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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_MANAGED_STACK_H_
#define ART_RUNTIME_MANAGED_STACK_H_
#include <cstdint>
#include <cstring>
#include <string>
#include <android-base/logging.h>
#include "base/locks.h"
#include "base/macros.h"
#include "base/bit_utils.h"
namespace art {
namespace mirror {
class Object;
} // namespace mirror
class ArtMethod;
class ShadowFrame;
template <typename T> class StackReference;
// The managed stack is used to record fragments of managed code stacks. Managed code stacks
// may either be shadow frames or lists of frames using fixed frame sizes. Transition records are
// necessary for transitions between code using different frame layouts and transitions into native
// code.
class PACKED(4) ManagedStack {
public:
ManagedStack()
: tagged_top_quick_frame_(TaggedTopQuickFrame::CreateNotTagged(nullptr)),
link_(nullptr),
top_shadow_frame_(nullptr) {}
void PushManagedStackFragment(ManagedStack* fragment) {
// Copy this top fragment into given fragment.
memcpy(fragment, this, sizeof(ManagedStack));
// Clear this fragment, which has become the top.
memset(this, 0, sizeof(ManagedStack));
// Link our top fragment onto the given fragment.
link_ = fragment;
}
void PopManagedStackFragment(const ManagedStack& fragment) {
DCHECK(&fragment == link_);
// Copy this given fragment back to the top.
memcpy(this, &fragment, sizeof(ManagedStack));
}
ManagedStack* GetLink() const {
return link_;
}
ArtMethod** GetTopQuickFrameKnownNotTagged() const {
return tagged_top_quick_frame_.GetSpKnownNotTagged();
}
ArtMethod** GetTopQuickFrame() const {
return tagged_top_quick_frame_.GetSp();
}
bool GetTopQuickFrameTag() const {
return tagged_top_quick_frame_.GetTag();
}
bool HasTopQuickFrame() const {
return tagged_top_quick_frame_.GetTaggedSp() != 0u;
}
void SetTopQuickFrame(ArtMethod** top) {
DCHECK(top_shadow_frame_ == nullptr);
DCHECK_ALIGNED(top, 4u);
tagged_top_quick_frame_ = TaggedTopQuickFrame::CreateNotTagged(top);
}
void SetTopQuickFrameTagged(ArtMethod** top) {
DCHECK(top_shadow_frame_ == nullptr);
DCHECK_ALIGNED(top, 4u);
tagged_top_quick_frame_ = TaggedTopQuickFrame::CreateTagged(top);
}
static constexpr size_t TaggedTopQuickFrameOffset() {
return OFFSETOF_MEMBER(ManagedStack, tagged_top_quick_frame_);
}
ALWAYS_INLINE ShadowFrame* PushShadowFrame(ShadowFrame* new_top_frame);
ALWAYS_INLINE ShadowFrame* PopShadowFrame();
ShadowFrame* GetTopShadowFrame() const {
return top_shadow_frame_;
}
bool HasTopShadowFrame() const {
return GetTopShadowFrame() != nullptr;
}
void SetTopShadowFrame(ShadowFrame* top) {
DCHECK_EQ(tagged_top_quick_frame_.GetTaggedSp(), 0u);
top_shadow_frame_ = top;
}
static size_t TopShadowFrameOffset() {
return OFFSETOF_MEMBER(ManagedStack, top_shadow_frame_);
}
size_t NumJniShadowFrameReferences() const REQUIRES_SHARED(Locks::mutator_lock_);
bool ShadowFramesContain(StackReference<mirror::Object>* shadow_frame_entry) const;
private:
// Encodes the top quick frame (which must be at least 4-byte aligned)
// and a flag that marks the GenericJNI trampoline.
class TaggedTopQuickFrame {
public:
static TaggedTopQuickFrame CreateNotTagged(ArtMethod** sp) {
DCHECK_ALIGNED(sp, 4u);
return TaggedTopQuickFrame(reinterpret_cast<uintptr_t>(sp));
}
static TaggedTopQuickFrame CreateTagged(ArtMethod** sp) {
DCHECK_ALIGNED(sp, 4u);
return TaggedTopQuickFrame(reinterpret_cast<uintptr_t>(sp) | 1u);
}
// Get SP known to be not tagged and non-null.
ArtMethod** GetSpKnownNotTagged() const {
DCHECK(!GetTag());
DCHECK_NE(tagged_sp_, 0u);
return reinterpret_cast<ArtMethod**>(tagged_sp_);
}
ArtMethod** GetSp() const {
return reinterpret_cast<ArtMethod**>(tagged_sp_ & ~static_cast<uintptr_t>(1u));
}
bool GetTag() const {
return (tagged_sp_ & 1u) != 0u;
}
uintptr_t GetTaggedSp() const {
return tagged_sp_;
}
private:
explicit TaggedTopQuickFrame(uintptr_t tagged_sp) : tagged_sp_(tagged_sp) { }
uintptr_t tagged_sp_;
};
static_assert(sizeof(TaggedTopQuickFrame) == sizeof(uintptr_t), "TaggedTopQuickFrame size check");
TaggedTopQuickFrame tagged_top_quick_frame_;
ManagedStack* link_;
ShadowFrame* top_shadow_frame_;
};
} // namespace art
#endif // ART_RUNTIME_MANAGED_STACK_H_
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