[wasm] Improve exception throwing code sequence.

This reduces the size a "Throw" or "Rethrow" takes in generated code by
switching from runtime calls to using WebAssembly runtime stubs. It also
removes a specialized runtime function and instead uses {Runtime_Throw}
which is generic and used by all code (including JavaScript code).

R=clemensh@chromium.org
BUG=v8:8091

Change-Id: Id4f637525f2ea9d81227931b1290d90ca5f376d1
Reviewed-on: https://chromium-review.googlesource.com/1243106
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56215}

src/builtins/builtins-definitions.h

@@ -1225,6 +1225,7 @@ namespace internal {
   TFC(WasmGrowMemory, WasmGrowMemory, 1)                                       \
   TFC(WasmStackGuard, NoContext, 1)                                            \
   TFC(WasmToNumber, TypeConversion, 1)                                         \
+  TFC(WasmThrow, WasmThrow, 1)                                                 \
   TFS(ThrowWasmTrapUnreachable)                                                \
   TFS(ThrowWasmTrapMemOutOfBounds)                                             \
   TFS(ThrowWasmTrapUnalignedAccess)                                            \
@@ -1496,6 +1497,7 @@ namespace internal {
   V(WasmGrowMemory)                      \
   V(WasmStackGuard)                      \
   V(WasmToNumber)                        \
+  V(WasmThrow)                           \
   V(DoubleToI)
 
 // The exception thrown in the following builtins are caught internally and will

src/builtins/builtins-wasm-gen.cc

@@ -80,6 +80,14 @@ TF_BUILTIN(WasmStackGuard, WasmBuiltinsAssembler) {
   TailCallRuntimeWithCEntry(Runtime::kWasmStackGuard, centry, context);
 }
 
+TF_BUILTIN(WasmThrow, WasmBuiltinsAssembler) {
+  TNode<Object> exception = UncheckedParameter(Descriptor::kException);
+  TNode<Object> instance = LoadInstanceFromFrame();
+  TNode<Code> centry = LoadCEntryFromInstance(instance);
+  TNode<Object> context = LoadContextFromInstance(instance);
+  TailCallRuntimeWithCEntry(Runtime::kThrow, centry, context, exception);
+}
+
 TF_BUILTIN(WasmGrowMemory, WasmBuiltinsAssembler) {
   TNode<Int32T> num_pages =
       UncheckedCast<Int32T>(Parameter(Descriptor::kNumPages));

src/compiler/wasm-compiler.cc

@@ -2083,7 +2083,16 @@ Node* WasmGraphBuilder::Throw(uint32_t exception_index,
     }
   }
   DCHECK_EQ(encoded_size, index);
-  return BuildCallToRuntime(Runtime::kWasmThrow, &except_obj, 1);
+  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);
+  return SetEffect(SetControl(
+      graph()->NewNode(mcgraph()->common()->Call(call_descriptor), call_target,
+                       except_obj, Effect(), Control())));
 }
 
 void WasmGraphBuilder::BuildEncodeException32BitValue(Node* except_obj,
@@ -2122,8 +2131,16 @@ Node* WasmGraphBuilder::BuildDecodeException32BitValue(Node* const* values,
 
 Node* WasmGraphBuilder::Rethrow(Node* except_obj) {
   needs_stack_check_ = true;
-  Node* result = BuildCallToRuntime(Runtime::kWasmThrow, &except_obj, 1);
-  return result;
+  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);
+  return SetEffect(SetControl(
+      graph()->NewNode(mcgraph()->common()->Call(call_descriptor), call_target,
+                       except_obj, Effect(), Control())));
 }
 
 Node* WasmGraphBuilder::ExceptionTagEqual(Node* caught_tag,

src/interface-descriptors.cc

@@ -344,6 +344,11 @@ void WasmGrowMemoryDescriptor::InitializePlatformSpecific(
   DefaultInitializePlatformSpecific(data, kParameterCount);
 }
 
+void WasmThrowDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  DefaultInitializePlatformSpecific(data, kParameterCount);
+}
+
 void CloneObjectWithVectorDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   DefaultInitializePlatformSpecific(data, kParameterCount);

src/interface-descriptors.h

@@ -74,6 +74,7 @@ namespace internal {
   V(FrameDropperTrampoline)           \
   V(RunMicrotasks)                    \
   V(WasmGrowMemory)                   \
+  V(WasmThrow)                        \
   V(CloneObjectWithVector)            \
   BUILTIN_LIST_TFS(V)
 
@@ -1085,6 +1086,14 @@ class WasmGrowMemoryDescriptor final : public CallInterfaceDescriptor {
   DECLARE_DESCRIPTOR(WasmGrowMemoryDescriptor, CallInterfaceDescriptor)
 };
 
+class WasmThrowDescriptor final : public CallInterfaceDescriptor {
+ public:
+  DEFINE_PARAMETERS_NO_CONTEXT(kException)
+  DEFINE_RESULT_AND_PARAMETER_TYPES(MachineType::AnyTagged(),  // result 1
+                                    MachineType::AnyTagged())  // kException
+  DECLARE_DESCRIPTOR(WasmThrowDescriptor, CallInterfaceDescriptor)
+};
+
 class CloneObjectWithVectorDescriptor final : public CallInterfaceDescriptor {
  public:
   DEFINE_PARAMETERS(kSource, kFlags, kSlot, kVector)

src/runtime/runtime-wasm.cc

@@ -122,16 +122,6 @@ RUNTIME_FUNCTION(Runtime_WasmThrowCreate) {
   return *exception;
 }
 
-RUNTIME_FUNCTION(Runtime_WasmThrow) {
-  // TODO(kschimpf): Can this be replaced with equivalent TurboFan code/calls.
-  SealHandleScope shs(isolate);
-  DCHECK_EQ(1, args.length());
-  DCHECK_NULL(isolate->context());
-  isolate->set_context(GetNativeContextFromWasmInstanceOnStackTop(isolate));
-  CONVERT_ARG_CHECKED(Object, except_obj, 0);
-  return isolate->Throw(except_obj);
-}
-
 RUNTIME_FUNCTION(Runtime_WasmExceptionGetTag) {
   // TODO(kschimpf): Can this be replaced with equivalent TurboFan code/calls.
   HandleScope scope(isolate);

src/runtime/runtime.h

@@ -530,7 +530,6 @@ namespace internal {
   F(WasmGrowMemory, 2, 1)          \
   F(WasmRunInterpreter, 2, 1)      \
   F(WasmStackGuard, 0, 1)          \
-  F(WasmThrow, 1, 1)               \
   F(WasmThrowCreate, 2, 1)         \
   F(WasmThrowTypeError, 0, 1)      \
   F(WasmCompileLazy, 2, 1)