text: // Copyright 2016 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "src/runtime/runtime-utils.h"
  
  #include "src/arguments.h"
  #include "src/assembler.h"
  #include "src/compiler/wasm-compiler.h"
  #include "src/conversions.h"
  #include "src/debug/debug.h"
  #include "src/factory.h"
  #include "src/frames-inl.h"
  #include "src/objects-inl.h"
  #include "src/trap-handler/trap-handler.h"
  #include "src/v8memory.h"
  #include "src/wasm/wasm-module.h"
  #include "src/wasm/wasm-objects.h"
  #include "src/wasm/wasm-opcodes.h"
  
  namespace v8 {
  namespace internal {
  
  namespace {
  WasmInstanceObject* GetWasmInstanceOnStackTop(Isolate* isolate) {
    DisallowHeapAllocation no_allocation;
    const Address entry = Isolate::c_entry_fp(isolate->thread_local_top());
    Address pc =
        Memory::Address_at(entry + StandardFrameConstants::kCallerPCOffset);
    Code* code = isolate->inner_pointer_to_code_cache()->GetCacheEntry(pc)->code;
    DCHECK_EQ(Code::WASM_FUNCTION, code->kind());
    WasmInstanceObject* owning_instance = wasm::GetOwningWasmInstance(code);
    CHECK_NOT_NULL(owning_instance);
    return owning_instance;
  }
  Context* GetWasmContextOnStackTop(Isolate* isolate) {
    return GetWasmInstanceOnStackTop(isolate)
        ->compiled_module()
        ->ptr_to_native_context();
  }
  }  // namespace
  
  RUNTIME_FUNCTION(Runtime_WasmMemorySize) {
    HandleScope scope(isolate);
    DCHECK_EQ(0, args.length());
  
    Handle<WasmInstanceObject> instance(GetWasmInstanceOnStackTop(isolate),
                                        isolate);
    return *isolate->factory()->NewNumberFromInt(
        wasm::GetInstanceMemorySize(isolate, instance));
  }
  
  RUNTIME_FUNCTION(Runtime_WasmGrowMemory) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
    CONVERT_UINT32_ARG_CHECKED(delta_pages, 0);
    Handle<WasmInstanceObject> instance(GetWasmInstanceOnStackTop(isolate),
                                        isolate);
  
    // Set the current isolate's context.
    DCHECK_NULL(isolate->context());
    isolate->set_context(instance->compiled_module()->ptr_to_native_context());
  
    return *isolate->factory()->NewNumberFromInt(
        wasm::GrowMemory(isolate, instance, delta_pages));
  }
  
  Object* ThrowRuntimeError(Isolate* isolate, int message_id, int byte_offset,
                            bool patch_source_position) {
    HandleScope scope(isolate);
    DCHECK_NULL(isolate->context());
    isolate->set_context(GetWasmContextOnStackTop(isolate));
    Handle<Object> error_obj = isolate->factory()->NewWasmRuntimeError(
        static_cast<MessageTemplate::Template>(message_id));
  
    if (!patch_source_position) {
      return isolate->Throw(*error_obj);
    }
  
    // For wasm traps, the byte offset (a.k.a source position) can not be
    // determined from relocation info, since the explicit checks for traps
    // converge in one singe block which calls this runtime function.
    // We hence pass the byte offset explicitely, and patch it into the top-most
    // frame (a wasm frame) on the collected stack trace.
    // TODO(wasm): This implementation is temporary, see bug #5007:
    // https://bugs.chromium.org/p/v8/issues/detail?id=5007
    Handle<JSObject> error = Handle<JSObject>::cast(error_obj);
    Handle<Object> stack_trace_obj = JSReceiver::GetDataProperty(
        error, isolate->factory()->stack_trace_symbol());
    // Patch the stack trace (array of <receiver, function, code, position>).
    if (stack_trace_obj->IsJSArray()) {
      Handle<FrameArray> stack_elements(
          FrameArray::cast(JSArray::cast(*stack_trace_obj)->elements()));
      DCHECK(stack_elements->Code(0)->kind() == AbstractCode::WASM_FUNCTION);
      DCHECK(stack_elements->Offset(0)->value() >= 0);
      stack_elements->SetOffset(0, Smi::FromInt(-1 - byte_offset));
    }
  
    // Patch the detailed stack trace (array of JSObjects with various
    // properties).
    Handle<Object> detailed_stack_trace_obj = JSReceiver::GetDataProperty(
        error, isolate->factory()->detailed_stack_trace_symbol());
    if (detailed_stack_trace_obj->IsJSArray()) {
      Handle<FixedArray> stack_elements(
          FixedArray::cast(JSArray::cast(*detailed_stack_trace_obj)->elements()));
      DCHECK_GE(stack_elements->length(), 1);
      Handle<JSObject> top_frame(JSObject::cast(stack_elements->get(0)));
      Handle<String> wasm_offset_key =
          isolate->factory()->InternalizeOneByteString(
              STATIC_CHAR_VECTOR("column"));
      LookupIterator it(top_frame, wasm_offset_key, top_frame,
                        LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
      if (it.IsFound()) {
        DCHECK(JSReceiver::GetDataProperty(&it)->IsSmi());
        // Make column number 1-based here.
        Maybe<bool> data_set = JSReceiver::SetDataProperty(
            &it, handle(Smi::FromInt(byte_offset + 1), isolate));
        DCHECK(data_set.IsJust() && data_set.FromJust() == true);
        USE(data_set);
      }
    }
  
    return isolate->Throw(*error_obj);
  }
  
  RUNTIME_FUNCTION(Runtime_ThrowWasmErrorFromTrapIf) {
    DCHECK_EQ(1, args.length());
    CONVERT_SMI_ARG_CHECKED(message_id, 0);
    return ThrowRuntimeError(isolate, message_id, 0, false);
  }
  
  RUNTIME_FUNCTION(Runtime_ThrowWasmError) {
    DCHECK_EQ(2, args.length());
    CONVERT_SMI_ARG_CHECKED(message_id, 0);
    CONVERT_SMI_ARG_CHECKED(byte_offset, 1);
    return ThrowRuntimeError(isolate, message_id, byte_offset, true);
  }
  
  RUNTIME_FUNCTION(Runtime_WasmThrowTypeError) {
    HandleScope scope(isolate);
    DCHECK_EQ(0, args.length());
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate, NewTypeError(MessageTemplate::kWasmTrapTypeError));
  }
  
  RUNTIME_FUNCTION(Runtime_WasmThrow) {
    HandleScope scope(isolate);
    DCHECK_EQ(2, args.length());
    CONVERT_SMI_ARG_CHECKED(lower, 0);
    CONVERT_SMI_ARG_CHECKED(upper, 1);
  
    const int32_t thrown_value = (upper << 16) | lower;
  
    // Set the current isolate's context.
    DCHECK_NULL(isolate->context());
    isolate->set_context(GetWasmContextOnStackTop(isolate));
  
    return isolate->Throw(*isolate->factory()->NewNumberFromInt(thrown_value));
  }
  
  RUNTIME_FUNCTION(Runtime_WasmGetCaughtExceptionValue) {
    HandleScope scope(isolate);
    DCHECK_EQ(1, args.length());
    Object* exception = args[0];
    // The unwinder will only deliver exceptions to wasm if the exception is a
    // Number or a Smi (which we have just converted to a Number.) This logic
    // lives in Isolate::is_catchable_by_wasm(Object*).
    CHECK(exception->IsNumber());
    return exception;
  }
  
  RUNTIME_FUNCTION(Runtime_SetThreadInWasm) {
    trap_handler::SetThreadInWasm();
    return isolate->heap()->undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_ClearThreadInWasm) {
    trap_handler::ClearThreadInWasm();
    return isolate->heap()->undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_WasmRunInterpreter) {
    DCHECK_EQ(3, args.length());
    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));
    Handle<WasmInstanceObject> instance =
        Handle<WasmInstanceObject>::cast(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);
  
    // Set the current isolate's context.
    DCHECK_NULL(isolate->context());
    isolate->set_context(instance->compiled_module()->ptr_to_native_context());
  
    trap_handler::ClearThreadInWasm();
    bool success = instance->debug_info()->RunInterpreter(func_index, arg_buffer);
    trap_handler::SetThreadInWasm();
  
    if (!success) {
      DCHECK(isolate->has_pending_exception());
      return isolate->heap()->exception();
    }
    return isolate->heap()->undefined_value();
  }
  
  RUNTIME_FUNCTION(Runtime_WasmStackGuard) {
    SealHandleScope shs(isolate);
    DCHECK_EQ(0, args.length());
  
    // Set the current isolate's context.
    DCHECK_NULL(isolate->context());
    isolate->set_context(GetWasmContextOnStackTop(isolate));
  
    // Check if this is a real stack overflow.
    StackLimitCheck check(isolate);
    if (check.JsHasOverflowed()) return isolate->StackOverflow();
  
    return isolate->stack_guard()->HandleInterrupts();
  }
  
  }  // namespace internal
  }  // namespace v8
  