[wasm] Add support for compiling WASM_INTERPRETER_ENTRY stubs

Also, add a runtime function to call the interpreter, passing a
stack-allocated buffer holding the arguments.
The WASM_INTERPRETER_ENTRY stub allocates the stack slot for the
arguments, fills it, and calls to the wasm interpreter.
It's abi is compatible with WASM functions, such that we can just
replace a call to a WASM_FUNCTION with a call to
WASM_INTERPRETER_ENTRY.
See tracking bug to get the overall picture.

BUG=v8:5822
R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2619803004
Cr-Commit-Position: refs/heads/master@{#42242}

src/compiler/wasm-compiler.cc

@@ -36,6 +36,7 @@
 #include "src/wasm/function-body-decoder.h"
 #include "src/wasm/wasm-limits.h"
 #include "src/wasm/wasm-module.h"
+#include "src/wasm/wasm-objects.h"
 #include "src/wasm/wasm-opcodes.h"
 #include "src/wasm/wasm-text.h"
 
@@ -70,9 +71,6 @@ Node* BuildCallToRuntime(Runtime::FunctionId f, JSGraph* jsgraph,
                          Handle<Context> context, Node** parameters,
                          int parameter_count, Node** effect_ptr,
                          Node* control) {
-  // At the moment we only allow 2 parameters. If more parameters are needed,
-  // then the size of {inputs} below has to be increased accordingly.
-  DCHECK(parameter_count <= 2);
   const Runtime::Function* fun = Runtime::FunctionForId(f);
   CallDescriptor* desc = Linkage::GetRuntimeCallDescriptor(
       jsgraph->zone(), f, fun->nargs, Operator::kNoProperties,
@@ -80,7 +78,11 @@ Node* BuildCallToRuntime(Runtime::FunctionId f, JSGraph* jsgraph,
   // CEntryStubConstant nodes have to be created and cached in the main
   // thread. At the moment this is only done for CEntryStubConstant(1).
   DCHECK_EQ(1, fun->result_size);
-  Node* inputs[8];
+  // At the moment we only allow 2 parameters. If more parameters are needed,
+  // increase this constant accordingly.
+  static const int kMaxParams = 3;
+  DCHECK_GE(kMaxParams, parameter_count);
+  Node* inputs[kMaxParams + 6];
   int count = 0;
   inputs[count++] = jsgraph->CEntryStubConstant(fun->result_size);
   for (int i = 0; i < parameter_count; i++) {
@@ -2927,6 +2929,101 @@ void WasmGraphBuilder::BuildWasmToJSWrapper(Handle<JSReceiver> target,
   Return(val);
 }
 
+void WasmGraphBuilder::BuildWasmInterpreterEntry(
+    uint32_t function_index, wasm::FunctionSig* sig,
+    Handle<WasmInstanceObject> instance) {
+  int wasm_count = static_cast<int>(sig->parameter_count());
+  int param_count = jsgraph()->machine()->Is64()
+                        ? wasm_count
+                        : Int64Lowering::GetParameterCountAfterLowering(sig);
+
+  // Build the start and the parameter nodes.
+  Node* start = Start(param_count + 3);
+  *effect_ = start;
+  *control_ = start;
+
+  // Compute size for the argument buffer.
+  int args_size_bytes = 0;
+  for (int i = 0; i < wasm_count; i++) {
+    args_size_bytes += 1 << ElementSizeLog2Of(sig->GetParam(i));
+  }
+
+  // The return value is also passed via this buffer:
+  DCHECK_GE(1, sig->return_count());
+  int return_size_bytes =
+      sig->return_count() == 0 ? 0 : 1 << ElementSizeLog2Of(sig->GetReturn(0));
+
+  // Get a stack slot for the arguments.
+  Node* arg_buffer = graph()->NewNode(jsgraph()->machine()->StackSlot(
+      std::max(args_size_bytes, return_size_bytes)));
+
+  // Now store all our arguments to the buffer.
+  int param_index = 0;
+  int offset = 0;
+  for (int i = 0; i < wasm_count; i++) {
+    Node* param = Param(param_index++);
+    bool is_i64_as_two_params =
+        jsgraph()->machine()->Is32() && sig->GetParam(i) == wasm::kWasmI64;
+    MachineRepresentation param_rep =
+        is_i64_as_two_params ? wasm::kWasmI32 : sig->GetParam(i);
+    StoreRepresentation store_rep(param_rep, WriteBarrierKind::kNoWriteBarrier);
+    *effect_ =
+        graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
+                         Int32Constant(offset), param, *effect_, *control_);
+    offset += 1 << ElementSizeLog2Of(param_rep);
+    // TODO(clemensh): Respect endianess here. Might need to swap upper and
+    // lower word.
+    if (is_i64_as_two_params) {
+      // Also store the upper half.
+      param = Param(param_index++);
+      StoreRepresentation store_rep(wasm::kWasmI32,
+                                    WriteBarrierKind::kNoWriteBarrier);
+      *effect_ =
+          graph()->NewNode(jsgraph()->machine()->Store(store_rep), arg_buffer,
+                           Int32Constant(offset), param, *effect_, *control_);
+      offset += 1 << ElementSizeLog2Of(wasm::kWasmI32);
+    }
+  }
+  DCHECK_EQ(param_count, param_index);
+  DCHECK_EQ(args_size_bytes, offset);
+
+  // We are passing the raw arg_buffer here. To the GC and other parts, it looks
+  // like a Smi (lowest bit not set). In the runtime function however, don't
+  // call Smi::value on it, but just cast it to a byte pointer.
+  Node* parameters[] = {
+      jsgraph()->HeapConstant(instance),       // wasm instance
+      jsgraph()->SmiConstant(function_index),  // function index
+      arg_buffer,                              // argument buffer
+  };
+  BuildCallToRuntime(Runtime::kWasmRunInterpreter, jsgraph(),
+                     jsgraph()->isolate()->native_context(), parameters,
+                     arraysize(parameters), effect_, *control_);
+
+  // Read back the return value.
+  if (jsgraph()->machine()->Is32() && sig->return_count() > 0 &&
+      sig->GetReturn() == wasm::kWasmI64) {
+    MachineType load_rep = wasm::WasmOpcodes::MachineTypeFor(wasm::kWasmI32);
+    Node* lower =
+        graph()->NewNode(jsgraph()->machine()->Load(load_rep), arg_buffer,
+                         Int32Constant(0), *effect_, *control_);
+    Node* upper =
+        graph()->NewNode(jsgraph()->machine()->Load(load_rep), arg_buffer,
+                         Int32Constant(sizeof(int32_t)), *effect_, *control_);
+    Return(upper, lower);
+  } else {
+    Node* val;
+    if (sig->return_count() == 0) {
+      val = Int32Constant(0);
+    } else {
+      MachineType load_rep =
+          wasm::WasmOpcodes::MachineTypeFor(sig->GetReturn());
+      val = graph()->NewNode(jsgraph()->machine()->Load(load_rep), arg_buffer,
+                             Int32Constant(0), *effect_, *control_);
+    }
+    Return(val);
+  }
+}
+
 Node* WasmGraphBuilder::MemBuffer(uint32_t offset) {
   DCHECK(module_ && module_->instance);
   if (offset == 0) {
@@ -3508,6 +3605,72 @@ Handle<Code> CompileWasmToJSWrapper(Isolate* isolate, Handle<JSReceiver> target,
   return code;
 }
 
+Handle<Code> CompileWasmInterpreterEntry(Isolate* isolate, uint32_t func_index,
+                                         wasm::FunctionSig* sig,
+                                         Handle<WasmInstanceObject> instance) {
+  //----------------------------------------------------------------------------
+  // Create the Graph
+  //----------------------------------------------------------------------------
+  Zone zone(isolate->allocator(), ZONE_NAME);
+  Graph graph(&zone);
+  CommonOperatorBuilder common(&zone);
+  MachineOperatorBuilder machine(&zone);
+  JSGraph jsgraph(isolate, &graph, &common, nullptr, nullptr, &machine);
+
+  Node* control = nullptr;
+  Node* effect = nullptr;
+
+  WasmGraphBuilder builder(nullptr, &zone, &jsgraph, sig);
+  builder.set_control_ptr(&control);
+  builder.set_effect_ptr(&effect);
+  builder.BuildWasmInterpreterEntry(func_index, sig, instance);
+
+  Handle<Code> code = Handle<Code>::null();
+  {
+    if (FLAG_trace_turbo_graph) {  // Simple textual RPO.
+      OFStream os(stdout);
+      os << "-- Wasm to interpreter graph -- " << std::endl;
+      os << AsRPO(graph);
+    }
+
+    // Schedule and compile to machine code.
+    CallDescriptor* incoming =
+        wasm::ModuleEnv::GetWasmCallDescriptor(&zone, sig);
+    if (machine.Is32()) {
+      incoming = wasm::ModuleEnv::GetI32WasmCallDescriptor(&zone, incoming);
+    }
+    Code::Flags flags = Code::ComputeFlags(Code::WASM_INTERPRETER_ENTRY);
+    EmbeddedVector<char, 32> debug_name;
+    int name_len = SNPrintF(debug_name, "wasm-to-interpreter#%d", func_index);
+    DCHECK(name_len > 0 && name_len < debug_name.length());
+    debug_name.Truncate(name_len);
+    DCHECK_EQ('\0', debug_name.start()[debug_name.length()]);
+
+    CompilationInfo info(debug_name, isolate, &zone, flags);
+    code = Pipeline::GenerateCodeForTesting(&info, incoming, &graph, nullptr);
+#ifdef ENABLE_DISASSEMBLER
+    if (FLAG_print_opt_code && !code.is_null()) {
+      OFStream os(stdout);
+      code->Disassemble(debug_name.start(), os);
+    }
+#endif
+
+    if (isolate->logger()->is_logging_code_events() ||
+        isolate->is_profiling()) {
+      RecordFunctionCompilation(CodeEventListener::FUNCTION_TAG, isolate, code,
+                                "wasm-to-interpreter", func_index,
+                                wasm::WasmName("module"), debug_name);
+    }
+  }
+
+  Handle<FixedArray> deopt_data = isolate->factory()->NewFixedArray(1, TENURED);
+  Handle<WeakCell> weak_instance = isolate->factory()->NewWeakCell(instance);
+  deopt_data->set(0, *weak_instance);
+  code->set_deoptimization_data(*deopt_data);
+
+  return code;
+}
+
 SourcePositionTable* WasmCompilationUnit::BuildGraphForWasmFunction(
     double* decode_ms) {
   base::ElapsedTimer decode_timer;

src/compiler/wasm-compiler.h

@@ -102,6 +102,12 @@ Handle<Code> CompileJSToWasmWrapper(Isolate* isolate,
                                     const wasm::WasmModule* module,
                                     Handle<Code> wasm_code, uint32_t index);
 
+// Compiles a stub that redirects a call to a wasm function to the wasm
+// interpreter. It's ABI compatible with the compiled wasm function.
+Handle<Code> CompileWasmInterpreterEntry(Isolate* isolate, uint32_t func_index,
+                                         wasm::FunctionSig* sig,
+                                         Handle<WasmInstanceObject> instance);
+
 // Abstracts details of building TurboFan graph nodes for WASM to separate
 // the WASM decoder from the internal details of TurboFan.
 class WasmTrapHelper;
@@ -182,6 +188,8 @@ class WasmGraphBuilder {
 
   void BuildJSToWasmWrapper(Handle<Code> wasm_code, wasm::FunctionSig* sig);
   void BuildWasmToJSWrapper(Handle<JSReceiver> target, wasm::FunctionSig* sig);
+  void BuildWasmInterpreterEntry(uint32_t func_index, wasm::FunctionSig* sig,
+                                 Handle<WasmInstanceObject> instance);
 
   Node* ToJS(Node* node, wasm::ValueType type);
   Node* FromJS(Node* node, Node* context, wasm::ValueType type);

src/runtime/runtime-wasm.cc

@@ -152,5 +152,28 @@ RUNTIME_FUNCTION(Runtime_WasmGetCaughtExceptionValue) {
   return exception;
 }
 
+RUNTIME_FUNCTION(Runtime_WasmRunInterpreter) {
+  DCHECK(args.length() == 3);
+  HandleScope scope(isolate);
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, instance_obj, 0);
+  CONVERT_NUMBER_CHECKED(int32_t, func_index, Int32, args[1]);
+  CONVERT_ARG_HANDLE_CHECKED(Object, arg_buffer_obj, 2);
+  CHECK(WasmInstanceObject::IsWasmInstanceObject(*instance_obj));
+
+  // The arg buffer is the raw pointer to the caller's stack. It looks like a
+  // Smi (lowest bit not set, as checked by IsSmi), but is no valid Smi. We just
+  // cast it back to the raw pointer.
+  CHECK(!arg_buffer_obj->IsHeapObject());
+  CHECK(arg_buffer_obj->IsSmi());
+  uint8_t* arg_buffer = reinterpret_cast<uint8_t*>(*arg_buffer_obj);
+
+  Handle<WasmInstanceObject> instance =
+      Handle<WasmInstanceObject>::cast(instance_obj);
+  Handle<WasmDebugInfo> debug_info =
+      WasmInstanceObject::GetOrCreateDebugInfo(instance);
+  WasmDebugInfo::RunInterpreter(debug_info, func_index, arg_buffer);
+  return isolate->heap()->undefined_value();
+}
+
 }  // namespace internal
 }  // namespace v8

src/runtime/runtime.h

@@ -943,7 +943,8 @@ namespace internal {
   F(ThrowWasmTrapRemByZero, 0, 1)            \
   F(ThrowWasmTrapFloatUnrepresentable, 0, 1) \
   F(ThrowWasmTrapFuncInvalid, 0, 1)          \
-  F(ThrowWasmTrapFuncSigMismatch, 0, 1)
+  F(ThrowWasmTrapFuncSigMismatch, 0, 1)      \
+  F(WasmRunInterpreter, 3, 1)
 
 #define FOR_EACH_INTRINSIC_RETURN_PAIR(F) \
   F(LoadLookupSlotForCall, 1, 2)

src/wasm/wasm-debug.cc

@@ -36,3 +36,9 @@ WasmDebugInfo *WasmDebugInfo::cast(Object *object) {
 WasmInstanceObject *WasmDebugInfo::wasm_instance() {
   return WasmInstanceObject::cast(get(kInstance));
 }
+
+void WasmDebugInfo::RunInterpreter(Handle<WasmDebugInfo> debug_info,
+                                   int func_index, uint8_t *arg_buffer) {
+  // TODO(clemensh): Implement this.
+  UNIMPLEMENTED();
+}

src/wasm/wasm-objects.h

@@ -383,6 +383,9 @@ class WasmDebugInfo : public FixedArray {
   static bool IsDebugInfo(Object*);
   static WasmDebugInfo* cast(Object*);
 
+  static void RunInterpreter(Handle<WasmDebugInfo>, int func_index,
+                             uint8_t* arg_buffer);
+
   DECLARE_GETTER(wasm_instance, WasmInstanceObject);
 };