[wasm][anyref] Implement re-export of mutable anyref globals

R=mstarzinger@chromium.org

Bug: v8:7581
Change-Id: If469467663e632a1dba3bd55ace830e1b2f38f7e
Reviewed-on: https://chromium-review.googlesource.com/c/1409427
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58824}

src/wasm/module-instantiate.cc

@@ -1358,17 +1358,28 @@ void InstanceBuilder::ProcessExports(Handle<WasmInstanceObject> instance) {
         if (global.mutability && global.imported) {
           Handle<FixedArray> buffers_array(
               instance->imported_mutable_globals_buffers(), isolate_);
-          untagged_buffer = buffers_array->GetValueChecked<JSArrayBuffer>(
-              isolate_, global.index);
-          Address global_addr =
-              instance->imported_mutable_globals()[global.index];
-
-          size_t buffer_size = untagged_buffer->byte_length();
-          Address backing_store =
-              reinterpret_cast<Address>(untagged_buffer->backing_store());
-          CHECK(global_addr >= backing_store &&
-                global_addr < backing_store + buffer_size);
-          offset = static_cast<uint32_t>(global_addr - backing_store);
+          if (global.type == kWasmAnyRef) {
+            tagged_buffer = buffers_array->GetValueChecked<FixedArray>(
+                isolate_, global.index);
+            // For anyref globals we store the relative offset in the
+            // imported_mutable_globals array instead of an absolute address.
+            Address addr = instance->imported_mutable_globals()[global.index];
+            DCHECK_LE(addr, static_cast<Address>(
+                                std::numeric_limits<uint32_t>::max()));
+            offset = static_cast<uint32_t>(addr);
+          } else {
+            untagged_buffer = buffers_array->GetValueChecked<JSArrayBuffer>(
+                isolate_, global.index);
+            Address global_addr =
+                instance->imported_mutable_globals()[global.index];
+
+            size_t buffer_size = untagged_buffer->byte_length();
+            Address backing_store =
+                reinterpret_cast<Address>(untagged_buffer->backing_store());
+            CHECK(global_addr >= backing_store &&
+                  global_addr < backing_store + buffer_size);
+            offset = static_cast<uint32_t>(global_addr - backing_store);
+          }
         } else {
           if (global.type == kWasmAnyRef) {
             tagged_buffer = handle(instance->tagged_globals_buffer(), isolate_);

test/mjsunit/wasm/anyref-globals.js

@@ -255,6 +255,11 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   const i3 = builder2.addImportedGlobal('exports', 'e3', kWasmAnyRef, true);
   const i4 = builder2.addImportedGlobal('exports', 'e4', kWasmAnyRef, true);
 
+  builder2.addExportOfKind("reexport1", kExternalGlobal, i1);
+  builder2.addExportOfKind("reexport2", kExternalGlobal, i2);
+  builder2.addExportOfKind("reexport3", kExternalGlobal, i3);
+  builder2.addExportOfKind("reexport4", kExternalGlobal, i4);
+
   builder2.addFunction("set_globals", kSig_v_rr)
     .addBody([
         kExprGetLocal, 0,
@@ -277,13 +282,32 @@ load("test/mjsunit/wasm/wasm-module-builder.js");
   assertSame(obj2, instance2.exports.get_global2());
   assertSame(obj3, instance2.exports.get_global3());
 
+  assertSame(obj2, instance2.exports.reexport2.value);
+  assertSame(obj3, instance2.exports.reexport3.value);
+
   // Check if instance2 can make changes visible for instance1.
   instance2.exports.set_globals(null, undefined);
   assertEquals(null, instance1.exports.get_global2());
   assertEquals(undefined, instance1.exports.get_global3());
 
+  assertEquals(null, instance2.exports.reexport2.value);
+  assertEquals(undefined, instance2.exports.reexport3.value);
+
   // Check if instance1 can make changes visible for instance2.
   instance1.exports.set_globals("foo", 66343);
   assertEquals("foo", instance2.exports.get_global2());
   assertEquals(66343, instance2.exports.get_global3());
+
+  assertEquals("foo", instance2.exports.reexport2.value);
+  assertEquals(66343, instance2.exports.reexport3.value);
+
+  const bar2 = {f: "oo"};
+  const bar3 = {b: "ar"};
+  instance2.exports.reexport2.value = bar2;
+  instance2.exports.reexport3.value = bar3;
+
+  assertSame(bar2, instance1.exports.get_global2());
+  assertSame(bar3, instance1.exports.get_global3());
+  assertSame(bar2, instance2.exports.get_global2());
+  assertSame(bar3, instance2.exports.get_global3());
 })();