local-handles-inl.h

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// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef V8_HANDLES_LOCAL_HANDLES_INL_H_
#define V8_HANDLES_LOCAL_HANDLES_INL_H_
 
#include "src/handles/local-handles.h"
// Include the non-inl header before the rest of the headers.
 
#include "src/base/sanitizer/msan.h"
#include "src/execution/isolate.h"
#include "src/execution/local-isolate.h"
 
namespace v8 {
namespace internal {
 
// static
V8_INLINE Address* LocalHandleScope::GetHandle(LocalHeap* local_heap,
                                               Address value) {
  DCHECK(local_heap->IsRunning());
  if (local_heap->is_main_thread())
    return LocalHandleScope::GetMainThreadHandle(local_heap, value);
 
  LocalHandles* handles = local_heap->handles();
  Address* result = handles->scope_.next;
  if (result == handles->scope_.limit) {
    result = handles->AddBlock();
  }
  DCHECK_LT(result, handles->scope_.limit);
  handles->scope_.next++;
  *result = value;
  return result;
}
 
LocalHandleScope::LocalHandleScope(LocalIsolate* local_isolate)
    : LocalHandleScope(local_isolate->heap()) {}
 
LocalHandleScope::LocalHandleScope(LocalHeap* local_heap) {
  DCHECK(local_heap->IsRunning());
 
  if (local_heap->is_main_thread()) {
    OpenMainThreadScope(local_heap);
  } else {
    LocalHandles* handles = local_heap->handles();
    local_heap_ = local_heap;
    prev_next_ = handles->scope_.next;
    prev_limit_ = handles->scope_.limit;
    handles->scope_.level++;
  }
}
 
LocalHandleScope::~LocalHandleScope() {
  if (local_heap_->is_main_thread()) {
#ifdef V8_ENABLE_CHECKS
    VerifyMainThreadScope();
#endif
    CloseMainThreadScope(local_heap_, prev_next_, prev_limit_);
  } else {
    CloseScope(local_heap_, prev_next_, prev_limit_);
  }
}
 
template <typename T, template <typename> typename HandleType>
  requires(std::is_convertible_v<HandleType<T>, DirectHandle<T>>)
HandleType<T> LocalHandleScope::CloseAndEscape(HandleType<T> handle_value) {
  HandleScopeData* current;
  Tagged<T> value = *handle_value;
  // Throw away all handles in the current scope.
  if (local_heap_->is_main_thread()) {
#ifdef V8_ENABLE_CHECKS
    VerifyMainThreadScope();
#endif
    current = local_heap_->heap()->isolate()->handle_scope_data();
    CloseMainThreadScope(local_heap_, prev_next_, prev_limit_);
  } else {
    current = &local_heap_->handles()->scope_;
    CloseScope(local_heap_, prev_next_, prev_limit_);
  }
  // Allocate one handle in the parent scope.
  DCHECK(current->level > current->sealed_level);
  HandleType<T> result(value, local_heap_);
  // Reinitialize the current scope (so that it's ready
  // to be used or closed again).
  prev_next_ = current->next;
  prev_limit_ = current->limit;
  current->level++;
  return result;
}
 
void LocalHandleScope::CloseScope(LocalHeap* local_heap, Address* prev_next,
                                  Address* prev_limit) {
  LocalHandles* handles = local_heap->handles();
  Address* old_limit = handles->scope_.limit;
 
  handles->scope_.next = prev_next;
  handles->scope_.limit = prev_limit;
  handles->scope_.level--;
 
  if (old_limit != handles->scope_.limit) {
    handles->RemoveUnusedBlocks();
    old_limit = handles->scope_.limit;
  }
 
#ifdef ENABLE_LOCAL_HANDLE_ZAPPING
  LocalHandles::ZapRange(handles->scope_.next, old_limit);
#endif
 
  MSAN_ALLOCATED_UNINITIALIZED_MEMORY(
      handles->scope_.next,
      static_cast<size_t>(reinterpret_cast<Address>(old_limit) -
                          reinterpret_cast<Address>(handles->scope_.next)));
}
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_HANDLES_LOCAL_HANDLES_INL_H_