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llvm-project/polly/lib/CodeGeneration.cpp

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//===------ 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/Transforms/Utils/BasicBlockUtils.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));
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.");
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);
}
Type *getVectorPtrTy(const Value *V, int vectorWidth) {
PointerType *pointerType = dyn_cast<PointerType>(V->getType());
assert(pointerType && "PointerType expected");
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();
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();
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;
}
/// @brief Get the memory access offset to be added to the base address
std::vector <Value*> getMemoryAccessIndex(isl_map *accessRelation,
Value *baseAddr) {
isl_int offsetMPZ;
isl_int_init(offsetMPZ);
assert((isl_map_dim(accessRelation, isl_dim_out) == 1)
&& "Only single dimensional access functions supported");
if (isl_map_plain_is_fixed(accessRelation, isl_dim_out,
0, &offsetMPZ) == -1)
errs() << "Only fixed value access functions supported\n";
// Convert the offset from MPZ to Value*.
APInt offset = APInt_from_MPZ(offsetMPZ);
Value *offsetValue = ConstantInt::get(Builder.getContext(), offset);
PointerType *baseAddrType = dyn_cast<PointerType>(baseAddr->getType());
Type *arrayType = baseAddrType->getElementType();
Type *arrayElementType = dyn_cast<ArrayType>(arrayType)->getElementType();
offsetValue = Builder.CreateSExtOrBitCast(offsetValue, arrayElementType);
std::vector<Value*> indexArray;
Value *nullValue = Constant::getNullValue(arrayElementType);
indexArray.push_back(nullValue);
indexArray.push_back(offsetValue);
isl_int_clear(offsetMPZ);
return indexArray;
}
/// @brief Get the new operand address according to the changed access in
/// JSCOP file.
Value *getNewAccessOperand(isl_map *newAccessRelation, Value *baseAddr,
const Value *oldOperand, ValueMapT &BBMap) {
std::vector<Value*> indexArray = getMemoryAccessIndex(newAccessRelation,
baseAddr);
Value *newOperand = Builder.CreateGEP(baseAddr, indexArray,
"p_newarrayidx_");
return newOperand;
}
/// @brief Generate the operand address
Value *generateLocationAccessed(const Instruction *Inst,
const Value *pointer, ValueMapT &BBMap ) {
MemoryAccess &access = statement.getAccessFor(Inst);
isl_map *currentAccessRelation = access.getAccessFunction();
isl_map *newAccessRelation = access.getNewAccessFunction();
assert(isl_map_has_equal_dim(currentAccessRelation, newAccessRelation)
&& "Current and new access function dimensions differ");
if (!newAccessRelation) {
Value *newPointer = getOperand(pointer, BBMap);
return newPointer;
}
Value *baseAddr = const_cast<Value*>(access.getBaseAddr());
Value *newPointer = getNewAccessOperand(newAccessRelation, baseAddr,
pointer, BBMap);
return newPointer;
}
Value *generateScalarLoad(const LoadInst *load, ValueMapT &BBMap) {
const Value *pointer = load->getPointerOperand();
const Instruction *Inst = dyn_cast<Instruction>(load);
Value *newPointer = generateLocationAccessed(Inst, 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)) {
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, 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, 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, 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, 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, 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;
ScopDetection *SD;
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 (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 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<Type*> Arguments(1, Builder.getInt8PtrTy());
FunctionType *FT = FunctionType::get(Builder.getVoidTy(), Arguments, false);
Function *FN = Function::Create(FT, Function::InternalLinkage, Name, M);
// Do not run any polly pass on the new function.
SD->markFunctionAsInvalid(FN);
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) {
std::vector<Type*> structMembers;
// Create the structure.
for (unsigned i = 0; i < OMPDataVals.size(); i++)
structMembers.push_back(OMPDataVals[i]->getType());
StructType *structTy = StructType::get(Builder.getContext(),
structMembers);
// 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();
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();
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);
// 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(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);
isl_point_free(p);
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);
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) && DP->isParallelFor(f)
&& (-1 != getNumberOfIterations(f))
&& (getNumberOfIterations(f) <= 16)) {
codegenForVector(f);
} else if (OpenMP && !parallelCodeGeneration && DP->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, "polly");
// 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;
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,
ScopDetection *sd, Dependences *dp, TargetData *td,
IRBuilder<> &B) :
S(scop), SE(se), DT(dt), SD(sd), DP(dp), TD(td), Builder(B),
ExpGen(Builder, NULL) {}
};
}
namespace {
class CodeGeneration : public ScopPass {
Region *region;
Scop *S;
DominatorTree *DT;
ScalarEvolution *SE;
ScopDetection *SD;
TargetData *TD;
RegionInfo *RI;
std::vector<std::string> parallelLoops;
public:
static char ID;
CodeGeneration() : ScopPass(ID) {}
// Adding prototypes required if OpenMP is enabled.
void addOpenMPDefinitions(IRBuilder<> &Builder)
{
Module *M = Builder.GetInsertBlock()->getParent()->getParent();
LLVMContext &Context = Builder.getContext();
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<Type*> Arguments(1, Builder.getInt8PtrTy());
FunctionType *FnArgTy = FunctionType::get(Builder.getVoidTy(), Arguments,
false);
PointerType *FnPtrTy = PointerType::getUnqual(FnArgTy);
std::vector<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<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<Type*>(), false);
Function::Create(FT, Function::ExternalLinkage,
"GOMP_loop_end_nowait", M);
}
}
// Split the entry edge of the region and generate a new basic block on this
// edge. This function also updates ScopInfo and RegionInfo.
//
// @param region The region where the entry edge will be splitted.
BasicBlock *splitEdgeAdvanced(Region *region) {
BasicBlock *newBlock;
BasicBlock *splitBlock;
newBlock = SplitEdge(region->getEnteringBlock(), region->getEntry(), this);
if (DT->dominates(region->getEntry(), newBlock)) {
// Update ScopInfo.
for (Scop::iterator SI = S->begin(), SE = S->end(); SI != SE; ++SI)
if ((*SI)->getBasicBlock() == newBlock) {
(*SI)->setBasicBlock(newBlock);
break;
}
// Update RegionInfo.
splitBlock = region->getEntry();
region->replaceEntry(newBlock);
RI->setRegionFor(newBlock, region);
} else {
RI->setRegionFor(newBlock, region->getParent());
splitBlock = newBlock;
}
return splitBlock;
}
// Create a split block that branches either to the old code or to a new basic
// block where the new code can be inserted.
//
// @param builder A builder that will be set to point to a basic block, where
// the new code can be generated.
// @return The split basic block.
BasicBlock *addSplitAndStartBlock(IRBuilder<> *builder) {
BasicBlock *splitBlock = splitEdgeAdvanced(region);
splitBlock->setName("polly.enterScop");
Function *function = splitBlock->getParent();
BasicBlock *startBlock = BasicBlock::Create(function->getContext(),
"polly.start", function);
splitBlock->getTerminator()->eraseFromParent();
builder->SetInsertPoint(splitBlock);
builder->CreateCondBr(builder->getTrue(), startBlock, region->getEntry());
DT->addNewBlock(startBlock, splitBlock);
// Start code generation here.
builder->SetInsertPoint(startBlock);
return splitBlock;
}
// Merge the control flow of the newly generated code with the existing code.
//
// @param splitBlock The basic block where the control flow was split between
// old and new version of the Scop.
// @param builder An IRBuilder that points to the last instruction of the
// newly generated code.
void mergeControlFlow(BasicBlock *splitBlock, IRBuilder<> *builder) {
BasicBlock *mergeBlock;
Region *R = region;
if (R->getExit()->getSinglePredecessor())
// No splitEdge required. A block with a single predecessor cannot have
// PHI nodes that would complicate life.
mergeBlock = R->getExit();
else {
mergeBlock = SplitEdge(R->getExitingBlock(), R->getExit(), this);
// SplitEdge will never split R->getExit(), as R->getExit() has more than
// one predecessor. Hence, mergeBlock is always a newly generated block.
mergeBlock->setName("polly.finalMerge");
R->replaceExit(mergeBlock);
}
builder->CreateBr(mergeBlock);
if (DT->dominates(splitBlock, mergeBlock))
DT->changeImmediateDominator(mergeBlock, splitBlock);
}
bool runOnScop(Scop &scop) {
S = &scop;
region = &S->getRegion();
DT = &getAnalysis<DominatorTree>();
Dependences *DP = &getAnalysis<Dependences>();
SE = &getAnalysis<ScalarEvolution>();
SD = &getAnalysis<ScopDetection>();
TD = &getAnalysis<TargetData>();
RI = &getAnalysis<RegionInfo>();
parallelLoops.clear();
assert(region->isSimple() && "Only simple regions are supported");
// In the CFG and we generate next to original code of the Scop the
// optimized version. Both the new and the original version of the code
// remain in the CFG. A branch statement decides which version is executed.
// At the moment, we always execute the newly generated version (the old one
// is dead code eliminated by the cleanup passes). Later we may decide to
// execute the new version only under certain conditions. This will be the
// case if we support constructs for which we cannot prove all assumptions
// at compile time.
//
// Before transformation:
//
// bb0
// |
// orig_scop
// |
// bb1
//
// After transformation:
// bb0
// |
// polly.splitBlock
// / \.
// | startBlock
// | |
// orig_scop new_scop
// \ /
// \ /
// bb1 (joinBlock)
IRBuilder<> builder(region->getEntry());
// The builder will be set to startBlock.
BasicBlock *splitBlock = addSplitAndStartBlock(&builder);
if (OpenMP)
addOpenMPDefinitions(builder);
ClastStmtCodeGen CodeGen(S, *SE, DT, SD, DP, TD, builder);
CloogInfo &C = getAnalysis<CloogInfo>();
CodeGen.codegen(C.getClast());
parallelLoops.insert(parallelLoops.begin(),
CodeGen.getParallelLoops().begin(),
CodeGen.getParallelLoops().end());
mergeControlFlow(splitBlock, &builder);
return true;
}
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<RegionInfo>();
AU.addRequired<ScopDetection>();
AU.addRequired<ScopInfo>();
AU.addRequired<TargetData>();
AU.addPreserved<CloogInfo>();
AU.addPreserved<Dependences>();
// FIXME: We do not create LoopInfo for the newly generated loops.
AU.addPreserved<LoopInfo>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<ScopDetection>();
AU.addPreserved<ScalarEvolution>();
// FIXME: We do not yet add regions for the newly generated code to the
// region tree.
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();
}
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