// Copyright 2014 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/compiler/gap-resolver.h"

#include "src/base/utils/random-number-generator.h"
#include "test/cctest/cctest.h"

using namespace v8::internal;
using namespace v8::internal::compiler;

// The state of our move interpreter is the mapping of operands to values. Note
// that the actual values don't really matter, all we care about is equality.
class InterpreterState {
 public:
  typedef std::vector<MoveOperands> Moves;

  void ExecuteInParallel(Moves moves) {
    InterpreterState copy(*this);
    for (Moves::iterator it = moves.begin(); it != moves.end(); ++it) {
      if (!it->IsRedundant()) write(it->destination(), copy.read(it->source()));
    }
  }

  bool operator==(const InterpreterState& other) const {
    return values_ == other.values_;
  }

  bool operator!=(const InterpreterState& other) const {
    return values_ != other.values_;
  }

 private:
  // Internally, the state is a normalized permutation of (kind,index) pairs.
  typedef std::pair<InstructionOperand::Kind, int> Key;
  typedef Key Value;
  typedef std::map<Key, Value> OperandMap;

  Value read(const InstructionOperand* op) const {
    OperandMap::const_iterator it = values_.find(KeyFor(op));
    return (it == values_.end()) ? ValueFor(op) : it->second;
  }

  void write(const InstructionOperand* op, Value v) {
    if (v == ValueFor(op)) {
      values_.erase(KeyFor(op));
    } else {
      values_[KeyFor(op)] = v;
    }
  }

  static Key KeyFor(const InstructionOperand* op) {
    return Key(op->kind(), op->index());
  }

  static Value ValueFor(const InstructionOperand* op) {
    return Value(op->kind(), op->index());
  }

  friend std::ostream& operator<<(std::ostream& os,
                                  const InterpreterState& is) {
    for (OperandMap::const_iterator it = is.values_.begin();
         it != is.values_.end(); ++it) {
      if (it != is.values_.begin()) os << " ";
      InstructionOperand source(it->first.first, it->first.second);
      InstructionOperand destination(it->second.first, it->second.second);
      os << MoveOperands(&source, &destination);
    }
    return os;
  }

  OperandMap values_;
};


// An abstract interpreter for moves, swaps and parallel moves.
class MoveInterpreter : public GapResolver::Assembler {
 public:
  virtual void AssembleMove(InstructionOperand* source,
                            InstructionOperand* destination) OVERRIDE {
    InterpreterState::Moves moves;
    moves.push_back(MoveOperands(source, destination));
    state_.ExecuteInParallel(moves);
  }

  virtual void AssembleSwap(InstructionOperand* source,
                            InstructionOperand* destination) OVERRIDE {
    InterpreterState::Moves moves;
    moves.push_back(MoveOperands(source, destination));
    moves.push_back(MoveOperands(destination, source));
    state_.ExecuteInParallel(moves);
  }

  void AssembleParallelMove(const ParallelMove* pm) {
    InterpreterState::Moves moves(pm->move_operands()->begin(),
                                  pm->move_operands()->end());
    state_.ExecuteInParallel(moves);
  }

  InterpreterState state() const { return state_; }

 private:
  InterpreterState state_;
};


class ParallelMoveCreator : public HandleAndZoneScope {
 public:
  ParallelMoveCreator() : rng_(CcTest::random_number_generator()) {}

  ParallelMove* Create(int size) {
    ParallelMove* parallel_move = new (main_zone()) ParallelMove(main_zone());
    std::set<InstructionOperand*, InstructionOperandComparator> seen;
    for (int i = 0; i < size; ++i) {
      MoveOperands mo(CreateRandomOperand(), CreateRandomOperand());
      if (!mo.IsRedundant() && seen.find(mo.destination()) == seen.end()) {
        parallel_move->AddMove(mo.source(), mo.destination(), main_zone());
        seen.insert(mo.destination());
      }
    }
    return parallel_move;
  }

 private:
  struct InstructionOperandComparator {
    bool operator()(const InstructionOperand* x,
                    const InstructionOperand* y) const {
      return (x->kind() < y->kind()) ||
             (x->kind() == y->kind() && x->index() < y->index());
    }
  };

  InstructionOperand* CreateRandomOperand() {
    int index = rng_->NextInt(6);
    switch (rng_->NextInt(5)) {
      case 0:
        return ConstantOperand::Create(index, main_zone());
      case 1:
        return StackSlotOperand::Create(index, main_zone());
      case 2:
        return DoubleStackSlotOperand::Create(index, main_zone());
      case 3:
        return RegisterOperand::Create(index, main_zone());
      case 4:
        return DoubleRegisterOperand::Create(index, main_zone());
    }
    UNREACHABLE();
    return NULL;
  }

 private:
  v8::base::RandomNumberGenerator* rng_;
};


TEST(FuzzResolver) {
  ParallelMoveCreator pmc;
  for (int size = 0; size < 20; ++size) {
    for (int repeat = 0; repeat < 50; ++repeat) {
      ParallelMove* pm = pmc.Create(size);

      // Note: The gap resolver modifies the ParallelMove, so interpret first.
      MoveInterpreter mi1;
      mi1.AssembleParallelMove(pm);

      MoveInterpreter mi2;
      GapResolver resolver(&mi2);
      resolver.Resolve(pm);

      CHECK(mi1.state() == mi2.state());
    }
  }
}