Function runCVP

lib/indcallsolver/CustomCVPPass.cpp:401–445

namespace ftg {
static bool runCVP(Module &M) {
  // Our custom lattice function and generic sparse propagation solver.
  CVPLatticeFunc Lattice;
  SparseSolver<CVPLatticeKey, CVPLatticeVal> Solver(&Lattice);

  // For each function in the module, if we can't track its arguments, let the
  // generic solver assume it is executable.
  for (Function &F : M)
    if (!F.isDeclaration() && !canTrackArgumentsInterprocedurally(&F))
      Solver.MarkBlockExecutable(&F.front());

  // Solver our custom lattice. In doing so, we will also build a set of
  // indirect call sites.
  Solver.Solve();

  // Attach metadata to the indirect call sites that were collected indicating
  // the set of functions they can possibly target.
  // CustomCVP take the value of stripPointerCasts instead of pure CalledValue.
  // According to evaluation result of CustomCVP, this value is more useful.
  bool Changed = false;
  MDBuilder MDB(M.getContext());
  for (Instruction *C : Lattice.getIndirectCalls()) {
    auto *CB = dyn_cast_or_null<CallBase>(C);
    if (!CB)
      continue;

    auto *CO = CB->getCalledOperand();
    if (!CO)
      continue;

    CO = CO->stripPointerCasts();
    if (!CO)
      continue;

    auto RegI = CVPLatticeKey(CO, IPOGrouping::Register);
    CVPLatticeVal LV = Solver.getExistingValueState(RegI);
    if (!LV.isFunctionSet() || LV.getFunctions().empty())
      continue;
    MDNode *Callees = MDB.createCallees(LV.getFunctions());
    C->setMetadata(LLVMContext::MD_callees, Callees);
    Changed = true;
  }

  return Changed;
}

PreservedAnalyses CustomCVPPass::run(Module &M, ModuleAnalysisManager &) {
  runCVP(M);