[wasm] Implement stepping in wasm code

test/cctest/wasm/test-wasm-breakpoints.cc

Index: test/cctest/wasm/test-wasm-breakpoints.cc
diff --git a/test/cctest/wasm/test-wasm-breakpoints.cc b/test/cctest/wasm/test-wasm-breakpoints.cc
index d287606a50d87b2b503f99e78836aaa65d2545d1..e574dd946de6237106367673ac42706489e9a6a6 100644
--- a/test/cctest/wasm/test-wasm-breakpoints.cc
+++ b/test/cctest/wasm/test-wasm-breakpoints.cc
@@ -3,7 +3,9 @@
 // found in the LICENSE file.
 
 #include "src/debug/debug-interface.h"
+#include "src/frames-inl.h"
 #include "src/property-descriptor.h"
+#include "src/utils.h"
 #include "src/wasm/wasm-macro-gen.h"
 #include "src/wasm/wasm-objects.h"
 
@@ -53,11 +55,24 @@ void CheckLocationsFail(WasmCompiledModule *compiled_module,
 
 class BreakHandler {
  public:
-  explicit BreakHandler(Isolate* isolate) : isolate_(isolate) {
+  enum Action { Continue, StepNext, StepIn, StepOut };
+  struct BreakPoint {
+    int position;
+    Action action;
+    BreakPoint(int position, Action action)
+        : position(position), action(action) {}
+  };
+
+  explicit BreakHandler(Isolate* isolate,
+                        std::initializer_list<BreakPoint> expected_breaks)
+      : isolate_(isolate), expected_breaks_(expected_breaks) {
     current_handler = this;
     isolate->debug()->SetMessageHandler(&HandleMessage);
   }
   ~BreakHandler() {
+    // Check that all expected breakpoints have been hit.
+    CHECK_EQ(count_, expected_breaks_.size());
+    // BreakHandlers must be correctly stacked.
     CHECK_EQ(this, current_handler);
     current_handler = nullptr;
     isolate_->debug()->SetMessageHandler(nullptr);
@@ -68,28 +83,60 @@ class BreakHandler {
  private:
   Isolate* isolate_;
   int count_ = 0;
+  std::vector<BreakPoint> expected_breaks_;
 
   static BreakHandler* current_handler;
 
+  static const char* ActionToArgs(Action action) {
+    switch (action) {
+      case Continue:
+        return "";
+      case StepNext:
+        return "\"stepaction\":\"next\"";
+      case StepIn:
+        return "\"stepaction\":\"in\"";
+      case StepOut:
+        return "\"stepaction\":\"out\"";
+      default:
+        UNREACHABLE();
+        return nullptr;
+    }
+  }
+
+  Action HandleBreak() {
+    printf("Break #%d\n", count_);
+    CHECK_GT(expected_breaks_.size(), count_);
+
+    // Check the current position.
+    StackTraceFrameIterator frame_it(isolate_);
+    auto summ = FrameSummary::GetTop(frame_it.frame()).AsWasmInterpreted();
+    CHECK_EQ(expected_breaks_[count_].position, summ.byte_offset());
+
+    return expected_breaks_[count_++].action;
+  }
+
   static void HandleMessage(const v8::Debug::Message& message) {
     // Ignore responses.
     if (!message.IsEvent()) return;
     // Ignore everything except break events.
     if (message.GetEvent() != v8::DebugEvent::Break) return;
 
-    printf("break!\n");
     CHECK_NOT_NULL(current_handler);
-    current_handler->count_ += 1;
-    // Don't run into an endless loop.
-    CHECK_GT(100, current_handler->count_);
+    Action next_action = current_handler->HandleBreak();
+
+    EmbeddedVector<char, 256> command;
+    command.Truncate(SNPrintF(
+        command,
+        "{\"type\":\"request\", \"command\":\"continue\", \"arguments\":{%s}}",
+        ActionToArgs(next_action)));
 
-    const char command[] = "{\"type\":\"request\", \"command\":\"continue\"}";
-    uint16_t command_u16[arraysize(command) - 1];
-    for (unsigned i = 0; i < arraysize(command) - 1; ++i) {
+    EmbeddedVector<uint16_t, 256> command_u16;
+    command_u16.Truncate(command.length());
+    for (unsigned i = 0, e = command.length(); i < e; ++i) {
       command_u16[i] = command[i];
     }
     current_handler->isolate_->debug()->EnqueueCommandMessage(
-        ArrayVector(command_u16), message.GetClientData());
+        command_u16, message.GetClientData());
   }
 };
 
@@ -175,8 +222,34 @@ TEST(TestSimpleBreak) {
       runner.module().WrapCode(runner.function_index());
   SetBreakpoint(runner, runner.function_index(), 4, 4);
 
-  BreakHandler count_breaks(isolate);
-  CHECK_EQ(0, count_breaks.count());
+  BreakHandler count_breaks(isolate, {{4, BreakHandler::Continue}});
+
+  Handle<Object> global(isolate->context()->global_object(), isolate);
+  MaybeHandle<Object> retval =
+      Execution::Call(isolate, main_fun_wrapper, global, 0, nullptr);
+  CHECK(!retval.is_null());
+  int result;
+  CHECK(retval.ToHandleChecked()->ToInt32(&result));
+  CHECK_EQ(14, result);
+}
+
+TEST(TestSimpleStepping) {
+  WasmRunner<int> runner(kExecuteCompiled);
+  BUILD(runner, WASM_I32_ADD(WASM_I32V_1(11), WASM_I32V_1(3)));
+
+  Isolate* isolate = runner.main_isolate();
+  Handle<JSFunction> main_fun_wrapper =
+      runner.module().WrapCode(runner.function_index());
+
+  // Set breakpoint at the first I32Const.
+  SetBreakpoint(runner, runner.function_index(), 1, 1);
+
+  BreakHandler count_breaks(isolate,
+                            {
+                                {1, BreakHandler::StepNext},  // I32Const
+                                {3, BreakHandler::StepNext},  // I32Const
+                                {5, BreakHandler::Continue}   // I32Add
+                            });
 
   Handle<Object> global(isolate->context()->global_object(), isolate);
   MaybeHandle<Object> retval =
@@ -185,6 +258,44 @@ TEST(TestSimpleBreak) {
   int result;
   CHECK(retval.ToHandleChecked()->ToInt32(&result));
   CHECK_EQ(14, result);
+}
 
-  CHECK_EQ(1, count_breaks.count());
+TEST(TestStepInAndOut) {
+  WasmRunner<int, int> runner(kExecuteCompiled);
+  WasmFunctionCompiler& f2 = runner.NewFunction<void>();
+  f2.AllocateLocal(ValueType::kWord32);
+
+  // Call f2 via indirect call, because a direct call requires f2 to exist when
+  // we compile main, but we need to compile main first so that the order of
+  // functions in the code section matches the function indexes.
+
+  // return arg0
+  BUILD(runner, WASM_RETURN1(WASM_GET_LOCAL(0)));
+  // for (int i = 0; i < 10; ++i) { f2(i); }
+  BUILD(f2, WASM_LOOP(
+                WASM_BR_IF(0, WASM_BINOP(kExprI32GeU, WASM_GET_LOCAL(0),
+                                         WASM_I32V_1(10))),
+                WASM_SET_LOCAL(
+                    0, WASM_BINOP(kExprI32Sub, WASM_GET_LOCAL(0), WASM_ONE)),
+                WASM_CALL_FUNCTION(runner.function_index(), WASM_GET_LOCAL(0)),
+                WASM_BR(1)));
+
+  Isolate* isolate = runner.main_isolate();
+  Handle<JSFunction> main_fun_wrapper =
+      runner.module().WrapCode(f2.function_index());
+
+  // Set first breakpoint on the GetLocal (offset 19) before the Call.
+  SetBreakpoint(runner, f2.function_index(), 19, 19);
+
+  BreakHandler count_breaks(isolate,
+                            {
+                                {19, BreakHandler::StepIn},   // GetLocal
+                                {21, BreakHandler::StepIn},   // Call
+                                {1, BreakHandler::StepOut},   // in f2
+                                {23, BreakHandler::Continue}  // After Call
+                            });
+
+  Handle<Object> global(isolate->context()->global_object(), isolate);
+  CHECK(!Execution::Call(isolate, main_fun_wrapper, global, 0, nullptr)
+             .is_null());
 }