art {
     29 
     30 namespace mirror {
     31 class Object;
     32 }  // namespace mirror
     33 
     34 class ArtMethod;
     35 class ShadowFrame;
     36 template <typename T> class StackReference;
     37 
     38 // The managed stack is used to record fragments of managed code stacks. Managed code stacks
     39 // may either be shadow frames or lists of frames using fixed frame sizes. Transition records are
     40 // necessary for transitions between code using different frame layouts and transitions into native
     41 // code.
     42 class PACKED(4) ManagedStack {
     43  public:
     44   ManagedStack()
     45       : top_quick_frame_(nullptr), link_(nullptr), top_shadow_frame_(nullptr) {}
     46 
     47   void PushManagedStackFragment(ManagedStack* fragment) {
     48     // Copy this top fragment into given fragment.
     49     memcpy(fragment, this, sizeof(ManagedStack));
     50     // Clear this fragment, which has become the top.
     51     memset(this, 0, sizeof(ManagedStack));
     52     // Link our top fragment onto the given fragment.
     53     link_ = fragment;
     54   }
     55 
     56   void PopManagedStackFragment(const ManagedStack& fragment) {
     57     DCHECK(&fragment == link_);
     58     // Copy this given fragment back to the top.
     59     memcpy(this, &fragment, sizeof(ManagedStack));
     60   }
     61 
     62   ManagedStack* GetLink() const {
     63     return link_;
     64   }
     65 
     66   ArtMethod** GetTopQuickFrame() const {
     67     return top_quick_frame_;
     68   }
     69 
     70   void SetTopQuickFrame(ArtMethod** top) {
     71     DCHECK(top_shadow_frame_ == nullptr);
     72     top_quick_frame_ = top;
     73   }
     74 
     75   static size_t TopQuickFrameOffset() {
     76     return OFFSETOF_MEMBER(ManagedStack, top_quick_frame_);
     77   }
     78 
     79   ALWAYS_INLINE ShadowFrame* PushShadowFrame(ShadowFrame* new_top_frame);
     80   ALWAYS_INLINE ShadowFrame* PopShadowFrame();
     81 
     82   ShadowFrame* GetTopShadowFrame() const {
     83     return top_shadow_frame_;
     84   }
     85 
     86   void SetTopShadowFrame(ShadowFrame* top) {
     87     DCHECK(top_quick_frame_ == nullptr);
     88     top_shadow_frame_ = top;
     89   }
     90 
     91   static size_t TopShadowFrameOffset() {
     92     return OFFSETOF_MEMBER(ManagedStack, top_shadow_frame_);
     93   }
     94 
     95   size_t NumJniShadowFrameReferences() const REQUIRES_SHARED(Locks::mutator_lock_);
     96 
     97   bool ShadowFramesContain(StackReference<mirror::Object>* shadow_frame_entry) const;
     98 
     99  private:
    100   ArtMethod** top_quick_frame_;
    101   ManagedStack* link_;
    102   ShadowFrame* top_shadow_frame_;
    103 };
    104 
    105 }  // namespace art
    106 
    107 #endif  // ART_RUNTIME_MANAGED_STACK_H_
    108