[wasm] Allow initialization of anyref tables

New spec changes allow anyref tables to be initialized with function
references.

R=mstarzinger@chromium.org

Bug: v8:7581
Change-Id: I59596e1e383408114b974fa10529ae15b8cf7a15
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627348Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61823}

src/wasm/module-decoder.cc

@@ -808,7 +808,8 @@ class ModuleDecoderImpl : public Decoder {
           errorf(pos, "out of bounds table index %u", table_index);
           break;
         }
-        if (module_->tables[table_index].type != kWasmAnyFunc) {
+        if (!ValueTypes::IsSubType(module_->tables[table_index].type,
+                                   kWasmAnyFunc)) {
           errorf(pos,
                  "Invalid element segment. Table %u is not of type AnyFunc",
                  table_index);
@@ -816,7 +817,7 @@ class ModuleDecoderImpl : public Decoder {
         }
       } else {
         ValueType type = consume_reference_type();
-        if (type != kWasmAnyFunc) {
+        if (!ValueTypes::IsSubType(type, kWasmAnyFunc)) {
           error(pc_ - 1, "invalid element segment type");
           break;
         }

src/wasm/module-instantiate.cc

@@ -1518,7 +1518,9 @@ bool LoadElemSegmentImpl(Isolate* isolate, Handle<WasmInstanceObject> instance,
     int entry_index = static_cast<int>(dst + i);
 
     if (func_index == WasmElemSegment::kNullIndex) {
+      if (table_object->type() == kWasmAnyFunc) {
         IndirectFunctionTableEntry(instance, entry_index).clear();
+      }
       WasmTableObject::Set(isolate, table_object, entry_index,
                            isolate->factory()->null_value());
       continue;
@@ -1530,12 +1532,21 @@ bool LoadElemSegmentImpl(Isolate* isolate, Handle<WasmInstanceObject> instance,
     // update the dispatch table if the first table of the instance is changed.
     // For all other tables, function calls do not use a dispatch table at
     // the moment.
-    if (elem_segment.table_index == 0) {
+    if (elem_segment.table_index == 0 && table_object->type() == kWasmAnyFunc) {
       uint32_t sig_id = module->signature_ids[function->sig_index];
       IndirectFunctionTableEntry(instance, entry_index)
           .Set(sig_id, instance, func_index);
     }
 
+    // For AnyRef tables, we have to generate the WasmExportedFunction eagerly.
+    // Later we cannot know if an entry is a placeholder or not.
+    if (table_object->type() == kWasmAnyRef) {
+      Handle<WasmExportedFunction> wasm_exported_function =
+          WasmInstanceObject::GetOrCreateWasmExportedFunction(isolate, instance,
+                                                              func_index);
+      WasmTableObject::Set(isolate, table_object, entry_index,
+                           wasm_exported_function);
+    } else {
       // Update the table object's other dispatch tables.
       MaybeHandle<WasmExportedFunction> wasm_exported_function =
           WasmInstanceObject::GetWasmExportedFunction(isolate, instance,
@@ -1552,7 +1563,9 @@ bool LoadElemSegmentImpl(Isolate* isolate, Handle<WasmInstanceObject> instance,
       // UpdateDispatchTables() updates all other dispatch tables, since
       // we have not yet added the dispatch table we are currently building.
       WasmTableObject::UpdateDispatchTables(isolate, table_object, entry_index,
-                                          function->sig, instance, func_index);
+                                            function->sig, instance,
+                                            func_index);
+    }
   }
   return ok;
 }

test/mjsunit/wasm/multi-table-element-section.js

@@ -6,21 +6,24 @@
 
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
-const value1 = 11;
-const value2 = 22;
-const value3 = 46;
-const value4 = 57;
-const value5 = 13;
-
-// The offsets for the initialization of tables. The segement for table2 should
-// overlap with the segment of table1, because table2 is actually the imported
-// table1.
-const offset1 = 2;
-const offset2 = offset1 + 1;
-const offset3 = 4;
-const offset4 = 1;
-
-const instance_for_import = (function() {
+(function TestInitMultipleTables() {
+  print(arguments.callee.name);
+
+  const value1 = 11;
+  const value2 = 22;
+  const value3 = 46;
+  const value4 = 57;
+  const value5 = 13;
+
+  // The offsets for the initialization of tables. The segement for table2 should
+  // overlap with the segment of table1, because table2 is actually the imported
+  // table1.
+  const offset1 = 2;
+  const offset2 = offset1 + 1;
+  const offset3 = 4;
+  const offset4 = 1;
+
+  const instance_for_import = (function () {
     const builder_for_import = new WasmModuleBuilder();
     const t1 = builder_for_import.addTable(kWasmAnyFunc, 15, 15)
       .exportAs("table").index;
@@ -35,42 +38,61 @@ const instance_for_import = (function() {
     assertEquals(value1, table1.get(offset1)());
     assertEquals(value2, table1.get(offset1 + 1)());
     return instance_for_import;
-})();
+  })();
 
-const builder = new WasmModuleBuilder();
+  const builder = new WasmModuleBuilder();
 
-const t2 = builder.addImportedTable("exports", "table", 15, 15);
-builder.addExportOfKind("table2", kExternalTable, t2);
-const t3 = builder.addTable(kWasmAnyFunc, 10).exportAs("table3").index;
-const t4 = builder.addTable(kWasmAnyFunc, 12).exportAs("table4").index;
+  const t2 = builder.addImportedTable("exports", "table", 15, 15);
+  builder.addExportOfKind("table2", kExternalTable, t2);
+  const t3 = builder.addTable(kWasmAnyFunc, 10).exportAs("table3").index;
+  const t4 = builder.addTable(kWasmAnyFunc, 12).exportAs("table4").index;
 
-const f3 = builder.addFunction('f3', kSig_i_v)
+  const f3 = builder.addFunction('f3', kSig_i_v)
     .addBody([kExprI32Const, value3]).index;
-const f4 = builder.addFunction('f4', kSig_i_v)
+  const f4 = builder.addFunction('f4', kSig_i_v)
     .addBody([kExprI32Const, value4]).index;
-const f5 = builder.addFunction('f5', kSig_i_v)
+  const f5 = builder.addFunction('f5', kSig_i_v)
     .addBody([kExprI32Const, value5]).index;
 
 
-builder.addElementSegment(t2, offset2, false, [f3, f4]);
-builder.addElementSegment(t3, offset3, false, [f5, f4]);
-builder.addElementSegment(t4, offset4, false, [f3, f5]);
-// Add one more overlapping offset
-builder.addElementSegment(t4, offset4 + 1, false, [f4, f3]);
-
-const instance = builder.instantiate(instance_for_import);
-// table2 == table1
-const table2 = instance.exports.table2;
-const table3 = instance.exports.table3;
-const table4 = instance.exports.table4;
-// table1 == table2
-assertEquals(value1, table2.get(offset1)());
-assertEquals(value3, table2.get(offset2)());
-assertEquals(value4, table2.get(offset2 + 1)());
-
-assertEquals(value5, table3.get(offset3)());
-assertEquals(value4, table3.get(offset3 + 1)());
-
-assertEquals(value3, table4.get(offset4)());
-assertEquals(value4, table4.get(offset4 + 1)());
-assertEquals(value3, table4.get(offset4 + 2)());
+  builder.addElementSegment(t2, offset2, false, [f3, f4]);
+  builder.addElementSegment(t3, offset3, false, [f5, f4]);
+  builder.addElementSegment(t4, offset4, false, [f3, f5]);
+  // Add one more overlapping offset
+  builder.addElementSegment(t4, offset4 + 1, false, [f4, f3]);
+
+  const instance = builder.instantiate(instance_for_import);
+  // table2 == table1
+  const table2 = instance.exports.table2;
+  const table3 = instance.exports.table3;
+  const table4 = instance.exports.table4;
+  // table1 == table2
+  assertEquals(value1, table2.get(offset1)());
+  assertEquals(value3, table2.get(offset2)());
+  assertEquals(value4, table2.get(offset2 + 1)());
+
+  assertEquals(value5, table3.get(offset3)());
+  assertEquals(value4, table3.get(offset3 + 1)());
+
+  assertEquals(value3, table4.get(offset4)());
+  assertEquals(value4, table4.get(offset4 + 1)());
+  assertEquals(value3, table4.get(offset4 + 2)());
+})();
+
+(function TestAnyRefTableWithAnyFuncInit() {
+  print(arguments.callee.name);
+  let builder = new WasmModuleBuilder();
+  const table = builder.addTable(kWasmAnyRef, 5).index;
+  builder.addExportOfKind("table", kExternalTable, table);
+  const f1 = builder.addFunction('f1', kSig_i_v)
+                    .addBody([kExprI32Const, 11])
+                    .exportFunc().index;
+  const f2 = builder.addFunction('f2', kSig_i_v)
+                    .addBody([kExprI32Const, 22])
+                    .exportFunc().index;
+
+  builder.addElementSegment(table, 1, false, [f1, f2]);
+  const instance = builder.instantiate();
+  assertEquals(instance.exports.table.get(1)(), 11);
+  assertEquals(instance.exports.table.get(2)(), 22);
+})();

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

@@ -1225,7 +1225,7 @@ TEST_F(WasmModuleVerifyTest, ElementSectionMixedTablesArbitraryOrder) {
   EXPECT_VERIFIES(data);
 }
 
-TEST_F(WasmModuleVerifyTest, ElementSectionDontInitAnyRefTable) {
+TEST_F(WasmModuleVerifyTest, ElementSectionInitAnyRefTableWithAnyFunc) {
   // Test that tables of type 'AnyRef' cannot be initialized by the element
   // section.
   WASM_FEATURE_SCOPE(anyref);
@@ -1251,9 +1251,11 @@ TEST_F(WasmModuleVerifyTest, ElementSectionDontInitAnyRefTable) {
               2,                         // elements count
               FUNC_INDEX(0),             // entry 0
               FUNC_INDEX(0)),            // entry 1
+      // code ----------------------------------------------------------------
+      ONE_EMPTY_BODY,
   };
 
-  EXPECT_FAILURE(data);
+  EXPECT_VERIFIES(data);
 }
 
 TEST_F(WasmModuleVerifyTest, ElementSectionDontInitAnyRefImportedTable) {