[wasm] prototype for breakpoint support.

src/wasm/wasm-debug.cc

Index: src/wasm/wasm-debug.cc
diff --git a/src/wasm/wasm-debug.cc b/src/wasm/wasm-debug.cc
index f1b01593cf437415f2d4143af5e03734149a2851..1ee45d5ccfa29de433ddedef17ec3b39a0e889a5 100644
--- a/src/wasm/wasm-debug.cc
+++ b/src/wasm/wasm-debug.cc
@@ -5,10 +5,15 @@
 #include "src/wasm/wasm-debug.h"
 
 #include "src/assert-scope.h"
+#include "src/compiler/wasm-compiler.h"
 #include "src/debug/debug.h"
 #include "src/factory.h"
+#include "src/frames-inl.h"
 #include "src/isolate.h"
+// We need src/assembler-$arch-inl.h, and macro-assembler.h includes this.
+#include "src/macro-assembler.h"
 #include "src/wasm/module-decoder.h"
+#include "src/wasm/wasm-interpreter.h"
 #include "src/wasm/wasm-module.h"
 
 using namespace v8::internal;
@@ -21,6 +26,9 @@ enum {
   kWasmDebugInfoWasmBytesHash,
   kWasmDebugInfoFunctionByteOffsets,
   kWasmDebugInfoFunctionScripts,
+  kWasmDebugInfoInterpreterAddr,
+  kWasmDebugInfoInterpretedFunctions,
+  kWasmDebugInfoDebugInfos,
   kWasmDebugInfoNumEntries
 };
 
@@ -68,17 +76,312 @@ std::pair<int, int> GetFunctionOffsetAndLength(Handle<WasmDebugInfo> debug_info,
 
 Vector<const uint8_t> GetFunctionBytes(Handle<WasmDebugInfo> debug_info,
                                        int func_index) {
-  SeqOneByteString *module_bytes =
-      wasm::GetWasmBytes(debug_info->wasm_object());
   std::pair<int, int> offset_and_length =
       GetFunctionOffsetAndLength(debug_info, func_index);
+  SeqOneByteString *module_bytes =
+      wasm::GetWasmBytes(debug_info->wasm_object());
   return Vector<const uint8_t>(
       module_bytes->GetChars() + offset_and_length.first,
       offset_and_length.second);
 }
 
+FixedArray *GetOrCreateInterpretedFunctions(Handle<WasmDebugInfo> debug_info) {
+  Object *maybe_arr = debug_info->get(kWasmDebugInfoInterpretedFunctions);
+  Isolate *isolate = debug_info->GetIsolate();
+  if (!maybe_arr->IsUndefined(isolate)) return FixedArray::cast(maybe_arr);
+
+  FixedArray *new_arr = *isolate->factory()->NewFixedArray(
+      wasm::GetNumberOfFunctions(debug_info->wasm_object()));
+  debug_info->set(kWasmDebugInfoInterpretedFunctions, new_arr);
+  return new_arr;
+}
+
+void RedirectFunction(Code *code, Code *old_target, Code *new_target) {
+  for (RelocIterator it(code, RelocInfo::kCodeTargetMask); !it.done();
+       it.next()) {
+    DCHECK(RelocInfo::IsCodeTarget(it.rinfo()->rmode()));
+    Code *target = Code::GetCodeFromTargetAddress(it.rinfo()->target_address());
+    if (target != old_target) continue;
+    it.rinfo()->set_target_address(new_target->instruction_start(),
+                                   SKIP_WRITE_BARRIER, SKIP_ICACHE_FLUSH);
+  }
+}
+
+void RedirectFunctionEverywhere(Handle<JSObject> wasm, Handle<Code> old_target,
+                                Handle<Code> new_target) {
+  // Redirect in all wasm functions.
+  for (int i = 0, e = wasm::GetNumberOfFunctions(*wasm); i < e; ++i)
+    RedirectFunction(wasm::GetWasmFunctionCode(*wasm, i), *old_target,
+                     *new_target);
+
+  // Redirect in the code of all exported functions.
+  Isolate *isolate = wasm->GetIsolate();
+  // For AsmJs modules, the exports are stored on the wasm object itself.
+  MaybeHandle<Object> maybe_exports =
+      JSReceiver::GetProperty(isolate, wasm, "exports");
+  Handle<JSObject> exports_object =
+      maybe_exports.is_null()
+          ? wasm
+          : Handle<JSObject>::cast(maybe_exports.ToHandleChecked());
+
+  Handle<FixedArray> values;
+  if (JSReceiver::GetOwnValues(Handle<JSReceiver>::cast(exports_object),
+                               ALL_PROPERTIES)
+          .ToHandle(&values)) {
+    for (int i = 0, e = values->length(); i != e; ++i) {
+      if (!values->get(i)->IsJSFunction()) continue;
+      Code *code = JSFunction::cast(values->get(i))->code();
+      RedirectFunction(code, *old_target, *new_target);
+    }
+  }
+}
+
+class InterpreterHandle {
+  v8::base::AccountingAllocator allocator;
+  Zone zone;
+  Handle<Object> global_ref;
+  std::unique_ptr<const WasmModule> module;
+  std::unique_ptr<WasmModuleInstance> module_instance;
+  Isolate *isolate;
+
+  uint8_t *parameter_buffer;
+  uint32_t parameter_buffer_size = 0;
+#ifdef DEBUG
+  // Track the function index for which the last buffer was allocated.
+  // This is updated on AllocateParameterBuffer, and checked at Execute.
+  uint32_t parameter_buffer_taken = static_cast<uint32_t>(-1);
+#endif
+
+ public:
+  WasmInterpreter interpreter;
+
+  // Initialize in the right order. WasmInterpreter has to be allocate in place,
+  // since it's not std::move'able.
+  explicit InterpreterHandle(WasmDebugInfo *debug_info)
+      : allocator(),
+        zone(&allocator),
+        module(CreateModule(&zone, debug_info)),
+        isolate(debug_info->GetIsolate()),
+        interpreter(CreateModuleInstance(module.get(), debug_info), &zone) {
+    global_ref = debug_info->GetIsolate()->global_handles()->Create(debug_info);
+    GlobalHandles::MakeWeak(global_ref.location(), this,
+                            InterpreterHandle::Finalize,
+                            v8::WeakCallbackType::kParameter);
+  }
+
+  static void Finalize(const v8::WeakCallbackInfo<void> &data) {
+    void *param = data.GetParameter();
+    InterpreterHandle *handle = reinterpret_cast<InterpreterHandle *>(param);
+    GlobalHandles::ClearWeakness(handle->global_ref.location());
+    GlobalHandles::Destroy(handle->global_ref.location());
+    delete handle;
+  }
+
+  static const WasmModule *CreateModule(Zone *zone, WasmDebugInfo *debug_info) {
+    SeqOneByteString *wasm_bytes =
+        wasm::GetWasmBytes(debug_info->wasm_object());
+    const byte *bytes_start = wasm_bytes->GetChars();
+    const byte *bytes_end = bytes_start + wasm_bytes->length();
+    ModuleResult module_result =
+        DecodeWasmModule(debug_info->GetIsolate(), zone, bytes_start, bytes_end,
+                         false, ModuleOrigin::kWasmOrigin);
+    DCHECK(module_result.ok());
+    return module_result.val;
+  }
+
+  static WasmModuleInstance *CreateModuleInstance(const WasmModule *module,
+                                                  WasmDebugInfo *debug_info) {
+    JSArrayBuffer *memory =
+        wasm::GetWasmMemoryBuffer(debug_info->wasm_object());
+
+    WasmModuleInstance *instance = new WasmModuleInstance(module);
+    instance->mem_start = reinterpret_cast<byte *>(memory->backing_store());
+    instance->mem_size = memory->byte_length()->Number();
+    instance->mem_buffer = handle(memory, debug_info->GetIsolate());
+
+    return instance;
+  }
+
+  uint8_t *GetParameterBuffer(uint32_t function_index) {
+    DCHECK_LE(function_index, module->functions.size());
+    DCHECK_EQ(static_cast<uint32_t>(-1), parameter_buffer_taken);
+#ifdef DEBUG
+    parameter_buffer_taken = function_index;
+#endif
+    uint32_t size_needed = 0;
+    FunctionSig *sig = module->functions[function_index].sig;
+    for (size_t i = 0, e = sig->parameter_count(); i != e; ++i) {
+      size_needed += 1 << ElementSizeLog2Of(sig->GetParam(i));
+    }
+    if (size_needed > parameter_buffer_size) {
+      uint32_t alloc_size = 2 * parameter_buffer_size;
+      if (size_needed > alloc_size) alloc_size = size_needed;
+      parameter_buffer = zone.NewArray<uint8_t>(alloc_size);
+      parameter_buffer_size = alloc_size;
+    }
+    return parameter_buffer;
+  }
+
+  void Execute(uint32_t func_index) {
+    DCHECK_EQ(parameter_buffer_taken, func_index);
+#ifdef DEBUG
+    parameter_buffer_taken = static_cast<uint32_t>(-1);
+#endif
+    FunctionSig *sig = module->functions[func_index].sig;
+    DCHECK_LE(sig->parameter_count(), static_cast<size_t>(kMaxInt));
+    int num_params = static_cast<int>(sig->parameter_count());
+    ScopedVector<WasmVal> wasm_args(num_params);
+    uint8_t *buf_ptr = parameter_buffer;
+    for (int i = 0; i < num_params; ++i) {
+      uint32_t param_size = 1 << ElementSizeLog2Of(sig->GetParam(i));
+      switch (sig->GetParam(i)) {
+        case kAstI32:
+          DCHECK_EQ(param_size, sizeof(uint32_t));
+          wasm_args[i] = WasmVal(*reinterpret_cast<uint32_t *>(buf_ptr));
+          break;
+        case kAstI64:
+          DCHECK_EQ(param_size, sizeof(uint64_t));
+          wasm_args[i] = WasmVal(*reinterpret_cast<uint64_t *>(buf_ptr));
+          break;
+        case kAstF32:
+          DCHECK_EQ(param_size, sizeof(float));
+          wasm_args[i] = WasmVal(*reinterpret_cast<float *>(buf_ptr));
+          break;
+        case kAstF64:
+          DCHECK_EQ(param_size, sizeof(double));
+          wasm_args[i] = WasmVal(*reinterpret_cast<double *>(buf_ptr));
+          break;
+        default:
+          UNREACHABLE();
+      }
+      buf_ptr += param_size;
+    }
+
+    WasmInterpreter::Thread *thread = interpreter.GetThread(0);
+    // We do not support reentering an already running interpreter at the moment
+    // (like INTERPRETER -> JS -> WASM -> INTERPRETER).
+    DCHECK(thread->state() == WasmInterpreter::STOPPED ||
+           thread->state() == WasmInterpreter::FINISHED);
+    thread->Reset();
+    thread->PushFrame(&module->functions[func_index], wasm_args.start());
+    WasmInterpreter::State state;
+    do {
+      state = thread->Run();
+      switch (state) {
+        case WasmInterpreter::State::PAUSED: {
+          // We hit a breakpoint.
+          StackTraceFrameIterator frame_it(isolate);
+          WasmInterpretedFrame *top_frame =
+              WasmInterpretedFrame::cast(frame_it.frame());
+          isolate->debug()->Break(top_frame);
+        } break;
+        case WasmInterpreter::State::FINISHED:
+          // Perfect, just break the switch and exit the loop.
+          break;
+        case WasmInterpreter::State::TRAPPED:
+          // TODO(clemensh): Generate appropriate JS exception.
+          UNIMPLEMENTED();
+          break;
+        // STOPPED and RUNNING should never occur here.
+        case WasmInterpreter::State::STOPPED:
+        case WasmInterpreter::State::RUNNING:
+        default:
+          UNREACHABLE();
+      }
+    } while (state != WasmInterpreter::State::FINISHED);
+  }
+
+  void EnsureInterpreterRedirect(Handle<WasmDebugInfo> debug_info,
+                                 int func_index) {
+    Isolate *isolate = debug_info->GetIsolate();
+    Handle<FixedArray> interpreted_functions(
+        GetOrCreateInterpretedFunctions(debug_info), isolate);
+    DCHECK_LT(func_index, interpreted_functions->length());
+    if (!interpreted_functions->get(func_index)->IsUndefined(isolate)) return;
+
+    Handle<JSObject> wasm(debug_info->wasm_object(), isolate);
+    Handle<Code> new_code = compiler::CompileWasmToInterpreter(
+        isolate, func_index, module->functions[func_index].sig, wasm);
+    Handle<Code> old_code(wasm::GetWasmFunctionCode(*wasm, func_index),
+                          isolate);
+    interpreted_functions->set(func_index, *new_code);
+
+    RedirectFunctionEverywhere(wasm, old_code, new_code);
+  }
+};
+
+InterpreterHandle *GetOrCreateInterpreterHandle(WasmDebugInfo *debug_info) {
+  DisallowHeapAllocation no_gc;
+  // We store the raw pointer to the InterpreterHandle in a slot in the debug
+  // info.
+  // Since the pointer is aligned, it will look like a Smi, and the gc will
+  // ignore it.
+  Object *handle_obj = debug_info->get(kWasmDebugInfoInterpreterAddr);
+  if (!handle_obj->IsUndefined(debug_info->GetIsolate())) {
+    DCHECK(!handle_obj->IsHeapObject());
+    return reinterpret_cast<InterpreterHandle *>(handle_obj);
+  }
+
+  InterpreterHandle *handle = new InterpreterHandle(debug_info);
+  handle_obj = reinterpret_cast<Object *>(handle);
+  DCHECK(!handle_obj->IsHeapObject());
+  debug_info->set(kWasmDebugInfoInterpreterAddr, handle_obj);
+  return handle;
+}
+
+InterpreterHandle *GetInterpreterHandleIfExists(WasmDebugInfo *debug_info) {
+  DisallowHeapAllocation no_gc;
+  Object *handle_obj = debug_info->get(kWasmDebugInfoInterpreterAddr);
+  return handle_obj->IsUndefined(debug_info->GetIsolate())
+             ? nullptr
+             : reinterpret_cast<InterpreterHandle *>(handle_obj);
+}
+
 }  // namespace
 
+WasmInstructionIterator::WasmInstructionIterator(const byte *start,
+                                                 const byte *end)
+    : start_(start), end_(end) {
+  base::AccountingAllocator allocator;
+  Zone tmp_zone(&allocator);
+  AstLocalDecls locals(&tmp_zone);
+  bool valid = DecodeLocalDecls(locals, start, end);
+  DCHECK(valid);
+  USE(valid);
+  pc_ = start + locals.decls_encoded_size;
+}
+
+void WasmInstructionIterator::Next() {
+  DCHECK(!Done());
+  int len = OpcodeLength(pc_, end_);
+  DCHECK_LE(0, len);  // 0 means validation error / read past the end.
+  pc_ += len;
+}
+
+Script *InterpreterFrameInfo::GetScript() const {
+  return WasmDebugInfo::GetFunctionScript(debug_info_, func_index_);
+}
+
+InterpreterFrameIterator::InterpreterFrameIterator(
+    Handle<WasmDebugInfo> debug_info)
+    : frame_nr_(0),
+      frame_count_(GetOrCreateInterpreterHandle(*debug_info)
+                       ->interpreter.GetThread(0)
+                       ->GetFrameCount()),
+      debug_info_(debug_info) {}
+
+InterpreterFrameInfo InterpreterFrameIterator::GetFrameInfo() const {
+  DCHECK(!Done());
+  WasmInterpreter::Thread *thread =
+      GetOrCreateInterpreterHandle(*debug_info_)->interpreter.GetThread(0);
+  DCHECK_EQ(frame_count_, thread->GetFrameCount());
+  DCHECK_LE(0, frame_nr_);
+  std::unique_ptr<const WasmInterpreterFrame> frame(
+      thread->GetFrame(frame_nr_));
+  return InterpreterFrameInfo(debug_info_, frame->function()->func_index,
+                              frame->pc());
+}
+
 Handle<WasmDebugInfo> WasmDebugInfo::New(Handle<JSObject> wasm) {
   Isolate *isolate = wasm->GetIsolate();
   Factory *factory = isolate->factory();
@@ -98,7 +401,7 @@ Handle<WasmDebugInfo> WasmDebugInfo::New(Handle<JSObject> wasm) {
   return Handle<WasmDebugInfo>::cast(arr);
 }
 
-bool WasmDebugInfo::IsDebugInfo(Object *object) {
+bool WasmDebugInfo::IsWasmDebugInfo(Object *object) {
   if (!object->IsFixedArray()) return false;
   FixedArray *arr = FixedArray::cast(object);
   Isolate *isolate = arr->GetIsolate();
@@ -108,11 +411,15 @@ bool WasmDebugInfo::IsDebugInfo(Object *object) {
          (arr->get(kWasmDebugInfoFunctionByteOffsets)->IsUndefined(isolate) ||
           arr->get(kWasmDebugInfoFunctionByteOffsets)->IsByteArray()) &&
          (arr->get(kWasmDebugInfoFunctionScripts)->IsUndefined(isolate) ||
-          arr->get(kWasmDebugInfoFunctionScripts)->IsFixedArray());
+          arr->get(kWasmDebugInfoFunctionScripts)->IsFixedArray()) &&
+         (arr->get(kWasmDebugInfoInterpretedFunctions)->IsUndefined(isolate) ||
+          arr->get(kWasmDebugInfoInterpretedFunctions)->IsFixedArray()) &&
+         (arr->get(kWasmDebugInfoDebugInfos)->IsUndefined(isolate) ||
+          arr->get(kWasmDebugInfoDebugInfos)->IsFixedArray());
 }
 
 WasmDebugInfo *WasmDebugInfo::cast(Object *object) {
-  DCHECK(IsDebugInfo(object));
+  DCHECK(IsWasmDebugInfo(object));
   return reinterpret_cast<WasmDebugInfo *>(object);
 }
 
@@ -120,6 +427,25 @@ JSObject *WasmDebugInfo::wasm_object() {
   return JSObject::cast(get(kWasmDebugInfoWasmObj));
 }
 
+void WasmDebugInfo::SetBreakpoint(Handle<WasmDebugInfo> debug_info,
+                                  int func_index, int byte_offset) {
+  DCHECK_LE(0, func_index);
+  DCHECK_LE(0, byte_offset);
+  InterpreterHandle *handle = GetOrCreateInterpreterHandle(*debug_info);
+  handle->EnsureInterpreterRedirect(debug_info, func_index);
+  handle->interpreter.SetBreakpoint(static_cast<uint32_t>(func_index),
+                                    byte_offset, true);
+}
+
+bool WasmDebugInfo::HasBreakpoint(int func_index, int byte_offset) {
+  DCHECK_LE(0, func_index);
+  DCHECK_LE(0, byte_offset);
+  InterpreterHandle *handle = GetInterpreterHandleIfExists(this);
+  return handle &&
+         handle->interpreter.GetBreakpoint(static_cast<uint32_t>(func_index),
+                                           byte_offset);
+}
+
 Script *WasmDebugInfo::GetFunctionScript(Handle<WasmDebugInfo> debug_info,
                                          int func_index) {
   Isolate *isolate = debug_info->GetIsolate();
@@ -228,3 +554,73 @@ Handle<FixedArray> WasmDebugInfo::GetFunctionOffsetTable(
 
   return offset_table;
 }
+
+DebugInfo *WasmDebugInfo::GetDebugInfo(Handle<WasmDebugInfo> debug_info,
+                                       int func_index) {
+  Object *maybe_arr = debug_info->get(kWasmDebugInfoDebugInfos);
+  Isolate *isolate = debug_info->GetIsolate();
+  Handle<FixedArray> arr;
+  if (maybe_arr->IsUndefined(isolate)) {
+    arr = isolate->factory()->NewFixedArray(
+        wasm::GetNumberOfFunctions(debug_info->wasm_object()));
+    debug_info->set(kWasmDebugInfoDebugInfos, *arr);
+  } else {
+    arr = handle(FixedArray::cast(maybe_arr));
+  }
+
+  DCHECK_LE(func_index, static_cast<uint32_t>(arr->length()));
+  Object *maybe_info = arr->get(static_cast<int>(func_index));
+  if (!maybe_info->IsUndefined(isolate)) return DebugInfo::cast(maybe_info);
+
+  Handle<AbstractCode> code(AbstractCode::cast(
+      wasm::GetWasmFunctionCode(debug_info->wasm_object(), func_index)));
+  Handle<DebugInfo> new_debug_info = isolate->factory()->NewDebugInfo(code);
+  arr->set(static_cast<int>(func_index), *new_debug_info);
+  return *new_debug_info;
+}
+
+WasmDebugInfo::InstructionType WasmDebugInfo::GetInstructionType(
+    int func_index, int byte_offset) {
+  SeqOneByteString *bytes = wasm::GetWasmBytes(wasm_object());
+  DCHECK(byte_offset >= 0 && byte_offset < bytes->length());
+  switch (static_cast<WasmOpcode>(bytes->Get(byte_offset))) {
+    case WasmOpcode::kExprReturn:
+      return RETURN;
+    case WasmOpcode::kExprCallImport:
+    case WasmOpcode::kExprCallFunction:
+    case WasmOpcode::kExprCallIndirect:
+      return CALL;
+    default:
+      return OTHER;
+  }
+}
+
+WasmInstructionIterator WasmDebugInfo::GetInstructionIterator(
+    Handle<WasmDebugInfo> debug_info, int func_index) {
+  Vector<const uint8_t> function_bytes =
+      GetFunctionBytes(debug_info, func_index);
+
+  return WasmInstructionIterator(function_bytes.start(), function_bytes.end());
+}
+
+InterpreterFrameIterator WasmDebugInfo::GetInterpreterFrameIterator() {
+  return InterpreterFrameIterator(handle(this));
+}
+
+Object *WasmDebugInfo::GetInterpreterArgBuffer(int func_index) {
+  printf("GetInterpreterArgBuffer %d\n", func_index);
+  DCHECK_LE(0, func_index);
+  InterpreterHandle *interp_handle = GetOrCreateInterpreterHandle(this);
+  uint8_t *buf =
+      interp_handle->GetParameterBuffer(static_cast<uint32_t>(func_index));
+  Object *obj = reinterpret_cast<Object *>(buf);
+  DCHECK(!obj->IsHeapObject());
+  return obj;
+}
+
+void WasmDebugInfo::RunInterpreter(int func_index) {
+  printf("RunInterpreter %d\n", func_index);
+  DCHECK_LE(0, func_index);
+  InterpreterHandle *interp_handle = GetOrCreateInterpreterHandle(this);
+  interp_handle->Execute(static_cast<uint32_t>(func_index));
+}