wasm/c-api: fix the index of StackTraceFrame

CreateFrameFromInternal always creates StackFrame from the frame at the index zero,
which is fine for the usage in Trap::origin, but is a bug for Trap::trace

Change-Id: Ia9471f600c5165ffc1c165b2f114b40acbe5b1e9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2465353
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70465}

AUTHORS

@@ -225,3 +225,4 @@ Zhao Jiazhong <kyslie3100@gmail.com>
 Zhongping Wang <kewpie.w.zp@gmail.com>
 柳荣一 <admin@web-tinker.com>
 Tianping Yang <yangtianping@oppo.com>
+Takeshi Yoneda <takeshi@tetrate.io>

src/wasm/c-api.cc

@@ -209,8 +209,7 @@ auto seal(const typename implement<C>::type* x) -> const C* {
 
 // Configuration
 
-struct ConfigImpl {
-};
+struct ConfigImpl {};
 
 template <>
 struct implement<Config> {
@@ -888,8 +887,8 @@ own<Instance> GetInstance(StoreImpl* store,
 
 own<Frame> CreateFrameFromInternal(i::Handle<i::FixedArray> frames, int index,
                                    i::Isolate* isolate, StoreImpl* store) {
-  i::Handle<i::StackTraceFrame> frame(i::StackTraceFrame::cast(frames->get(0)),
-                                      isolate);
+  i::Handle<i::StackTraceFrame> frame(
+      i::StackTraceFrame::cast(frames->get(index)), isolate);
   i::Handle<i::WasmInstanceObject> instance =
       i::StackTraceFrame::GetWasmInstance(frame);
   uint32_t func_index = i::StackTraceFrame::GetWasmFunctionIndex(frame);

test/wasm-api-tests/traps.cc

@@ -40,10 +40,13 @@ TEST_F(WasmCapiTest, Traps) {
   uint32_t callback_index = builder()->AddImport(CStrVector("callback"), &sig);
   byte code[] = {WASM_CALL_FUNCTION0(callback_index)};
   AddExportedFunction(CStrVector("callback"), code, sizeof(code), &sig);
-  // The first constant is a 4-byte dummy so that the {unreachable} trap
-  // has a more interesting offset.
-  byte code2[] = {WASM_I32V_3(0), WASM_UNREACHABLE, WASM_I32V_1(1)};
+
+  byte code2[] = {WASM_CALL_FUNCTION0(3)};
   AddExportedFunction(CStrVector("unreachable"), code2, sizeof(code2), &sig);
+  // The first constant is a 4-byte dummy so that the {unreachable} trap
+  // has a more interesting offset. This is called by code2.
+  byte code3[] = {WASM_I32V_3(0), WASM_UNREACHABLE, WASM_I32V_1(1)};
+  AddFunction(code3, sizeof(code3), &sig);
 
   own<FuncType> func_type =
       FuncType::make(ownvec<ValType>::make(),
@@ -65,8 +68,10 @@ TEST_F(WasmCapiTest, Traps) {
   ASSERT_TRUE(result.ok());
   const WasmFunction* func1 = &result.value()->functions[1];
   const WasmFunction* func2 = &result.value()->functions[2];
+  const WasmFunction* func3 = &result.value()->functions[3];
   const uint32_t func1_offset = func1->code.offset();
   const uint32_t func2_offset = func2->code.offset();
+  const uint32_t func3_offset = func3->code.offset();
 
   Func* cpp_trapping_func = GetExportedFunction(0);
   own<Trap> cpp_trap = cpp_trapping_func->call();
@@ -91,15 +96,22 @@ TEST_F(WasmCapiTest, Traps) {
   ExpectMessage("Uncaught RuntimeError: unreachable", wasm_trap->message());
   frame = wasm_trap->origin();
   EXPECT_TRUE(frame->instance()->same(instance()));
-  EXPECT_EQ(2u, frame->func_index());
+  EXPECT_EQ(3u, frame->func_index());
   EXPECT_EQ(5u, frame->func_offset());
-  EXPECT_EQ(func2_offset + frame->func_offset(), frame->module_offset());
+  EXPECT_EQ(func3_offset + frame->func_offset(), frame->module_offset());
   trace = wasm_trap->trace();
-  EXPECT_EQ(1u, trace.size());
+  EXPECT_EQ(2u, trace.size());
+
   frame.reset(trace[0].release());
   EXPECT_TRUE(frame->instance()->same(instance()));
-  EXPECT_EQ(2u, frame->func_index());
+  EXPECT_EQ(3u, frame->func_index());
   EXPECT_EQ(5u, frame->func_offset());
+  EXPECT_EQ(func3_offset + frame->func_offset(), frame->module_offset());
+
+  frame.reset(trace[1].release());
+  EXPECT_TRUE(frame->instance()->same(instance()));
+  EXPECT_EQ(2u, frame->func_index());
+  EXPECT_EQ(1u, frame->func_offset());
   EXPECT_EQ(func2_offset + frame->func_offset(), frame->module_offset());
 }
 

test/wasm-api-tests/wasm-api-test.h

@@ -79,6 +79,12 @@ class WasmCapiTest : public ::testing::Test {
     builder()->AddExport(name, fun);
   }
 
+  void AddFunction(byte code[], size_t code_size, FunctionSig* sig) {
+    WasmFunctionBuilder* fun = builder()->AddFunction(sig);
+    fun->EmitCode(code, static_cast<uint32_t>(code_size));
+    fun->Emit(kExprEnd);
+  }
+
   Func* GetExportedFunction(size_t index) {
     DCHECK_GT(exports_.size(), index);
     Extern* exported = exports_[index].get();