Add ImportResolver interface and use it for global imports

src/ir/import-utils.h

@@ -19,6 +19,7 @@
 
 #include "literal.h"
 #include "wasm.h"
+#include "wasm/import-name.h"
 
 namespace wasm {
 
@@ -123,6 +124,37 @@ struct ImportInfo {
   Index getNumDefinedTags() { return wasm.tags.size() - getNumImportedTags(); }
 };
 
+class ImportResolver {
+public:
+  virtual ~ImportResolver() = default;
+
+  // Returns null if the `name` wasn't found. The returned Literals* lives as
+  // long as the ImportResolver instance.
+  virtual Literals* getGlobalOrNull(ImportName name, Type type) const = 0;
+};
+
+// Looks up imports from the given `linkedInstances`.
+template<typename ModuleRunnerType>
+class LinkedInstancesImportResolver : public ImportResolver {
+public:
+  LinkedInstancesImportResolver(
+    std::map<Name, std::shared_ptr<ModuleRunnerType>> linkedInstances)
+    : linkedInstances(std::move(linkedInstances)) {}
+
+  Literals* getGlobalOrNull(ImportName name, Type type) const override {
+    auto it = linkedInstances.find(name.module);
+    if (it == linkedInstances.end()) {
+      return nullptr;
+    }
+
+    ModuleRunnerType* instance = it->second.get();
+    return instance->getExportedGlobalOrNull(name.name);
+  }
+
+private:
+  const std::map<Name, std::shared_ptr<ModuleRunnerType>> linkedInstances;
+};
+
 } // namespace wasm
 
 #endif // wasm_ir_import_h

src/shell-interface.h

@@ -129,20 +129,6 @@ struct ShellExternalInterface : ModuleRunner::ExternalInterface {
       wasm, [&](Table* table) { tables[table->name].resize(table->initial); });
   }
 
-  void importGlobals(std::map<Name, Literals>& globals, Module& wasm) override {
-    ModuleUtils::iterImportedGlobals(wasm, [&](Global* import) {
-      auto inst = getImportInstance(import);
-      auto* exportedGlobal = inst->wasm.getExportOrNull(import->base);
-      if (!exportedGlobal || exportedGlobal->kind != ExternalKind::Global) {
-        trap((std::stringstream()
-              << "importGlobals: unknown import: " << import->module.str << "."
-              << import->name.str)
-               .str());
-      }
-      globals[import->name] = inst->globals[*exportedGlobal->getInternalName()];
-    });
-  }
-
   Literal getImportedFunction(Function* import) override {
     // TODO: We should perhaps restrict the types with which the well-known
     // functions can be imported.

src/tools/wasm-ctor-eval.cpp

@@ -67,13 +67,36 @@ bool isNullableAndMutable(Expression* ref, Index fieldIndex) {
 // the output.
 #define RECOMMENDATION "\n       recommendation: "
 
+class EvallingModuleRunner;
+
+class EvallingImportResolver : public ImportResolver {
+public:
+  EvallingImportResolver(
+    std::map<Name, std::shared_ptr<EvallingModuleRunner>> linkedInstances,
+    ModuleRunnerBase<EvallingModuleRunner>::ExternalInterface*
+      externalInterface)
+    : externalInterface(externalInterface) {}
+
+  Literals* getGlobalOrNull(ImportName name, Type type) const override {
+    externalInterface->trap("Accessed imported global");
+    return nullptr;
+  }
+
+private:
+  ModuleRunnerBase<EvallingModuleRunner>::ExternalInterface* externalInterface;
+};
+
 class EvallingModuleRunner : public ModuleRunnerBase<EvallingModuleRunner> {
 public:
   EvallingModuleRunner(
     Module& wasm,
     ExternalInterface* externalInterface,
     std::map<Name, std::shared_ptr<EvallingModuleRunner>> linkedInstances_ = {})
-    : ModuleRunnerBase(wasm, externalInterface, linkedInstances_) {}
+    : ModuleRunnerBase(wasm,
+                       externalInterface,
+                       std::make_shared<EvallingImportResolver>(
+                         linkedInstances_, externalInterface),
+                       linkedInstances_) {}
 
   Flow visitGlobalGet(GlobalGet* curr) {
     // Error on reads of imported globals.
@@ -147,19 +170,6 @@ std::unique_ptr<Module> buildEnvModule(Module& wasm) {
     }
   });
 
-  ModuleUtils::iterImportedGlobals(wasm, [&](Global* global) {
-    if (global->module == env->name) {
-      auto* copied = ModuleUtils::copyGlobal(global, *env);
-      copied->module = Name();
-      copied->base = Name();
-
-      Builder builder(*env);
-      copied->init = builder.makeConst(Literal::makeZero(global->type));
-      env->addExport(
-        builder.makeExport(global->base, copied->name, ExternalKind::Global));
-    }
-  });
-
   // create an exported memory with the same initial and max size
   ModuleUtils::iterImportedMemories(wasm, [&](Memory* memory) {
     if (memory->module == env->name) {
@@ -231,26 +241,6 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
     }
   }
 
-  void importGlobals(GlobalValueSet& globals, Module& wasm_) override {
-    ModuleUtils::iterImportedGlobals(wasm_, [&](Global* global) {
-      auto it = linkedInstances.find(global->module);
-      if (it != linkedInstances.end()) {
-        auto* inst = it->second.get();
-        auto* globalExport = inst->wasm.getExportOrNull(global->base);
-        if (!globalExport || globalExport->kind != ExternalKind::Global) {
-          throw FailToEvalException(std::string("importGlobals: ") +
-                                    global->module.toString() + "." +
-                                    global->base.toString());
-        }
-        globals[global->name] = inst->globals[*globalExport->getInternalName()];
-      } else {
-        throw FailToEvalException(std::string("importGlobals: ") +
-                                  global->module.toString() + "." +
-                                  global->base.toString());
-      }
-    });
-  }
-
   Literal getImportedFunction(Function* import) override {
     auto f = [import, this](const Literals& arguments) -> Flow {
       Name WASI("wasi_snapshot_preview1");
@@ -558,8 +548,8 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
   void applyGlobalsToModule() {
     if (!wasm->features.hasGC()) {
       // Without GC, we can simply serialize the globals in place as they are.
-      for (const auto& [name, values] : instance->globals) {
-        wasm->getGlobal(name)->init = getSerialization(values);
+      for (const auto& [name, values] : instance->allGlobals) {
+        wasm->getGlobal(name)->init = getSerialization(*values);
       }
       return;
     }
@@ -590,9 +580,9 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
       // for it. (If there is no value, then this is a new global we've added
       // during execution, for whom we've already set up a proper serialized
       // value when we created it.)
-      auto iter = instance->globals.find(oldGlobal->name);
-      if (iter != instance->globals.end()) {
-        oldGlobal->init = getSerialization(iter->second, name);
+      auto iter = instance->allGlobals.find(oldGlobal->name);
+      if (iter != instance->allGlobals.end()) {
+        oldGlobal->init = getSerialization(*iter->second, name);
       }
 
       // Add the global back to the module.

src/tools/wasm-shell.cpp

@@ -280,7 +280,7 @@ struct Shell {
       }
       auto& instance = it->second;
       try {
-        return instance->getExportedGlobal(get->name);
+        return instance->getExportedGlobalOrTrap(get->name);
       } catch (TrapException&) {
         return TrapResult{};
       } catch (...) {