Пример #1
0
/// Performs polyhedral dead iteration elimination by:
/// o Assuming that the last write to each location is live.
/// o Following each RAW dependency from a live iteration backwards and adding
///   that iteration to the live set.
///
/// To ensure the set of live iterations does not get too complex we always
/// combine a certain number of precise steps with one approximating step that
/// simplifies the life set with an affine hull.
bool DeadCodeElim::eliminateDeadCode(Scop &S, int PreciseSteps) {
  DependenceInfo &DI = getAnalysis<DependenceInfo>();
  const Dependences &D = DI.getDependences(Dependences::AL_Statement);

  if (!D.hasValidDependences())
    return false;

  isl_union_set *Live = getLiveOut(S);
  isl_union_map *Dep =
      D.getDependences(Dependences::TYPE_RAW | Dependences::TYPE_RED);
  Dep = isl_union_map_reverse(Dep);

  if (PreciseSteps == -1)
    Live = isl_union_set_affine_hull(Live);

  isl_union_set *OriginalDomain = S.getDomains();
  int Steps = 0;
  while (true) {
    isl_union_set *Extra;
    Steps++;

    Extra =
        isl_union_set_apply(isl_union_set_copy(Live), isl_union_map_copy(Dep));

    if (isl_union_set_is_subset(Extra, Live)) {
      isl_union_set_free(Extra);
      break;
    }

    Live = isl_union_set_union(Live, Extra);

    if (Steps > PreciseSteps) {
      Steps = 0;
      Live = isl_union_set_affine_hull(Live);
    }

    Live = isl_union_set_intersect(Live, isl_union_set_copy(OriginalDomain));
  }
  isl_union_map_free(Dep);
  isl_union_set_free(OriginalDomain);

  bool Changed = S.restrictDomains(isl_union_set_coalesce(Live));

  // FIXME: We can probably avoid the recomputation of all dependences by
  // updating them explicitly.
  if (Changed)
    DI.recomputeDependences(Dependences::AL_Statement);
  return Changed;
}
Пример #2
0
void IslAstInfo::printScop(raw_ostream &OS, Scop &S) const {
  isl_ast_print_options *Options;
  isl_ast_node *RootNode = getAst();
  Function *F = S.getRegion().getEntry()->getParent();

  OS << ":: isl ast :: " << F->getName() << " :: " << S.getRegion().getNameStr()
     << "\n";

  if (!RootNode) {
    OS << ":: isl ast generation and code generation was skipped!\n\n";
    OS << ":: This is either because no useful optimizations could be applied "
          "(use -polly-process-unprofitable to enforce code generation) or "
          "because earlier passes such as dependence analysis timed out (use "
          "-polly-dependences-computeout=0 to set dependence analysis timeout "
          "to infinity)\n\n";
    return;
  }

  isl_ast_expr *RunCondition = getRunCondition();
  char *RtCStr, *AstStr;

  Options = isl_ast_print_options_alloc(S.getIslCtx());
  Options = isl_ast_print_options_set_print_for(Options, cbPrintFor, nullptr);

  isl_printer *P = isl_printer_to_str(S.getIslCtx());
  P = isl_printer_print_ast_expr(P, RunCondition);
  RtCStr = isl_printer_get_str(P);
  P = isl_printer_flush(P);
  P = isl_printer_indent(P, 4);
  P = isl_printer_set_output_format(P, ISL_FORMAT_C);
  P = isl_ast_node_print(RootNode, P, Options);
  AstStr = isl_printer_get_str(P);

  isl_union_map *Schedule =
      isl_union_map_intersect_domain(S.getSchedule(), S.getDomains());

  DEBUG({
    dbgs() << S.getContextStr() << "\n";
    dbgs() << stringFromIslObj(Schedule);
  });
Пример #3
0
bool IslScheduleOptimizer::runOnScop(Scop &S) {
  Dependences *D = &getAnalysis<Dependences>();

  if (!D->hasValidDependences())
    return false;

  isl_schedule_free(LastSchedule);
  LastSchedule = nullptr;

  // Build input data.
  int ValidityKinds =
      Dependences::TYPE_RAW | Dependences::TYPE_WAR | Dependences::TYPE_WAW;
  int ProximityKinds;

  if (OptimizeDeps == "all")
    ProximityKinds =
        Dependences::TYPE_RAW | Dependences::TYPE_WAR | Dependences::TYPE_WAW;
  else if (OptimizeDeps == "raw")
    ProximityKinds = Dependences::TYPE_RAW;
  else {
    errs() << "Do not know how to optimize for '" << OptimizeDeps << "'"
           << " Falling back to optimizing all dependences.\n";
    ProximityKinds =
        Dependences::TYPE_RAW | Dependences::TYPE_WAR | Dependences::TYPE_WAW;
  }

  isl_union_set *Domain = S.getDomains();

  if (!Domain)
    return false;

  isl_union_map *Validity = D->getDependences(ValidityKinds);
  isl_union_map *Proximity = D->getDependences(ProximityKinds);

  // Simplify the dependences by removing the constraints introduced by the
  // domains. This can speed up the scheduling time significantly, as large
  // constant coefficients will be removed from the dependences. The
  // introduction of some additional dependences reduces the possible
  // transformations, but in most cases, such transformation do not seem to be
  // interesting anyway. In some cases this option may stop the scheduler to
  // find any schedule.
  if (SimplifyDeps == "yes") {
    Validity = isl_union_map_gist_domain(Validity, isl_union_set_copy(Domain));
    Validity = isl_union_map_gist_range(Validity, isl_union_set_copy(Domain));
    Proximity =
        isl_union_map_gist_domain(Proximity, isl_union_set_copy(Domain));
    Proximity = isl_union_map_gist_range(Proximity, isl_union_set_copy(Domain));
  } else if (SimplifyDeps != "no") {
    errs() << "warning: Option -polly-opt-simplify-deps should either be 'yes' "
              "or 'no'. Falling back to default: 'yes'\n";
  }

  DEBUG(dbgs() << "\n\nCompute schedule from: ");
  DEBUG(dbgs() << "Domain := "; isl_union_set_dump(Domain); dbgs() << ";\n");
  DEBUG(dbgs() << "Proximity := "; isl_union_map_dump(Proximity);
        dbgs() << ";\n");
  DEBUG(dbgs() << "Validity := "; isl_union_map_dump(Validity);
        dbgs() << ";\n");

  int IslFusionStrategy;

  if (FusionStrategy == "max") {
    IslFusionStrategy = ISL_SCHEDULE_FUSE_MAX;
  } else if (FusionStrategy == "min") {
    IslFusionStrategy = ISL_SCHEDULE_FUSE_MIN;
  } else {
    errs() << "warning: Unknown fusion strategy. Falling back to maximal "
              "fusion.\n";
    IslFusionStrategy = ISL_SCHEDULE_FUSE_MAX;
  }

  int IslMaximizeBands;

  if (MaximizeBandDepth == "yes") {
    IslMaximizeBands = 1;
  } else if (MaximizeBandDepth == "no") {
    IslMaximizeBands = 0;
  } else {
    errs() << "warning: Option -polly-opt-maximize-bands should either be 'yes'"
              " or 'no'. Falling back to default: 'yes'\n";
    IslMaximizeBands = 1;
  }

  isl_options_set_schedule_fuse(S.getIslCtx(), IslFusionStrategy);
  isl_options_set_schedule_maximize_band_depth(S.getIslCtx(), IslMaximizeBands);
  isl_options_set_schedule_max_constant_term(S.getIslCtx(), MaxConstantTerm);
  isl_options_set_schedule_max_coefficient(S.getIslCtx(), MaxCoefficient);

  isl_options_set_on_error(S.getIslCtx(), ISL_ON_ERROR_CONTINUE);

  isl_schedule_constraints *ScheduleConstraints;
  ScheduleConstraints = isl_schedule_constraints_on_domain(Domain);
  ScheduleConstraints =
      isl_schedule_constraints_set_proximity(ScheduleConstraints, Proximity);
  ScheduleConstraints = isl_schedule_constraints_set_validity(
      ScheduleConstraints, isl_union_map_copy(Validity));
  ScheduleConstraints =
      isl_schedule_constraints_set_coincidence(ScheduleConstraints, Validity);
  isl_schedule *Schedule;
  Schedule = isl_schedule_constraints_compute_schedule(ScheduleConstraints);
  isl_options_set_on_error(S.getIslCtx(), ISL_ON_ERROR_ABORT);

  // In cases the scheduler is not able to optimize the code, we just do not
  // touch the schedule.
  if (!Schedule)
    return false;

  DEBUG(dbgs() << "Schedule := "; isl_schedule_dump(Schedule); dbgs() << ";\n");

  isl_union_map *ScheduleMap = getScheduleMap(Schedule);

  for (ScopStmt *Stmt : S) {
    isl_map *StmtSchedule;
    isl_set *Domain = Stmt->getDomain();
    isl_union_map *StmtBand;
    StmtBand = isl_union_map_intersect_domain(isl_union_map_copy(ScheduleMap),
                                              isl_union_set_from_set(Domain));
    if (isl_union_map_is_empty(StmtBand)) {
      StmtSchedule = isl_map_from_domain(isl_set_empty(Stmt->getDomainSpace()));
      isl_union_map_free(StmtBand);
    } else {
      assert(isl_union_map_n_map(StmtBand) == 1);
      StmtSchedule = isl_map_from_union_map(StmtBand);
    }

    Stmt->setScattering(StmtSchedule);
  }

  isl_union_map_free(ScheduleMap);
  LastSchedule = Schedule;

  unsigned MaxScatDims = 0;

  for (ScopStmt *Stmt : S)
    MaxScatDims = std::max(Stmt->getNumScattering(), MaxScatDims);

  extendScattering(S, MaxScatDims);
  return false;
}
Пример #4
0
bool IslScheduleOptimizer::runOnScop(Scop &S) {

  // Skip empty SCoPs but still allow code generation as it will delete the
  // loops present but not needed.
  if (S.getSize() == 0) {
    S.markAsOptimized();
    return false;
  }

  const Dependences &D =
      getAnalysis<DependenceInfo>().getDependences(Dependences::AL_Statement);

  if (!D.hasValidDependences())
    return false;

  isl_schedule_free(LastSchedule);
  LastSchedule = nullptr;

  // Build input data.
  int ValidityKinds =
      Dependences::TYPE_RAW | Dependences::TYPE_WAR | Dependences::TYPE_WAW;
  int ProximityKinds;

  if (OptimizeDeps == "all")
    ProximityKinds =
        Dependences::TYPE_RAW | Dependences::TYPE_WAR | Dependences::TYPE_WAW;
  else if (OptimizeDeps == "raw")
    ProximityKinds = Dependences::TYPE_RAW;
  else {
    errs() << "Do not know how to optimize for '" << OptimizeDeps << "'"
           << " Falling back to optimizing all dependences.\n";
    ProximityKinds =
        Dependences::TYPE_RAW | Dependences::TYPE_WAR | Dependences::TYPE_WAW;
  }

  isl_union_set *Domain = S.getDomains();

  if (!Domain)
    return false;

  isl_union_map *Validity = D.getDependences(ValidityKinds);
  isl_union_map *Proximity = D.getDependences(ProximityKinds);

  // Simplify the dependences by removing the constraints introduced by the
  // domains. This can speed up the scheduling time significantly, as large
  // constant coefficients will be removed from the dependences. The
  // introduction of some additional dependences reduces the possible
  // transformations, but in most cases, such transformation do not seem to be
  // interesting anyway. In some cases this option may stop the scheduler to
  // find any schedule.
  if (SimplifyDeps == "yes") {
    Validity = isl_union_map_gist_domain(Validity, isl_union_set_copy(Domain));
    Validity = isl_union_map_gist_range(Validity, isl_union_set_copy(Domain));
    Proximity =
        isl_union_map_gist_domain(Proximity, isl_union_set_copy(Domain));
    Proximity = isl_union_map_gist_range(Proximity, isl_union_set_copy(Domain));
  } else if (SimplifyDeps != "no") {
    errs() << "warning: Option -polly-opt-simplify-deps should either be 'yes' "
              "or 'no'. Falling back to default: 'yes'\n";
  }

  DEBUG(dbgs() << "\n\nCompute schedule from: ");
  DEBUG(dbgs() << "Domain := " << stringFromIslObj(Domain) << ";\n");
  DEBUG(dbgs() << "Proximity := " << stringFromIslObj(Proximity) << ";\n");
  DEBUG(dbgs() << "Validity := " << stringFromIslObj(Validity) << ";\n");

  unsigned IslSerializeSCCs;

  if (FusionStrategy == "max") {
    IslSerializeSCCs = 0;
  } else if (FusionStrategy == "min") {
    IslSerializeSCCs = 1;
  } else {
    errs() << "warning: Unknown fusion strategy. Falling back to maximal "
              "fusion.\n";
    IslSerializeSCCs = 0;
  }

  int IslMaximizeBands;

  if (MaximizeBandDepth == "yes") {
    IslMaximizeBands = 1;
  } else if (MaximizeBandDepth == "no") {
    IslMaximizeBands = 0;
  } else {
    errs() << "warning: Option -polly-opt-maximize-bands should either be 'yes'"
              " or 'no'. Falling back to default: 'yes'\n";
    IslMaximizeBands = 1;
  }

  isl_options_set_schedule_serialize_sccs(S.getIslCtx(), IslSerializeSCCs);
  isl_options_set_schedule_maximize_band_depth(S.getIslCtx(), IslMaximizeBands);
  isl_options_set_schedule_max_constant_term(S.getIslCtx(), MaxConstantTerm);
  isl_options_set_schedule_max_coefficient(S.getIslCtx(), MaxCoefficient);
  isl_options_set_tile_scale_tile_loops(S.getIslCtx(), 0);

  isl_options_set_on_error(S.getIslCtx(), ISL_ON_ERROR_CONTINUE);

  isl_schedule_constraints *ScheduleConstraints;
  ScheduleConstraints = isl_schedule_constraints_on_domain(Domain);
  ScheduleConstraints =
      isl_schedule_constraints_set_proximity(ScheduleConstraints, Proximity);
  ScheduleConstraints = isl_schedule_constraints_set_validity(
      ScheduleConstraints, isl_union_map_copy(Validity));
  ScheduleConstraints =
      isl_schedule_constraints_set_coincidence(ScheduleConstraints, Validity);
  isl_schedule *Schedule;
  Schedule = isl_schedule_constraints_compute_schedule(ScheduleConstraints);
  isl_options_set_on_error(S.getIslCtx(), ISL_ON_ERROR_ABORT);

  // In cases the scheduler is not able to optimize the code, we just do not
  // touch the schedule.
  if (!Schedule)
    return false;

  DEBUG({
    auto *P = isl_printer_to_str(S.getIslCtx());
    P = isl_printer_set_yaml_style(P, ISL_YAML_STYLE_BLOCK);
    P = isl_printer_print_schedule(P, Schedule);
    dbgs() << "NewScheduleTree: \n" << isl_printer_get_str(P) << "\n";
    isl_printer_free(P);
  });