control.cpp

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/*
 * Copyright 2010 2011 2012 2014 Helge Bahmann <hcb@chaoticmind.net>
 * Copyright 2013 2014 Nico Reißmann <nico.reissmann@gmail.com>
 * See COPYING for terms of redistribution.
 */
 
#include <jlm/rvsdg/bitstring/constant.hpp>
#include <jlm/rvsdg/control.hpp>
#include <jlm/rvsdg/Trace.hpp>
#include <jlm/util/Hash.hpp>
 
namespace jlm::rvsdg
{
 
ControlType::~ControlType() noexcept = default;
 
ControlType::ControlType(size_t nalternatives)
    : Type(),
      nalternatives_(nalternatives)
{}
 
std::string
ControlType::debug_string() const
{
  return jlm::util::strfmt("ctl(", nalternatives_, ")");
}
 
bool
ControlType::operator==(const Type & other) const noexcept
{
  auto type = dynamic_cast<const ControlType *>(&other);
  return type && type->nalternatives_ == nalternatives_;
}
 
std::size_t
ControlType::ComputeHash() const noexcept
{
  auto typeHash = typeid(ControlType).hash_code();
  auto numAlternativesHash = std::hash<size_t>()(nalternatives_);
  return util::CombineHashes(typeHash, numAlternativesHash);
}
 
TypeKind
ControlType::Kind() const noexcept
{
  return TypeKind::Value;
}
 
std::shared_ptr<const ControlType>
ControlType::Create(std::size_t nalternatives)
{
  static const ControlType static_instances[4] = {
    // ControlType(0) is not valid, but put it in here so
    // the static array indexing works correctly
    ControlType(0),
    ControlType(1),
    ControlType(2),
    ControlType(3)
  };
 
  if (nalternatives < 4)
  {
    if (nalternatives == 0)
    {
      throw util::Error("Alternatives of a control type must be non-zero.");
    }
    return std::shared_ptr<const ControlType>(
        std::shared_ptr<void>(),
        &static_instances[nalternatives]);
  }
  else
  {
    return std::make_shared<ControlType>(nalternatives);
  }
}
 
ControlValueRepresentation::ControlValueRepresentation(size_t alternative, size_t nalternatives)
    : alternative_(alternative),
      nalternatives_(nalternatives)
{
  if (alternative >= nalternatives)
    throw util::Error("Alternative is bigger than the number of possible alternatives.");
}
 
ControlConstantOperation::~ControlConstantOperation() noexcept = default;
 
ControlConstantOperation::ControlConstantOperation(ControlValueRepresentation value)
    : NullaryOperation(ControlType::Create(value.nalternatives())),
      value_(std::move(value))
{}
 
bool
ControlConstantOperation::operator==(const Operation & other) const noexcept
{
  const auto operation = dynamic_cast<const ControlConstantOperation *>(&other);
  return operation && operation->value_ == value_;
}
 
std::string
ControlConstantOperation::debug_string() const
{
  return jlm::util::strfmt("CTL(", value_.alternative(), ")");
}
 
std::unique_ptr<Operation>
ControlConstantOperation::copy() const
{
  return std::make_unique<ControlConstantOperation>(value_);
}
 
MatchOperation::~MatchOperation() noexcept = default;
 
MatchOperation::MatchOperation(
    size_t nbits,
    const std::unordered_map<uint64_t, uint64_t> & mapping,
    uint64_t default_alternative,
    size_t nalternatives)
    : UnaryOperation(BitType::Create(nbits), ControlType::Create(nalternatives)),
      default_alternative_(default_alternative),
      mapping_(mapping)
{}
 
bool
MatchOperation::operator==(const Operation & other) const noexcept
{
  auto op = dynamic_cast<const MatchOperation *>(&other);
  return op && op->default_alternative_ == default_alternative_ && op->mapping_ == mapping_
      && op->nbits() == nbits() && op->nalternatives() == nalternatives();
}
 
unop_reduction_path_t
MatchOperation::can_reduce_operand(const jlm::rvsdg::Output * arg) const noexcept
{
  auto & tracedOutput = traceOutputIntraProcedurally(*arg);
  if (auto node = rvsdg::TryGetOwnerNode<SimpleNode>(tracedOutput))
  {
    if (dynamic_cast<const BitConstantOperation *>(&node->GetOperation()))
      return unop_reduction_constant;
  }
 
  return unop_reduction_none;
}
 
jlm::rvsdg::Output *
MatchOperation::reduce_operand(unop_reduction_path_t path, jlm::rvsdg::Output * arg) const
{
  if (path == unop_reduction_constant)
  {
    auto & tracedOutput = traceOutputIntraProcedurally(*arg);
    auto [_, constantOperation] = TryGetSimpleNodeAndOptionalOp<BitConstantOperation>(tracedOutput);
    JLM_ASSERT(constantOperation);
    return &ControlConstantOperation::create(
        *arg->region(),
        nalternatives(),
        alternative(constantOperation->value().to_uint()));
  }
 
  return nullptr;
}
 
std::string
MatchOperation::debug_string() const
{
  size_t n = 0;
  std::ostringstream oss;
  constexpr size_t maxAlternatives = 3;
  for (auto [input, subregionId] : mapping_)
  {
    if (n < maxAlternatives)
    {
      oss << input << " -> " << subregionId << ", ";
      n++;
    }
    else
    {
      oss << "..., ";
      break;
    }
  }
  oss << default_alternative_;
 
  return "MATCH[" + oss.str() + "]";
}
 
std::unique_ptr<Operation>
MatchOperation::copy() const
{
  return std::make_unique<MatchOperation>(*this);
}
 
}