示例#1
0
文件: IslAst.cpp 项目: jeremyhu/polly
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);
  });
示例#2
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;
}
示例#3
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);
  });
示例#4
0
bool JSONImporter::runOnScop(Scop &S) {
  const Dependences &D =
      getAnalysis<DependenceInfo>().getDependences(Dependences::AL_Statement);
  const DataLayout &DL = S.getFunction().getParent()->getDataLayout();

  std::string FileName = ImportDir + "/" + getFileName(S);

  std::string FunctionName = S.getFunction().getName();
  errs() << "Reading JScop '" << S.getNameStr() << "' in function '"
         << FunctionName << "' from '" << FileName << "'.\n";
  ErrorOr<std::unique_ptr<MemoryBuffer>> result =
      MemoryBuffer::getFile(FileName);
  std::error_code ec = result.getError();

  if (ec) {
    errs() << "File could not be read: " << ec.message() << "\n";
    return false;
  }

  Json::Reader reader;
  Json::Value jscop;

  bool parsingSuccessful = reader.parse(result.get()->getBufferStart(), jscop);

  if (!parsingSuccessful) {
    errs() << "JSCoP file could not be parsed\n";
    return false;
  }

  isl_set *OldContext = S.getContext();
  isl_set *NewContext =
      isl_set_read_from_str(S.getIslCtx(), jscop["context"].asCString());

  for (unsigned i = 0; i < isl_set_dim(OldContext, isl_dim_param); i++) {
    isl_id *id = isl_set_get_dim_id(OldContext, isl_dim_param, i);
    NewContext = isl_set_set_dim_id(NewContext, isl_dim_param, i, id);
  }

  isl_set_free(OldContext);
  S.setContext(NewContext);

  StatementToIslMapTy NewSchedule;

  int index = 0;

  for (ScopStmt &Stmt : S) {
    Json::Value schedule = jscop["statements"][index]["schedule"];
    isl_map *m = isl_map_read_from_str(S.getIslCtx(), schedule.asCString());
    isl_space *Space = Stmt.getDomainSpace();

    // Copy the old tuple id. This is necessary to retain the user pointer,
    // that stores the reference to the ScopStmt this schedule belongs to.
    m = isl_map_set_tuple_id(m, isl_dim_in,
                             isl_space_get_tuple_id(Space, isl_dim_set));
    for (unsigned i = 0; i < isl_space_dim(Space, isl_dim_param); i++) {
      isl_id *id = isl_space_get_dim_id(Space, isl_dim_param, i);
      m = isl_map_set_dim_id(m, isl_dim_param, i, id);
    }
    isl_space_free(Space);
    NewSchedule[&Stmt] = m;
    index++;
  }

  if (!D.isValidSchedule(S, &NewSchedule)) {
    errs() << "JScop file contains a schedule that changes the "
           << "dependences. Use -disable-polly-legality to continue anyways\n";
    for (StatementToIslMapTy::iterator SI = NewSchedule.begin(),
                                       SE = NewSchedule.end();
         SI != SE; ++SI)
      isl_map_free(SI->second);
    return false;
  }

  auto ScheduleMap = isl_union_map_empty(S.getParamSpace());
  for (ScopStmt &Stmt : S) {
    if (NewSchedule.find(&Stmt) != NewSchedule.end())
      ScheduleMap = isl_union_map_add_map(ScheduleMap, NewSchedule[&Stmt]);
    else
      ScheduleMap = isl_union_map_add_map(ScheduleMap, Stmt.getSchedule());
  }

  S.setSchedule(ScheduleMap);

  int statementIdx = 0;
  for (ScopStmt &Stmt : S) {
    int memoryAccessIdx = 0;
    for (MemoryAccess *MA : Stmt) {
      Json::Value accesses = jscop["statements"][statementIdx]["accesses"]
                                  [memoryAccessIdx]["relation"];
      isl_map *newAccessMap =
          isl_map_read_from_str(S.getIslCtx(), accesses.asCString());
      isl_map *currentAccessMap = MA->getAccessRelation();

      if (isl_map_dim(newAccessMap, isl_dim_param) !=
          isl_map_dim(currentAccessMap, isl_dim_param)) {
        errs() << "JScop file changes the number of parameter dimensions\n";
        isl_map_free(currentAccessMap);
        isl_map_free(newAccessMap);
        return false;
      }

      isl_id *OutId = isl_map_get_tuple_id(currentAccessMap, isl_dim_out);
      newAccessMap = isl_map_set_tuple_id(newAccessMap, isl_dim_out, OutId);

      if (MA->isArrayKind()) {
        // We keep the old alignment, thus we cannot allow accesses to memory
        // locations that were not accessed before if the alignment of the
        // access is not the default alignment.
        bool SpecialAlignment = true;
        if (LoadInst *LoadI = dyn_cast<LoadInst>(MA->getAccessInstruction())) {
          SpecialAlignment =
              DL.getABITypeAlignment(LoadI->getType()) != LoadI->getAlignment();
        } else if (StoreInst *StoreI =
                       dyn_cast<StoreInst>(MA->getAccessInstruction())) {
          SpecialAlignment =
              DL.getABITypeAlignment(StoreI->getValueOperand()->getType()) !=
              StoreI->getAlignment();
        }

        if (SpecialAlignment) {
          isl_set *newAccessSet = isl_map_range(isl_map_copy(newAccessMap));
          isl_set *currentAccessSet =
              isl_map_range(isl_map_copy(currentAccessMap));
          bool isSubset = isl_set_is_subset(newAccessSet, currentAccessSet);
          isl_set_free(newAccessSet);
          isl_set_free(currentAccessSet);

          if (!isSubset) {
            errs() << "JScop file changes the accessed memory\n";
            isl_map_free(currentAccessMap);
            isl_map_free(newAccessMap);
            return false;
          }
        }
      }

      // We need to copy the isl_ids for the parameter dimensions to the new
      // map. Without doing this the current map would have different
      // ids then the new one, even though both are named identically.
      for (unsigned i = 0; i < isl_map_dim(currentAccessMap, isl_dim_param);
           i++) {
        isl_id *id = isl_map_get_dim_id(currentAccessMap, isl_dim_param, i);
        newAccessMap = isl_map_set_dim_id(newAccessMap, isl_dim_param, i, id);
      }

      // Copy the old tuple id. This is necessary to retain the user pointer,
      // that stores the reference to the ScopStmt this access belongs to.
      isl_id *Id = isl_map_get_tuple_id(currentAccessMap, isl_dim_in);
      newAccessMap = isl_map_set_tuple_id(newAccessMap, isl_dim_in, Id);

      if (!isl_map_has_equal_space(currentAccessMap, newAccessMap)) {
        errs() << "JScop file contains access function with incompatible "
               << "dimensions\n";
        isl_map_free(currentAccessMap);
        isl_map_free(newAccessMap);
        return false;
      }

      auto NewAccessDomain = isl_map_domain(isl_map_copy(newAccessMap));
      auto CurrentAccessDomain = isl_map_domain(isl_map_copy(currentAccessMap));

      NewAccessDomain =
          isl_set_intersect_params(NewAccessDomain, S.getContext());
      CurrentAccessDomain =
          isl_set_intersect_params(CurrentAccessDomain, S.getContext());

      if (isl_set_is_subset(CurrentAccessDomain, NewAccessDomain) ==
          isl_bool_false) {
        errs() << "Mapping not defined for all iteration domain elements\n";
        isl_set_free(CurrentAccessDomain);
        isl_set_free(NewAccessDomain);
        isl_map_free(currentAccessMap);
        isl_map_free(newAccessMap);
        return false;
      }

      isl_set_free(CurrentAccessDomain);
      isl_set_free(NewAccessDomain);

      if (!isl_map_is_equal(newAccessMap, currentAccessMap)) {
        // Statistics.
        ++NewAccessMapFound;
        newAccessStrings.push_back(accesses.asCString());
        MA->setNewAccessRelation(newAccessMap);
      } else {
        isl_map_free(newAccessMap);
      }
      isl_map_free(currentAccessMap);
      memoryAccessIdx++;
    }
    statementIdx++;
  }

  return false;
}
示例#5
0
文件: Pocc.cpp 项目: SameerAsal/Polly
bool Pocc::runTransform(Scop &S) {
  Dependences *D = &getAnalysis<Dependences>();

  // Create the scop file.
  SmallString<128> TempDir;
  SmallString<128> ScopFile;
  llvm::sys::path::system_temp_directory(/*erasedOnReboot=*/true, TempDir);
  ScopFile = TempDir;
  llvm::sys::path::append(ScopFile, "polly.scop");

  FILE *F = fopen(ScopFile.c_str(), "w");

  arguments.clear();

  if (!F) {
    errs() << "Cannot open file: " << TempDir.c_str() << "\n";
    errs() << "Skipping export.\n";
    return false;
  }

  ScopLib scoplib(&S);
  scoplib.print(F);
  fclose(F);

  // Execute pocc
  std::string pocc = sys::FindProgramByName("pocc");

  arguments.push_back("pocc");
  arguments.push_back("--read-scop");
  arguments.push_back(ScopFile.c_str());
  arguments.push_back("--pluto-tile-scat");
  arguments.push_back("--candl-dep-isl-simp");
  arguments.push_back("--cloogify-scheds");
  arguments.push_back("--output-scop");
  arguments.push_back("--pluto");
  arguments.push_back("--pluto-bounds");
  arguments.push_back("10");
  arguments.push_back("--pluto-fuse");

  arguments.push_back(PlutoFuse.c_str());

  if (!DisablePollyTiling)
    arguments.push_back("--pluto-tile");

  if (PollyVectorizerChoice != VECTORIZER_NONE)
    arguments.push_back("--pluto-prevector");

  arguments.push_back(0);

  PlutoStdout = TempDir;
  llvm::sys::path::append(PlutoStdout, "pluto.stdout");
  PlutoStderr = TempDir;
  llvm::sys::path::append(PlutoStderr, "pluto.stderr");

  std::vector<llvm::StringRef> Redirect;
  Redirect.push_back(0);
  Redirect.push_back(PlutoStdout.c_str());
  Redirect.push_back(PlutoStderr.c_str());

  sys::ExecuteAndWait(pocc, &arguments[0], 0,
                      (const llvm::StringRef **)&Redirect[0]);

  // Read the created scop file
  SmallString<128> NewScopFile;
  NewScopFile = TempDir;
  llvm::sys::path::append(NewScopFile, "polly.pocc.c.scop");

  FILE *poccFile = fopen(NewScopFile.c_str(), "r");
  ScopLib newScoplib(&S, poccFile, D);

  if (!newScoplib.updateScattering()) {
    errs() << "Failure when calculating the optimization with "
              "the following command: ";
    for (std::vector<const char *>::const_iterator AI = arguments.begin(),
                                                   AE = arguments.end();
         AI != AE; ++AI)
      if (*AI)
        errs() << " " << *AI;
    errs() << "\n";
    return false;
  } else
    fclose(poccFile);

  if (PollyVectorizerChoice == VECTORIZER_NONE)
    return false;

  // Find the innermost dimension that is not a constant dimension. This
  // dimension will be vectorized.
  unsigned scatterDims = S.getScatterDim();
  int lastLoop = scatterDims - 1;

  while (lastLoop) {
    bool isSingleValued = true;

    for (Scop::iterator SI = S.begin(), SE = S.end(); SI != SE; ++SI) {
      isl_map *scat = (*SI)->getScattering();
      isl_map *projected = isl_map_project_out(scat, isl_dim_out, lastLoop,
                                               scatterDims - lastLoop);

      if (!isl_map_is_bijective(projected)) {
        isSingleValued = false;
        break;
      }
    }

    if (!isSingleValued)
      break;

    lastLoop--;
  }

  // Strip mine the innermost loop.
  for (Scop::iterator SI = S.begin(), SE = S.end(); SI != SE; ++SI) {
    isl_map *scat = (*SI)->getScattering();
    int scatDims = (*SI)->getNumScattering();
    isl_space *Space = isl_space_alloc(S.getIslCtx(), S.getNumParams(),
                                       scatDims, scatDims + 1);
    isl_basic_map *map = isl_basic_map_universe(isl_space_copy(Space));
    isl_local_space *LSpace = isl_local_space_from_space(Space);

    for (int i = 0; i <= lastLoop - 1; i++) {
      isl_constraint *c = isl_equality_alloc(isl_local_space_copy(LSpace));

      isl_constraint_set_coefficient_si(c, isl_dim_in, i, 1);
      isl_constraint_set_coefficient_si(c, isl_dim_out, i, -1);

      map = isl_basic_map_add_constraint(map, c);
    }

    for (int i = lastLoop; i < scatDims; i++) {
      isl_constraint *c = isl_equality_alloc(isl_local_space_copy(LSpace));

      isl_constraint_set_coefficient_si(c, isl_dim_in, i, 1);
      isl_constraint_set_coefficient_si(c, isl_dim_out, i + 1, -1);

      map = isl_basic_map_add_constraint(map, c);
    }

    isl_constraint *c;

    int vectorWidth = 4;
    c = isl_inequality_alloc(isl_local_space_copy(LSpace));
    isl_constraint_set_coefficient_si(c, isl_dim_out, lastLoop, -vectorWidth);
    isl_constraint_set_coefficient_si(c, isl_dim_out, lastLoop + 1, 1);
    map = isl_basic_map_add_constraint(map, c);

    c = isl_inequality_alloc(LSpace);
    isl_constraint_set_coefficient_si(c, isl_dim_out, lastLoop, vectorWidth);
    isl_constraint_set_coefficient_si(c, isl_dim_out, lastLoop + 1, -1);
    isl_constraint_set_constant_si(c, vectorWidth - 1);
    map = isl_basic_map_add_constraint(map, c);

    isl_map *transform = isl_map_from_basic_map(map);
    transform = isl_map_set_tuple_name(transform, isl_dim_out, "scattering");
    transform = isl_map_set_tuple_name(transform, isl_dim_in, "scattering");

    scat = isl_map_apply_range(scat, isl_map_copy(transform));
    (*SI)->setScattering(scat);
  }

  return false;
}