AliasAnalysis.cpp

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/*
 * Copyright 2025 Håvard Krogstie <krogstie.havard@gmail.com>
 * See COPYING for terms of redistribution.
 */
 
#include <jlm/llvm/ir/operators/IntegerOperations.hpp>
#include <jlm/llvm/ir/operators/IOBarrier.hpp>
#include <jlm/llvm/opt/alias-analyses/AliasAnalysis.hpp>
#include <jlm/rvsdg/bitstring/constant.hpp>
#include <jlm/rvsdg/lambda.hpp>
#include <jlm/rvsdg/Phi.hpp>
#include <jlm/rvsdg/theta.hpp>
 
namespace jlm::llvm::aa
{
 
AliasAnalysis::AliasAnalysis() = default;
 
AliasAnalysis::~AliasAnalysis() noexcept = default;
 
static bool
AreAliasResponsesCompatible(
    AliasAnalysis::AliasQueryResponse a,
    AliasAnalysis::AliasQueryResponse b)
{
  if (a == AliasAnalysis::NoAlias)
    return b != AliasAnalysis::MustAlias;
  if (a == AliasAnalysis::MayAlias)
    return true;
  if (a == AliasAnalysis::MustAlias)
    return b != AliasAnalysis::NoAlias;
  JLM_UNREACHABLE("Unknown alias response");
}
 
ChainedAliasAnalysis::ChainedAliasAnalysis(
    std::shared_ptr<AliasAnalysis> first,
    std::shared_ptr<AliasAnalysis> second)
    : First_(std::move(first)),
      Second_(std::move(second))
{}
 
ChainedAliasAnalysis::~ChainedAliasAnalysis() noexcept = default;
 
AliasAnalysis::AliasQueryResponse
ChainedAliasAnalysis::Query(
    const rvsdg::Output & p1,
    size_t s1,
    const rvsdg::Output & p2,
    size_t s2)
{
  const auto firstResponse = First_->Query(p1, s1, p2, s2);
  if (firstResponse == MayAlias)
    return Second_->Query(p1, s1, p2, s2);
 
  // When building with asserts, always query the second analysis and double check
  JLM_ASSERT(AreAliasResponsesCompatible(firstResponse, Second_->Query(p1, s1, p2, s2)));
  return firstResponse;
}
 
std::string
ChainedAliasAnalysis::ToString() const
{
  return util::strfmt("ChainedAA(", First_->ToString(), ",", Second_->ToString(), ")");
}
 
bool
IsPointerCompatible(const rvsdg::Output & value)
{
  return IsOrContains<PointerType>(*value.Type());
}
 
}