[wasm] Support for restricted table imports.

This CL implements basic table import functionality.

Missing: growing of tables (WebAssembly.Grow) doesn't change dispatch tables
Missing: allowing larger table imports than minimum size

R=rossberg@chromium.org,bradnelson@chromium.org
BUG=v8:5507

Review-Url: https://codereview.chromium.org/2454503005
Cr-Commit-Position: refs/heads/master@{#40661}

src/compiler/wasm-compiler.cc

@@ -298,6 +298,7 @@ WasmGraphBuilder::WasmGraphBuilder(
       mem_buffer_(nullptr),
       mem_size_(nullptr),
       function_tables_(zone),
+      function_table_sizes_(zone),
       control_(nullptr),
       effect_(nullptr),
       cur_buffer_(def_buffer_),
@@ -1712,7 +1713,7 @@ Node* WasmGraphBuilder::GrowMemory(Node* input) {
       graph(), jsgraph()->common(),
       graph()->NewNode(
           jsgraph()->machine()->Uint32LessThanOrEqual(), input,
-          jsgraph()->Uint32Constant(wasm::WasmModule::kMaxMemPages)),
+          jsgraph()->Uint32Constant(wasm::WasmModule::kV8MaxPages)),
       BranchHint::kTrue);
 
   check_input_range.Chain(*control_);
@@ -2154,28 +2155,17 @@ Node* WasmGraphBuilder::CallDirect(uint32_t index, Node** args, Node*** rets,
   return BuildWasmCall(sig, args, rets, position);
 }
 
-Node* WasmGraphBuilder::CallIndirect(uint32_t index, Node** args, Node*** rets,
+Node* WasmGraphBuilder::CallIndirect(uint32_t sig_index, Node** args,
+                                     Node*** rets,
                                      wasm::WasmCodePosition position) {
   DCHECK_NOT_NULL(args[0]);
   DCHECK(module_ && module_->instance);
 
-  MachineOperatorBuilder* machine = jsgraph()->machine();
-
-  // Compute the code object by loading it from the function table.
-  Node* key = args[0];
-
   // Assume only one table for now.
-  DCHECK_LE(module_->instance->function_tables.size(), 1u);
-  // Bounds check the index.
-  uint32_t table_size =
-      module_->IsValidTable(0) ? module_->GetTable(0)->max_size : 0;
-  wasm::FunctionSig* sig = module_->GetSignature(index);
-  if (table_size > 0) {
-    // Bounds check against the table size.
-    Node* size = Uint32Constant(table_size);
-    Node* in_bounds = graph()->NewNode(machine->Uint32LessThan(), key, size);
-    trap_->AddTrapIfFalse(wasm::kTrapFuncInvalid, in_bounds, position);
-  } else {
+  uint32_t table_index = 0;
+  wasm::FunctionSig* sig = module_->GetSignature(sig_index);
+
+  if (!module_->IsValidTable(table_index)) {
     // No function table. Generate a trap and return a constant.
     trap_->AddTrapIfFalse(wasm::kTrapFuncInvalid, Int32Constant(0), position);
     (*rets) = Buffer(sig->return_count());
@@ -2184,7 +2174,16 @@ Node* WasmGraphBuilder::CallIndirect(uint32_t index, Node** args, Node*** rets,
     }
     return trap_->GetTrapValue(sig);
   }
-  Node* table = FunctionTable(0);
+
+  EnsureFunctionTableNodes();
+  MachineOperatorBuilder* machine = jsgraph()->machine();
+  Node* key = args[0];
+
+  // Bounds check against the table size.
+  Node* size = function_table_sizes_[table_index];
+  Node* in_bounds = graph()->NewNode(machine->Uint32LessThan(), key, size);
+  trap_->AddTrapIfFalse(wasm::kTrapFuncInvalid, in_bounds, position);
+  Node* table = function_tables_[table_index];
 
   // Load signature from the table and check.
   // The table is a FixedArray; signatures are encoded as SMIs.
@@ -2208,6 +2207,7 @@ Node* WasmGraphBuilder::CallIndirect(uint32_t index, Node** args, Node*** rets,
   }
 
   // Load code object from the table.
+  uint32_t table_size = module_->module->function_tables[table_index].min_size;
   uint32_t offset = fixed_offset + kPointerSize * table_size;
   Node* load_code = graph()->NewNode(
       machine->Load(MachineType::AnyTagged()), table,
@@ -2854,17 +2854,15 @@ Node* WasmGraphBuilder::MemSize(uint32_t offset) {
   }
 }
 
-Node* WasmGraphBuilder::FunctionTable(uint32_t index) {
-  DCHECK(module_ && module_->instance &&
-         index < module_->instance->function_tables.size());
-  if (!function_tables_.size()) {
-    for (size_t i = 0; i < module_->instance->function_tables.size(); ++i) {
-      DCHECK(!module_->instance->function_tables[i].is_null());
-      function_tables_.push_back(
-          HeapConstant(module_->instance->function_tables[i]));
-    }
+void WasmGraphBuilder::EnsureFunctionTableNodes() {
+  if (function_tables_.size() > 0) return;
+  for (size_t i = 0; i < module_->instance->function_tables.size(); ++i) {
+    auto handle = module_->instance->function_tables[i];
+    DCHECK(!handle.is_null());
+    function_tables_.push_back(HeapConstant(handle));
+    uint32_t table_size = module_->module->function_tables[i].min_size;
+    function_table_sizes_.push_back(Uint32Constant(table_size));
   }
-  return function_tables_[index];
 }
 
 Node* WasmGraphBuilder::GetGlobal(uint32_t index) {

src/compiler/wasm-compiler.h

@@ -170,7 +170,7 @@ class WasmGraphBuilder {
   Node* ToJS(Node* node, wasm::LocalType type);
   Node* FromJS(Node* node, Node* context, wasm::LocalType type);
   Node* Invert(Node* node);
-  Node* FunctionTable(uint32_t index);
+  void EnsureFunctionTableNodes();
 
   //-----------------------------------------------------------------------
   // Operations that concern the linear memory.
@@ -219,6 +219,7 @@ class WasmGraphBuilder {
   Node* mem_buffer_;
   Node* mem_size_;
   NodeVector function_tables_;
+  NodeVector function_table_sizes_;
   Node** control_;
   Node** effect_;
   Node** cur_buffer_;

src/wasm/module-decoder.cc

@@ -31,8 +31,6 @@ namespace {
 const char* kNameString = "name";
 const size_t kNameStringLength = 4;
 
-static const uint32_t kMaxTableSize = 1 << 28;
-
 LocalType TypeOf(const WasmModule* module, const WasmInitExpr& expr) {
   switch (expr.kind) {
     case WasmInitExpr::kNone:
@@ -311,19 +309,22 @@ class ModuleDecoder : public Decoder {
             // ===== Imported table ==========================================
             import->index =
                 static_cast<uint32_t>(module->function_tables.size());
-            module->function_tables.push_back(
-                {0, 0, std::vector<int32_t>(), true, false, SignatureMap()});
+            module->function_tables.push_back({0, 0, false,
+                                               std::vector<int32_t>(), true,
+                                               false, SignatureMap()});
             expect_u8("element type", kWasmAnyFunctionTypeForm);
             WasmIndirectFunctionTable* table = &module->function_tables.back();
-            consume_resizable_limits("element count", "elements", kMaxTableSize,
-                                     &table->size, &table->max_size);
+            consume_resizable_limits(
+                "element count", "elements", WasmModule::kV8MaxTableSize,
+                &table->min_size, &table->has_max, &table->max_size);
             break;
           }
           case kExternalMemory: {
             // ===== Imported memory =========================================
-            consume_resizable_limits(
-                "memory", "pages", WasmModule::kMaxLegalPages,
-                &module->min_mem_pages, &module->max_mem_pages);
+            bool has_max = false;
+            consume_resizable_limits("memory", "pages", WasmModule::kV8MaxPages,
+                                     &module->min_mem_pages, &has_max,
+                                     &module->max_mem_pages);
             break;
           }
           case kExternalGlobal: {
@@ -375,15 +376,16 @@ class ModuleDecoder : public Decoder {
         error(pos, pos, "invalid table count %d, maximum 1", table_count);
       }
       if (module->function_tables.size() < 1) {
-        module->function_tables.push_back(
-            {0, 0, std::vector<int32_t>(), false, false, SignatureMap()});
+        module->function_tables.push_back({0, 0, false, std::vector<int32_t>(),
+                                           false, false, SignatureMap()});
       }
 
       for (uint32_t i = 0; ok() && i < table_count; i++) {
         WasmIndirectFunctionTable* table = &module->function_tables.back();
         expect_u8("table type", kWasmAnyFunctionTypeForm);
-        consume_resizable_limits("table elements", "elements", kMaxUInt32,
-                                 &table->size, &table->max_size);
+        consume_resizable_limits("table elements", "elements",
+                                 WasmModule::kV8MaxTableSize, &table->min_size,
+                                 &table->has_max, &table->max_size);
       }
       section_iter.advance();
     }
@@ -398,8 +400,9 @@ class ModuleDecoder : public Decoder {
       }
 
       for (uint32_t i = 0; ok() && i < memory_count; i++) {
-        consume_resizable_limits("memory", "pages", WasmModule::kMaxLegalPages,
-                                 &module->min_mem_pages,
+        bool has_max = false;
+        consume_resizable_limits("memory", "pages", WasmModule::kV8MaxPages,
+                                 &module->min_mem_pages, &has_max,
                                  &module->max_mem_pages);
       }
       section_iter.advance();
@@ -623,7 +626,6 @@ class ModuleDecoder : public Decoder {
 
     if (ok()) {
       CalculateGlobalOffsets(module);
-      PreinitializeIndirectFunctionTables(module);
     }
     const WasmModule* finished_module = module;
     ModuleResult result = toResult(finished_module);
@@ -749,30 +751,6 @@ class ModuleDecoder : public Decoder {
     module->globals_size = offset;
   }
 
-  // TODO(titzer): this only works without overlapping initializations from
-  // global bases for entries
-  void PreinitializeIndirectFunctionTables(WasmModule* module) {
-    // Fill all tables with invalid entries first.
-    for (WasmIndirectFunctionTable& table : module->function_tables) {
-      table.values.resize(table.size);
-      for (size_t i = 0; i < table.size; i++) {
-        table.values[i] = kInvalidFunctionIndex;
-      }
-    }
-    for (WasmTableInit& init : module->table_inits) {
-      if (init.offset.kind != WasmInitExpr::kI32Const) continue;
-      if (init.table_index >= module->function_tables.size()) continue;
-      WasmIndirectFunctionTable& table =
-          module->function_tables[init.table_index];
-      for (size_t i = 0; i < init.entries.size(); i++) {
-        size_t index = i + init.offset.val.i32_const;
-        if (index < table.values.size()) {
-          table.values[index] = init.entries[i];
-        }
-      }
-    }
-  }
-
   // Verifies the body (code) of a given function.
   void VerifyFunctionBody(uint32_t func_num, ModuleEnv* menv,
                           WasmFunction* function) {
@@ -866,29 +844,33 @@ class ModuleDecoder : public Decoder {
 
   void consume_resizable_limits(const char* name, const char* units,
                                 uint32_t max_value, uint32_t* initial,
-                                uint32_t* maximum) {
+                                bool* has_max, uint32_t* maximum) {
     uint32_t flags = consume_u32v("resizable limits flags");
     const byte* pos = pc();
     *initial = consume_u32v("initial size");
+    *has_max = false;
     if (*initial > max_value) {
       error(pos, pos,
-            "initial %s size (%u %s) is larger than maximum allowable (%u)",
+            "initial %s size (%u %s) is larger than implementation limit (%u)",
             name, *initial, units, max_value);
     }
     if (flags & 1) {
+      *has_max = true;
       pos = pc();
       *maximum = consume_u32v("maximum size");
       if (*maximum > max_value) {
-        error(pos, pos,
-              "maximum %s size (%u %s) is larger than maximum allowable (%u)",
-              name, *maximum, units, max_value);
+        error(
+            pos, pos,
+            "maximum %s size (%u %s) is larger than implementation limit (%u)",
+            name, *maximum, units, max_value);
       }
       if (*maximum < *initial) {
         error(pos, pos, "maximum %s size (%u %s) is less than initial (%u %s)",
               name, *maximum, units, *initial, units);
       }
     } else {
-      *maximum = 0;
+      *has_max = false;
+      *maximum = max_value;
     }
   }
 

src/wasm/wasm-interpreter.cc

@@ -663,16 +663,13 @@ static inline int32_t ExecuteGrowMemory(uint32_t delta_pages,
                                         WasmInstance* instance) {
   // TODO(ahaas): Move memory allocation to wasm-module.cc for better
   // encapsulation.
-  if (delta_pages > wasm::WasmModule::kMaxMemPages) {
+  if (delta_pages > wasm::WasmModule::kV8MaxPages) {
     return -1;
   }
   uint32_t old_size = instance->mem_size;
   uint32_t new_size;
   byte* new_mem_start;
   if (instance->mem_size == 0) {
-    if (delta_pages > wasm::WasmModule::kMaxMemPages) {
-      return -1;
-    }
     // TODO(gdeepti): Fix bounds check to take into account size of memtype.
     new_size = delta_pages * wasm::WasmModule::kPageSize;
     new_mem_start = static_cast<byte*>(calloc(new_size, sizeof(byte)));
@@ -683,7 +680,7 @@ static inline int32_t ExecuteGrowMemory(uint32_t delta_pages,
     DCHECK_NOT_NULL(instance->mem_start);
     new_size = old_size + delta_pages * wasm::WasmModule::kPageSize;
     if (new_size >
-        wasm::WasmModule::kMaxMemPages * wasm::WasmModule::kPageSize) {
+        wasm::WasmModule::kV8MaxPages * wasm::WasmModule::kPageSize) {
       return -1;
     }
     new_mem_start = static_cast<byte*>(realloc(instance->mem_start, new_size));
@@ -695,9 +692,6 @@ static inline int32_t ExecuteGrowMemory(uint32_t delta_pages,
   }
   instance->mem_start = new_mem_start;
   instance->mem_size = new_size;
-  // realloc
-  // update mem_start
-  // update mem_size
   return static_cast<int32_t>(old_size / WasmModule::kPageSize);
 }
 

src/wasm/wasm-js.cc

@@ -29,6 +29,7 @@ namespace v8 {
 
 static const int kWasmTableArrayFieldIndex = 0;
 static const int kWasmTableMaximumFieldIndex = 1;
+static const int kWasmTableDispatchTablesFieldIndex = 2;
 
 enum WasmMemoryObjectData {
   kWasmMemoryBuffer,
@@ -37,8 +38,8 @@ enum WasmMemoryObjectData {
 };
 
 enum WasmInternalFieldCountData {
-  kWasmTableInternalFieldCount = 2,
-  kWasmMemoryInternalFieldCount
+  kWasmTableInternalFieldCount = 3,
+  kWasmMemoryInternalFieldCount = 3
 };
 
 namespace {
@@ -518,9 +519,19 @@ void WebAssemblyTableSet(const v8::FunctionCallbackInfo<v8::Value>& args) {
     return;
   }
 
-  i::Handle<i::FixedArray>::cast(array)->set(i, *value);
+  i::Handle<i::FixedArray> dispatch_tables(
+      i::FixedArray::cast(
+          receiver->GetInternalField(kWasmTableDispatchTablesFieldIndex)),
+      i_isolate);
+  if (value->IsNull(i_isolate)) {
+    i::wasm::UpdateDispatchTables(i_isolate, dispatch_tables, i,
+                                  i::Handle<i::JSFunction>::null());
+  } else {
+    i::wasm::UpdateDispatchTables(i_isolate, dispatch_tables, i,
+                                  i::Handle<i::JSFunction>::cast(value));
+  }
 
-  // TODO(titzer): update relevant instances.
+  i::Handle<i::FixedArray>::cast(array)->set(i, *value);
 }
 
 void WebAssemblyMemoryGrow(const v8::FunctionCallbackInfo<v8::Value>& args) {
@@ -612,26 +623,60 @@ i::Handle<i::JSObject> i::WasmJs::CreateWasmMemoryObject(
 
 i::Handle<i::JSObject> i::WasmJs::CreateWasmTableObject(
     i::Isolate* i_isolate, uint32_t initial, bool has_maximum, uint32_t maximum,
-    i::Handle<i::FixedArray>* array) {
+    i::Handle<i::FixedArray>* js_functions) {
   i::Handle<i::JSFunction> table_ctor(
       i_isolate->native_context()->wasm_table_constructor());
   i::Handle<i::JSObject> table_obj =
       i_isolate->factory()->NewJSObject(table_ctor);
-  *array = i_isolate->factory()->NewFixedArray(initial);
+  *js_functions = i_isolate->factory()->NewFixedArray(initial);
   i::Object* null = i_isolate->heap()->null_value();
   // TODO(titzer): consider moving FixedArray to size_t.
-  for (int i = 0; i < static_cast<int>(initial); ++i) (*array)->set(i, null);
-  table_obj->SetInternalField(kWasmTableArrayFieldIndex, *(*array));
+  for (int i = 0; i < static_cast<int>(initial); ++i) {
+    (*js_functions)->set(i, null);
+  }
+  table_obj->SetInternalField(kWasmTableArrayFieldIndex, *(*js_functions));
   table_obj->SetInternalField(
       kWasmTableMaximumFieldIndex,
       has_maximum
           ? static_cast<i::Object*>(i::Smi::FromInt(maximum))
           : static_cast<i::Object*>(i_isolate->heap()->undefined_value()));
+  Handle<FixedArray> dispatch_tables = i_isolate->factory()->NewFixedArray(0);
+  table_obj->SetInternalField(kWasmTableDispatchTablesFieldIndex,
+                              *dispatch_tables);
   i::Handle<i::Symbol> table_sym(i_isolate->native_context()->wasm_table_sym());
   i::Object::SetProperty(table_obj, table_sym, table_obj, i::STRICT).Check();
   return table_obj;
 }
 
+i::Handle<i::FixedArray> i::WasmJs::AddWasmTableDispatchTable(
+    i::Isolate* i_isolate, i::Handle<i::JSObject> table_obj,
+    i::Handle<i::JSObject> instance, int table_index,
+    i::Handle<i::FixedArray> dispatch_table) {
+  DCHECK(IsWasmTableObject(i_isolate, table_obj));
+  i::Handle<i::FixedArray> dispatch_tables(
+      i::FixedArray::cast(
+          table_obj->GetInternalField(kWasmTableDispatchTablesFieldIndex)),
+      i_isolate);
+  DCHECK_EQ(0, dispatch_tables->length() % 3);
+
+  if (instance.is_null()) return dispatch_tables;
+  // TODO(titzer): use weak cells here to avoid leaking instances.
+
+  // Grow the dispatch table and add a new pair at the end.
+  i::Handle<i::FixedArray> new_dispatch_tables =
+      i_isolate->factory()->CopyFixedArrayAndGrow(dispatch_tables, 3);
+
+  new_dispatch_tables->set(dispatch_tables->length() + 0, *instance);
+  new_dispatch_tables->set(dispatch_tables->length() + 1,
+                           Smi::FromInt(table_index));
+  new_dispatch_tables->set(dispatch_tables->length() + 2, *dispatch_table);
+
+  table_obj->SetInternalField(kWasmTableDispatchTablesFieldIndex,
+                              *new_dispatch_tables);
+
+  return new_dispatch_tables;
+}
+
 // TODO(titzer): we use the API to create the function template because the
 // internal guts are too ugly to replicate here.
 static i::Handle<i::FunctionTemplateInfo> NewTemplate(i::Isolate* i_isolate,
@@ -817,17 +862,35 @@ void WasmJs::InstallWasmMapsIfNeeded(Isolate* isolate,
   }
 }
 
-bool WasmJs::IsWasmMemoryObject(Isolate* isolate, Handle<Object> value) {
+static bool HasBrand(i::Handle<i::Object> value, i::Handle<i::Symbol> symbol) {
   if (value->IsJSObject()) {
     i::Handle<i::JSObject> object = i::Handle<i::JSObject>::cast(value);
-    i::Handle<i::Symbol> sym(isolate->context()->wasm_memory_sym(), isolate);
-    Maybe<bool> has_brand = i::JSObject::HasOwnProperty(object, sym);
+    Maybe<bool> has_brand = i::JSObject::HasOwnProperty(object, symbol);
     if (has_brand.IsNothing()) return false;
     if (has_brand.ToChecked()) return true;
   }
   return false;
 }
 
+bool WasmJs::IsWasmMemoryObject(Isolate* isolate, Handle<Object> value) {
+  i::Handle<i::Symbol> symbol(isolate->context()->wasm_memory_sym(), isolate);
+  return HasBrand(value, symbol);
+}
+
+bool WasmJs::IsWasmTableObject(Isolate* isolate, Handle<Object> value) {
+  i::Handle<i::Symbol> symbol(isolate->context()->wasm_table_sym(), isolate);
+  return HasBrand(value, symbol);
+}
+
+Handle<FixedArray> WasmJs::GetWasmTableFunctions(Isolate* isolate,
+                                                 Handle<JSObject> value) {
+  DCHECK(IsWasmTableObject(isolate, value));
+  Handle<Object> arr(
+      JSObject::cast(*value)->GetInternalField(kWasmTableArrayFieldIndex),
+      isolate);
+  return Handle<FixedArray>::cast(arr);
+}
+
 Handle<JSArrayBuffer> WasmJs::GetWasmMemoryArrayBuffer(Isolate* isolate,
                                                        Handle<Object> value) {
   DCHECK(IsWasmMemoryObject(isolate, value));
@@ -847,7 +910,7 @@ uint32_t WasmJs::GetWasmMemoryMaximumSize(Isolate* isolate,
   DCHECK(IsWasmMemoryObject(isolate, value));
   Object* max_mem =
       JSObject::cast(*value)->GetInternalField(kWasmMemoryMaximum);
-  if (max_mem->IsUndefined(isolate)) return wasm::WasmModule::kMaxMemPages;
+  if (max_mem->IsUndefined(isolate)) return wasm::WasmModule::kV8MaxPages;
   uint32_t max_pages = Smi::cast(max_mem)->value();
   return max_pages;
 }

src/wasm/wasm-js.h

@@ -24,16 +24,25 @@ class WasmJs {
                                       Handle<JSGlobalObject> global,
                                       Handle<Context> context);
 
+  // WebAssembly.Table.
+  static Handle<JSObject> CreateWasmTableObject(
+      Isolate* isolate, uint32_t initial, bool has_maximum, uint32_t maximum,
+      Handle<FixedArray>* js_functions);
+
+  static bool IsWasmTableObject(Isolate* isolate, Handle<Object> value);
+
+  static Handle<FixedArray> GetWasmTableFunctions(Isolate* isolate,
+                                                  Handle<JSObject> object);
+
+  static Handle<FixedArray> AddWasmTableDispatchTable(
+      Isolate* isolate, Handle<JSObject> table_obj, Handle<JSObject> instance,
+      int table_index, Handle<FixedArray> dispatch_table);
+
+  // WebAssembly.Memory
   static Handle<JSObject> CreateWasmMemoryObject(Isolate* isolate,
                                                  Handle<JSArrayBuffer> buffer,
                                                  bool has_maximum, int maximum);
 
-  static Handle<JSObject> CreateWasmTableObject(Isolate* isolate,
-                                                uint32_t initial,
-                                                bool has_maximum,
-                                                uint32_t maximum,
-                                                Handle<FixedArray>* array);
-
   static bool IsWasmMemoryObject(Isolate* isolate, Handle<Object> value);
 
   static Handle<JSArrayBuffer> GetWasmMemoryArrayBuffer(Isolate* isolate,

src/wasm/wasm-module.h

@@ -133,8 +133,10 @@ struct WasmDataSegment {
 
 // Static representation of a wasm indirect call table.
 struct WasmIndirectFunctionTable {
-  uint32_t size;                // initial table size.
+  uint32_t min_size;            // minimum table size.
   uint32_t max_size;            // maximum table size.
+  bool has_max;                 // true if there is a maximum size.
+  // TODO(titzer): Move this to WasmInstance. Needed by interpreter only.
   std::vector<int32_t> values;  // function table, -1 indicating invalid.
   bool imported;                // true if imported.
   bool exported;                // true if exported.
@@ -173,9 +175,9 @@ class WasmCompiledModule;
 // Static representation of a module.
 struct V8_EXPORT_PRIVATE WasmModule {
   static const uint32_t kPageSize = 0x10000;    // Page size, 64kb.
-  static const uint32_t kMaxLegalPages = 65536;  // Maximum legal pages
   static const uint32_t kMinMemPages = 1;       // Minimum memory size = 64kb
-  static const uint32_t kMaxMemPages = 16384;   // Maximum memory size =  1gb
+  static const size_t kV8MaxPages = 16384;      // Maximum memory size = 1gb
+  static const size_t kV8MaxTableSize = 16 * 1024 * 1024;
 
   Zone* owned_zone;
   const byte* module_start = nullptr;  // starting address for the module bytes
@@ -557,6 +559,9 @@ int32_t GetInstanceMemorySize(Isolate* isolate, Handle<JSObject> instance);
 int32_t GrowInstanceMemory(Isolate* isolate, Handle<JSObject> instance,
                            uint32_t pages);
 
+void UpdateDispatchTables(Isolate* isolate, Handle<FixedArray> dispatch_tables,
+                          int index, Handle<JSFunction> js_function);
+
 namespace testing {
 
 void ValidateInstancesChain(Isolate* isolate, Handle<JSObject> wasm_module,

test/cctest/wasm/wasm-run-utils.h

@@ -223,10 +223,12 @@ class TestingModule : public ModuleEnv {
 
   void AddIndirectFunctionTable(uint16_t* function_indexes,
                                 uint32_t table_size) {
-    module_.function_tables.push_back({table_size, table_size,
+    module_.function_tables.push_back({table_size, table_size, true,
                                        std::vector<int32_t>(), false, false,
                                        SignatureMap()});
     WasmIndirectFunctionTable& table = module_.function_tables.back();
+    table.min_size = table_size;
+    table.max_size = table_size;
     for (uint32_t i = 0; i < table_size; ++i) {
       table.values.push_back(function_indexes[i]);
       table.map.FindOrInsert(module_.functions[function_indexes[i]].sig);

test/mjsunit/wasm/indirect-tables.js

@@ -30,6 +30,8 @@ function AddFunctions(builder) {
   return {mul: mul, add: add, sub: sub};
 }
 
+function js_div(a, b) { return (a / b) | 0; }
+
 (function ExportedTableTest() {
   print("ExportedTableTest...");
 
@@ -56,8 +58,6 @@ function AddFunctions(builder) {
 
   let module = new WebAssembly.Module(builder.toBuffer());
 
-  function js_div(a, b) { return (a / b) | 0; }
-
   for (let i = 0; i < 5; i++) {
     print(" base = " + i);
     let instance = new WebAssembly.Instance(module, {base: i, js_div: js_div});
@@ -100,3 +100,278 @@ function AddFunctions(builder) {
     assertEquals(-44, exp_div(-88.1, 2));
   }
 })();
+
+
+(function ImportedTableTest() {
+  let kTableSize = 10;
+  print("ImportedTableTest...");
+  var builder = new WasmModuleBuilder();
+
+  let d = builder.addImport("js_div", kSig_i_ii);
+  let f = AddFunctions(builder);
+  builder.setFunctionTableLength(kTableSize);
+  let g = builder.addImportedGlobal("base", undefined, kAstI32);
+  builder.addFunctionTableInit(g, true, [f.mul.index, f.add.index,
+                                         f.sub.index,
+                                         d]);
+  builder.addExportOfKind("table", kExternalTable, 0);
+
+  let m1 = new WebAssembly.Module(builder.toBuffer());
+
+  var builder = new WasmModuleBuilder();
+
+  builder.addImportedTable("table", undefined, kTableSize, kTableSize);
+  builder.addFunction("main", kSig_i_ii)
+    .addBody([
+      kExprI32Const, 33,  // --
+      kExprGetLocal, 0,   // --
+      kExprGetLocal, 1,   // --
+      kExprCallIndirect, 0, kTableZero])  // --
+    .exportAs("main");
+
+  let m2 = new WebAssembly.Module(builder.toBuffer());
+
+  // Run 5 trials at different table bases.
+  for (let i = 0; i < 5; i++) {
+    print(" base = " + i);
+    let i1 = new WebAssembly.Instance(m1, {base: i, js_div: js_div});
+    let table = i1.exports.table;
+    assertEquals(10, table.length);
+    let i2 = new WebAssembly.Instance(m2, {table: table});
+    let main = i2.exports.main;
+
+    for (var j = 0; j < i; j++) {
+      assertThrows(() => main(0, j));
+      assertSame(null, table.get(j));
+    }
+
+    // mul
+    assertEquals("function", typeof table.get(i+0));
+    assertEquals(0, main(0, i+0));
+    assertEquals(66, main(2, i+0));
+
+    // add
+    assertEquals("function", typeof table.get(i+1));
+    assertEquals(33, main(0, i+1));
+    assertEquals(38, main(5, i+1));
+
+    // sub
+    assertEquals("function", typeof table.get(i+2));
+    assertEquals(32, main(1, i+2));
+    assertEquals(28, main(5, i+2));
+
+    // div
+    assertEquals("function", typeof table.get(i+3));
+    assertEquals(8, main(4, i+3));
+    assertEquals(3, main(11, i+3));
+
+    for (var j = i + 4; j < (kTableSize + 5); j++) {
+      assertThrows(x => main(0, j));
+      if (j < kTableSize) assertSame(null, table.get(j));
+    }
+  }
+})();
+
+(function ImportedTableTest() {
+  let kTableSize = 10;
+  print("ManualTableTest...");
+
+  var builder = new WasmModuleBuilder();
+
+  let d = builder.addImport("js_div", kSig_i_ii);
+  builder.addImportedTable("table", undefined, kTableSize, kTableSize);
+  let g = builder.addImportedGlobal("base", undefined, kAstI32);
+  let f = AddFunctions(builder);
+  builder.addFunctionTableInit(g, true, [f.mul.index, f.add.index,
+                                         f.sub.index,
+                                         d]);
+  builder.addFunction("main", kSig_i_ii)
+    .addBody([
+      kExprI32Const, 55,  // --
+      kExprGetLocal, 0,   // --
+      kExprGetLocal, 1,   // --
+      kExprCallIndirect, 0, kTableZero])  // --
+    .exportAs("main");
+
+  let m2 = new WebAssembly.Module(builder.toBuffer());
+
+  // Run 5 trials at different table bases.
+  for (let i = 0; i < 5; i++) {
+    print(" base = " + i);
+    let table = new WebAssembly.Table({element: "anyfunc",
+                                       initial: kTableSize});
+    assertEquals(10, table.length);
+    let i2 = new WebAssembly.Instance(m2, {base: i, table: table,
+                                           js_div: js_div});
+    let main = i2.exports.main;
+
+    for (var j = 0; j < i; j++) {
+      assertThrows(() => main(0, j));
+      assertSame(null, table.get(j));
+    }
+
+    // mul
+    assertEquals("function", typeof table.get(i+0));
+    assertEquals(0, main(0, i+0));
+    assertEquals(110, main(2, i+0));
+
+    // add
+    assertEquals("function", typeof table.get(i+1));
+    assertEquals(55, main(0, i+1));
+    assertEquals(60, main(5, i+1));
+
+    // sub
+    assertEquals("function", typeof table.get(i+2));
+    assertEquals(54, main(1, i+2));
+    assertEquals(50, main(5, i+2));
+
+    // div
+    assertEquals("function", typeof table.get(i+3));
+    assertEquals(13, main(4, i+3));
+    assertEquals(5, main(11, i+3));
+
+    for (var j = i + 4; j < (kTableSize + 5); j++) {
+      assertThrows(x => main(0, j));
+      if (j < kTableSize) assertSame(null, table.get(j));
+    }
+  }
+})();
+
+
+(function CumulativeTest() {
+  print("CumulativeTest...");
+
+  let kTableSize = 10;
+  let table = new WebAssembly.Table({element: "anyfunc", initial: 10});
+
+  var builder = new WasmModuleBuilder();
+
+  builder.addImportedTable("table", undefined, kTableSize, kTableSize);
+  let g = builder.addImportedGlobal("base", undefined, kAstI32);
+  let sig_index = builder.addType(kSig_i_v);
+  builder.addFunction("g", sig_index)
+    .addBody([
+      kExprGetGlobal, g
+    ]);
+  builder.addFunction("main", kSig_i_ii)
+    .addBody([
+      kExprGetLocal, 0,
+      kExprCallIndirect, sig_index, kTableZero])  // --
+    .exportAs("main");
+  builder.addFunctionTableInit(g, true, [g]);
+
+  let module = new WebAssembly.Module(builder.toBuffer());
+
+  for (var i = 0; i < kTableSize; i++) {
+    print(" base = " + i);
+    let instance = new WebAssembly.Instance(module, {base: i, table: table});
+
+    for (var j = 0; j < kTableSize; j++) {
+      let func = table.get(j);
+      if (j > i) {
+        assertSame(null, func);
+        assertTraps(kTrapFuncSigMismatch, () => instance.exports.main(j));
+      } else {
+        assertEquals("function", typeof func);
+        assertEquals(j, func());
+        assertEquals(j, instance.exports.main(j));
+      }
+    }
+  }
+})();
+
+(function TwoWayTest() {
+  print("TwoWayTest...");
+  let kTableSize = 3;
+
+  // Module {m1} defines the table and exports it.
+  var builder = new WasmModuleBuilder();
+  builder.addType(kSig_i_i);
+  builder.addType(kSig_i_ii);
+  var sig_index1 = builder.addType(kSig_i_v);
+  var f1 = builder.addFunction("f1", sig_index1)
+    .addBody([kExprI32Const, 11]);
+
+  builder.addFunction("main", kSig_i_ii)
+    .addBody([
+      kExprGetLocal, 0,   // --
+      kExprCallIndirect, sig_index1, kTableZero])  // --
+    .exportAs("main");
+
+  builder.setFunctionTableLength(kTableSize);
+  builder.addFunctionTableInit(0, false, [f1.index]);
+  builder.addExportOfKind("table", kExternalTable, 0);
+
+  var m1 = new WebAssembly.Module(builder.toBuffer());
+
+  // Module {m2} imports the table and adds {f2}.
+  var builder = new WasmModuleBuilder();
+  builder.addType(kSig_i_ii);
+  var sig_index2 = builder.addType(kSig_i_v);
+  var f2 = builder.addFunction("f2", sig_index2)
+    .addBody([kExprI32Const, 22]);
+
+  builder.addFunction("main", kSig_i_ii)
+    .addBody([
+      kExprGetLocal, 0,   // --
+      kExprCallIndirect, sig_index2, kTableZero])  // --
+    .exportAs("main");
+
+  builder.setFunctionTableLength(kTableSize);
+  builder.addFunctionTableInit(1, false, [f2.index]);
+  builder.addImportedTable("table", undefined, kTableSize, kTableSize);
+
+  var m2 = new WebAssembly.Module(builder.toBuffer());
+
+  assertFalse(sig_index1 == sig_index2);
+
+  var i1 = new WebAssembly.Instance(m1);
+  var i2 = new WebAssembly.Instance(m2, {table: i1.exports.table});
+
+  assertEquals(11, i1.exports.main(0));
+  assertEquals(11, i2.exports.main(0));
+
+  assertEquals(22, i1.exports.main(1));
+  assertEquals(22, i2.exports.main(1));
+
+  assertThrows(() => i1.exports.main(2));
+  assertThrows(() => i2.exports.main(2));
+  assertThrows(() => i1.exports.main(3));
+  assertThrows(() => i2.exports.main(3));
+
+})();
+
+(function MismatchedTableSize() {
+  print("MismatchedTableSize...");
+  let kTableSize = 5;
+
+  for (var expsize = 1; expsize < 4; expsize++) {
+    for (var impsize = 1; impsize < 4; impsize++) {
+      print(" expsize = " + expsize + ", impsize = " + impsize);
+      var builder = new WasmModuleBuilder();
+      builder.setFunctionTableLength(expsize);
+      builder.addExportOfKind("expfoo", kExternalTable, 0);
+
+      let m1 = new WebAssembly.Module(builder.toBuffer());
+
+      var builder = new WasmModuleBuilder();
+      builder.addImportedTable("impfoo", undefined, impsize, impsize);
+
+      let m2 = new WebAssembly.Module(builder.toBuffer());
+
+      var i1 = new WebAssembly.Instance(m1);
+
+      // TODO(titzer): v8 currently requires import table size to match
+      // export table size.
+      var ffi = {impfoo: i1.exports.expfoo};
+      if (expsize == impsize) {
+        var i2 = new WebAssembly.Instance(m2, ffi);
+      } else {
+        assertThrows(() => new WebAssembly.Instance(m2, ffi));
+      }
+    }
+  }
+
+
+
+})();

test/mjsunit/wasm/wasm-module-builder.js

@@ -204,6 +204,12 @@ class WasmModuleBuilder {
     return this;
   }
 
+  addImportedTable(module, name, initial, maximum) {
+    let o = {module: module, name: name, kind: kExternalTable, initial: initial,
+             maximum: maximum};
+    this.imports.push(o);
+  }
+
   addExport(name, index) {
     this.exports.push({name: name, kind: kExternalFunction, index: index});
     return this;
@@ -289,6 +295,12 @@ class WasmModuleBuilder {
             section.emit_u8(has_max ? 1 : 0); // flags
             section.emit_u32v(imp.initial); // initial
             if (has_max) section.emit_u32v(imp.maximum); // maximum
+          } else if (imp.kind == kExternalTable) {
+            section.emit_u8(kWasmAnyFunctionTypeForm);
+            var has_max = (typeof imp.maximum) != "undefined";
+            section.emit_u8(has_max ? 1 : 0); // flags
+            section.emit_u32v(imp.initial); // initial
+            if (has_max) section.emit_u32v(imp.maximum); // maximum
           } else {
             throw new Error("unknown/unsupported import kind " + imp.kind);
           }

test/unittests/wasm/module-decoder-unittest.cc

@@ -510,8 +510,7 @@ TEST_F(WasmModuleVerifyTest, OneIndirectFunction) {
     EXPECT_EQ(1, result.val->signatures.size());
     EXPECT_EQ(1, result.val->functions.size());
     EXPECT_EQ(1, result.val->function_tables.size());
-    EXPECT_EQ(1, result.val->function_tables[0].values.size());
-    EXPECT_EQ(-1, result.val->function_tables[0].values[0]);
+    EXPECT_EQ(1, result.val->function_tables[0].min_size);
   }
   if (result.val) delete result.val;
 }
@@ -537,8 +536,7 @@ TEST_F(WasmModuleVerifyTest, OneIndirectFunction_one_entry) {
     EXPECT_EQ(1, result.val->signatures.size());
     EXPECT_EQ(1, result.val->functions.size());
     EXPECT_EQ(1, result.val->function_tables.size());
-    EXPECT_EQ(1, result.val->function_tables[0].values.size());
-    EXPECT_EQ(0, result.val->function_tables[0].values[0]);
+    EXPECT_EQ(1, result.val->function_tables[0].min_size);
   }
   if (result.val) delete result.val;
 }
@@ -575,10 +573,7 @@ TEST_F(WasmModuleVerifyTest, MultipleIndirectFunctions) {
     EXPECT_EQ(2, result.val->signatures.size());
     EXPECT_EQ(4, result.val->functions.size());
     EXPECT_EQ(1, result.val->function_tables.size());
-    EXPECT_EQ(8, result.val->function_tables[0].values.size());
-    for (int i = 0; i < 8; i++) {
-      EXPECT_EQ(i & 3, result.val->function_tables[0].values[i]);
-    }
+    EXPECT_EQ(8, result.val->function_tables[0].min_size);
   }
   if (result.val) delete result.val;
 }