[maglev] Support LdaModuleVariable and StaModuleVariable

Bug: v8:7700
Change-Id: I036ac71324e0c1c96a4da4aacdb5a6718726db31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3821203
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Cr-Commit-Position: refs/heads/main@{#82347}

src/maglev/maglev-graph-builder.cc

@@ -1110,8 +1110,59 @@ void MaglevGraphBuilder::VisitGetKeyedProperty() {
       AddNewNode<GetKeyedGeneric>({context, object, key}, feedback_source));
 }
 
-MAGLEV_UNIMPLEMENTED_BYTECODE(LdaModuleVariable)
-MAGLEV_UNIMPLEMENTED_BYTECODE(StaModuleVariable)
+void MaglevGraphBuilder::VisitLdaModuleVariable() {
+  // LdaModuleVariable <cell_index> <depth>
+  int cell_index = iterator_.GetImmediateOperand(0);
+  int depth = iterator_.GetUnsignedImmediateOperand(1);
+
+  ValueNode* context = GetContext();
+  for (int i = 0; i < depth; i++) {
+    context = AddNewNode<LoadTaggedField>(
+        {context}, Context::OffsetOfElementAt(Context::PREVIOUS_INDEX));
+  }
+  ValueNode* module = AddNewNode<LoadTaggedField>(
+      {context}, Context::OffsetOfElementAt(Context::EXTENSION_INDEX));
+  ValueNode* exports_or_imports;
+  if (cell_index > 0) {
+    exports_or_imports = AddNewNode<LoadTaggedField>(
+        {module}, SourceTextModule::kRegularExportsOffset);
+    // The actual array index is (cell_index - 1).
+    cell_index -= 1;
+  } else {
+    exports_or_imports = AddNewNode<LoadTaggedField>(
+        {module}, SourceTextModule::kRegularImportsOffset);
+    // The actual array index is (-cell_index - 1).
+    cell_index = -cell_index - 1;
+  }
+  ValueNode* cell = LoadFixedArrayElement(exports_or_imports, cell_index);
+  SetAccumulator(AddNewNode<LoadTaggedField>({cell}, Cell::kValueOffset));
+}
+
+void MaglevGraphBuilder::VisitStaModuleVariable() {
+  // StaModuleVariable <cell_index> <depth>
+  int cell_index = iterator_.GetImmediateOperand(0);
+  if (V8_UNLIKELY(cell_index < 0)) {
+    BuildCallRuntime(Runtime::kAbort,
+                     {GetSmiConstant(static_cast<int>(
+                         AbortReason::kUnsupportedModuleOperation))});
+    return;
+  }
+  ValueNode* context = GetContext();
+  int depth = iterator_.GetUnsignedImmediateOperand(1);
+  for (int i = 0; i < depth; i++) {
+    context = AddNewNode<LoadTaggedField>(
+        {context}, Context::OffsetOfElementAt(Context::PREVIOUS_INDEX));
+  }
+  ValueNode* module = AddNewNode<LoadTaggedField>(
+      {context}, Context::OffsetOfElementAt(Context::EXTENSION_INDEX));
+  ValueNode* exports = AddNewNode<LoadTaggedField>(
+      {module}, SourceTextModule::kRegularExportsOffset);
+  // The actual array index is (cell_index - 1).
+  cell_index -= 1;
+  ValueNode* cell = LoadFixedArrayElement(exports, cell_index);
+  AddNewNode<StoreTaggedFieldWithWriteBarrier>({cell, GetAccumulatorTagged()},
+                                               Cell::kValueOffset);
+}
 
 bool MaglevGraphBuilder::TryBuildMonomorphicStoreFromSmiHandler(
     ValueNode* object, const compiler::MapRef& map, int32_t handler) {

src/maglev/maglev-graph-builder.h

@@ -608,6 +608,11 @@ class MaglevGraphBuilder {
     return GetFloat64(iterator_.GetRegisterOperand(operand_index));
   }
 
+  ValueNode* LoadFixedArrayElement(ValueNode* node, int index) {
+    return AddNewNode<LoadTaggedField>({node},
+                                       FixedArray::OffsetOfElementAt(index));
+  }
+
   template <typename NodeT>
   void SetAccumulator(NodeT* node) {
     // Accumulator stores are equivalent to stores to the virtual accumulator

test/mjsunit/maglev/lda-module-variable-import.mjs

@@ -0,0 +1,8 @@
+// Copyright 2022 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.
+
+// Flags: --allow-natives-syntax --maglev --no-stress-opt --no-always-turbofan
+
+const b = 1;
+export {b};

test/mjsunit/maglev/lda-module-variable.mjs

@@ -0,0 +1,33 @@
+// Copyright 2022 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.
+
+// Flags: --allow-natives-syntax --maglev --no-stress-opt --no-always-turbofan
+
+// Test LdaModuleVariable with imports.
+import {b} from './lda-module-variable-import.mjs'
+
+function bar(y) {
+  // b = 1.
+  return b + y;
+};
+%PrepareFunctionForOptimization(bar);
+assertEquals(2, bar(1));
+assertEquals(3, bar(2));
+%OptimizeMaglevOnNextCall(bar);
+assertEquals(2, bar(1));
+assertEquals(3, bar(2));
+assertTrue(isMaglevved(bar));
+
+// Test LdaModuleVariable with exports.
+export let x = 1;
+function foo(y) { return x + y };
+
+%PrepareFunctionForOptimization(foo);
+assertEquals(2, foo(1));
+assertEquals(3, foo(2));
+%OptimizeMaglevOnNextCall(foo);
+assertEquals(2, foo(1));
+assertEquals(3, foo(2));
+assertTrue(isMaglevved(foo));
+

test/mjsunit/maglev/sta-module-variable.mjs

@@ -0,0 +1,20 @@
+// Copyright 2022 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.
+
+// Flags: --allow-natives-syntax --maglev --no-stress-opt --no-always-turbofan
+
+export let x = 1;
+function foo(y) {
+  x = x + 1;
+  return x + y;
+};
+
+%PrepareFunctionForOptimization(foo);
+assertEquals(3, foo(1));
+assertEquals(4, foo(1));
+%OptimizeMaglevOnNextCall(foo);
+assertEquals(5, foo(1));
+assertEquals(6, foo(1));
+assertTrue(isMaglevved(foo));
+