WasmTable.h - mozsearch

Enable keyboard shortcuts

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-

 * vim: set ts=8 sts=2 et sw=2 tw=80:

 * Copyright 2016 Mozilla Foundation

 * 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 wasm_table_h

#define wasm_table_h

#include "gc/Policy.h"

#include "wasm/WasmCode.h"

namespace js {

namespace wasm {

// A Table is an indexable array of opaque values. Tables are first-class

// stateful objects exposed to WebAssembly. asm.js also uses Tables to represent

// its homogeneous function-pointer tables.

//

// A table of FuncRef holds FunctionTableElems, which are (code*,instance*)

// pairs, where the instance must be traced.

//

// A table of AnyRef holds pointers, which must be traced.

using TableAnyRefVector = GCVector<HeapPtr<AnyRef>, 0, SystemAllocPolicy>;

class Table : public ShareableBase<Table> {

  using InstanceSet =

      WeakCache<GCHashSet<WeakHeapPtr<WasmInstanceObject*>,

                          StableCellHasher<WeakHeapPtr<WasmInstanceObject*>>,

                          SystemAllocPolicy>>;

  using FuncRefVector = Vector<FunctionTableElem, 0, SystemAllocPolicy>;

  WeakHeapPtr<WasmTableObject*> maybeObject_;

  InstanceSet observers_;

  FuncRefVector functions_;    // either functions_ has data

  TableAnyRefVector objects_;  // or objects_, but not both

  const RefType elemType_;

  const bool isAsmJS_;

  uint32_t length_;

  const Maybe<uint32_t> maximum_;

  template <class>

  friend struct js::MallocProvider;

  Table(JSContext* cx, const TableDesc& desc,

        Handle<WasmTableObject*> maybeObject, FuncRefVector&& functions);

  Table(JSContext* cx, const TableDesc& desc,

        Handle<WasmTableObject*> maybeObject, TableAnyRefVector&& objects);

  void tracePrivate(JSTracer* trc);

  friend class js::WasmTableObject;

 public:

  static RefPtr<Table> create(JSContext* cx, const TableDesc& desc,

                              Handle<WasmTableObject*> maybeObject);

  ~Table();

  void trace(JSTracer* trc);

  RefType elemType() const { return elemType_; }

  TableRepr repr() const { return elemType_.tableRepr(); }

  bool isAsmJS() const {

    MOZ_ASSERT(elemType_.isFuncHierarchy());

    return isAsmJS_;

  bool isFunction() const { return elemType().isFuncHierarchy(); }

  uint32_t length() const { return length_; }

  Maybe<uint32_t> maximum() const { return maximum_; }

  // Raw pointer to the table for use in TableInstanceData.

  uint8_t* instanceElements() const;

  // set/get/fillFuncRef is allowed only on table-of-funcref.

  // get/fillAnyRef is allowed only on table-of-anyref.

  // setNull is allowed on either.

  const FunctionTableElem& getFuncRef(uint32_t index) const;

  [[nodiscard]] bool getFuncRef(JSContext* cx, uint32_t index,

                                MutableHandleFunction fun) const;

  void setFuncRef(uint32_t index, JSFunction* func);

  void setFuncRef(uint32_t index, void* code, Instance* instance);

  void fillFuncRef(uint32_t index, uint32_t fillCount, FuncRef ref,

                   JSContext* cx);

  AnyRef getAnyRef(uint32_t index) const;

  void setAnyRef(uint32_t index, AnyRef ref);

  void fillAnyRef(uint32_t index, uint32_t fillCount, AnyRef ref);

  // Sets ref automatically using the correct setter depending on the ref and

  // table type (setNull, setFuncRef, or setAnyRef)

  void setRef(uint32_t index, AnyRef ref);

  // Get the element at index and convert it to a JS value.

  [[nodiscard]] bool getValue(JSContext* cx, uint32_t index,

                              MutableHandleValue result) const;

  void setNull(uint32_t index);

  // Copy entry from |srcTable| at |srcIndex| to this table at |dstIndex|.  Used

  // by table.copy.  May OOM if it needs to box up a function during an upcast.

  [[nodiscard]] bool copy(JSContext* cx, const Table& srcTable,

                          uint32_t dstIndex, uint32_t srcIndex);

  // grow() returns (uint32_t)-1 if it could not grow.

  [[nodiscard]] uint32_t grow(uint32_t delta);

  [[nodiscard]] bool movingGrowable() const;

  [[nodiscard]] bool addMovingGrowObserver(JSContext* cx,

                                           WasmInstanceObject* instance);

  void fillUninitialized(uint32_t index, uint32_t fillCount, HandleAnyRef ref,

                         JSContext* cx);

#ifdef DEBUG

  void assertRangeNull(uint32_t index, uint32_t length) const;

  void assertRangeNotNull(uint32_t index, uint32_t length) const;

#endif  // DEBUG

  // about:memory reporting:

  size_t sizeOfExcludingThis(MallocSizeOf mallocSizeOf) const;

  size_t gcMallocBytes() const;

};

using SharedTable = RefPtr<Table>;

using SharedTableVector = Vector<SharedTable, 0, SystemAllocPolicy>;

}  // namespace wasm

}  // namespace js

#endif  // wasm_table_h