Introduce WasmValue for debugging

WasmValue holds a Wasm value with its type. This will be exposed to the
inspector (via a to-be-created class in debug_interface.h) for debugging
in DevTools.

Design at http://doc/1XQlX6DWsv6BPYnRtw-JZSASPEjsRlyXLnke7TTQ9Wrg.

Bug: v8:10347
Change-Id: Ib523e617d46fdf1adb13d13bf49749c4ce23a126
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2132720Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67029}

src/compiler/types.cc

@@ -351,6 +351,7 @@ Type::bitset BitsetType::Lub(const MapRefLike& map) {
     case TUPLE2_TYPE:
     case BREAK_POINT_TYPE:
     case BREAK_POINT_INFO_TYPE:
+    case WASM_VALUE_TYPE:
     case CACHED_TEMPLATE_OBJECT_TYPE:
     case ENUM_CACHE_TYPE:
     case WASM_CAPI_FUNCTION_DATA_TYPE:

src/diagnostics/objects-printer.cc

@@ -2199,6 +2199,12 @@ void DebugInfo::DebugInfoPrint(std::ostream& os) {  // NOLINT
   os << "\n - coverage_info: " << Brief(coverage_info());
 }
 
+void WasmValue::WasmValuePrint(std::ostream& os) {  // NOLINT
+  PrintHeader(os, "WasmValue");
+  os << "\n - value_type: " << value_type();
+  os << "\n - bytes: " << Brief(bytes());
+}
+
 void StackTraceFrame::StackTraceFramePrint(std::ostream& os) {  // NOLINT
   PrintHeader(os, "StackTraceFrame");
   os << "\n - frame_index: " << frame_index();

src/heap/factory.cc

@@ -3019,6 +3019,15 @@ Handle<DebugInfo> Factory::NewDebugInfo(Handle<SharedFunctionInfo> shared) {
   return debug_info;
 }
 
+Handle<WasmValue> Factory::NewWasmValue(int value_type,
+                                        Handle<ByteArray> bytes) {
+  Handle<WasmValue> wasm_value =
+      Handle<WasmValue>::cast(NewStruct(WASM_VALUE_TYPE, AllocationType::kOld));
+  wasm_value->set_value_type(value_type);
+  wasm_value->set_bytes(*bytes);
+  return wasm_value;
+}
+
 Handle<BreakPointInfo> Factory::NewBreakPointInfo(int source_position) {
   Handle<BreakPointInfo> new_break_point_info = Handle<BreakPointInfo>::cast(
       NewStruct(BREAK_POINT_INFO_TYPE, AllocationType::kOld));

src/heap/factory.h

@@ -734,6 +734,8 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
 
   Handle<DebugInfo> NewDebugInfo(Handle<SharedFunctionInfo> shared);
 
+  Handle<WasmValue> NewWasmValue(int32_t value_type, Handle<ByteArray> bytes);
+
   // Return a map for given number of properties using the map cache in the
   // native context.
   Handle<Map> ObjectLiteralMapFromCache(Handle<NativeContext> native_context,

src/objects/debug-objects-inl.h

@@ -23,6 +23,8 @@ TQ_OBJECT_CONSTRUCTORS_IMPL(BreakPointInfo)
 TQ_OBJECT_CONSTRUCTORS_IMPL(CoverageInfo)
 TQ_OBJECT_CONSTRUCTORS_IMPL(DebugInfo)
 
+TQ_OBJECT_CONSTRUCTORS_IMPL(WasmValue)
+
 NEVER_READ_ONLY_SPACE_IMPL(DebugInfo)
 
 BIT_FIELD_ACCESSORS(DebugInfo, debugger_hints, side_effect_state,

src/objects/debug-objects.h

@@ -202,6 +202,14 @@ class BreakPoint : public TorqueGeneratedBreakPoint<BreakPoint, Struct> {
   TQ_OBJECT_CONSTRUCTORS(BreakPoint)
 };
 
+// Holds Wasm values. This is used by the inspector.
+class WasmValue : public TorqueGeneratedWasmValue<WasmValue, Struct> {
+ public:
+  DECL_PRINTER(WasmValue)
+
+  TQ_OBJECT_CONSTRUCTORS(WasmValue)
+};
+
 }  // namespace internal
 }  // namespace v8
 

src/objects/debug-objects.tq

@@ -69,3 +69,13 @@ extern class CoverageInfo extends HeapObject {
   const slot_count: int32;
   slots[slot_count]: CoverageInfoSlot;
 }
+
+@generateCppClass
+extern class WasmValue extends Struct {
+  // The type, should map to ValueType::Kind values in value-type.h.
+  value_type: Smi;
+  // Holds the actual value. For example, if this holds a Wasm i32, this will
+  // be of length 4, for s128, it will have length 16. These values are
+  // represented by the respective C++ types, and memcpy-ed in.
+  bytes: ByteArray;
+}

src/objects/objects-definitions.h

@@ -157,7 +157,8 @@ namespace internal {
     wasm_exported_function_data)                                              \
   V(_, WASM_INDIRECT_FUNCTION_TABLE_TYPE, WasmIndirectFunctionTable,          \
     wasm_indirect_function_table)                                             \
-  V(_, WASM_JS_FUNCTION_DATA_TYPE, WasmJSFunctionData, wasm_js_function_data)
+  V(_, WASM_JS_FUNCTION_DATA_TYPE, WasmJSFunctionData, wasm_js_function_data) \
+  V(_, WASM_VALUE_TYPE, WasmValue, wasm_value)
 
 #define STRUCT_LIST_GENERATOR(V, _) STRUCT_LIST_GENERATOR_BASE(V, _)
 

src/objects/objects.h

@@ -181,6 +181,7 @@
 //         - SourceTextModule
 //         - SyntheticModule
 //       - SourceTextModuleInfoEntry
+//       - WasmValue
 //     - FeedbackCell
 //     - FeedbackVector
 //     - PreparseData