[wasm] Perform exception value encoding/decoding in code.

This removes some unnecessary runtime calls when encoding/decoding
values stored in exception objects. It reduces code size of the
generated code.

R=clemensh@chromium.org
BUG=v8:8341

Change-Id: I2394994be01d3071e58bfa2bfbba8bf72a6a04a5
Reviewed-on: https://chromium-review.googlesource.com/c/1293373
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56860}

src/compiler/wasm-compiler.cc

@@ -98,6 +98,17 @@ MachineType assert_size(int expected_size, MachineType type) {
   LOAD_TAGGED_POINTER(                           \
       array_node, wasm::ObjectAccess::ElementOffsetInTaggedFixedArray(index))
 
+// TODO(mstarzinger): This macro only works for Smi values and needs to be
+// extended appropriately before it can be used for tagged pointers.
+#define STORE_FIXED_ARRAY_SLOT(array_node, index, value)               \
+  SetEffect(graph()->NewNode(                                          \
+      mcgraph()->machine()->Store(StoreRepresentation(                 \
+          MachineRepresentation::kTaggedSigned, kNoWriteBarrier)),     \
+      array_node,                                                      \
+      mcgraph()->Int32Constant(                                        \
+          wasm::ObjectAccess::ElementOffsetInTaggedFixedArray(index)), \
+      value, Effect(), Control()))
+
 constexpr uint32_t kBytesPerExceptionValuesArrayElement = 2;
 
 void MergeControlToEnd(MachineGraph* mcgraph, Node* node) {
@@ -2055,6 +2066,8 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
   Node* except_obj =
       BuildCallToRuntime(Runtime::kWasmThrowCreate, create_parameters,
                          arraysize(create_parameters));
+  Node* values_array =
+      BuildCallToRuntime(Runtime::kWasmExceptionGetValues, &except_obj, 1);
   uint32_t index = 0;
   const wasm::WasmExceptionSig* sig = exception->sig;
   MachineOperatorBuilder* m = mcgraph()->machine();
@@ -2065,7 +2078,7 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
         value = graph()->NewNode(m->BitcastFloat32ToInt32(), value);
         V8_FALLTHROUGH;
       case wasm::kWasmI32:
-        BuildEncodeException32BitValue(except_obj, &index, value);
+        BuildEncodeException32BitValue(values_array, &index, value);
         break;
       case wasm::kWasmF64:
         value = graph()->NewNode(m->BitcastFloat64ToInt64(), value);
@@ -2074,9 +2087,9 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
         Node* upper32 = graph()->NewNode(
             m->TruncateInt64ToInt32(),
             Binop(wasm::kExprI64ShrU, value, Int64Constant(32)));
-        BuildEncodeException32BitValue(except_obj, &index, upper32);
+        BuildEncodeException32BitValue(values_array, &index, upper32);
         Node* lower32 = graph()->NewNode(m->TruncateInt64ToInt32(), value);
-        BuildEncodeException32BitValue(except_obj, &index, lower32);
+        BuildEncodeException32BitValue(values_array, &index, lower32);
         break;
       }
       default:
@@ -2096,25 +2109,17 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
                        except_obj, Effect(), Control())));
 }
 
-void WasmGraphBuilder::BuildEncodeException32BitValue(Node* except_obj,
+void WasmGraphBuilder::BuildEncodeException32BitValue(Node* values_array,
                                                       uint32_t* index,
                                                       Node* value) {
   MachineOperatorBuilder* machine = mcgraph()->machine();
-  Node* upper_parameters[] = {
-      except_obj, BuildChangeUint31ToSmi(Int32Constant(*index)),
-      BuildChangeUint31ToSmi(
-          graph()->NewNode(machine->Word32Shr(), value, Int32Constant(16))),
-  };
-  BuildCallToRuntime(Runtime::kWasmExceptionSetElement, upper_parameters,
-                     arraysize(upper_parameters));
+  Node* upper_halfword_as_smi = BuildChangeUint31ToSmi(
+      graph()->NewNode(machine->Word32Shr(), value, Int32Constant(16)));
+  STORE_FIXED_ARRAY_SLOT(values_array, *index, upper_halfword_as_smi);
   ++(*index);
-  Node* lower_parameters[] = {
-      except_obj, BuildChangeUint31ToSmi(Int32Constant(*index)),
-      BuildChangeUint31ToSmi(graph()->NewNode(machine->Word32And(), value,
-                                              Int32Constant(0xFFFFu))),
-  };
-  BuildCallToRuntime(Runtime::kWasmExceptionSetElement, lower_parameters,
-                     arraysize(lower_parameters));
+  Node* lower_halfword_as_smi = BuildChangeUint31ToSmi(
+      graph()->NewNode(machine->Word32And(), value, Int32Constant(0xFFFFu)));
+  STORE_FIXED_ARRAY_SLOT(values_array, *index, lower_halfword_as_smi);
   ++(*index);
 }
 
@@ -2169,13 +2174,12 @@ Node** WasmGraphBuilder::GetExceptionValues(
   // call causes an exception.
 
   // Start by getting the encoded values from the exception.
+  Node* values_array =
+      BuildCallToRuntime(Runtime::kWasmExceptionGetValues, &except_obj, 1);
   uint32_t encoded_size = GetExceptionEncodedSize(except_decl);
   Node** values = Buffer(encoded_size);
   for (uint32_t i = 0; i < encoded_size; ++i) {
-    Node* parameters[] = {except_obj,
-                          BuildChangeUint31ToSmi(Uint32Constant(i))};
-    values[i] = BuildCallToRuntime(Runtime::kWasmExceptionGetElement,
-                                   parameters, arraysize(parameters));
+    values[i] = LOAD_FIXED_ARRAY_SLOT(values_array, i);
   }
 
   // Now convert the leading entries to the corresponding parameter values.
@@ -5482,6 +5486,7 @@ AssemblerOptions WasmAssemblerOptions() {
 #undef LOAD_INSTANCE_FIELD
 #undef LOAD_TAGGED_POINTER
 #undef LOAD_FIXED_ARRAY_SLOT
+#undef STORE_FIXED_ARRAY_SLOT
 
 }  // namespace compiler
 }  // namespace internal

src/compiler/wasm-compiler.h

@@ -463,7 +463,7 @@ class WasmGraphBuilder {
   Node* BuildAsmjsStoreMem(MachineType type, Node* index, Node* val);
 
   uint32_t GetExceptionEncodedSize(const wasm::WasmException* exception) const;
-  void BuildEncodeException32BitValue(Node* except_obj, uint32_t* index,
+  void BuildEncodeException32BitValue(Node* values_array, uint32_t* index,
                                       Node* value);
   Node* BuildDecodeException32BitValue(Node* const* values, uint32_t* index);
 

src/runtime/runtime-wasm.cc

@@ -142,37 +142,10 @@ RUNTIME_FUNCTION(Runtime_WasmExceptionGetTag) {
   return ReadOnlyRoots(isolate).undefined_value();
 }
 
-RUNTIME_FUNCTION(Runtime_WasmExceptionGetElement) {
+RUNTIME_FUNCTION(Runtime_WasmExceptionGetValues) {
   // TODO(kschimpf): Can this be replaced with equivalent TurboFan code/calls.
   HandleScope scope(isolate);
-  DCHECK_EQ(2, args.length());
-  DCHECK_NULL(isolate->context());
-  isolate->set_context(GetNativeContextFromWasmInstanceOnStackTop(isolate));
-  CONVERT_ARG_CHECKED(Object, except_obj_raw, 0);
-  // TODO(mstarzinger): Manually box because parameters are not visited yet.
-  Handle<Object> except_obj(except_obj_raw, isolate);
-  if (!except_obj.is_null() && except_obj->IsJSReceiver()) {
-    Handle<JSReceiver> exception(JSReceiver::cast(*except_obj), isolate);
-    Handle<Object> values_obj;
-    if (JSReceiver::GetProperty(
-            isolate, exception,
-            isolate->factory()->wasm_exception_values_symbol())
-            .ToHandle(&values_obj)) {
-      if (values_obj->IsFixedArray()) {
-        Handle<FixedArray> values = Handle<FixedArray>::cast(values_obj);
-        CONVERT_SMI_ARG_CHECKED(index, 1);
-        CHECK_LT(index, values->length());
-        return values->get(index);
-      }
-    }
-  }
-  return Smi::FromInt(0);
-}
-
-RUNTIME_FUNCTION(Runtime_WasmExceptionSetElement) {
-  // TODO(kschimpf): Can this be replaced with equivalent TurboFan code/calls.
-  HandleScope scope(isolate);
-  DCHECK_EQ(3, args.length());
+  DCHECK_EQ(1, args.length());
   DCHECK_NULL(isolate->context());
   isolate->set_context(GetNativeContextFromWasmInstanceOnStackTop(isolate));
   CONVERT_ARG_CHECKED(Object, except_obj_raw, 0);
@@ -180,18 +153,13 @@ RUNTIME_FUNCTION(Runtime_WasmExceptionSetElement) {
   Handle<Object> except_obj(except_obj_raw, isolate);
   if (!except_obj.is_null() && except_obj->IsJSReceiver()) {
     Handle<JSReceiver> exception(JSReceiver::cast(*except_obj), isolate);
-    Handle<Object> values_obj;
+    Handle<Object> values;
     if (JSReceiver::GetProperty(
             isolate, exception,
             isolate->factory()->wasm_exception_values_symbol())
-            .ToHandle(&values_obj)) {
-      if (values_obj->IsFixedArray()) {
-        Handle<FixedArray> values = Handle<FixedArray>::cast(values_obj);
-        CONVERT_SMI_ARG_CHECKED(index, 1);
-        CHECK_LT(index, values->length());
-        CONVERT_ARG_CHECKED(Object, value, 2);
-        values->set(index, value);
-      }
+            .ToHandle(&values)) {
+      DCHECK(values->IsFixedArray());
+      return *values;
     }
   }
   return ReadOnlyRoots(isolate).undefined_value();

src/runtime/runtime.h

@@ -536,8 +536,7 @@ namespace internal {
 #define FOR_EACH_INTRINSIC_WASM(F, I) \
   F(ThrowWasmError, 1, 1)             \
   F(ThrowWasmStackOverflow, 0, 1)     \
-  F(WasmExceptionGetElement, 2, 1)    \
-  F(WasmExceptionSetElement, 3, 1)    \
+  F(WasmExceptionGetValues, 1, 1)     \
   F(WasmExceptionGetTag, 1, 1)        \
   F(WasmGrowMemory, 2, 1)             \
   F(WasmRunInterpreter, 2, 1)         \