[wasm] Use a builtin instead of runtime function

... for creating a FixedArray.
Calling builtins is generally cheaper than calling into the runtime, and
this also saves us a int->Smi conversion.
The builtin still has the "Wasm" prefix, since it's only used in wasm
for now.

R=thibaudm@chromium.org

Bug: v8:11453
Change-Id: I0c5b6b71ae1b07608f51e685014a0e8dc0034111
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2698674Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72839}

src/builtins/wasm.tq

@@ -192,6 +192,12 @@ builtin WasmRefFunc(index: uint32): Object {
   }
 }
 
+builtin WasmAllocateFixedArray(size: intptr): FixedArray {
+  if (size == 0) return kEmptyFixedArray;
+  return UnsafeCast<FixedArray>(AllocateFixedArray(
+      ElementsKind::PACKED_ELEMENTS, size, AllocationFlag::kNone));
+}
+
 builtin WasmThrow(tag: Object, values: FixedArray): JSAny {
   tail runtime::WasmThrow(LoadContextFromFrame(), tag, values);
 }

src/compiler/wasm-compiler.cc

@@ -2277,11 +2277,20 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
                               wasm::WasmCodePosition position) {
   needs_stack_check_ = true;
   uint32_t encoded_size = WasmExceptionPackage::GetEncodedSize(exception);
-  Node* encoded_size_smi =
-      BuildChangeUint31ToSmi(mcgraph()->Uint32Constant(encoded_size));
-  Node* values_array = BuildCallToRuntime(
-      Runtime::kWasmCreateFixedArrayForThrow, &encoded_size_smi, 1);
-  SetSourcePosition(values_array, position);
+
+  Node* values_array;
+  {
+    WasmAllocateFixedArrayDescriptor interface_descriptor;
+    auto* call_descriptor = Linkage::GetStubCallDescriptor(
+        mcgraph()->zone(), interface_descriptor,
+        interface_descriptor.GetStackParameterCount(), CallDescriptor::kNoFlags,
+        Operator::kNoProperties, StubCallMode::kCallWasmRuntimeStub);
+    Node* call_target = mcgraph()->RelocatableIntPtrConstant(
+        wasm::WasmCode::kWasmAllocateFixedArray, RelocInfo::WASM_STUB_CALL);
+    values_array = gasm_->Call(call_descriptor, call_target,
+                               gasm_->IntPtrConstant(encoded_size));
+    SetSourcePosition(values_array, position);
+  }
 
   uint32_t index = 0;
   const wasm::WasmExceptionSig* sig = exception->sig;
@@ -2339,17 +2348,20 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
 
   Node* exception_tag = LoadExceptionTagFromTable(exception_index);
 
-  WasmThrowDescriptor interface_descriptor;
-  auto call_descriptor = Linkage::GetStubCallDescriptor(
-      mcgraph()->zone(), interface_descriptor,
-      interface_descriptor.GetStackParameterCount(), CallDescriptor::kNoFlags,
-      Operator::kNoProperties, StubCallMode::kCallWasmRuntimeStub);
-  Node* call_target = mcgraph()->RelocatableIntPtrConstant(
-      wasm::WasmCode::kWasmThrow, RelocInfo::WASM_STUB_CALL);
-  Node* call =
-      gasm_->Call(call_descriptor, call_target, exception_tag, values_array);
-  SetSourcePosition(call, position);
-  return call;
+  Node* throw_call;
+  {
+    WasmThrowDescriptor interface_descriptor;
+    auto* call_descriptor = Linkage::GetStubCallDescriptor(
+        mcgraph()->zone(), interface_descriptor,
+        interface_descriptor.GetStackParameterCount(), CallDescriptor::kNoFlags,
+        Operator::kNoProperties, StubCallMode::kCallWasmRuntimeStub);
+    Node* call_target = mcgraph()->RelocatableIntPtrConstant(
+        wasm::WasmCode::kWasmThrow, RelocInfo::WASM_STUB_CALL);
+    throw_call =
+        gasm_->Call(call_descriptor, call_target, exception_tag, values_array);
+    SetSourcePosition(throw_call, position);
+  }
+  return throw_call;
 }
 
 void WasmGraphBuilder::BuildEncodeException32BitValue(Node* values_array,

src/runtime/runtime-wasm.cc

@@ -148,27 +148,14 @@ RUNTIME_FUNCTION(Runtime_WasmThrowJSTypeError) {
       isolate, NewTypeError(MessageTemplate::kWasmTrapJSTypeError));
 }
 
-RUNTIME_FUNCTION(Runtime_WasmCreateFixedArrayForThrow) {
-  ClearThreadInWasmScope clear_wasm_flag;
-  // TODO(wasm): Replace this by equivalent TurboFan code.
-  HandleScope scope(isolate);
-  DCHECK_EQ(1, args.length());
-  DCHECK(isolate->context().is_null());
-  isolate->set_context(GetNativeContextFromWasmInstanceOnStackTop(isolate));
-  CONVERT_SMI_ARG_CHECKED(size, 0);
-  Handle<FixedArray> values = isolate->factory()->NewFixedArray(size);
-  return *values;
-}
-
 RUNTIME_FUNCTION(Runtime_WasmThrow) {
   // Do not clear the flag in a scope. The unwinder will set it if the exception
   // is caught by a wasm frame, otherwise we keep it cleared.
   trap_handler::ClearThreadInWasm();
   HandleScope scope(isolate);
   DCHECK_EQ(2, args.length());
-  // The context is still set from WasmCreateFixedArrayForThrow.
-  DCHECK_EQ(isolate->context(),
-            GetNativeContextFromWasmInstanceOnStackTop(isolate));
+  isolate->set_context(GetNativeContextFromWasmInstanceOnStackTop(isolate));
+
   CONVERT_ARG_CHECKED(WasmExceptionTag, tag_raw, 0);
   CONVERT_ARG_CHECKED(FixedArray, values_raw, 1);
   // TODO(wasm): Manually box because parameters are not visited yet.

src/runtime/runtime.h

@@ -579,7 +579,6 @@ namespace internal {
   F(WasmAtomicNotify, 3, 1)             \
   F(WasmMemoryGrow, 2, 1)               \
   F(WasmStackGuard, 0, 1)               \
-  F(WasmCreateFixedArrayForThrow, 1, 1) \
   F(WasmThrow, 2, 1)                    \
   F(WasmReThrow, 1, 1)                  \
   F(WasmThrowJSTypeError, 0, 1)         \

src/wasm/wasm-code-manager.h

@@ -71,6 +71,7 @@ struct WasmModule;
   V(WasmTableSet)                        \
   V(WasmStackGuard)                      \
   V(WasmStackOverflow)                   \
+  V(WasmAllocateFixedArray)              \
   V(WasmThrow)                           \
   V(WasmRethrow)                         \
   V(WasmTraceEnter)                      \