types.cc

// Copyright 2017 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 <iostream>

#include "src/torque/declarable.h"
#include "src/torque/type-oracle.h"
#include "src/torque/types.h"

namespace v8 {
namespace internal {
namespace torque {

std::string Type::ToString() const {
  if (aliases_.size() == 0) return ToExplicitString();
  if (aliases_.size() == 1) return *aliases_.begin();
  std::stringstream result;
  int i = 0;
  for (const std::string& alias : aliases_) {
    if (i == 0) {
      result << alias << " (aka. ";
    } else if (i == 1) {
      result << alias;
    } else {
      result << ", " << alias;
    }
    ++i;
  }
  result << ")";
  return result.str();
}

bool Type::IsSubtypeOf(const Type* supertype) const {
  if (supertype->IsTopType()) return true;
  if (IsNever()) return true;
  if (const UnionType* union_type = UnionType::DynamicCast(supertype)) {
    return union_type->IsSupertypeOf(this);
  }
  const Type* subtype = this;
  while (subtype != nullptr) {
    if (subtype == supertype) return true;
    subtype = subtype->parent();
  }
  return false;
}

// static
const Type* Type::CommonSupertype(const Type* a, const Type* b) {
  int diff = a->Depth() - b->Depth();
  const Type* a_supertype = a;
  const Type* b_supertype = b;
  for (; diff > 0; --diff) a_supertype = a_supertype->parent();
  for (; diff < 0; ++diff) b_supertype = b_supertype->parent();
  while (a_supertype && b_supertype) {
    if (a_supertype == b_supertype) return a_supertype;
    a_supertype = a_supertype->parent();
    b_supertype = b_supertype->parent();
  }
  ReportError("types " + a->ToString() + " and " + b->ToString() +
              " have no common supertype");
}

int Type::Depth() const {
  int result = 0;
  for (const Type* current = parent_; current; current = current->parent_) {
    ++result;
  }
  return result;
}

bool Type::IsAbstractName(const std::string& name) const {
  if (!IsAbstractType()) return false;
  return AbstractType::cast(this)->name() == name;
}

std::string AbstractType::GetGeneratedTNodeTypeName() const {
  return generated_type_;
}

std::string FunctionPointerType::ToExplicitString() const {
  std::stringstream result;
  result << "builtin (";
  PrintCommaSeparatedList(result, parameter_types_);
  result << ") => " << *return_type_;
  return result.str();
}

std::string FunctionPointerType::MangledName() const {
  std::stringstream result;
  result << "FT";
  for (const Type* t : parameter_types_) {
    std::string arg_type_string = t->MangledName();
    result << arg_type_string.size() << arg_type_string;
  }
  std::string return_type_string = return_type_->MangledName();
  result << return_type_string.size() << return_type_string;
  return result.str();
}

std::string UnionType::ToExplicitString() const {
  std::stringstream result;
  result << "(";
  bool first = true;
  for (const Type* t : types_) {
    if (!first) {
      result << " | ";
    }
    first = false;
    result << *t;
  }
  result << ")";
  return result.str();
}

std::string UnionType::MangledName() const {
  std::stringstream result;
  result << "UT";
  for (const Type* t : types_) {
    std::string arg_type_string = t->MangledName();
    result << arg_type_string.size() << arg_type_string;
  }
  return result.str();
}

std::string UnionType::GetGeneratedTNodeTypeName() const {
  if (types_.size() <= 3) {
    std::set<std::string> members;
    for (const Type* t : types_) {
      members.insert(t->GetGeneratedTNodeTypeName());
    }
    if (members == std::set<std::string>{"Smi", "HeapNumber"}) {
      return "Number";
    }
    if (members == std::set<std::string>{"Smi", "HeapNumber", "BigInt"}) {
      return "Numeric";
    }
  }
  return parent()->GetGeneratedTNodeTypeName();
}

const Type* UnionType::NonConstexprVersion() const {
  if (IsConstexpr()) {
    auto it = types_.begin();
    UnionType result((*it)->NonConstexprVersion());
    ++it;
    for (; it != types_.end(); ++it) {
      result.Extend((*it)->NonConstexprVersion());
    }
    return TypeOracle::GetUnionType(std::move(result));
  }
  return this;
}

void UnionType::RecomputeParent() {
  const Type* parent = nullptr;
  for (const Type* t : types_) {
    if (parent == nullptr) {
      parent = t;
    } else {
      parent = CommonSupertype(parent, t);
    }
  }
  set_parent(parent);
}

void UnionType::Subtract(const Type* t) {
  for (auto it = types_.begin(); it != types_.end();) {
    if ((*it)->IsSubtypeOf(t)) {
      it = types_.erase(it);
    } else {
      ++it;
    }
  }
  if (types_.size() == 0) types_.insert(TypeOracle::GetNeverType());
  RecomputeParent();
}

const Type* SubtractType(const Type* a, const Type* b) {
  UnionType result = UnionType::FromType(a);
  result.Subtract(b);
  return TypeOracle::GetUnionType(result);
}

std::string StructType::ToExplicitString() const {
  std::stringstream result;
  result << "{";
  PrintCommaSeparatedList(result, fields_);
  result << "}";
  return result.str();
}

std::string StructType::GetGeneratedTypeName() const {
  return namespace_->ExternalName() + "::" + GetStructName();
}

void PrintSignature(std::ostream& os, const Signature& sig, bool with_names) {
  os << "(";
  for (size_t i = 0; i < sig.parameter_types.types.size(); ++i) {
    if (i == 0 && sig.implicit_count != 0) os << "implicit ";
    if (sig.implicit_count > 0 && sig.implicit_count == i) {
      os << ")(";
    } else {
      if (i > 0) os << ", ";
    }
    if (with_names && !sig.parameter_names.empty()) {
      if (i < sig.parameter_names.size()) {
        os << sig.parameter_names[i] << ": ";
      }
    }
    os << *sig.parameter_types.types[i];
  }
  if (sig.parameter_types.var_args) {
    if (sig.parameter_names.size()) os << ", ";
    os << "...";
  }
  os << ")";
  os << ": " << *sig.return_type;

  if (sig.labels.empty()) return;

  os << " labels ";
  for (size_t i = 0; i < sig.labels.size(); ++i) {
    if (i > 0) os << ", ";
    os << sig.labels[i].name;
    if (sig.labels[i].types.size() > 0) os << "(" << sig.labels[i].types << ")";
  }
}

std::ostream& operator<<(std::ostream& os, const NameAndType& name_and_type) {
  os << name_and_type.name;
  os << ": ";
  os << *name_and_type.type;
  return os;
}

std::ostream& operator<<(std::ostream& os, const Signature& sig) {
  PrintSignature(os, sig, true);
  return os;
}

std::ostream& operator<<(std::ostream& os, const TypeVector& types) {
  PrintCommaSeparatedList(os, types);
  return os;
}

std::ostream& operator<<(std::ostream& os, const ParameterTypes& p) {
  PrintCommaSeparatedList(os, p.types);
  if (p.var_args) {
    if (p.types.size() > 0) os << ", ";
    os << "...";
  }
  return os;
}

bool Signature::HasSameTypesAs(const Signature& other,
                               ParameterMode mode) const {
  auto compare_types = GetTypes();
  auto other_compare_types = other.GetTypes();
  if (mode == ParameterMode::kIgnoreImplicit) {
    compare_types = GetExplicitTypes();
    other_compare_types = other.GetExplicitTypes();
  }
  if (!(compare_types == other_compare_types &&
        parameter_types.var_args == other.parameter_types.var_args &&
        return_type == other.return_type)) {
    return false;
  }
  if (labels.size() != other.labels.size()) {
    return false;
  }
  size_t i = 0;
  for (const auto& l : labels) {
    if (l.types != other.labels[i++].types) {
      return false;
    }
  }
  return true;
}

bool IsAssignableFrom(const Type* to, const Type* from) {
  if (to == from) return true;
  if (from->IsSubtypeOf(to)) return true;
  return TypeOracle::IsImplicitlyConvertableFrom(to, from);
}

bool operator<(const Type& a, const Type& b) {
  return a.MangledName() < b.MangledName();
}

VisitResult ProjectStructField(VisitResult structure,
                               const std::string& fieldname) {
  DCHECK(structure.IsOnStack());
  BottomOffset begin = structure.stack_range().begin();
  const StructType* type = StructType::cast(structure.type());
  for (auto& field : type->fields()) {
    BottomOffset end = begin + LoweredSlotCount(field.type);
    if (field.name == fieldname) {
      return VisitResult(field.type, StackRange{begin, end});
    }
    begin = end;
  }
  UNREACHABLE();
}

namespace {
void AppendLoweredTypes(const Type* type, std::vector<const Type*>* result) {
  DCHECK_NE(type, TypeOracle::GetNeverType());
  if (type->IsConstexpr()) return;
  if (type == TypeOracle::GetVoidType()) return;
  if (auto* s = StructType::DynamicCast(type)) {
    for (const NameAndType& field : s->fields()) {
      AppendLoweredTypes(field.type, result);
    }
  } else {
    result->push_back(type);
  }
}
}  // namespace

TypeVector LowerType(const Type* type) {
  TypeVector result;
  AppendLoweredTypes(type, &result);
  return result;
}

size_t LoweredSlotCount(const Type* type) { return LowerType(type).size(); }

TypeVector LowerParameterTypes(const TypeVector& parameters) {
  std::vector<const Type*> result;
  for (const Type* t : parameters) {
    AppendLoweredTypes(t, &result);
  }
  return result;
}

TypeVector LowerParameterTypes(const ParameterTypes& parameter_types,
                               size_t arg_count) {
  std::vector<const Type*> result = LowerParameterTypes(parameter_types.types);
  for (size_t i = parameter_types.types.size(); i < arg_count; ++i) {
    DCHECK(parameter_types.var_args);
    AppendLoweredTypes(TypeOracle::GetObjectType(), &result);
  }
  return result;
}

VisitResult VisitResult::NeverResult() {
  VisitResult result;
  result.type_ = TypeOracle::GetNeverType();
  return result;
}

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