src/torque/csa-generator.cc

// Copyright 2018 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/torque/csa-generator.h"

#include "src/common/globals.h"
#include "src/torque/type-oracle.h"
#include "src/torque/types.h"
#include "src/torque/utils.h"

namespace v8 {
namespace internal {
namespace torque {

base::Optional<Stack<std::string>> CSAGenerator::EmitGraph(
    Stack<std::string> parameters) {
  for (BottomOffset i = 0; i < parameters.AboveTop(); ++i) {
    SetDefinitionVariable(DefinitionLocation::Parameter(i.offset),
                          parameters.Peek(i));
  }

  for (Block* block : cfg_.blocks()) {
    if (block->IsDead()) continue;

    out() << "  compiler::CodeAssemblerParameterizedLabel<";
    bool first = true;
    DCHECK_EQ(block->InputTypes().Size(), block->InputDefinitions().Size());
    for (BottomOffset i = 0; i < block->InputTypes().AboveTop(); ++i) {
      if (block->InputDefinitions().Peek(i).IsPhiFromBlock(block)) {
        if (!first) out() << ", ";
        out() << block->InputTypes().Peek(i)->GetGeneratedTNodeTypeName();
        first = false;
      }
    }
    out() << "> " << BlockName(block) << "(&ca_, compiler::CodeAssemblerLabel::"
          << (block->IsDeferred() ? "kDeferred" : "kNonDeferred") << ");\n";
  }

  EmitInstruction(GotoInstruction{cfg_.start()}, &parameters);
  for (Block* block : cfg_.blocks()) {
    if (cfg_.end() && *cfg_.end() == block) continue;
    if (block->IsDead()) continue;
    out() << "\n";

    // Redirect the output of non-declarations into a buffer and only output
    // declarations right away.
    std::stringstream out_buffer;
    std::ostream* old_out = out_;
    out_ = &out_buffer;

    out() << "  if (" << BlockName(block) << ".is_used()) {\n";
    EmitBlock(block);
    out() << "  }\n";

    // All declarations have been printed now, so we can append the buffered
    // output and redirect back to the original output stream.
    out_ = old_out;
    out() << out_buffer.str();
  }
  if (cfg_.end()) {
    out() << "\n";
    return EmitBlock(*cfg_.end());
  }
  return base::nullopt;
}

Stack<std::string> CSAGenerator::EmitBlock(const Block* block) {
  Stack<std::string> stack;
  std::stringstream phi_names;

  for (BottomOffset i = 0; i < block->InputTypes().AboveTop(); ++i) {
    const auto& def = block->InputDefinitions().Peek(i);
    stack.Push(DefinitionToVariable(def));
    if (def.IsPhiFromBlock(block)) {
      decls() << "  TNode<"
              << block->InputTypes().Peek(i)->GetGeneratedTNodeTypeName()
              << "> " << stack.Top() << ";\n";
      phi_names << ", &" << stack.Top();
    }
  }
  out() << "    ca_.Bind(&" << BlockName(block) << phi_names.str() << ");\n";

  for (const Instruction& instruction : block->instructions()) {
    EmitInstruction(instruction, &stack);
  }
  return stack;
}

void CSAGenerator::EmitSourcePosition(SourcePosition pos, bool always_emit) {
  const std::string& file = SourceFileMap::AbsolutePath(pos.source);
  if (always_emit || !previous_position_.CompareStartIgnoreColumn(pos)) {
    // Lines in Torque SourcePositions are zero-based, while the
    // CodeStubAssembler and downwind systems are one-based.
    out() << "    ca_.SetSourcePosition(\"" << file << "\", "
          << (pos.start.line + 1) << ");\n";
    previous_position_ = pos;
  }
}

bool CSAGenerator::IsEmptyInstruction(const Instruction& instruction) {
  switch (instruction.kind()) {
    case InstructionKind::kPeekInstruction:
    case InstructionKind::kPokeInstruction:
    case InstructionKind::kDeleteRangeInstruction:
    case InstructionKind::kPushUninitializedInstruction:
    case InstructionKind::kPushBuiltinPointerInstruction:
    case InstructionKind::kUnsafeCastInstruction:
      return true;
    default:
      return false;
  }
}

void CSAGenerator::EmitInstruction(const Instruction& instruction,
                                   Stack<std::string>* stack) {
#ifdef DEBUG
  if (!IsEmptyInstruction(instruction)) {
    EmitSourcePosition(instruction->pos);
  }
#endif

  switch (instruction.kind()) {
#define ENUM_ITEM(T)          \
  case InstructionKind::k##T: \
    return EmitInstruction(instruction.Cast<T>(), stack);
    TORQUE_INSTRUCTION_LIST(ENUM_ITEM)
#undef ENUM_ITEM
  }
}

void CSAGenerator::EmitInstruction(const PeekInstruction& instruction,
                                   Stack<std::string>* stack) {
  stack->Push(stack->Peek(instruction.slot));
}

void CSAGenerator::EmitInstruction(const PokeInstruction& instruction,
                                   Stack<std::string>* stack) {
  stack->Poke(instruction.slot, stack->Top());
  stack->Pop();
}

void CSAGenerator::EmitInstruction(const DeleteRangeInstruction& instruction,
                                   Stack<std::string>* stack) {
  stack->DeleteRange(instruction.range);
}

void CSAGenerator::EmitInstruction(
    const PushUninitializedInstruction& instruction,
    Stack<std::string>* stack) {
  // TODO(tebbi): This can trigger an error in CSA if it is used. Instead, we
  // should prevent usage of uninitialized in the type system. This
  // requires "if constexpr" being evaluated at Torque time.
  const std::string str = "ca_.Uninitialized<" +
                          instruction.type->GetGeneratedTNodeTypeName() + ">()";
  stack->Push(str);
  SetDefinitionVariable(instruction.GetValueDefinition(), str);
}

void CSAGenerator::EmitInstruction(
    const PushBuiltinPointerInstruction& instruction,
    Stack<std::string>* stack) {
  const std::string str =
      "ca_.UncheckedCast<BuiltinPtr>(ca_.SmiConstant(Builtins::k" +
      instruction.external_name + "))";
  stack->Push(str);
  SetDefinitionVariable(instruction.GetValueDefinition(), str);
}

void CSAGenerator::EmitInstruction(
    const NamespaceConstantInstruction& instruction,
    Stack<std::string>* stack) {
  const Type* type = instruction.constant->type();
  std::vector<std::string> results;

  const auto lowered = LowerType(type);
  for (std::size_t i = 0; i < lowered.size(); ++i) {
    results.push_back(DefinitionToVariable(instruction.GetValueDefinition(i)));
    stack->Push(results.back());
    decls() << "  TNode<" << lowered[i]->GetGeneratedTNodeTypeName() << "> "
            << stack->Top() << ";\n";
  }

  out() << "    ";
  if (type->StructSupertype()) {
    out() << "std::tie(";
    PrintCommaSeparatedList(out(), results);
    out() << ") = ";
  } else if (results.size() == 1) {
    out() << results[0] << " = ";
  }
  out() << instruction.constant->external_name() << "(state_)";
  if (type->StructSupertype()) {
    out() << ".Flatten();\n";
  } else {
    out() << ";\n";
  }
}

void CSAGenerator::ProcessArgumentsCommon(
    const TypeVector& parameter_types, std::vector<std::string>* args,
    std::vector<std::string>* constexpr_arguments, Stack<std::string>* stack) {
  for (auto it = parameter_types.rbegin(); it != parameter_types.rend(); ++it) {
    const Type* type = *it;
    VisitResult arg;
    if (type->IsConstexpr()) {
      args->push_back(std::move(constexpr_arguments->back()));
      constexpr_arguments->pop_back();
    } else {
      std::stringstream s;
      size_t slot_count = LoweredSlotCount(type);
      VisitResult arg = VisitResult(type, stack->TopRange(slot_count));
      EmitCSAValue(arg, *stack, s);
      args->push_back(s.str());
      stack->PopMany(slot_count);
    }
  }
  std::reverse(args->begin(), args->end());
}

void CSAGenerator::EmitInstruction(const CallIntrinsicInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::vector<std::string> constexpr_arguments =
      instruction.constexpr_arguments;
  std::vector<std::string> args;
  TypeVector parameter_types =
      instruction.intrinsic->signature().parameter_types.types;
  ProcessArgumentsCommon(parameter_types, &args, &constexpr_arguments, stack);

  Stack<std::string> pre_call_stack = *stack;
  const Type* return_type = instruction.intrinsic->signature().return_type;
  std::vector<std::string> results;

  const auto lowered = LowerType(return_type);
  for (std::size_t i = 0; i < lowered.size(); ++i) {
    results.push_back(DefinitionToVariable(instruction.GetValueDefinition(i)));
    stack->Push(results.back());
    decls() << "  TNode<" << lowered[i]->GetGeneratedTNodeTypeName() << "> "
            << stack->Top() << ";\n";
  }

  out() << "    ";
  if (return_type->StructSupertype()) {
    out() << "std::tie(";
    PrintCommaSeparatedList(out(), results);
    out() << ") = ";
  } else {
    if (results.size() == 1) {
      out() << results[0] << " = ";
    }
  }

  if (instruction.intrinsic->ExternalName() == "%RawDownCast") {
    if (parameter_types.size() != 1) {
      ReportError("%RawDownCast must take a single parameter");
    }
    const Type* original_type = parameter_types[0];
    bool is_subtype =
        return_type->IsSubtypeOf(original_type) ||
        (original_type == TypeOracle::GetUninitializedHeapObjectType() &&
         return_type->IsSubtypeOf(TypeOracle::GetHeapObjectType()));
    if (!is_subtype) {
      ReportError("%RawDownCast error: ", *return_type, " is not a subtype of ",
                  *original_type);
    }
    if (!original_type->StructSupertype() &&
        return_type->GetGeneratedTNodeTypeName() !=
            original_type->GetGeneratedTNodeTypeName()) {
      if (return_type->IsSubtypeOf(TypeOracle::GetTaggedType())) {
        out() << "TORQUE_CAST";
      } else {
        out() << "ca_.UncheckedCast<"
              << return_type->GetGeneratedTNodeTypeName() << ">";
      }
    }
  } else if (instruction.intrinsic->ExternalName() == "%FromConstexpr") {
    if (parameter_types.size() != 1 || !parameter_types[0]->IsConstexpr()) {
      ReportError(
          "%FromConstexpr must take a single parameter with constexpr "
          "type");
    }
    if (return_type->IsConstexpr()) {
      ReportError("%FromConstexpr must return a non-constexpr type");
    }
    if (return_type->IsSubtypeOf(TypeOracle::GetSmiType())) {
      out() << "ca_.SmiConstant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetNumberType())) {
      out() << "ca_.NumberConstant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetStringType())) {
      out() << "ca_.StringConstant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetObjectType())) {
      ReportError(
          "%FromConstexpr cannot cast to subclass of HeapObject unless it's a "
          "String or Number");
    } else if (return_type->IsSubtypeOf(TypeOracle::GetIntPtrType())) {
      out() << "ca_.IntPtrConstant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetUIntPtrType())) {
      out() << "ca_.UintPtrConstant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetInt32Type())) {
      out() << "ca_.Int32Constant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetUint32Type())) {
      out() << "ca_.Uint32Constant";
    } else if (return_type->IsSubtypeOf(TypeOracle::GetBoolType())) {
      out() << "ca_.BoolConstant";
    } else {
      std::stringstream s;
      s << "%FromConstexpr does not support return type " << *return_type;
      ReportError(s.str());
    }
    // Wrap the raw constexpr value in a static_cast to ensure that
    // enums get properly casted to their backing integral value.
    out() << "(CastToUnderlyingTypeIfEnum";
  } else {
    ReportError("no built in intrinsic with name " +
                instruction.intrinsic->ExternalName());
  }

  out() << "(";
  PrintCommaSeparatedList(out(), args);
  if (instruction.intrinsic->ExternalName() == "%FromConstexpr") {
    out() << ")";
  }
  if (return_type->StructSupertype()) {
    out() << ").Flatten();\n";
  } else {
    out() << ");\n";
  }
}

void CSAGenerator::EmitInstruction(const CallCsaMacroInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::vector<std::string> constexpr_arguments =
      instruction.constexpr_arguments;
  std::vector<std::string> args;
  TypeVector parameter_types =
      instruction.macro->signature().parameter_types.types;
  ProcessArgumentsCommon(parameter_types, &args, &constexpr_arguments, stack);

  Stack<std::string> pre_call_stack = *stack;
  const Type* return_type = instruction.macro->signature().return_type;
  std::vector<std::string> results;

  const auto lowered = LowerType(return_type);
  for (std::size_t i = 0; i < lowered.size(); ++i) {
    results.push_back(DefinitionToVariable(instruction.GetValueDefinition(i)));
    stack->Push(results.back());
    decls() << "  TNode<" << lowered[i]->GetGeneratedTNodeTypeName() << "> "
            << stack->Top() << ";\n";
  }

  std::string catch_name =
      PreCallableExceptionPreparation(instruction.catch_block);
  out() << "    ";
  bool needs_flattening = return_type->StructSupertype().has_value();
  if (needs_flattening) {
    out() << "std::tie(";
    PrintCommaSeparatedList(out(), results);
    out() << ") = ";
  } else {
    if (results.size() == 1) {
      out() << results[0] << " = ";
    } else {
      DCHECK_EQ(0, results.size());
    }
  }
  if (ExternMacro* extern_macro = ExternMacro::DynamicCast(instruction.macro)) {
    out() << extern_macro->external_assembler_name() << "(state_).";
  } else {
    args.insert(args.begin(), "state_");
  }
  out() << instruction.macro->ExternalName() << "(";
  PrintCommaSeparatedList(out(), args);
  if (needs_flattening) {
    out() << ").Flatten();\n";
  } else {
    out() << ");\n";
  }
  PostCallableExceptionPreparation(catch_name, return_type,
                                   instruction.catch_block, &pre_call_stack,
                                   instruction.GetExceptionObjectDefinition());
}

void CSAGenerator::EmitInstruction(
    const CallCsaMacroAndBranchInstruction& instruction,
    Stack<std::string>* stack) {
  std::vector<std::string> constexpr_arguments =
      instruction.constexpr_arguments;
  std::vector<std::string> args;
  TypeVector parameter_types =
      instruction.macro->signature().parameter_types.types;
  ProcessArgumentsCommon(parameter_types, &args, &constexpr_arguments, stack);

  Stack<std::string> pre_call_stack = *stack;
  std::vector<std::string> results;
  const Type* return_type = instruction.macro->signature().return_type;

  if (return_type != TypeOracle::GetNeverType()) {
    const auto lowered = LowerType(return_type);
    for (std::size_t i = 0; i < lowered.size(); ++i) {
      results.push_back(
          DefinitionToVariable(instruction.GetValueDefinition(i)));
      decls() << "  TNode<" << lowered[i]->GetGeneratedTNodeTypeName() << "> "
              << results.back() << ";\n";
    }
  }

  std::vector<std::string> label_names;
  std::vector<std::vector<std::string>> var_names;
  const LabelDeclarationVector& labels = instruction.macro->signature().labels;
  DCHECK_EQ(labels.size(), instruction.label_blocks.size());
  for (size_t i = 0; i < labels.size(); ++i) {
    TypeVector label_parameters = labels[i].types;
    label_names.push_back(FreshLabelName());
    var_names.push_back({});
    for (size_t j = 0; j < label_parameters.size(); ++j) {
      var_names[i].push_back(FreshNodeName());
      const auto def = instruction.GetLabelValueDefinition(i, j);
      SetDefinitionVariable(def, var_names[i].back() + ".value()");
      decls() << "    compiler::TypedCodeAssemblerVariable<"
              << label_parameters[j]->GetGeneratedTNodeTypeName() << "> "
              << var_names[i][j] << "(&ca_);\n";
    }
    out() << "    compiler::CodeAssemblerLabel " << label_names[i]
          << "(&ca_);\n";
  }

  std::string catch_name =
      PreCallableExceptionPreparation(instruction.catch_block);
  out() << "    ";
  if (results.size() == 1) {
    out() << results[0] << " = ";
  } else if (results.size() > 1) {
    out() << "std::tie(";
    PrintCommaSeparatedList(out(), results);
    out() << ") = ";
  }
  if (ExternMacro* extern_macro = ExternMacro::DynamicCast(instruction.macro)) {
    out() << extern_macro->external_assembler_name() << "(state_).";
  } else {
    args.insert(args.begin(), "state_");
  }
  out() << instruction.macro->ExternalName() << "(";
  PrintCommaSeparatedList(out(), args);
  bool first = args.empty();
  for (size_t i = 0; i < label_names.size(); ++i) {
    if (!first) out() << ", ";
    out() << "&" << label_names[i];
    first = false;
    for (size_t j = 0; j < var_names[i].size(); ++j) {
      out() << ", &" << var_names[i][j];
    }
  }
  if (return_type->StructSupertype()) {
    out() << ").Flatten();\n";
  } else {
    out() << ");\n";
  }

  PostCallableExceptionPreparation(catch_name, return_type,
                                   instruction.catch_block, &pre_call_stack,
                                   instruction.GetExceptionObjectDefinition());

  if (instruction.return_continuation) {
    out() << "    ca_.Goto(&" << BlockName(*instruction.return_continuation);
    DCHECK_EQ(stack->Size() + results.size(),
              (*instruction.return_continuation)->InputDefinitions().Size());

    const auto& input_definitions =
        (*instruction.return_continuation)->InputDefinitions();
    for (BottomOffset i = 0; i < input_definitions.AboveTop(); ++i) {
      if (input_definitions.Peek(i).IsPhiFromBlock(
              *instruction.return_continuation)) {
        out() << ", "
              << (i < stack->AboveTop() ? stack->Peek(i) : results[i.offset]);
      }
    }
    out() << ");\n";
  }
  for (size_t l = 0; l < label_names.size(); ++l) {
    out() << "    if (" << label_names[l] << ".is_used()) {\n";
    out() << "      ca_.Bind(&" << label_names[l] << ");\n";
    out() << "      ca_.Goto(&" << BlockName(instruction.label_blocks[l]);
    DCHECK_EQ(stack->Size() + var_names[l].size(),
              instruction.label_blocks[l]->InputDefinitions().Size());

    const auto& label_definitions =
        instruction.label_blocks[l]->InputDefinitions();

    BottomOffset i = 0;
    for (; i < stack->AboveTop(); ++i) {
      if (label_definitions.Peek(i).IsPhiFromBlock(
              instruction.label_blocks[l])) {
        out() << ", " << stack->Peek(i);
      }
    }
    for (std::size_t k = 0; k < var_names[l].size(); ++k, ++i) {
      if (label_definitions.Peek(i).IsPhiFromBlock(
              instruction.label_blocks[l])) {
        out() << ", " << var_names[l][k] << ".value()";
      }
    }
    out() << ");\n";
    out() << "    }\n";
  }
}

void CSAGenerator::EmitInstruction(const CallBuiltinInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::vector<std::string> arguments = stack->PopMany(instruction.argc);
  std::vector<const Type*> result_types =
      LowerType(instruction.builtin->signature().return_type);
  if (instruction.is_tailcall) {
    out() << "   CodeStubAssembler(state_).TailCallBuiltin(Builtins::k"
          << instruction.builtin->ExternalName() << ", ";
    PrintCommaSeparatedList(out(), arguments);
    out() << ");\n";
  } else {
    std::string result_name;
    if (result_types.size() == 1) {
      result_name = DefinitionToVariable(instruction.GetValueDefinition(0));
      decls() << "  TNode<" << result_types[0]->GetGeneratedTNodeTypeName()
              << "> " << result_name << ";\n";
    }
    std::string catch_name =
        PreCallableExceptionPreparation(instruction.catch_block);
    Stack<std::string> pre_call_stack = *stack;
    if (result_types.size() == 1) {
      std::string generated_type = result_types[0]->GetGeneratedTNodeTypeName();
      stack->Push(result_name);
      out() << "    " << result_name << " = ";
      if (generated_type != "Object") out() << "TORQUE_CAST(";
      out() << "CodeStubAssembler(state_).CallBuiltin(Builtins::k"
            << instruction.builtin->ExternalName() << ", ";
      PrintCommaSeparatedList(out(), arguments);
      if (generated_type != "Object") out() << ")";
      out() << ");\n";
    } else {
      DCHECK_EQ(0, result_types.size());
      // TODO(tebbi): Actually, builtins have to return a value, so we should
      // not have to handle this case.
      out() << "    CodeStubAssembler(state_).CallBuiltin(Builtins::k"
            << instruction.builtin->ExternalName() << ", ";
      PrintCommaSeparatedList(out(), arguments);
      out() << ");\n";
    }
    PostCallableExceptionPreparation(
        catch_name,
        result_types.size() == 0 ? TypeOracle::GetVoidType() : result_types[0],
        instruction.catch_block, &pre_call_stack,
        instruction.GetExceptionObjectDefinition());
  }
}

void CSAGenerator::EmitInstruction(
    const CallBuiltinPointerInstruction& instruction,
    Stack<std::string>* stack) {
  std::vector<std::string> function_and_arguments =
      stack->PopMany(1 + instruction.argc);
  std::vector<const Type*> result_types =
      LowerType(instruction.type->return_type());
  if (result_types.size() != 1) {
    ReportError("builtins must have exactly one result");
  }
  if (instruction.is_tailcall) {
    ReportError("tail-calls to builtin pointers are not supported");
  }

  DCHECK_EQ(1, instruction.GetValueDefinitionCount());
  stack->Push(DefinitionToVariable(instruction.GetValueDefinition(0)));
  std::string generated_type = result_types[0]->GetGeneratedTNodeTypeName();
  decls() << "  TNode<" << generated_type << "> " << stack->Top() << ";\n";
  out() << stack->Top() << " = ";
  if (generated_type != "Object") out() << "TORQUE_CAST(";
  out() << "CodeStubAssembler(state_).CallBuiltinPointer(Builtins::"
           "CallableFor(ca_."
           "isolate(),"
           "ExampleBuiltinForTorqueFunctionPointerType("
        << instruction.type->function_pointer_type_id() << ")).descriptor(), ";
  PrintCommaSeparatedList(out(), function_and_arguments);
  out() << ")";
  if (generated_type != "Object") out() << ")";
  out() << ";\n";
}

std::string CSAGenerator::PreCallableExceptionPreparation(
    base::Optional<Block*> catch_block) {
  std::string catch_name;
  if (catch_block) {
    catch_name = FreshCatchName();
    out() << "    compiler::CodeAssemblerExceptionHandlerLabel " << catch_name
          << "__label(&ca_, compiler::CodeAssemblerLabel::kDeferred);\n";
    out() << "    { compiler::ScopedExceptionHandler s(&ca_, &" << catch_name
          << "__label);\n";
  }
  return catch_name;
}

void CSAGenerator::PostCallableExceptionPreparation(
    const std::string& catch_name, const Type* return_type,
    base::Optional<Block*> catch_block, Stack<std::string>* stack,
    const base::Optional<DefinitionLocation>& exception_object_definition) {
  if (catch_block) {
    DCHECK(exception_object_definition);
    std::string block_name = BlockName(*catch_block);
    out() << "    }\n";
    out() << "    if (" << catch_name << "__label.is_used()) {\n";
    out() << "      compiler::CodeAssemblerLabel " << catch_name
          << "_skip(&ca_);\n";
    if (!return_type->IsNever()) {
      out() << "      ca_.Goto(&" << catch_name << "_skip);\n";
    }
    decls() << "      TNode<Object> "
            << DefinitionToVariable(*exception_object_definition) << ";\n";
    out() << "      ca_.Bind(&" << catch_name << "__label, &"
          << DefinitionToVariable(*exception_object_definition) << ");\n";
    out() << "      ca_.Goto(&" << block_name;

    DCHECK_EQ(stack->Size() + 1, (*catch_block)->InputDefinitions().Size());
    const auto& input_definitions = (*catch_block)->InputDefinitions();
    for (BottomOffset i = 0; i < input_definitions.AboveTop(); ++i) {
      if (input_definitions.Peek(i).IsPhiFromBlock(*catch_block)) {
        if (i < stack->AboveTop()) {
          out() << ", " << stack->Peek(i);
        } else {
          DCHECK_EQ(i, stack->AboveTop());
          out() << ", " << DefinitionToVariable(*exception_object_definition);
        }
      }
    }
    out() << ");\n";

    if (!return_type->IsNever()) {
      out() << "      ca_.Bind(&" << catch_name << "_skip);\n";
    }
    out() << "    }\n";
  }
}

void CSAGenerator::EmitInstruction(const CallRuntimeInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::vector<std::string> arguments = stack->PopMany(instruction.argc);
  const Type* return_type =
      instruction.runtime_function->signature().return_type;
  std::vector<const Type*> result_types;
  if (return_type != TypeOracle::GetNeverType()) {
    result_types = LowerType(return_type);
  }
  if (result_types.size() > 1) {
    ReportError("runtime function must have at most one result");
  }
  if (instruction.is_tailcall) {
    out() << "    CodeStubAssembler(state_).TailCallRuntime(Runtime::k"
          << instruction.runtime_function->ExternalName() << ", ";
    PrintCommaSeparatedList(out(), arguments);
    out() << ");\n";
  } else {
    std::string result_name;
    if (result_types.size() == 1) {
      result_name = DefinitionToVariable(instruction.GetValueDefinition(0));
      decls() << "  TNode<" << result_types[0]->GetGeneratedTNodeTypeName()
              << "> " << result_name << ";\n";
    }
    std::string catch_name =
        PreCallableExceptionPreparation(instruction.catch_block);
    Stack<std::string> pre_call_stack = *stack;
    if (result_types.size() == 1) {
      std::string generated_type = result_types[0]->GetGeneratedTNodeTypeName();
      stack->Push(result_name);
      out() << "    " << result_name << " = ";
      if (generated_type != "Object") out() << "TORQUE_CAST(";
      out() << "CodeStubAssembler(state_).CallRuntime(Runtime::k"
            << instruction.runtime_function->ExternalName() << ", ";
      PrintCommaSeparatedList(out(), arguments);
      out() << ")";
      if (generated_type != "Object") out() << ")";
      out() << "; \n";
    } else {
      DCHECK_EQ(0, result_types.size());
      out() << "    CodeStubAssembler(state_).CallRuntime(Runtime::k"
            << instruction.runtime_function->ExternalName() << ", ";
      PrintCommaSeparatedList(out(), arguments);
      out() << ");\n";
      if (return_type == TypeOracle::GetNeverType()) {
        out() << "    CodeStubAssembler(state_).Unreachable();\n";
      } else {
        DCHECK(return_type == TypeOracle::GetVoidType());
      }
    }
    PostCallableExceptionPreparation(
        catch_name, return_type, instruction.catch_block, &pre_call_stack,
        instruction.GetExceptionObjectDefinition());
  }
}

void CSAGenerator::EmitInstruction(const BranchInstruction& instruction,
                                   Stack<std::string>* stack) {
  out() << "    ca_.Branch(" << stack->Pop() << ", &"
        << BlockName(instruction.if_true) << ", std::vector<Node*>{";

  const auto& true_definitions = instruction.if_true->InputDefinitions();
  DCHECK_EQ(stack->Size(), true_definitions.Size());
  bool first = true;
  for (BottomOffset i = 0; i < stack->AboveTop(); ++i) {
    if (true_definitions.Peek(i).IsPhiFromBlock(instruction.if_true)) {
      if (!first) out() << ", ";
      out() << stack->Peek(i);
      first = false;
    }
  }

  out() << "}, &" << BlockName(instruction.if_false) << ", std::vector<Node*>{";

  const auto& false_definitions = instruction.if_false->InputDefinitions();
  DCHECK_EQ(stack->Size(), false_definitions.Size());
  first = true;
  for (BottomOffset i = 0; i < stack->AboveTop(); ++i) {
    if (false_definitions.Peek(i).IsPhiFromBlock(instruction.if_false)) {
      if (!first) out() << ", ";
      out() << stack->Peek(i);
      first = false;
    }
  }

  out() << "});\n";
}

void CSAGenerator::EmitInstruction(
    const ConstexprBranchInstruction& instruction, Stack<std::string>* stack) {
  out() << "    if ((" << instruction.condition << ")) {\n";
  out() << "      ca_.Goto(&" << BlockName(instruction.if_true);

  const auto& true_definitions = instruction.if_true->InputDefinitions();
  DCHECK_EQ(stack->Size(), true_definitions.Size());
  for (BottomOffset i = 0; i < stack->AboveTop(); ++i) {
    if (true_definitions.Peek(i).IsPhiFromBlock(instruction.if_true)) {
      out() << ", " << stack->Peek(i);
    }
  }

  out() << ");\n";
  out() << "    } else {\n";
  out() << "      ca_.Goto(&" << BlockName(instruction.if_false);

  const auto& false_definitions = instruction.if_false->InputDefinitions();
  DCHECK_EQ(stack->Size(), false_definitions.Size());
  for (BottomOffset i = 0; i < stack->AboveTop(); ++i) {
    if (false_definitions.Peek(i).IsPhiFromBlock(instruction.if_false)) {
      out() << ", " << stack->Peek(i);
    }
  }

  out() << ");\n";
  out() << "    }\n";
}

void CSAGenerator::EmitInstruction(const GotoInstruction& instruction,
                                   Stack<std::string>* stack) {
  out() << "    ca_.Goto(&" << BlockName(instruction.destination);
  const auto& destination_definitions =
      instruction.destination->InputDefinitions();
  DCHECK_EQ(stack->Size(), destination_definitions.Size());
  for (BottomOffset i = 0; i < stack->AboveTop(); ++i) {
    if (destination_definitions.Peek(i).IsPhiFromBlock(
            instruction.destination)) {
      out() << ", " << stack->Peek(i);
    }
  }
  out() << ");\n";
}

void CSAGenerator::EmitInstruction(const GotoExternalInstruction& instruction,
                                   Stack<std::string>* stack) {
  for (auto it = instruction.variable_names.rbegin();
       it != instruction.variable_names.rend(); ++it) {
    out() << "    *" << *it << " = " << stack->Pop() << ";\n";
  }
  out() << "    ca_.Goto(" << instruction.destination << ");\n";
}

void CSAGenerator::EmitInstruction(const ReturnInstruction& instruction,
                                   Stack<std::string>* stack) {
  if (*linkage_ == Builtin::kVarArgsJavaScript) {
    out() << "    " << ARGUMENTS_VARIABLE_STRING << ".PopAndReturn(";
  } else {
    out() << "    CodeStubAssembler(state_).Return(";
  }
  out() << stack->Pop() << ");\n";
}

void CSAGenerator::EmitInstruction(
    const PrintConstantStringInstruction& instruction,
    Stack<std::string>* stack) {
  out() << "    CodeStubAssembler(state_).Print("
        << StringLiteralQuote(instruction.message) << ");\n";
}

void CSAGenerator::EmitInstruction(const AbortInstruction& instruction,
                                   Stack<std::string>* stack) {
  switch (instruction.kind) {
    case AbortInstruction::Kind::kUnreachable:
      DCHECK(instruction.message.empty());
      out() << "    CodeStubAssembler(state_).Unreachable();\n";
      break;
    case AbortInstruction::Kind::kDebugBreak:
      DCHECK(instruction.message.empty());
      out() << "    CodeStubAssembler(state_).DebugBreak();\n";
      break;
    case AbortInstruction::Kind::kAssertionFailure: {
      std::string file = StringLiteralQuote(
          SourceFileMap::PathFromV8Root(instruction.pos.source));
      out() << "    CodeStubAssembler(state_).FailAssert("
            << StringLiteralQuote(instruction.message) << ", " << file << ", "
            << instruction.pos.start.line + 1 << ");\n";
      break;
    }
  }
}

void CSAGenerator::EmitInstruction(const UnsafeCastInstruction& instruction,
                                   Stack<std::string>* stack) {
  const std::string str =
      "ca_.UncheckedCast<" +
      instruction.destination_type->GetGeneratedTNodeTypeName() + ">(" +
      stack->Top() + ")";
  stack->Poke(stack->AboveTop() - 1, str);
  SetDefinitionVariable(instruction.GetValueDefinition(), str);
}

void CSAGenerator::EmitInstruction(const LoadReferenceInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::string result_name =
      DefinitionToVariable(instruction.GetValueDefinition());

  std::string offset = stack->Pop();
  std::string object = stack->Pop();
  stack->Push(result_name);

  decls() << "  " << instruction.type->GetGeneratedTypeName() << " "
          << result_name << ";\n";
  out() << "    " << result_name
        << " = CodeStubAssembler(state_).LoadReference<"
        << instruction.type->GetGeneratedTNodeTypeName()
        << ">(CodeStubAssembler::Reference{" << object << ", " << offset
        << "});\n";
}

void CSAGenerator::EmitInstruction(const StoreReferenceInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::string value = stack->Pop();
  std::string offset = stack->Pop();
  std::string object = stack->Pop();

  out() << "    CodeStubAssembler(state_).StoreReference<"
        << instruction.type->GetGeneratedTNodeTypeName()
        << ">(CodeStubAssembler::"
           "Reference{"
        << object << ", " << offset << "}, " << value << ");\n";
}

namespace {
std::string GetBitFieldSpecialization(const BitFieldStructType* container,
                                      const BitField& field) {
  std::stringstream stream;
  stream << "base::BitField<"
         << field.name_and_type.type->GetConstexprGeneratedTypeName() << ", "
         << field.offset << ", " << field.num_bits << ", "
         << container->GetConstexprGeneratedTypeName() << ">";
  return stream.str();
}
}  // namespace

void CSAGenerator::EmitInstruction(const LoadBitFieldInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::string result_name =
      DefinitionToVariable(instruction.GetValueDefinition());

  std::string bit_field_struct = stack->Pop();
  stack->Push(result_name);

  const BitFieldStructType* source_type = instruction.bit_field_struct_type;
  const Type* result_type = instruction.bit_field.name_and_type.type;
  bool source_uintptr = source_type->IsSubtypeOf(TypeOracle::GetUIntPtrType());
  bool result_uintptr = result_type->IsSubtypeOf(TypeOracle::GetUIntPtrType());
  std::string source_word_type = source_uintptr ? "WordT" : "Word32T";
  std::string decoder =
      source_uintptr
          ? (result_uintptr ? "DecodeWord" : "DecodeWord32FromWord")
          : (result_uintptr ? "DecodeWordFromWord32" : "DecodeWord32");

  decls() << "  " << result_type->GetGeneratedTypeName() << " " << result_name
          << ";\n";
  out() << "    " << result_name << " = ca_.UncheckedCast<"
        << result_type->GetGeneratedTNodeTypeName()
        << ">(CodeStubAssembler(state_)." << decoder << "<"
        << GetBitFieldSpecialization(source_type, instruction.bit_field)
        << ">(ca_.UncheckedCast<" << source_word_type << ">("
        << bit_field_struct << ")));\n";
}

void CSAGenerator::EmitInstruction(const StoreBitFieldInstruction& instruction,
                                   Stack<std::string>* stack) {
  std::string result_name =
      DefinitionToVariable(instruction.GetValueDefinition());

  std::string value = stack->Pop();
  std::string bit_field_struct = stack->Pop();
  stack->Push(result_name);

  const BitFieldStructType* struct_type = instruction.bit_field_struct_type;
  const Type* field_type = instruction.bit_field.name_and_type.type;
  bool struct_uintptr = struct_type->IsSubtypeOf(TypeOracle::GetUIntPtrType());
  bool field_uintptr = field_type->IsSubtypeOf(TypeOracle::GetUIntPtrType());
  std::string struct_word_type = struct_uintptr ? "WordT" : "Word32T";
  std::string field_word_type = field_uintptr ? "UintPtrT" : "Uint32T";
  std::string encoder =
      struct_uintptr ? (field_uintptr ? "UpdateWord" : "UpdateWord32InWord")
                     : (field_uintptr ? "UpdateWordInWord32" : "UpdateWord32");

  decls() << "  " << struct_type->GetGeneratedTypeName() << " " << result_name
          << ";\n";
  out() << "    " << result_name << " = ca_.UncheckedCast<"
        << struct_type->GetGeneratedTNodeTypeName()
        << ">(CodeStubAssembler(state_)." << encoder << "<"
        << GetBitFieldSpecialization(struct_type, instruction.bit_field)
        << ">(ca_.UncheckedCast<" << struct_word_type << ">("
        << bit_field_struct << "), ca_.UncheckedCast<" << field_word_type
        << ">(" << value << ")));\n";
}

// static
void CSAGenerator::EmitCSAValue(VisitResult result,
                                const Stack<std::string>& values,
                                std::ostream& out) {
  if (!result.IsOnStack()) {
    out << result.constexpr_value();
  } else if (auto struct_type = result.type()->StructSupertype()) {
    out << (*struct_type)->GetGeneratedTypeName() << "{";
    bool first = true;
    for (auto& field : (*struct_type)->fields()) {
      if (!first) {
        out << ", ";
      }
      first = false;
      EmitCSAValue(ProjectStructField(result, field.name_and_type.name), values,
                   out);
    }
    out << "}";
  } else {
    DCHECK_EQ(1, result.stack_range().Size());
    out << "TNode<" << result.type()->GetGeneratedTNodeTypeName() << ">{"
        << values.Peek(result.stack_range().begin()) << "}";
  }
}

}  // namespace torque
}  // namespace internal
}  // namespace v8