Add initial version of Polly

This version is equivalent to commit ba26ebece8f5be84e9bd6315611d412af797147e
in the old git repository.

llvm-svn: 130476
diff --git a/polly/lib/CodeGeneration.cpp b/polly/lib/CodeGeneration.cpp
new file mode 100644
index 0000000..c4e524f
--- /dev/null
+++ b/polly/lib/CodeGeneration.cpp
@@ -0,0 +1,1497 @@
+//===------ CodeGeneration.cpp - Code generate the Scops. -----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The CodeGeneration pass takes a Scop created by ScopInfo and translates it
+// back to LLVM-IR using Cloog.
+//
+// The Scop describes the high level memory behaviour of a control flow region.
+// Transformation passes can update the schedule (execution order) of statements
+// in the Scop. Cloog is used to generate an abstract syntax tree (clast) that
+// reflects the updated execution order. This clast is used to create new
+// LLVM-IR that is computational equivalent to the original control flow region,
+// but executes its code in the new execution order defined by the changed
+// scattering.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "polly-codegen"
+
+#include "polly/LinkAllPasses.h"
+#include "polly/Support/GICHelper.h"
+#include "polly/Support/ScopHelper.h"
+#include "polly/Cloog.h"
+#include "polly/Dependences.h"
+#include "polly/ScopInfo.h"
+#include "polly/TempScopInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/IRBuilder.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Module.h"
+#include "llvm/ADT/SetVector.h"
+
+#define CLOOG_INT_GMP 1
+#include "cloog/cloog.h"
+#include "cloog/isl/cloog.h"
+
+#include <vector>
+#include <utility>
+
+using namespace polly;
+using namespace llvm;
+
+struct isl_set;
+
+namespace polly {
+
+static cl::opt<bool>
+Vector("enable-polly-vector",
+       cl::desc("Enable polly vector code generation"), cl::Hidden,
+       cl::value_desc("Vector code generation enabled if true"),
+       cl::init(false));
+
+static cl::opt<bool>
+OpenMP("enable-polly-openmp",
+       cl::desc("Generate OpenMP parallel code"), cl::Hidden,
+       cl::value_desc("OpenMP code generation enabled if true"),
+       cl::init(false));
+
+static cl::opt<bool>
+AtLeastOnce("enable-polly-atLeastOnce",
+       cl::desc("Give polly the hint, that every loop is executed at least"
+                "once"), cl::Hidden,
+       cl::value_desc("OpenMP code generation enabled if true"),
+       cl::init(false));
+
+static cl::opt<bool>
+Aligned("enable-polly-aligned",
+       cl::desc("Assumed aligned memory accesses."), cl::Hidden,
+       cl::value_desc("OpenMP code generation enabled if true"),
+       cl::init(false));
+
+static cl::opt<std::string>
+CodegenOnly("polly-codegen-only",
+            cl::desc("Codegen only this function"), cl::Hidden,
+            cl::value_desc("The function name to codegen"),
+            cl::ValueRequired, cl::init(""));
+
+typedef DenseMap<const Value*, Value*> ValueMapT;
+typedef DenseMap<const char*, Value*> CharMapT;
+typedef std::vector<ValueMapT> VectorValueMapT;
+
+// Create a new loop.
+//
+// @param Builder The builder used to create the loop.  It also defines the
+//                place where to create the loop.
+// @param UB      The upper bound of the loop iv.
+// @param Stride  The number by which the loop iv is incremented after every
+//                iteration.
+static void createLoop(IRBuilder<> *Builder, Value *LB, Value *UB, APInt Stride,
+                PHINode*& IV, BasicBlock*& AfterBB, Value*& IncrementedIV,
+                DominatorTree *DT) {
+  Function *F = Builder->GetInsertBlock()->getParent();
+  LLVMContext &Context = F->getContext();
+
+  BasicBlock *PreheaderBB = Builder->GetInsertBlock();
+  BasicBlock *HeaderBB = BasicBlock::Create(Context, "polly.loop_header", F);
+  BasicBlock *BodyBB = BasicBlock::Create(Context, "polly.loop_body", F);
+  AfterBB = BasicBlock::Create(Context, "polly.after_loop", F);
+
+  Builder->CreateBr(HeaderBB);
+  DT->addNewBlock(HeaderBB, PreheaderBB);
+
+  Builder->SetInsertPoint(BodyBB);
+
+  Builder->SetInsertPoint(HeaderBB);
+
+  // Use the type of upper and lower bound.
+  assert(LB->getType() == UB->getType()
+         && "Different types for upper and lower bound.");
+
+  const IntegerType *LoopIVType = dyn_cast<IntegerType>(UB->getType());
+  assert(LoopIVType && "UB is not integer?");
+
+  // IV
+  IV = Builder->CreatePHI(LoopIVType, 2, "polly.loopiv");
+  IV->addIncoming(LB, PreheaderBB);
+
+  // IV increment.
+  Value *StrideValue = ConstantInt::get(LoopIVType,
+                                        Stride.zext(LoopIVType->getBitWidth()));
+  IncrementedIV = Builder->CreateAdd(IV, StrideValue, "polly.next_loopiv");
+
+  // Exit condition.
+  if (AtLeastOnce) { // At least on iteration.
+    UB = Builder->CreateAdd(UB, Builder->getInt64(1));
+    Value *CMP = Builder->CreateICmpEQ(IV, UB);
+    Builder->CreateCondBr(CMP, AfterBB, BodyBB);
+  } else { // Maybe not executed at all.
+    Value *CMP = Builder->CreateICmpSLE(IV, UB);
+    Builder->CreateCondBr(CMP, BodyBB, AfterBB);
+  }
+  DT->addNewBlock(BodyBB, HeaderBB);
+  DT->addNewBlock(AfterBB, HeaderBB);
+
+  Builder->SetInsertPoint(BodyBB);
+}
+
+class BlockGenerator {
+  IRBuilder<> &Builder;
+  ValueMapT &VMap;
+  VectorValueMapT &ValueMaps;
+  Scop &S;
+  ScopStmt &statement;
+  isl_set *scatteringDomain;
+
+public:
+  BlockGenerator(IRBuilder<> &B, ValueMapT &vmap, VectorValueMapT &vmaps,
+                 ScopStmt &Stmt, isl_set *domain)
+    : Builder(B), VMap(vmap), ValueMaps(vmaps), S(*Stmt.getParent()),
+    statement(Stmt), scatteringDomain(domain) {}
+
+  const Region &getRegion() {
+    return S.getRegion();
+  }
+
+  Value* makeVectorOperand(Value *operand, int vectorWidth) {
+    if (operand->getType()->isVectorTy())
+      return operand;
+
+    VectorType *vectorType = VectorType::get(operand->getType(), vectorWidth);
+    Value *vector = UndefValue::get(vectorType);
+    vector = Builder.CreateInsertElement(vector, operand, Builder.getInt32(0));
+
+    std::vector<Constant*> splat;
+
+    for (int i = 0; i < vectorWidth; i++)
+      splat.push_back (Builder.getInt32(0));
+
+    Constant *splatVector = ConstantVector::get(splat);
+
+    return Builder.CreateShuffleVector(vector, vector, splatVector);
+  }
+
+  Value* getOperand(const Value *OldOperand, ValueMapT &BBMap,
+                    ValueMapT *VectorMap = 0) {
+    const Instruction *OpInst = dyn_cast<Instruction>(OldOperand);
+
+    if (!OpInst)
+      return const_cast<Value*>(OldOperand);
+
+    if (VectorMap && VectorMap->count(OldOperand))
+      return (*VectorMap)[OldOperand];
+
+    // IVS and Parameters.
+    if (VMap.count(OldOperand)) {
+      Value *NewOperand = VMap[OldOperand];
+
+      // Insert a cast if types are different
+      if (OldOperand->getType()->getScalarSizeInBits()
+          < NewOperand->getType()->getScalarSizeInBits())
+        NewOperand = Builder.CreateTruncOrBitCast(NewOperand,
+                                                   OldOperand->getType());
+
+      return NewOperand;
+    }
+
+    // Instructions calculated in the current BB.
+    if (BBMap.count(OldOperand)) {
+      return BBMap[OldOperand];
+    }
+
+    // Ignore instructions that are referencing ops in the old BB. These
+    // instructions are unused. They where replace by new ones during
+    // createIndependentBlocks().
+    if (getRegion().contains(OpInst->getParent()))
+      return NULL;
+
+    return const_cast<Value*>(OldOperand);
+  }
+
+  const Type *getVectorPtrTy(const Value *V, int vectorWidth) {
+    const PointerType *pointerType = dyn_cast<PointerType>(V->getType());
+    assert(pointerType && "PointerType expected");
+
+    const Type *scalarType = pointerType->getElementType();
+    VectorType *vectorType = VectorType::get(scalarType, vectorWidth);
+
+    return PointerType::getUnqual(vectorType);
+  }
+
+  /// @brief Load a vector from a set of adjacent scalars
+  ///
+  /// In case a set of scalars is known to be next to each other in memory,
+  /// create a vector load that loads those scalars
+  ///
+  /// %vector_ptr= bitcast double* %p to <4 x double>*
+  /// %vec_full = load <4 x double>* %vector_ptr
+  ///
+  Value *generateStrideOneLoad(const LoadInst *load, ValueMapT &BBMap,
+                               int size) {
+    const Value *pointer = load->getPointerOperand();
+    const Type *vectorPtrType = getVectorPtrTy(pointer, size);
+    Value *newPointer = getOperand(pointer, BBMap);
+    Value *VectorPtr = Builder.CreateBitCast(newPointer, vectorPtrType,
+                                             "vector_ptr");
+    LoadInst *VecLoad = Builder.CreateLoad(VectorPtr,
+                                        load->getNameStr()
+                                        + "_p_vec_full");
+    if (!Aligned)
+      VecLoad->setAlignment(8);
+
+    return VecLoad;
+  }
+
+  /// @brief Load a vector initialized from a single scalar in memory
+  ///
+  /// In case all elements of a vector are initialized to the same
+  /// scalar value, this value is loaded and shuffeled into all elements
+  /// of the vector.
+  ///
+  /// %splat_one = load <1 x double>* %p
+  /// %splat = shufflevector <1 x double> %splat_one, <1 x
+  ///       double> %splat_one, <4 x i32> zeroinitializer
+  ///
+  Value *generateStrideZeroLoad(const LoadInst *load, ValueMapT &BBMap,
+                                int size) {
+    const Value *pointer = load->getPointerOperand();
+    const Type *vectorPtrType = getVectorPtrTy(pointer, 1);
+    Value *newPointer = getOperand(pointer, BBMap);
+    Value *vectorPtr = Builder.CreateBitCast(newPointer, vectorPtrType,
+                                             load->getNameStr() + "_p_vec_p");
+    LoadInst *scalarLoad= Builder.CreateLoad(vectorPtr,
+                                          load->getNameStr() + "_p_splat_one");
+
+    if (!Aligned)
+      scalarLoad->setAlignment(8);
+
+    std::vector<Constant*> splat;
+
+    for (int i = 0; i < size; i++)
+      splat.push_back (Builder.getInt32(0));
+
+    Constant *splatVector = ConstantVector::get(splat);
+
+    Value *vectorLoad = Builder.CreateShuffleVector(scalarLoad, scalarLoad,
+                                                    splatVector,
+                                                    load->getNameStr()
+                                                    + "_p_splat");
+    return vectorLoad;
+  }
+
+  /// @Load a vector from scalars distributed in memory
+  ///
+  /// In case some scalars a distributed randomly in memory. Create a vector
+  /// by loading each scalar and by inserting one after the other into the
+  /// vector.
+  ///
+  /// %scalar_1= load double* %p_1
+  /// %vec_1 = insertelement <2 x double> undef, double %scalar_1, i32 0
+  /// %scalar 2 = load double* %p_2
+  /// %vec_2 = insertelement <2 x double> %vec_1, double %scalar_1, i32 1
+  ///
+  Value *generateUnknownStrideLoad(const LoadInst *load,
+                                   VectorValueMapT &scalarMaps,
+                                   int size) {
+    const Value *pointer = load->getPointerOperand();
+    VectorType *vectorType = VectorType::get(
+      dyn_cast<PointerType>(pointer->getType())->getElementType(), size);
+
+    Value *vector = UndefValue::get(vectorType);
+
+    for (int i = 0; i < size; i++) {
+      Value *newPointer = getOperand(pointer, scalarMaps[i]);
+      Value *scalarLoad = Builder.CreateLoad(newPointer,
+                                             load->getNameStr() + "_p_scalar_");
+      vector = Builder.CreateInsertElement(vector, scalarLoad,
+                                           Builder.getInt32(i),
+                                           load->getNameStr() + "_p_vec_");
+    }
+
+    return vector;
+  }
+
+  Value *generateScalarLoad(const LoadInst *load, ValueMapT &BBMap) {
+    const Value *pointer = load->getPointerOperand();
+    Value *newPointer = getOperand(pointer, BBMap);
+    Value *scalarLoad = Builder.CreateLoad(newPointer,
+                                           load->getNameStr() + "_p_scalar_");
+    return scalarLoad;
+  }
+
+  /// @brief Load a value (or several values as a vector) from memory.
+  void generateLoad(const LoadInst *load, ValueMapT &vectorMap,
+                    VectorValueMapT &scalarMaps, int vectorWidth) {
+
+    if (scalarMaps.size() == 1) {
+      scalarMaps[0][load] = generateScalarLoad(load, scalarMaps[0]);
+      return;
+    }
+
+    Value *newLoad;
+
+    MemoryAccess &Access = statement.getAccessFor(load);
+
+    assert(scatteringDomain && "No scattering domain available");
+
+    if (Access.isStrideZero(scatteringDomain))
+      newLoad = generateStrideZeroLoad(load, scalarMaps[0], vectorWidth);
+    else if (Access.isStrideOne(scatteringDomain))
+      newLoad = generateStrideOneLoad(load, scalarMaps[0], vectorWidth);
+    else
+      newLoad = generateUnknownStrideLoad(load, scalarMaps, vectorWidth);
+
+    vectorMap[load] = newLoad;
+  }
+
+  void copyInstruction(const Instruction *Inst, ValueMapT &BBMap,
+                       ValueMapT &vectorMap, VectorValueMapT &scalarMaps,
+                       int vectorDimension, int vectorWidth) {
+    // If this instruction is already in the vectorMap, a vector instruction
+    // was already issued, that calculates the values of all dimensions. No
+    // need to create any more instructions.
+    if (vectorMap.count(Inst))
+      return;
+
+    // Terminator instructions control the control flow. They are explicitally
+    // expressed in the clast and do not need to be copied.
+    if (Inst->isTerminator())
+      return;
+
+    if (const LoadInst *load = dyn_cast<LoadInst>(Inst)) {
+      generateLoad(load, vectorMap, scalarMaps, vectorWidth);
+      return;
+    }
+
+    if (const BinaryOperator *binaryInst = dyn_cast<BinaryOperator>(Inst)) {
+      Value *opZero = Inst->getOperand(0);
+      Value *opOne = Inst->getOperand(1);
+
+      // This is an old instruction that can be ignored.
+      if (!opZero && !opOne)
+        return;
+
+      bool isVectorOp = vectorMap.count(opZero) || vectorMap.count(opOne);
+
+      if (isVectorOp && vectorDimension > 0)
+        return;
+
+      Value *newOpZero, *newOpOne;
+      newOpZero = getOperand(opZero, BBMap, &vectorMap);
+      newOpOne = getOperand(opOne, BBMap, &vectorMap);
+
+
+      std::string name;
+      if (isVectorOp) {
+        newOpZero = makeVectorOperand(newOpZero, vectorWidth);
+        newOpOne = makeVectorOperand(newOpOne, vectorWidth);
+        name =  Inst->getNameStr() + "p_vec";
+      } else
+        name = Inst->getNameStr() + "p_sca";
+
+      Value *newInst = Builder.CreateBinOp(binaryInst->getOpcode(), newOpZero,
+                                           newOpOne, name);
+      if (isVectorOp)
+        vectorMap[Inst] = newInst;
+      else
+        BBMap[Inst] = newInst;
+
+      return;
+    }
+
+    if (const StoreInst *store = dyn_cast<StoreInst>(Inst)) {
+      if (vectorMap.count(store->getValueOperand()) > 0) {
+
+        // We only need to generate one store if we are in vector mode.
+        if (vectorDimension > 0)
+          return;
+
+        MemoryAccess &Access = statement.getAccessFor(store);
+
+        assert(scatteringDomain && "No scattering domain available");
+
+        const Value *pointer = store->getPointerOperand();
+        Value *vector = getOperand(store->getValueOperand(), BBMap, &vectorMap);
+
+        if (Access.isStrideOne(scatteringDomain)) {
+          const Type *vectorPtrType = getVectorPtrTy(pointer, vectorWidth);
+          Value *newPointer = getOperand(pointer, BBMap, &vectorMap);
+
+          Value *VectorPtr = Builder.CreateBitCast(newPointer, vectorPtrType,
+                                                   "vector_ptr");
+          StoreInst *Store = Builder.CreateStore(vector, VectorPtr);
+
+          if (!Aligned)
+            Store->setAlignment(8);
+        } else {
+          for (unsigned i = 0; i < scalarMaps.size(); i++) {
+            Value *scalar = Builder.CreateExtractElement(vector,
+                                                         Builder.getInt32(i));
+            Value *newPointer = getOperand(pointer, scalarMaps[i]);
+            Builder.CreateStore(scalar, newPointer);
+          }
+        }
+
+        return;
+      }
+    }
+
+    Instruction *NewInst = Inst->clone();
+
+    // Copy the operands in temporary vector, as an in place update
+    // fails if an instruction is referencing the same operand twice.
+    std::vector<Value*> Operands(NewInst->op_begin(), NewInst->op_end());
+
+    // Replace old operands with the new ones.
+    for (std::vector<Value*>::iterator UI = Operands.begin(),
+         UE = Operands.end(); UI != UE; ++UI) {
+      Value *newOperand = getOperand(*UI, BBMap);
+
+      if (!newOperand) {
+        assert(!isa<StoreInst>(NewInst)
+               && "Store instructions are always needed!");
+        delete NewInst;
+        return;
+      }
+
+      NewInst->replaceUsesOfWith(*UI, newOperand);
+    }
+
+    Builder.Insert(NewInst);
+    BBMap[Inst] = NewInst;
+
+    if (!NewInst->getType()->isVoidTy())
+      NewInst->setName("p_" + Inst->getName());
+  }
+
+  int getVectorSize() {
+    return ValueMaps.size();
+  }
+
+  bool isVectorBlock() {
+    return getVectorSize() > 1;
+  }
+
+  // Insert a copy of a basic block in the newly generated code.
+  //
+  // @param Builder The builder used to insert the code. It also specifies
+  //                where to insert the code.
+  // @param BB      The basic block to copy
+  // @param VMap    A map returning for any old value its new equivalent. This
+  //                is used to update the operands of the statements.
+  //                For new statements a relation old->new is inserted in this
+  //                map.
+  void copyBB(BasicBlock *BB, DominatorTree *DT) {
+    Function *F = Builder.GetInsertBlock()->getParent();
+    LLVMContext &Context = F->getContext();
+    BasicBlock *CopyBB = BasicBlock::Create(Context,
+                                            "polly.stmt_" + BB->getNameStr(),
+                                            F);
+    Builder.CreateBr(CopyBB);
+    DT->addNewBlock(CopyBB, Builder.GetInsertBlock());
+    Builder.SetInsertPoint(CopyBB);
+
+    // Create two maps that store the mapping from the original instructions of
+    // the old basic block to their copies in the new basic block. Those maps
+    // are basic block local.
+    //
+    // As vector code generation is supported there is one map for scalar values
+    // and one for vector values.
+    //
+    // In case we just do scalar code generation, the vectorMap is not used and
+    // the scalarMap has just one dimension, which contains the mapping.
+    //
+    // In case vector code generation is done, an instruction may either appear
+    // in the vector map once (as it is calculating >vectorwidth< values at a
+    // time. Or (if the values are calculated using scalar operations), it
+    // appears once in every dimension of the scalarMap.
+    VectorValueMapT scalarBlockMap(getVectorSize());
+    ValueMapT vectorBlockMap;
+
+    for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
+         II != IE; ++II)
+      for (int i = 0; i < getVectorSize(); i++) {
+        if (isVectorBlock())
+          VMap = ValueMaps[i];
+
+        copyInstruction(II, scalarBlockMap[i], vectorBlockMap,
+                        scalarBlockMap, i, getVectorSize());
+      }
+  }
+};
+
+/// Class to generate LLVM-IR that calculates the value of a clast_expr.
+class ClastExpCodeGen {
+  IRBuilder<> &Builder;
+  const CharMapT *IVS;
+
+  Value *codegen(const clast_name *e, const Type *Ty) {
+    CharMapT::const_iterator I = IVS->find(e->name);
+
+    if (I != IVS->end())
+      return Builder.CreateSExtOrBitCast(I->second, Ty);
+    else
+      llvm_unreachable("Clast name not found");
+  }
+
+  Value *codegen(const clast_term *e, const Type *Ty) {
+    APInt a = APInt_from_MPZ(e->val);
+
+    Value *ConstOne = ConstantInt::get(Builder.getContext(), a);
+    ConstOne = Builder.CreateSExtOrBitCast(ConstOne, Ty);
+
+    if (e->var) {
+      Value *var = codegen(e->var, Ty);
+      return Builder.CreateMul(ConstOne, var);
+    }
+
+    return ConstOne;
+  }
+
+  Value *codegen(const clast_binary *e, const Type *Ty) {
+    Value *LHS = codegen(e->LHS, Ty);
+
+    APInt RHS_AP = APInt_from_MPZ(e->RHS);
+
+    Value *RHS = ConstantInt::get(Builder.getContext(), RHS_AP);
+    RHS = Builder.CreateSExtOrBitCast(RHS, Ty);
+
+    switch (e->type) {
+    case clast_bin_mod:
+      return Builder.CreateSRem(LHS, RHS);
+    case clast_bin_fdiv:
+      {
+        // floord(n,d) ((n < 0) ? (n - d + 1) : n) / d
+        Value *One = ConstantInt::get(Builder.getInt1Ty(), 1);
+        Value *Zero = ConstantInt::get(Builder.getInt1Ty(), 0);
+        One = Builder.CreateZExtOrBitCast(One, Ty);
+        Zero = Builder.CreateZExtOrBitCast(Zero, Ty);
+        Value *Sum1 = Builder.CreateSub(LHS, RHS);
+        Value *Sum2 = Builder.CreateAdd(Sum1, One);
+        Value *isNegative = Builder.CreateICmpSLT(LHS, Zero);
+        Value *Dividend = Builder.CreateSelect(isNegative, Sum2, LHS);
+        return Builder.CreateSDiv(Dividend, RHS);
+      }
+    case clast_bin_cdiv:
+      {
+        // ceild(n,d) ((n < 0) ? n : (n + d - 1)) / d
+        Value *One = ConstantInt::get(Builder.getInt1Ty(), 1);
+        Value *Zero = ConstantInt::get(Builder.getInt1Ty(), 0);
+        One = Builder.CreateZExtOrBitCast(One, Ty);
+        Zero = Builder.CreateZExtOrBitCast(Zero, Ty);
+        Value *Sum1 = Builder.CreateAdd(LHS, RHS);
+        Value *Sum2 = Builder.CreateSub(Sum1, One);
+        Value *isNegative = Builder.CreateICmpSLT(LHS, Zero);
+        Value *Dividend = Builder.CreateSelect(isNegative, LHS, Sum2);
+        return Builder.CreateSDiv(Dividend, RHS);
+      }
+    case clast_bin_div:
+      return Builder.CreateSDiv(LHS, RHS);
+    default:
+      llvm_unreachable("Unknown clast binary expression type");
+    };
+  }
+
+  Value *codegen(const clast_reduction *r, const Type *Ty) {
+    assert((   r->type == clast_red_min
+            || r->type == clast_red_max
+            || r->type == clast_red_sum)
+           && "Clast reduction type not supported");
+    Value *old = codegen(r->elts[0], Ty);
+
+    for (int i=1; i < r->n; ++i) {
+      Value *exprValue = codegen(r->elts[i], Ty);
+
+      switch (r->type) {
+      case clast_red_min:
+        {
+          Value *cmp = Builder.CreateICmpSLT(old, exprValue);
+          old = Builder.CreateSelect(cmp, old, exprValue);
+          break;
+        }
+      case clast_red_max:
+        {
+          Value *cmp = Builder.CreateICmpSGT(old, exprValue);
+          old = Builder.CreateSelect(cmp, old, exprValue);
+          break;
+        }
+      case clast_red_sum:
+        old = Builder.CreateAdd(old, exprValue);
+        break;
+      default:
+        llvm_unreachable("Clast unknown reduction type");
+      }
+    }
+
+    return old;
+  }
+
+public:
+
+  // A generator for clast expressions.
+  //
+  // @param B The IRBuilder that defines where the code to calculate the
+  //          clast expressions should be inserted.
+  // @param IVMAP A Map that translates strings describing the induction
+  //              variables to the Values* that represent these variables
+  //              on the LLVM side.
+  ClastExpCodeGen(IRBuilder<> &B, CharMapT *IVMap) : Builder(B), IVS(IVMap) {}
+
+  // Generates code to calculate a given clast expression.
+  //
+  // @param e The expression to calculate.
+  // @return The Value that holds the result.
+  Value *codegen(const clast_expr *e, const Type *Ty) {
+    switch(e->type) {
+      case clast_expr_name:
+	return codegen((const clast_name *)e, Ty);
+      case clast_expr_term:
+	return codegen((const clast_term *)e, Ty);
+      case clast_expr_bin:
+	return codegen((const clast_binary *)e, Ty);
+      case clast_expr_red:
+	return codegen((const clast_reduction *)e, Ty);
+      default:
+        llvm_unreachable("Unknown clast expression!");
+    }
+  }
+
+  // @brief Reset the CharMap.
+  //
+  // This function is called to reset the CharMap to new one, while generating
+  // OpenMP code.
+  void setIVS(CharMapT *IVSNew) {
+    IVS = IVSNew;
+  }
+
+};
+
+class ClastStmtCodeGen {
+  // The Scop we code generate.
+  Scop *S;
+  ScalarEvolution &SE;
+
+  DominatorTree *DT;
+  Dependences *DP;
+  TargetData *TD;
+
+  // The Builder specifies the current location to code generate at.
+  IRBuilder<> &Builder;
+
+  // Map the Values from the old code to their counterparts in the new code.
+  ValueMapT ValueMap;
+
+  // clastVars maps from the textual representation of a clast variable to its
+  // current *Value. clast variables are scheduling variables, original
+  // induction variables or parameters. They are used either in loop bounds or
+  // to define the statement instance that is executed.
+  //
+  //   for (s = 0; s < n + 3; ++i)
+  //     for (t = s; t < m; ++j)
+  //       Stmt(i = s + 3 * m, j = t);
+  //
+  // {s,t,i,j,n,m} is the set of clast variables in this clast.
+  CharMapT *clastVars;
+
+  // Codegenerator for clast expressions.
+  ClastExpCodeGen ExpGen;
+
+  // Do we currently generate parallel code?
+  bool parallelCodeGeneration;
+
+  std::vector<std::string> parallelLoops;
+
+public:
+
+  const std::vector<std::string> &getParallelLoops() {
+    return parallelLoops;
+  }
+
+  protected:
+  void codegen(const clast_assignment *a) {
+    (*clastVars)[a->LHS] = ExpGen.codegen(a->RHS,
+      TD->getIntPtrType(Builder.getContext()));
+  }
+
+  void codegen(const clast_assignment *a, ScopStmt *Statement,
+               unsigned Dimension, int vectorDim,
+               std::vector<ValueMapT> *VectorVMap = 0) {
+    Value *RHS = ExpGen.codegen(a->RHS,
+      TD->getIntPtrType(Builder.getContext()));
+
+    assert(!a->LHS && "Statement assignments do not have left hand side");
+    const PHINode *PN;
+    PN = Statement->getInductionVariableForDimension(Dimension);
+    const Value *V = PN;
+
+    if (PN->getNumOperands() == 2)
+      V = *(PN->use_begin());
+
+    if (VectorVMap)
+      (*VectorVMap)[vectorDim][V] = RHS;
+
+    ValueMap[V] = RHS;
+  }
+
+  void codegenSubstitutions(const clast_stmt *Assignment,
+                            ScopStmt *Statement, int vectorDim = 0,
+                            std::vector<ValueMapT> *VectorVMap = 0) {
+    int Dimension = 0;
+
+    while (Assignment) {
+      assert(CLAST_STMT_IS_A(Assignment, stmt_ass)
+             && "Substitions are expected to be assignments");
+      codegen((const clast_assignment *)Assignment, Statement, Dimension,
+              vectorDim, VectorVMap);
+      Assignment = Assignment->next;
+      Dimension++;
+    }
+  }
+
+  void codegen(const clast_user_stmt *u, std::vector<Value*> *IVS = NULL,
+               const char *iterator = NULL, isl_set *scatteringDomain = 0) {
+    ScopStmt *Statement = (ScopStmt *)u->statement->usr;
+    BasicBlock *BB = Statement->getBasicBlock();
+
+    if (u->substitutions)
+      codegenSubstitutions(u->substitutions, Statement);
+
+    int vectorDimensions = IVS ? IVS->size() : 1;
+
+    VectorValueMapT VectorValueMap(vectorDimensions);
+
+    if (IVS) {
+      assert (u->substitutions && "Substitutions expected!");
+      int i = 0;
+      for (std::vector<Value*>::iterator II = IVS->begin(), IE = IVS->end();
+           II != IE; ++II) {
+        (*clastVars)[iterator] = *II;
+        codegenSubstitutions(u->substitutions, Statement, i, &VectorValueMap);
+        i++;
+      }
+    }
+
+    BlockGenerator Generator(Builder, ValueMap, VectorValueMap, *Statement,
+                             scatteringDomain);
+    Generator.copyBB(BB, DT);
+  }
+
+  void codegen(const clast_block *b) {
+    if (b->body)
+      codegen(b->body);
+  }
+
+  /// @brief Create a classical sequential loop.
+  void codegenForSequential(const clast_for *f, Value *lowerBound = 0,
+                                                Value *upperBound = 0) {
+    APInt Stride = APInt_from_MPZ(f->stride);
+    PHINode *IV;
+    Value *IncrementedIV;
+    BasicBlock *AfterBB;
+    // The value of lowerbound and upperbound will be supplied, if this
+    // function is called while generating OpenMP code. Otherwise get
+    // the values.
+    assert(((lowerBound && upperBound) || (!lowerBound && !upperBound))
+                                && "Either give both bounds or none");
+    if (lowerBound == 0 || upperBound == 0) {
+        lowerBound = ExpGen.codegen(f->LB,
+                                    TD->getIntPtrType(Builder.getContext()));
+        upperBound = ExpGen.codegen(f->UB,
+                                    TD->getIntPtrType(Builder.getContext()));
+    }
+    createLoop(&Builder, lowerBound, upperBound, Stride, IV, AfterBB,
+               IncrementedIV, DT);
+
+    // Add loop iv to symbols.
+    (*clastVars)[f->iterator] = IV;
+
+    if (f->body)
+      codegen(f->body);
+
+    // Loop is finished, so remove its iv from the live symbols.
+    clastVars->erase(f->iterator);
+
+    BasicBlock *HeaderBB = *pred_begin(AfterBB);
+    BasicBlock *LastBodyBB = Builder.GetInsertBlock();
+    Builder.CreateBr(HeaderBB);
+    IV->addIncoming(IncrementedIV, LastBodyBB);
+    Builder.SetInsertPoint(AfterBB);
+  }
+
+  /// @brief Check if a loop is parallel
+  ///
+  /// Detect if a clast_for loop can be executed in parallel.
+  ///
+  /// @param f The clast for loop to check.
+  bool isParallelFor(const clast_for *f) {
+    isl_set *loopDomain = isl_set_from_cloog_domain(f->domain);
+    assert(loopDomain && "Cannot access domain of loop");
+
+    bool isParallel = DP->isParallelDimension(loopDomain,
+                                              isl_set_n_dim(loopDomain));
+
+    if (isParallel)
+      DEBUG(dbgs() << "Parallel loop with induction variable '" << f->iterator
+            << "' found\n";);
+
+    return isParallel;
+  }
+
+  /// @brief Add a new definition of an openmp subfunction.
+  Function* addOpenMPSubfunction(Module *M) {
+    Function *F = Builder.GetInsertBlock()->getParent();
+    const std::string &Name = F->getNameStr() + ".omp_subfn";
+
+    std::vector<const Type*> Arguments(1, Builder.getInt8PtrTy());
+    FunctionType *FT = FunctionType::get(Builder.getVoidTy(), Arguments, false);
+    Function *FN = Function::Create(FT, Function::InternalLinkage, Name, M);
+
+    Function::arg_iterator AI = FN->arg_begin();
+    AI->setName("omp.userContext");
+
+    return FN;
+  }
+
+  /// @brief Add values to the OpenMP structure.
+  ///
+  /// Create the subfunction structure and add the values from the list.
+  Value *addValuesToOpenMPStruct(SetVector<Value*> OMPDataVals,
+                                 Function *SubFunction) {
+    Module *M = Builder.GetInsertBlock()->getParent()->getParent();
+    std::vector<const Type*> structMembers;
+
+    // Create the structure.
+    for (unsigned i = 0; i < OMPDataVals.size(); i++)
+      structMembers.push_back(OMPDataVals[i]->getType());
+
+    const std::string &Name = SubFunction->getNameStr() + ".omp.userContext";
+    StructType *structTy = StructType::get(Builder.getContext(),
+                                           structMembers);
+    M->addTypeName(Name, structTy);
+
+    // Store the values into the structure.
+    Value *structData = Builder.CreateAlloca(structTy, 0, "omp.userContext");
+    for (unsigned i = 0; i < OMPDataVals.size(); i++) {
+      Value *storeAddr = Builder.CreateStructGEP(structData, i);
+      Builder.CreateStore(OMPDataVals[i], storeAddr);
+    }
+
+    return structData;
+  }
+
+  /// @brief Create OpenMP structure values.
+  ///
+  /// Create a list of values that has to be stored into the subfuncition
+  /// structure.
+  SetVector<Value*> createOpenMPStructValues() {
+    SetVector<Value*> OMPDataVals;
+
+    // Push the clast variables available in the clastVars.
+    for (CharMapT::iterator I = clastVars->begin(), E = clastVars->end();
+         I != E; I++)
+     OMPDataVals.insert(I->second);
+
+    // Push the base addresses of memory references.
+    for (Scop::iterator SI = S->begin(), SE = S->end(); SI != SE; ++SI) {
+      ScopStmt *Stmt = *SI;
+      for (SmallVector<MemoryAccess*, 8>::iterator I = Stmt->memacc_begin(),
+           E = Stmt->memacc_end(); I != E; ++I) {
+        Value *BaseAddr = const_cast<Value*>((*I)->getBaseAddr());
+        OMPDataVals.insert((BaseAddr));
+      }
+    }
+
+    return OMPDataVals;
+  }
+
+  /// @brief Extract the values from the subfunction parameter.
+  ///
+  /// Extract the values from the subfunction parameter and update the clast
+  /// variables to point to the new values.
+  void extractValuesFromOpenMPStruct(CharMapT *clastVarsOMP,
+                                     SetVector<Value*> OMPDataVals,
+                                     Value *userContext) {
+    // Extract the clast variables.
+    unsigned i = 0;
+    for (CharMapT::iterator I = clastVars->begin(), E = clastVars->end();
+         I != E; I++) {
+      Value *loadAddr = Builder.CreateStructGEP(userContext, i);
+      (*clastVarsOMP)[I->first] = Builder.CreateLoad(loadAddr);
+      i++;
+    }
+
+    // Extract the base addresses of memory references.
+    for (unsigned j = i; j < OMPDataVals.size(); j++) {
+      Value *loadAddr = Builder.CreateStructGEP(userContext, j);
+      Value *baseAddr = OMPDataVals[j];
+      ValueMap[baseAddr] = Builder.CreateLoad(loadAddr);
+    }
+
+  }
+
+  /// @brief Add body to the subfunction.
+  void addOpenMPSubfunctionBody(Function *FN, const clast_for *f,
+                                Value *structData,
+                                SetVector<Value*> OMPDataVals) {
+    Module *M = Builder.GetInsertBlock()->getParent()->getParent();
+    LLVMContext &Context = FN->getContext();
+    const IntegerType *intPtrTy = TD->getIntPtrType(Context);
+
+    // Store the previous basic block.
+    BasicBlock *PrevBB = Builder.GetInsertBlock();
+
+    // Create basic blocks.
+    BasicBlock *HeaderBB = BasicBlock::Create(Context, "omp.setup", FN);
+    BasicBlock *ExitBB = BasicBlock::Create(Context, "omp.exit", FN);
+    BasicBlock *checkNextBB = BasicBlock::Create(Context, "omp.checkNext", FN);
+    BasicBlock *loadIVBoundsBB = BasicBlock::Create(Context, "omp.loadIVBounds",
+                                                    FN);
+
+    DT->addNewBlock(HeaderBB, PrevBB);
+    DT->addNewBlock(ExitBB, HeaderBB);
+    DT->addNewBlock(checkNextBB, HeaderBB);
+    DT->addNewBlock(loadIVBoundsBB, HeaderBB);
+
+    // Fill up basic block HeaderBB.
+    Builder.SetInsertPoint(HeaderBB);
+    Value *lowerBoundPtr = Builder.CreateAlloca(intPtrTy, 0,
+                                                "omp.lowerBoundPtr");
+    Value *upperBoundPtr = Builder.CreateAlloca(intPtrTy, 0,
+                                                "omp.upperBoundPtr");
+    Value *userContext = Builder.CreateBitCast(FN->arg_begin(),
+                                               structData->getType(),
+                                               "omp.userContext");
+
+    CharMapT clastVarsOMP;
+    extractValuesFromOpenMPStruct(&clastVarsOMP, OMPDataVals, userContext);
+
+    Builder.CreateBr(checkNextBB);
+
+    // Add code to check if another set of iterations will be executed.
+    Builder.SetInsertPoint(checkNextBB);
+    Function *runtimeNextFunction = M->getFunction("GOMP_loop_runtime_next");
+    Value *ret1 = Builder.CreateCall2(runtimeNextFunction,
+                                      lowerBoundPtr, upperBoundPtr);
+    Value *hasNextSchedule = Builder.CreateTrunc(ret1, Builder.getInt1Ty(),
+                                                 "omp.hasNextScheduleBlock");
+    Builder.CreateCondBr(hasNextSchedule, loadIVBoundsBB, ExitBB);
+
+    // Add code to to load the iv bounds for this set of iterations.
+    Builder.SetInsertPoint(loadIVBoundsBB);
+    Value *lowerBound = Builder.CreateLoad(lowerBoundPtr, "omp.lowerBound");
+    Value *upperBound = Builder.CreateLoad(upperBoundPtr, "omp.upperBound");
+
+    // Subtract one as the upper bound provided by openmp is a < comparison
+    // whereas the codegenForSequential function creates a <= comparison.
+    upperBound = Builder.CreateSub(upperBound, ConstantInt::get(intPtrTy, 1),
+                                   "omp.upperBoundAdjusted");
+
+    // Use clastVarsOMP during code generation of the OpenMP subfunction.
+    CharMapT *oldClastVars = clastVars;
+    clastVars = &clastVarsOMP;
+    ExpGen.setIVS(&clastVarsOMP);
+
+    codegenForSequential(f, lowerBound, upperBound);
+
+    // Restore the old clastVars.
+    clastVars = oldClastVars;
+    ExpGen.setIVS(oldClastVars);
+
+    Builder.CreateBr(checkNextBB);
+
+    // Add code to terminate this openmp subfunction.
+    Builder.SetInsertPoint(ExitBB);
+    Function *endnowaitFunction = M->getFunction("GOMP_loop_end_nowait");
+    Builder.CreateCall(endnowaitFunction);
+    Builder.CreateRetVoid();
+
+    // Restore the builder back to previous basic block.
+    Builder.SetInsertPoint(PrevBB);
+  }
+
+  /// @brief Create an OpenMP parallel for loop.
+  ///
+  /// This loop reflects a loop as if it would have been created by an OpenMP
+  /// statement.
+  void codegenForOpenMP(const clast_for *f) {
+    Module *M = Builder.GetInsertBlock()->getParent()->getParent();
+    const IntegerType *intPtrTy = TD->getIntPtrType(Builder.getContext());
+
+    Function *SubFunction = addOpenMPSubfunction(M);
+    SetVector<Value*> OMPDataVals = createOpenMPStructValues();
+    Value *structData = addValuesToOpenMPStruct(OMPDataVals, SubFunction);
+
+    addOpenMPSubfunctionBody(SubFunction, f, structData, OMPDataVals);
+
+    // Create call for GOMP_parallel_loop_runtime_start.
+    Value *subfunctionParam = Builder.CreateBitCast(structData,
+                                                    Builder.getInt8PtrTy(),
+                                                    "omp_data");
+
+    Value *numberOfThreads = Builder.getInt32(0);
+    Value *lowerBound = ExpGen.codegen(f->LB, intPtrTy);
+    Value *upperBound = ExpGen.codegen(f->UB, intPtrTy);
+
+    // Add one as the upper bound provided by openmp is a < comparison
+    // whereas the codegenForSequential function creates a <= comparison.
+    upperBound = Builder.CreateAdd(upperBound, ConstantInt::get(intPtrTy, 1));
+    APInt APStride = APInt_from_MPZ(f->stride);
+    Value *stride = ConstantInt::get(intPtrTy,
+                                     APStride.zext(intPtrTy->getBitWidth()));
+
+    SmallVector<Value *, 6> Arguments;
+    Arguments.push_back(SubFunction);
+    Arguments.push_back(subfunctionParam);
+    Arguments.push_back(numberOfThreads);
+    Arguments.push_back(lowerBound);
+    Arguments.push_back(upperBound);
+    Arguments.push_back(stride);
+
+    Function *parallelStartFunction =
+      M->getFunction("GOMP_parallel_loop_runtime_start");
+    Builder.CreateCall(parallelStartFunction, Arguments.begin(),
+                       Arguments.end());
+
+    // Create call to the subfunction.
+    Builder.CreateCall(SubFunction, subfunctionParam);
+
+    // Create call for GOMP_parallel_end.
+    Function *FN = M->getFunction("GOMP_parallel_end");
+    Builder.CreateCall(FN);
+  }
+
+  bool isInnermostLoop(const clast_for *f) {
+    const clast_stmt *stmt = f->body;
+
+    while (stmt) {
+      if (!CLAST_STMT_IS_A(stmt, stmt_user))
+        return false;
+
+      stmt = stmt->next;
+    }
+
+    return true;
+  }
+
+  /// @brief Get the number of loop iterations for this loop.
+  /// @param f The clast for loop to check.
+  int getNumberOfIterations(const clast_for *f) {
+    isl_set *loopDomain = isl_set_copy(isl_set_from_cloog_domain(f->domain));
+    isl_set *tmp = isl_set_copy(loopDomain);
+
+    // Calculate a map similar to the identity map, but with the last input
+    // and output dimension not related.
+    //  [i0, i1, i2, i3] -> [i0, i1, i2, o0]
+    isl_dim *dim = isl_set_get_dim(loopDomain);
+    dim = isl_dim_drop_outputs(dim, isl_set_n_dim(loopDomain) - 2, 1);
+    dim = isl_dim_map_from_set(dim);
+    isl_map *identity = isl_map_identity(dim);
+    identity = isl_map_add_dims(identity, isl_dim_in, 1);
+    identity = isl_map_add_dims(identity, isl_dim_out, 1);
+
+    isl_map *map = isl_map_from_domain_and_range(tmp, loopDomain);
+    map = isl_map_intersect(map, identity);
+
+    isl_map *lexmax = isl_map_lexmax(isl_map_copy(map));
+    isl_map *lexmin = isl_map_lexmin(isl_map_copy(map));
+    isl_map *sub = isl_map_sum(lexmax, isl_map_neg(lexmin));
+
+    isl_set *elements = isl_map_range(sub);
+
+    if (!isl_set_is_singleton(elements))
+      return -1;
+
+    isl_point *p = isl_set_sample_point(elements);
+
+    isl_int v;
+    isl_int_init(v);
+    isl_point_get_coordinate(p, isl_dim_set, isl_set_n_dim(loopDomain) - 1, &v);
+    int numberIterations = isl_int_get_si(v);
+    isl_int_clear(v);
+
+    return (numberIterations) / isl_int_get_si(f->stride) + 1;
+  }
+
+  /// @brief Create vector instructions for this loop.
+  void codegenForVector(const clast_for *f) {
+    DEBUG(dbgs() << "Vectorizing loop '" << f->iterator << "'\n";);
+    int vectorWidth = getNumberOfIterations(f);
+
+    Value *LB = ExpGen.codegen(f->LB,
+      TD->getIntPtrType(Builder.getContext()));
+
+    APInt Stride = APInt_from_MPZ(f->stride);
+    const IntegerType *LoopIVType = dyn_cast<IntegerType>(LB->getType());
+    Stride =  Stride.zext(LoopIVType->getBitWidth());
+    Value *StrideValue = ConstantInt::get(LoopIVType, Stride);
+
+    std::vector<Value*> IVS(vectorWidth);
+    IVS[0] = LB;
+
+    for (int i = 1; i < vectorWidth; i++)
+      IVS[i] = Builder.CreateAdd(IVS[i-1], StrideValue, "p_vector_iv");
+
+    isl_set *scatteringDomain = isl_set_from_cloog_domain(f->domain);
+
+    // Add loop iv to symbols.
+    (*clastVars)[f->iterator] = LB;
+
+    const clast_stmt *stmt = f->body;
+
+    while (stmt) {
+      codegen((const clast_user_stmt *)stmt, &IVS, f->iterator,
+              scatteringDomain);
+      stmt = stmt->next;
+    }
+
+    // Loop is finished, so remove its iv from the live symbols.
+    clastVars->erase(f->iterator);
+  }
+
+  void codegen(const clast_for *f) {
+    if (Vector && isInnermostLoop(f) && isParallelFor(f)
+        && (-1 != getNumberOfIterations(f))
+        && (getNumberOfIterations(f) <= 16)) {
+      codegenForVector(f);
+    } else if (OpenMP && !parallelCodeGeneration && isParallelFor(f)) {
+      parallelCodeGeneration = true;
+      parallelLoops.push_back(f->iterator);
+      codegenForOpenMP(f);
+      parallelCodeGeneration = false;
+    } else
+      codegenForSequential(f);
+  }
+
+  Value *codegen(const clast_equation *eq) {
+    Value *LHS = ExpGen.codegen(eq->LHS,
+      TD->getIntPtrType(Builder.getContext()));
+    Value *RHS = ExpGen.codegen(eq->RHS,
+      TD->getIntPtrType(Builder.getContext()));
+    CmpInst::Predicate P;
+
+    if (eq->sign == 0)
+      P = ICmpInst::ICMP_EQ;
+    else if (eq->sign > 0)
+      P = ICmpInst::ICMP_SGE;
+    else
+      P = ICmpInst::ICMP_SLE;
+
+    return Builder.CreateICmp(P, LHS, RHS);
+  }
+
+  void codegen(const clast_guard *g) {
+    Function *F = Builder.GetInsertBlock()->getParent();
+    LLVMContext &Context = F->getContext();
+    BasicBlock *ThenBB = BasicBlock::Create(Context, "polly.then", F);
+    BasicBlock *MergeBB = BasicBlock::Create(Context, "polly.merge", F);
+    DT->addNewBlock(ThenBB, Builder.GetInsertBlock());
+    DT->addNewBlock(MergeBB, Builder.GetInsertBlock());
+
+    Value *Predicate = codegen(&(g->eq[0]));
+
+    for (int i = 1; i < g->n; ++i) {
+      Value *TmpPredicate = codegen(&(g->eq[i]));
+      Predicate = Builder.CreateAnd(Predicate, TmpPredicate);
+    }
+
+    Builder.CreateCondBr(Predicate, ThenBB, MergeBB);
+    Builder.SetInsertPoint(ThenBB);
+
+    codegen(g->then);
+
+    Builder.CreateBr(MergeBB);
+    Builder.SetInsertPoint(MergeBB);
+  }
+
+  void codegen(const clast_stmt *stmt) {
+    if	    (CLAST_STMT_IS_A(stmt, stmt_root))
+      assert(false && "No second root statement expected");
+    else if (CLAST_STMT_IS_A(stmt, stmt_ass))
+      codegen((const clast_assignment *)stmt);
+    else if (CLAST_STMT_IS_A(stmt, stmt_user))
+      codegen((const clast_user_stmt *)stmt);
+    else if (CLAST_STMT_IS_A(stmt, stmt_block))
+      codegen((const clast_block *)stmt);
+    else if (CLAST_STMT_IS_A(stmt, stmt_for))
+      codegen((const clast_for *)stmt);
+    else if (CLAST_STMT_IS_A(stmt, stmt_guard))
+      codegen((const clast_guard *)stmt);
+
+    if (stmt->next)
+      codegen(stmt->next);
+  }
+
+  void addParameters(const CloogNames *names) {
+    SCEVExpander Rewriter(SE);
+
+    // Create an instruction that specifies the location where the parameters
+    // are expanded.
+    CastInst::CreateIntegerCast(ConstantInt::getTrue(Builder.getContext()),
+                                  Builder.getInt16Ty(), false, "insertInst",
+                                  Builder.GetInsertBlock());
+
+    int i = 0;
+    for (Scop::param_iterator PI = S->param_begin(), PE = S->param_end();
+         PI != PE; ++PI) {
+      assert(i < names->nb_parameters && "Not enough parameter names");
+
+      const SCEV *Param = *PI;
+      const Type *Ty = Param->getType();
+
+      Instruction *insertLocation = --(Builder.GetInsertBlock()->end());
+      Value *V = Rewriter.expandCodeFor(Param, Ty, insertLocation);
+      (*clastVars)[names->parameters[i]] = V;
+
+      ++i;
+    }
+  }
+
+  public:
+  void codegen(const clast_root *r) {
+    clastVars = new CharMapT();
+    addParameters(r->names);
+    ExpGen.setIVS(clastVars);
+
+    parallelCodeGeneration = false;
+
+    const clast_stmt *stmt = (const clast_stmt*) r;
+    if (stmt->next)
+      codegen(stmt->next);
+
+    delete clastVars;
+  }
+
+  ClastStmtCodeGen(Scop *scop, ScalarEvolution &se, DominatorTree *dt,
+                   Dependences *dp, TargetData *td, IRBuilder<> &B) :
+    S(scop), SE(se), DT(dt), DP(dp), TD(td), Builder(B), ExpGen(Builder, NULL) {}
+
+};
+}
+
+namespace {
+class CodeGeneration : public ScopPass {
+  Region *region;
+  Scop *S;
+  DominatorTree *DT;
+  ScalarEvolution *SE;
+  ScopDetection *SD;
+  CloogInfo *C;
+  LoopInfo *LI;
+  TargetData *TD;
+
+  std::vector<std::string> parallelLoops;
+
+  public:
+  static char ID;
+
+  CodeGeneration() : ScopPass(ID) {}
+
+  void createSeSeEdges(Region *R) {
+    BasicBlock *newEntry = createSingleEntryEdge(R, this);
+
+    for (Scop::iterator SI = S->begin(), SE = S->end(); SI != SE; ++SI)
+      if ((*SI)->getBasicBlock() == R->getEntry())
+        (*SI)->setBasicBlock(newEntry);
+
+    createSingleExitEdge(R, this);
+  }
+
+
+  // Adding prototypes required if OpenMP is enabled.
+  void addOpenMPDefinitions(IRBuilder<> &Builder)
+  {
+    Module *M = Builder.GetInsertBlock()->getParent()->getParent();
+    LLVMContext &Context = Builder.getContext();
+    const IntegerType *intPtrTy = TD->getIntPtrType(Context);
+
+    if (!M->getFunction("GOMP_parallel_end")) {
+      FunctionType *FT = FunctionType::get(Type::getVoidTy(Context), false);
+      Function::Create(FT, Function::ExternalLinkage, "GOMP_parallel_end", M);
+    }
+
+    if (!M->getFunction("GOMP_parallel_loop_runtime_start")) {
+      // Type of first argument.
+      std::vector<const Type*> Arguments(1, Builder.getInt8PtrTy());
+      FunctionType *FnArgTy = FunctionType::get(Builder.getVoidTy(), Arguments,
+                                                false);
+      PointerType *FnPtrTy = PointerType::getUnqual(FnArgTy);
+
+      std::vector<const Type*> args;
+      args.push_back(FnPtrTy);
+      args.push_back(Builder.getInt8PtrTy());
+      args.push_back(Builder.getInt32Ty());
+      args.push_back(intPtrTy);
+      args.push_back(intPtrTy);
+      args.push_back(intPtrTy);
+
+      FunctionType *type = FunctionType::get(Builder.getVoidTy(), args, false);
+      Function::Create(type, Function::ExternalLinkage,
+                       "GOMP_parallel_loop_runtime_start", M);
+    }
+
+    if (!M->getFunction("GOMP_loop_runtime_next")) {
+      PointerType *intLongPtrTy = PointerType::getUnqual(intPtrTy);
+
+      std::vector<const Type*> args;
+      args.push_back(intLongPtrTy);
+      args.push_back(intLongPtrTy);
+
+      FunctionType *type = FunctionType::get(Builder.getInt8Ty(), args, false);
+      Function::Create(type, Function::ExternalLinkage,
+                       "GOMP_loop_runtime_next", M);
+    }
+
+    if (!M->getFunction("GOMP_loop_end_nowait")) {
+      FunctionType *FT = FunctionType::get(Builder.getVoidTy(),
+                                           std::vector<const Type*>(), false);
+      Function::Create(FT, Function::ExternalLinkage,
+		       "GOMP_loop_end_nowait", M);
+    }
+  }
+
+  bool runOnScop(Scop &scop) {
+    S = &scop;
+    region = &S->getRegion();
+    Region *R = region;
+    DT = &getAnalysis<DominatorTree>();
+    Dependences *DP = &getAnalysis<Dependences>();
+    SE = &getAnalysis<ScalarEvolution>();
+    LI = &getAnalysis<LoopInfo>();
+    C = &getAnalysis<CloogInfo>();
+    SD = &getAnalysis<ScopDetection>();
+    TD = &getAnalysis<TargetData>();
+
+    Function *F = R->getEntry()->getParent();
+
+    parallelLoops.clear();
+
+    if (CodegenOnly != "" && CodegenOnly != F->getNameStr()) {
+      errs() << "Codegenerating only function '" << CodegenOnly
+        << "' skipping '" << F->getNameStr() << "' \n";
+      return false;
+    }
+
+    createSeSeEdges(R);
+
+    // Create a basic block in which to start code generation.
+    BasicBlock *PollyBB = BasicBlock::Create(F->getContext(), "pollyBB", F);
+    IRBuilder<> Builder(PollyBB);
+    DT->addNewBlock(PollyBB, R->getEntry());
+
+    const clast_root *clast = (const clast_root *) C->getClast();
+
+    ClastStmtCodeGen CodeGen(S, *SE, DT, DP, TD, Builder);
+
+    if (OpenMP)
+      addOpenMPDefinitions(Builder);
+
+    CodeGen.codegen(clast);
+
+    // Save the parallel loops generated.
+    parallelLoops.insert(parallelLoops.begin(),
+                         CodeGen.getParallelLoops().begin(),
+                         CodeGen.getParallelLoops().end());
+
+    BasicBlock *AfterScop = *pred_begin(R->getExit());
+    Builder.CreateBr(AfterScop);
+
+    BasicBlock *successorBlock = *succ_begin(R->getEntry());
+
+    // Update old PHI nodes to pass LLVM verification.
+    std::vector<PHINode*> PHINodes;
+    for (BasicBlock::iterator SI = successorBlock->begin(),
+         SE = successorBlock->getFirstNonPHI(); SI != SE; ++SI) {
+      PHINode *PN = static_cast<PHINode*>(&*SI);
+      PHINodes.push_back(PN);
+    }
+
+    for (std::vector<PHINode*>::iterator PI = PHINodes.begin(),
+         PE = PHINodes.end(); PI != PE; ++PI)
+      (*PI)->removeIncomingValue(R->getEntry());
+
+    DT->changeImmediateDominator(AfterScop, Builder.GetInsertBlock());
+
+    BasicBlock *OldRegionEntry = *succ_begin(R->getEntry());
+
+    // Enable the new polly code.
+    R->getEntry()->getTerminator()->setSuccessor(0, PollyBB);
+
+    // Remove old Scop nodes from dominator tree.
+    std::vector<DomTreeNode*> ToVisit;
+    std::vector<DomTreeNode*> Visited;
+    ToVisit.push_back(DT->getNode(OldRegionEntry));
+
+    while (!ToVisit.empty()) {
+      DomTreeNode *Node = ToVisit.back();
+
+      ToVisit.pop_back();
+
+      if (AfterScop == Node->getBlock())
+        continue;
+
+      Visited.push_back(Node);
+
+      std::vector<DomTreeNode*> Children = Node->getChildren();
+      ToVisit.insert(ToVisit.end(), Children.begin(), Children.end());
+    }
+
+    for (std::vector<DomTreeNode*>::reverse_iterator I = Visited.rbegin(),
+         E = Visited.rend(); I != E; ++I)
+      DT->eraseNode((*I)->getBlock());
+
+    R->getParent()->removeSubRegion(R);
+
+    // And forget the Scop if we remove the region.
+    SD->forgetScop(*R);
+
+    return false;
+  }
+
+  virtual void printScop(raw_ostream &OS) const {
+    for (std::vector<std::string>::const_iterator PI = parallelLoops.begin(),
+         PE = parallelLoops.end(); PI != PE; ++PI)
+      OS << "Parallel loop with iterator '" << *PI << "' generated\n";
+  }
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.addRequired<CloogInfo>();
+    AU.addRequired<Dependences>();
+    AU.addRequired<DominatorTree>();
+    AU.addRequired<ScalarEvolution>();
+    AU.addRequired<LoopInfo>();
+    AU.addRequired<RegionInfo>();
+    AU.addRequired<ScopDetection>();
+    AU.addRequired<ScopInfo>();
+    AU.addRequired<TargetData>();
+
+    AU.addPreserved<CloogInfo>();
+    AU.addPreserved<Dependences>();
+    AU.addPreserved<LoopInfo>();
+    AU.addPreserved<DominatorTree>();
+    AU.addPreserved<PostDominatorTree>();
+    AU.addPreserved<ScopDetection>();
+    AU.addPreserved<ScalarEvolution>();
+    AU.addPreserved<RegionInfo>();
+    AU.addPreserved<TempScopInfo>();
+    AU.addPreserved<ScopInfo>();
+    AU.addPreservedID(IndependentBlocksID);
+  }
+};
+}
+
+char CodeGeneration::ID = 1;
+
+static RegisterPass<CodeGeneration>
+Z("polly-codegen", "Polly - Create LLVM-IR from the polyhedral information");
+
+Pass* polly::createCodeGenerationPass() {
+  return new CodeGeneration();
+}