Use ImportResolver for table imports

Author: stevenfontanella

src/ir/CMakeLists.txt

@@ -20,6 +20,7 @@ set(ir_SOURCES
   public-type-validator.cpp
   ReFinalize.cpp
   return-utils.cpp
+  runtime-table.cpp
   stack-utils.cpp
   table-utils.cpp
   type-updating.cpp

src/ir/import-utils.h

@@ -18,6 +18,7 @@
 #define wasm_ir_import_h
 
 #include "ir/import-name.h"
+#include "ir/runtime-table.h"
 #include "literal.h"
 #include "wasm.h"
 
@@ -131,6 +132,10 @@ class ImportResolver {
   // Returns null if the `name` wasn't found. The returned Literals* lives as
   // long as the ImportResolver instance.
   virtual Literals* getGlobalOrNull(ImportNames name, Type type) const = 0;
+
+  // TODO: new type for TableType or just re-use the existing one?
+  virtual RuntimeTable* getTableOrNull(ImportNames name,
+                                       const Table& type) const = 0;
 };
 
 // Looks up imports from the given `linkedInstances`.
@@ -151,6 +156,17 @@ class LinkedInstancesImportResolver : public ImportResolver {
     return instance->getExportedGlobalOrNull(name.name);
   }
 
+  RuntimeTable* getTableOrNull(ImportNames name,
+                               const Table& type) const override {
+    auto it = linkedInstances.find(name.module);
+    if (it == linkedInstances.end()) {
+      return nullptr;
+    }
+
+    ModuleRunnerType* instance = it->second.get();
+    return instance->getExportedTableOrNull(name.name);
+  }
+
 private:
   const std::map<Name, std::shared_ptr<ModuleRunnerType>> linkedInstances;
 };

src/ir/runtime-table.h

@@ -0,0 +1,39 @@
+#ifndef wasm_ir_runtime_table_h
+#define wasm_ir_runtime_table_h
+
+#include <stddef.h>
+#include <vector>
+
+#include "literal.h"
+#include "wasm.h"
+
+namespace wasm {
+
+// Traps on out of bounds access
+class RuntimeTable {
+public:
+  // TODO: constructor for initial contents?
+  RuntimeTable(Table table_, std::function<void(std::string_view s)> trap_)
+    : tableMeta_(table_), trap(trap_) {}
+
+  void set(std::size_t i, Literal l);
+
+  Literal get(std::size_t i) const;
+
+  // Returns nullopt if the table grew beyond the max possible size.
+  [[nodiscard]] std::optional<std::size_t> grow(std::size_t delta,
+                                                Literal fill);
+
+  std::size_t size() const { return table.size(); }
+
+  const Table* tableMeta() const { return &tableMeta_; }
+
+private:
+  const Table tableMeta_;
+  std::vector<Literal> table;
+  std::function<void(std::string_view)> trap;
+};
+
+} // namespace wasm
+
+#endif // wasm_ir_runtime_table_h

src/shell-interface.h

@@ -34,9 +34,6 @@ namespace wasm {
 // An exception emitted when exit() is called.
 struct ExitException {};
 
-// An exception emitted when a wasm trap occurs.
-struct TrapException {};
-
 // An exception emitted when a host limitation is hit. (These are not wasm traps
 // as they are not in the spec; for example, the spec has no limit on how much
 // GC memory may be allocated, but hosts have limits.)
@@ -93,7 +90,6 @@ struct ShellExternalInterface : ModuleRunner::ExternalInterface {
   };
 
   std::map<Name, Memory> memories;
-  std::unordered_map<Name, std::vector<Literal>> tables;
   std::map<Name, std::shared_ptr<ModuleRunner>> linkedInstances;
 
   ShellExternalInterface(
@@ -125,8 +121,6 @@ struct ShellExternalInterface : ModuleRunner::ExternalInterface {
       shellMemory.resize(memory->initial * wasm::Memory::kPageSize);
       memories[memory->name] = shellMemory;
     });
-    ModuleUtils::iterDefinedTables(
-      wasm, [&](Table* table) { tables[table->name].resize(table->initial); });
   }
 
   Literal getImportedFunction(Function* import) override {
@@ -255,35 +249,6 @@ struct ShellExternalInterface : ModuleRunner::ExternalInterface {
     auto& memory = it->second;
     memory.set<std::array<uint8_t, 16>>(addr, value);
   }
-
-  Index tableSize(Name tableName) override {
-    return (Index)tables[tableName].size();
-  }
-
-  void
-  tableStore(Name tableName, Address index, const Literal& entry) override {
-    auto& table = tables[tableName];
-    if (index >= table.size()) {
-      trap("out of bounds table access");
-    } else {
-      table[index] = entry;
-    }
-  }
-
-  Literal tableLoad(Name tableName, Address index) override {
-    auto it = tables.find(tableName);
-    if (it == tables.end()) {
-      trap("tableGet on non-existing table");
-    }
-
-    auto& table = it->second;
-    if (index >= table.size()) {
-      trap("out of bounds table access");
-    }
-
-    return table[index];
-  }
-
   bool
   growMemory(Name memoryName, Address /*oldSize*/, Address newSize) override {
     // Apply a reasonable limit on memory size, 1GB, to avoid DOS on the
@@ -299,20 +264,6 @@ struct ShellExternalInterface : ModuleRunner::ExternalInterface {
     memory.resize(newSize);
     return true;
   }
-
-  bool growTable(Name name,
-                 const Literal& value,
-                 Index /*oldSize*/,
-                 Index newSize) override {
-    // Apply a reasonable limit on table size, 1GB, to avoid DOS on the
-    // interpreter.
-    if (newSize > 1024 * 1024 * 1024) {
-      return false;
-    }
-    tables[name].resize(newSize, value);
-    return true;
-  }
-
   void trap(std::string_view why) override {
     std::cout << "[trap " << why << "]\n";
     throw TrapException();

src/tools/execution-results.h

@@ -142,19 +142,21 @@ struct LoggingExternalInterface : public ShellExternalInterface {
             throwJSException();
           }
           auto index = arguments[0].getUnsigned();
-          if (index >= tables[exportedTable].size()) {
+          auto* table = instance->allTables[exportedTable];
+          if (index >= table->size()) {
             throwJSException();
           }
-          return {tableLoad(exportedTable, index)};
+          return table->get(index);
         } else if (import->base == "table-set") {
           if (!exportedTable) {
             throwJSException();
           }
           auto index = arguments[0].getUnsigned();
-          if (index >= tables[exportedTable].size()) {
+          auto* table = instance->allTables[exportedTable];
+          if (index >= table->size()) {
             throwJSException();
           }
-          tableStore(exportedTable, index, arguments[1]);
+          table->set(index, arguments[1]);
           return {};
         } else if (import->base == "call-export") {
           callExportAsJS(arguments[0].geti32());

src/tools/wasm-ctor-eval.cpp

@@ -80,6 +80,11 @@ class EvallingImportResolver : public ImportResolver {
     return &stubLiteral;
   }
 
+  RuntimeTable* getTableOrNull(ImportNames name,
+                               const Table& type) const override {
+    throw FailToEvalException{"Imported table access."};
+  }
+
 private:
   mutable Literals stubLiteral;
 };
@@ -156,17 +161,6 @@ std::unique_ptr<Module> buildEnvModule(Module& wasm) {
     }
   });
 
-  // create tables with similar initial and max values
-  ModuleUtils::iterImportedTables(wasm, [&](Table* table) {
-    if (table->module == env->name) {
-      auto* copied = ModuleUtils::copyTable(table, *env);
-      copied->module = Name();
-      copied->base = Name();
-      env->addExport(Builder(*env).makeExport(
-        table->base, copied->name, ExternalKind::Table));
-    }
-  });
-
   // create an exported memory with the same initial and max size
   ModuleUtils::iterImportedMemories(wasm, [&](Memory* memory) {
     if (memory->module == env->name) {
@@ -316,68 +310,6 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
   }
 
   // We assume the table is not modified FIXME
-  Literal tableLoad(Name tableName, Address index) override {
-    auto* table = wasm->getTableOrNull(tableName);
-    if (!table) {
-      throw FailToEvalException("tableLoad on non-existing table");
-    }
-
-    // Look through the segments and find the value. Segments can overlap,
-    // so we want the last one.
-    Expression* value = nullptr;
-    for (auto& segment : wasm->elementSegments) {
-      if (segment->table != tableName) {
-        continue;
-      }
-
-      Index start;
-      // look for the index in this segment. if it has a constant offset, we
-      // look in the proper range. if it instead gets a global, we rely on the
-      // fact that when not dynamically linking then the table is loaded at
-      // offset 0.
-      if (auto* c = segment->offset->dynCast<Const>()) {
-        start = c->value.getInteger();
-      } else if (segment->offset->is<GlobalGet>()) {
-        start = 0;
-      } else {
-        // wasm spec only allows const and global.get there
-        WASM_UNREACHABLE("invalid expr type");
-      }
-      auto end = start + segment->data.size();
-      if (start <= index && index < end) {
-        value = segment->data[index - start];
-      }
-    }
-
-    if (!value) {
-      // No segment had a value for this.
-      return Literal::makeNull(HeapTypes::func);
-    }
-    if (!Properties::isConstantExpression(value)) {
-      throw FailToEvalException("tableLoad of non-literal");
-    }
-    if (auto* r = value->dynCast<RefFunc>()) {
-      return instance->makeFuncData(r->func, r->type);
-    }
-    return Properties::getLiteral(value);
-  }
-
-  Index tableSize(Name tableName) override {
-    // See tableLoad above, we assume the table is not modified FIXME
-    return wasm->getTableOrNull(tableName)->initial;
-  }
-
-  // called during initialization
-  void
-  tableStore(Name tableName, Address index, const Literal& value) override {
-    // We allow stores to the table during initialization, but not after, as we
-    // assume the table does not change at runtime.
-    // TODO: Allow table changes by updating the table later like we do with the
-    //       memory, by tracking and serializing them.
-    if (instanceInitialized) {
-      throw FailToEvalException("tableStore after init: TODO");
-    }
-  }
 
   int8_t load8s(Address addr, Name memoryName) override {
     return doLoad<int8_t>(addr, memoryName);
@@ -431,13 +363,6 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
     throw FailToEvalException("grow memory");
   }
 
-  bool growTable(Name /*name*/,
-                 const Literal& /*value*/,
-                 Index /*oldSize*/,
-                 Index /*newSize*/) override {
-    throw FailToEvalException("grow table");
-  }
-
   void trap(std::string_view why) override {
     throw FailToEvalException(std::string("trap: ") + std::string(why));
   }
@@ -1145,6 +1070,9 @@ EvalCtorOutcome evalCtor(EvallingModuleRunner& instance,
           std::cout << "  ...stopping due to non-constant func\n";
         }
         break;
+      } catch (TrapException trap) {
+        std::cout << "  ...stopping due to trap";
+        break;
       }
 
       if (flow.breakTo == NONCONSTANT_FLOW) {