ScalarEvolutionExpander.cpp revision 203954
11541Srgrimes//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===// 21541Srgrimes// 31541Srgrimes// The LLVM Compiler Infrastructure 485895Srwatson// 51541Srgrimes// This file is distributed under the University of Illinois Open Source 685895Srwatson// License. See LICENSE.TXT for details. 71541Srgrimes// 81541Srgrimes//===----------------------------------------------------------------------===// 91541Srgrimes// 101541Srgrimes// This file contains the implementation of the scalar evolution expander, 111541Srgrimes// which is used to generate the code corresponding to a given scalar evolution 121541Srgrimes// expression. 131541Srgrimes// 141541Srgrimes//===----------------------------------------------------------------------===// 151541Srgrimes 161541Srgrimes#include "llvm/Analysis/ScalarEvolutionExpander.h" 171541Srgrimes#include "llvm/Analysis/LoopInfo.h" 181541Srgrimes#include "llvm/LLVMContext.h" 191541Srgrimes#include "llvm/Target/TargetData.h" 201541Srgrimes#include "llvm/ADT/STLExtras.h" 211541Srgrimesusing namespace llvm; 221541Srgrimes 231541Srgrimes/// InsertNoopCastOfTo - Insert a cast of V to the specified type, 241541Srgrimes/// which must be possible with a noop cast, doing what we can to share 251541Srgrimes/// the casts. 261541SrgrimesValue *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) { 271541Srgrimes Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false); 281541Srgrimes assert((Op == Instruction::BitCast || 291541Srgrimes Op == Instruction::PtrToInt || 301541Srgrimes Op == Instruction::IntToPtr) && 311541Srgrimes "InsertNoopCastOfTo cannot perform non-noop casts!"); 321541Srgrimes assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) && 331541Srgrimes "InsertNoopCastOfTo cannot change sizes!"); 341541Srgrimes 351541Srgrimes // Short-circuit unnecessary bitcasts. 361541Srgrimes if (Op == Instruction::BitCast && V->getType() == Ty) 371541Srgrimes return V; 381541Srgrimes 391541Srgrimes // Short-circuit unnecessary inttoptr<->ptrtoint casts. 401541Srgrimes if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) && 4150477Speter SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) { 421541Srgrimes if (CastInst *CI = dyn_cast<CastInst>(V)) 431541Srgrimes if ((CI->getOpcode() == Instruction::PtrToInt || 441541Srgrimes CI->getOpcode() == Instruction::IntToPtr) && 451541Srgrimes SE.getTypeSizeInBits(CI->getType()) == 461541Srgrimes SE.getTypeSizeInBits(CI->getOperand(0)->getType())) 471541Srgrimes return CI->getOperand(0); 4831778Seivind if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 4975426Srwatson if ((CE->getOpcode() == Instruction::PtrToInt || 5031778Seivind CE->getOpcode() == Instruction::IntToPtr) && 511541Srgrimes SE.getTypeSizeInBits(CE->getType()) == 5276166Smarkm SE.getTypeSizeInBits(CE->getOperand(0)->getType())) 531541Srgrimes return CE->getOperand(0); 5441059Speter } 5570317Sjake 5676166Smarkm if (Constant *C = dyn_cast<Constant>(V)) 571541Srgrimes return ConstantExpr::getCast(Op, C, Ty); 5886304Sjhb 5976166Smarkm if (Argument *A = dyn_cast<Argument>(V)) { 601541Srgrimes // Check to see if there is already a cast! 6131891Ssef for (Value::use_iterator UI = A->use_begin(), E = A->use_end(); 6265495Struckman UI != E; ++UI) 6361287Srwatson if ((*UI)->getType() == Ty) 6472786Srwatson if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) 651541Srgrimes if (CI->getOpcode() == Op) { 6630354Sphk // If the cast isn't the first instruction of the function, move it. 6730354Sphk if (BasicBlock::iterator(CI) != 6880735Srwatson A->getParent()->getEntryBlock().begin()) { 6980735Srwatson // Recreate the cast at the beginning of the entry block. 7080735Srwatson // The old cast is left in place in case it is being used 7187138Srwatson // as an insert point. 7287138Srwatson Instruction *NewCI = 7387138Srwatson CastInst::Create(Op, V, Ty, "", 7412221Sbde A->getParent()->getEntryBlock().begin()); 7511332Sswallace NewCI->takeName(CI); 761541Srgrimes CI->replaceAllUsesWith(NewCI); 771541Srgrimes return NewCI; 7812221Sbde } 791541Srgrimes return CI; 8058717Sdillon } 8182749Sdillon 8258717Sdillon Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), 8370317Sjake A->getParent()->getEntryBlock().begin()); 8482749Sdillon rememberInstruction(I); 8582749Sdillon return I; 8682749Sdillon } 871541Srgrimes 881549Srgrimes Instruction *I = cast<Instruction>(V); 8983366Sjulian 9083366Sjulian // Check to see if there is already a cast. If there is, use it. 9111332Sswallace for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); 921541Srgrimes UI != E; ++UI) { 9383366Sjulian if ((*UI)->getType() == Ty) 9485564Sdillon if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) 951541Srgrimes if (CI->getOpcode() == Op) { 9685564Sdillon BasicBlock::iterator It = I; ++It; 9783366Sjulian if (isa<InvokeInst>(I)) 981541Srgrimes It = cast<InvokeInst>(I)->getNormalDest()->begin(); 9974728Sjhb while (isa<PHINode>(It)) ++It; 10083366Sjulian if (It != BasicBlock::iterator(CI)) { 10174728Sjhb // Recreate the cast after the user. 1021541Srgrimes // The old cast is left in place in case it is being used 10385564Sdillon // as an insert point. 1041541Srgrimes Instruction *NewCI = CastInst::Create(Op, V, Ty, "", It); 1051541Srgrimes NewCI->takeName(CI); 1061541Srgrimes CI->replaceAllUsesWith(NewCI); 10770317Sjake rememberInstruction(NewCI); 10882749Sdillon return NewCI; 10970317Sjake } 11070317Sjake rememberInstruction(CI); 11112221Sbde return CI; 11211332Sswallace } 11311332Sswallace } 11411332Sswallace BasicBlock::iterator IP = I; ++IP; 11512221Sbde if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 11682749Sdillon IP = II->getNormalDest()->begin(); 11782749Sdillon while (isa<PHINode>(IP)) ++IP; 11882749Sdillon Instruction *CI = CastInst::Create(Op, V, Ty, V->getName(), IP); 1191541Srgrimes rememberInstruction(CI); 1201549Srgrimes return CI; 12183366Sjulian} 12283366Sjulian 12311332Sswallace/// InsertBinop - Insert the specified binary operator, doing a small amount 1241541Srgrimes/// of work to avoid inserting an obviously redundant operation. 12583366SjulianValue *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, 12685564Sdillon Value *LHS, Value *RHS) { 1271541Srgrimes // Fold a binop with constant operands. 12885564Sdillon if (Constant *CLHS = dyn_cast<Constant>(LHS)) 12974728Sjhb if (Constant *CRHS = dyn_cast<Constant>(RHS)) 13083366Sjulian return ConstantExpr::get(Opcode, CLHS, CRHS); 13174728Sjhb 13285564Sdillon // Do a quick scan to see if we have this binop nearby. If so, reuse it. 1331541Srgrimes unsigned ScanLimit = 6; 1341541Srgrimes BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin(); 1351541Srgrimes // Scanning starts from the last instruction before the insertion point. 13658717Sdillon BasicBlock::iterator IP = Builder.GetInsertPoint(); 13758717Sdillon if (IP != BlockBegin) { 13858717Sdillon --IP; 13958717Sdillon for (; ScanLimit; --IP, --ScanLimit) { 14058717Sdillon if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS && 14112221Sbde IP->getOperand(1) == RHS) 14211332Sswallace return IP; 14311332Sswallace if (IP == BlockBegin) break; 14411332Sswallace } 14512221Sbde } 14682749Sdillon 14782749Sdillon // If we haven't found this binop, insert it. 14882749Sdillon Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp"); 1491549Srgrimes rememberInstruction(BO); 15083366Sjulian return BO; 15183366Sjulian} 15211332Sswallace 1531541Srgrimes/// FactorOutConstant - Test if S is divisible by Factor, using signed 15483366Sjulian/// division. If so, update S with Factor divided out and return true. 1551541Srgrimes/// S need not be evenly divisble if a reasonable remainder can be 15682749Sdillon/// computed. 15783366Sjulian/// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made 15882749Sdillon/// unnecessary; in its place, just signed-divide Ops[i] by the scale and 1591541Srgrimes/// check to see if the divide was folded. 1601541Srgrimesstatic bool FactorOutConstant(const SCEV *&S, 1611541Srgrimes const SCEV *&Remainder, 16228401Speter const SCEV *Factor, 16312221Sbde ScalarEvolution &SE, 16428401Speter const TargetData *TD) { 16528401Speter // Everything is divisible by one. 16628401Speter if (Factor->isOne()) 16728401Speter return true; 16828401Speter 16982749Sdillon // x/x == 1. 17082749Sdillon if (S == Factor) { 17182749Sdillon S = SE.getIntegerSCEV(1, S->getType()); 17228401Speter return true; 17383366Sjulian } 17483366Sjulian 17528401Speter // For a Constant, check for a multiple of the given factor. 17628401Speter if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) { 17783366Sjulian // 0/x == 0. 17841726Struckman if (C->isZero()) 17982749Sdillon return true; 18085564Sdillon // Check for divisibility. 18141726Struckman if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) { 18285564Sdillon ConstantInt *CI = 18328401Speter ConstantInt::get(SE.getContext(), 18483366Sjulian C->getValue()->getValue().sdiv( 18584825Sjhb FC->getValue()->getValue())); 18684825Sjhb // If the quotient is zero and the remainder is non-zero, reject 18775893Sjhb // the value at this scale. It will be considered for subsequent 18884825Sjhb // smaller scales. 18984825Sjhb if (!CI->isZero()) { 19084825Sjhb const SCEV *Div = SE.getConstant(CI); 19175893Sjhb S = Div; 19275893Sjhb Remainder = 19385564Sdillon SE.getAddExpr(Remainder, 19482749Sdillon SE.getConstant(C->getValue()->getValue().srem( 19528401Speter FC->getValue()->getValue()))); 19628401Speter return true; 19728401Speter } 19828401Speter } 19928401Speter } 20028401Speter 20128401Speter // In a Mul, check if there is a constant operand which is a multiple 20228401Speter // of the given factor. 20328401Speter if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) { 20428401Speter if (TD) { 20528401Speter // With TargetData, the size is known. Check if there is a constant 20682749Sdillon // operand which is a multiple of the given factor. If so, we can 20782749Sdillon // factor it. 20882749Sdillon const SCEVConstant *FC = cast<SCEVConstant>(Factor); 20928401Speter if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0))) 21083366Sjulian if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) { 21183366Sjulian const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands(); 21228401Speter SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(), 21328401Speter MOperands.end()); 21483366Sjulian NewMulOps[0] = 21541726Struckman SE.getConstant(C->getValue()->getValue().sdiv( 21682749Sdillon FC->getValue()->getValue())); 21741726Struckman S = SE.getMulExpr(NewMulOps); 21882749Sdillon return true; 21984825Sjhb } 22083366Sjulian } else { 22184825Sjhb // Without TargetData, check if Factor can be factored out of any of the 22284825Sjhb // Mul's operands. If so, we can just remove it. 22384825Sjhb for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { 22484825Sjhb const SCEV *SOp = M->getOperand(i); 22584825Sjhb const SCEV *Remainder = SE.getIntegerSCEV(0, SOp->getType()); 22684825Sjhb if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) && 22775893Sjhb Remainder->isZero()) { 22875893Sjhb const SmallVectorImpl<const SCEV *> &MOperands = M->getOperands(); 22982749Sdillon SmallVector<const SCEV *, 4> NewMulOps(MOperands.begin(), 23082749Sdillon MOperands.end()); 23128401Speter NewMulOps[i] = SOp; 23228401Speter S = SE.getMulExpr(NewMulOps); 23328401Speter return true; 23458941Sdillon } 23558941Sdillon } 23658941Sdillon } 23728401Speter } 23811332Sswallace 23911332Sswallace // In an AddRec, check if both start and step are divisible. 24011332Sswallace if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) { 24112221Sbde const SCEV *Step = A->getStepRecurrence(SE); 24211332Sswallace const SCEV *StepRem = SE.getIntegerSCEV(0, Step->getType()); 24382749Sdillon if (!FactorOutConstant(Step, StepRem, Factor, SE, TD)) 24482749Sdillon return false; 24582749Sdillon if (!StepRem->isZero()) 2461541Srgrimes return false; 2471549Srgrimes const SCEV *Start = A->getStart(); 24883366Sjulian if (!FactorOutConstant(Start, Remainder, Factor, SE, TD)) 24983366Sjulian return false; 25011332Sswallace S = SE.getAddRecExpr(Start, Step, A->getLoop()); 2511541Srgrimes return true; 25283366Sjulian } 2531541Srgrimes 25482749Sdillon return false; 25583366Sjulian} 2561541Srgrimes 25783366Sjulian/// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs 2581541Srgrimes/// is the number of SCEVAddRecExprs present, which are kept at the end of 25982749Sdillon/// the list. 2601541Srgrimes/// 2611541Srgrimesstatic void SimplifyAddOperands(SmallVectorImpl<const SCEV *> &Ops, 2621541Srgrimes const Type *Ty, 26358941Sdillon ScalarEvolution &SE) { 26458941Sdillon unsigned NumAddRecs = 0; 26558941Sdillon for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i) 26612221Sbde ++NumAddRecs; 26711332Sswallace // Group Ops into non-addrecs and addrecs. 26811332Sswallace SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs); 26911332Sswallace SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end()); 27012221Sbde // Let ScalarEvolution sort and simplify the non-addrecs list. 27111332Sswallace const SCEV *Sum = NoAddRecs.empty() ? 2721541Srgrimes SE.getIntegerSCEV(0, Ty) : 2731549Srgrimes SE.getAddExpr(NoAddRecs); 27483366Sjulian // If it returned an add, use the operands. Otherwise it simplified 27583366Sjulian // the sum into a single value, so just use that. 27611332Sswallace if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum)) 2771541Srgrimes Ops = Add->getOperands(); 27882749Sdillon else { 27983366Sjulian Ops.clear(); 28082749Sdillon if (!Sum->isZero()) 2811541Srgrimes Ops.push_back(Sum); 2821541Srgrimes } 2831541Srgrimes // Then append the addrecs. 28458941Sdillon Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end()); 28558941Sdillon} 28658941Sdillon 28712221Sbde/// SplitAddRecs - Flatten a list of add operands, moving addrec start values 28811332Sswallace/// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}. 28911332Sswallace/// This helps expose more opportunities for folding parts of the expressions 29011332Sswallace/// into GEP indices. 29112221Sbde/// 29211332Sswallacestatic void SplitAddRecs(SmallVectorImpl<const SCEV *> &Ops, 29382749Sdillon const Type *Ty, 29482749Sdillon ScalarEvolution &SE) { 29582749Sdillon // Find the addrecs. 2961541Srgrimes SmallVector<const SCEV *, 8> AddRecs; 2971549Srgrimes for (unsigned i = 0, e = Ops.size(); i != e; ++i) 29883366Sjulian while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) { 29983366Sjulian const SCEV *Start = A->getStart(); 30011332Sswallace if (Start->isZero()) break; 3011541Srgrimes const SCEV *Zero = SE.getIntegerSCEV(0, Ty); 30283366Sjulian AddRecs.push_back(SE.getAddRecExpr(Zero, 3031541Srgrimes A->getStepRecurrence(SE), 30482749Sdillon A->getLoop())); 30583366Sjulian if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) { 3061541Srgrimes Ops[i] = Zero; 30783366Sjulian Ops.insert(Ops.end(), Add->op_begin(), Add->op_end()); 3081541Srgrimes e += Add->getNumOperands(); 30982749Sdillon } else { 3101541Srgrimes Ops[i] = Start; 3111541Srgrimes } 3121541Srgrimes } 3131541Srgrimes if (!AddRecs.empty()) { 3141541Srgrimes // Add the addrecs onto the end of the list. 3151541Srgrimes Ops.insert(Ops.end(), AddRecs.begin(), AddRecs.end()); 3161541Srgrimes // Resort the operand list, moving any constants to the front. 3171541Srgrimes SimplifyAddOperands(Ops, Ty, SE); 31812221Sbde } 31911332Sswallace} 32011332Sswallace 32111332Sswallace/// expandAddToGEP - Expand an addition expression with a pointer type into 32212221Sbde/// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps 32311332Sswallace/// BasicAliasAnalysis and other passes analyze the result. See the rules 32482749Sdillon/// for getelementptr vs. inttoptr in 32582749Sdillon/// http://llvm.org/docs/LangRef.html#pointeraliasing 32682749Sdillon/// for details. 3271541Srgrimes/// 3281549Srgrimes/// Design note: The correctness of using getelementptr here depends on 32983366Sjulian/// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as 33083366Sjulian/// they may introduce pointer arithmetic which may not be safely converted 33111332Sswallace/// into getelementptr. 3321541Srgrimes/// 33383366Sjulian/// Design note: It might seem desirable for this function to be more 3341541Srgrimes/// loop-aware. If some of the indices are loop-invariant while others 33582749Sdillon/// aren't, it might seem desirable to emit multiple GEPs, keeping the 33683366Sjulian/// loop-invariant portions of the overall computation outside the loop. 33782749Sdillon/// However, there are a few reasons this is not done here. Hoisting simple 3381541Srgrimes/// arithmetic is a low-level optimization that often isn't very 3391541Srgrimes/// important until late in the optimization process. In fact, passes 3401541Srgrimes/// like InstructionCombining will combine GEPs, even if it means 34112221Sbde/// pushing loop-invariant computation down into loops, so even if the 3421541Srgrimes/// GEPs were split here, the work would quickly be undone. The 3431541Srgrimes/// LoopStrengthReduction pass, which is usually run quite late (and 3441541Srgrimes/// after the last InstructionCombining pass), takes care of hoisting 3451541Srgrimes/// loop-invariant portions of expressions, after considering what 34612221Sbde/// can be folded using target addressing modes. 34782749Sdillon/// 34882749SdillonValue *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, 34982749Sdillon const SCEV *const *op_end, 3501549Srgrimes const PointerType *PTy, 35183366Sjulian const Type *Ty, 35283366Sjulian Value *V) { 3531541Srgrimes const Type *ElTy = PTy->getElementType(); 3541541Srgrimes SmallVector<Value *, 4> GepIndices; 35582749Sdillon SmallVector<const SCEV *, 8> Ops(op_begin, op_end); 35683366Sjulian bool AnyNonZeroIndices = false; 35777183Srwatson 35882749Sdillon // Split AddRecs up into parts as either of the parts may be usable 3591541Srgrimes // without the other. 36082749Sdillon SplitAddRecs(Ops, Ty, SE); 36182749Sdillon 3621541Srgrimes // Descend down the pointer's type and attempt to convert the other 36383366Sjulian // operands into GEP indices, at each level. The first index in a GEP 36482749Sdillon // indexes into the array implied by the pointer operand; the rest of 36582749Sdillon // the indices index into the element or field type selected by the 3661541Srgrimes // preceding index. 36782749Sdillon for (;;) { 36882749Sdillon // If the scale size is not 0, attempt to factor out a scale for 36982749Sdillon // array indexing. 37082749Sdillon SmallVector<const SCEV *, 8> ScaledOps; 37177183Srwatson if (ElTy->isSized()) { 37277183Srwatson const SCEV *ElSize = SE.getSizeOfExpr(ElTy); 37382749Sdillon if (!ElSize->isZero()) { 37482749Sdillon SmallVector<const SCEV *, 8> NewOps; 37582749Sdillon for (unsigned i = 0, e = Ops.size(); i != e; ++i) { 37683366Sjulian const SCEV *Op = Ops[i]; 37782749Sdillon const SCEV *Remainder = SE.getIntegerSCEV(0, Ty); 37882749Sdillon if (FactorOutConstant(Op, Remainder, ElSize, SE, SE.TD)) { 37982749Sdillon // Op now has ElSize factored out. 3801541Srgrimes ScaledOps.push_back(Op); 3811541Srgrimes if (!Remainder->isZero()) 38212221Sbde NewOps.push_back(Remainder); 38312207Sbde AnyNonZeroIndices = true; 38411332Sswallace } else { 38511332Sswallace // The operand was not divisible, so add it to the list of operands 38612221Sbde // we'll scan next iteration. 38711332Sswallace NewOps.push_back(Ops[i]); 38882749Sdillon } 38982749Sdillon } 39082749Sdillon // If we made any changes, update Ops. 3911541Srgrimes if (!ScaledOps.empty()) { 3921549Srgrimes Ops = NewOps; 39383366Sjulian SimplifyAddOperands(Ops, Ty, SE); 39483366Sjulian } 39512207Sbde } 3961541Srgrimes } 39782749Sdillon 39883366Sjulian // Record the scaled array index for this level of the type. If 3991541Srgrimes // we didn't find any operands that could be factored, tentatively 40082749Sdillon // assume that element zero was selected (since the zero offset 4011541Srgrimes // would obviously be folded away). 40282749Sdillon Value *Scaled = ScaledOps.empty() ? 4031541Srgrimes Constant::getNullValue(Ty) : 4041541Srgrimes expandCodeFor(SE.getAddExpr(ScaledOps), Ty); 40583366Sjulian GepIndices.push_back(Scaled); 40682749Sdillon 4071541Srgrimes // Collect struct field index operands. 40882749Sdillon while (const StructType *STy = dyn_cast<StructType>(ElTy)) { 40982749Sdillon bool FoundFieldNo = false; 4101541Srgrimes // An empty struct has no fields. 4111541Srgrimes if (STy->getNumElements() == 0) break; 4121541Srgrimes if (SE.TD) { 4131541Srgrimes // With TargetData, field offsets are known. See if a constant offset 4141541Srgrimes // falls within any of the struct fields. 4151541Srgrimes if (Ops.empty()) break; 4161541Srgrimes if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0])) 4171541Srgrimes if (SE.getTypeSizeInBits(C->getType()) <= 64) { 4181541Srgrimes const StructLayout &SL = *SE.TD->getStructLayout(STy); 4191541Srgrimes uint64_t FullOffset = C->getValue()->getZExtValue(); 4201541Srgrimes if (FullOffset < SL.getSizeInBytes()) { 4211541Srgrimes unsigned ElIdx = SL.getElementContainingOffset(FullOffset); 4221541Srgrimes GepIndices.push_back( 4231541Srgrimes ConstantInt::get(Type::getInt32Ty(Ty->getContext()), ElIdx)); 4241541Srgrimes ElTy = STy->getTypeAtIndex(ElIdx); 42512221Sbde Ops[0] = 4261541Srgrimes SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx)); 4271541Srgrimes AnyNonZeroIndices = true; 4281541Srgrimes FoundFieldNo = true; 4291541Srgrimes } 43012221Sbde } 43182749Sdillon } else { 43282749Sdillon // Without TargetData, just check for an offsetof expression of the 43382749Sdillon // appropriate struct type. 4341541Srgrimes for (unsigned i = 0, e = Ops.size(); i != e; ++i) 4351549Srgrimes if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) { 43683366Sjulian const Type *CTy; 43783366Sjulian Constant *FieldNo; 4381541Srgrimes if (U->isOffsetOf(CTy, FieldNo) && CTy == STy) { 4391541Srgrimes GepIndices.push_back(FieldNo); 44083366Sjulian ElTy = 4411541Srgrimes STy->getTypeAtIndex(cast<ConstantInt>(FieldNo)->getZExtValue()); 4421541Srgrimes Ops[i] = SE.getConstant(Ty, 0); 44375448Srwatson AnyNonZeroIndices = true; 4441541Srgrimes FoundFieldNo = true; 44520677Sbde break; 44620677Sbde } 44782749Sdillon } 44882749Sdillon } 44982749Sdillon // If no struct field offsets were found, tentatively assume that 45086304Sjhb // field zero was selected (since the zero offset would obviously 4511541Srgrimes // be folded away). 45275893Sjhb if (!FoundFieldNo) { 45375893Sjhb ElTy = STy->getTypeAtIndex(0u); 45475893Sjhb GepIndices.push_back( 45582749Sdillon Constant::getNullValue(Type::getInt32Ty(Ty->getContext()))); 45682749Sdillon } 45775893Sjhb } 45879335Srwatson 45975893Sjhb if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) 46082749Sdillon ElTy = ATy->getElementType(); 46175893Sjhb else 46275893Sjhb break; 46375893Sjhb } 46475893Sjhb 46582749Sdillon // If none of the operands were convertable to proper GEP indices, cast 46682749Sdillon // the base to i8* and do an ugly getelementptr with that. It's still 46775893Sjhb // better than ptrtoint+arithmetic+inttoptr at least. 46875893Sjhb if (!AnyNonZeroIndices) { 46975893Sjhb // Cast the base to i8*. 47082749Sdillon V = InsertNoopCastOfTo(V, 47182749Sdillon Type::getInt8PtrTy(Ty->getContext(), PTy->getAddressSpace())); 47275893Sjhb 47375893Sjhb // Expand the operands for a plain byte offset. 4741541Srgrimes Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty); 47575893Sjhb 47675893Sjhb // Fold a GEP with constant operands. 47775893Sjhb if (Constant *CLHS = dyn_cast<Constant>(V)) 47875893Sjhb if (Constant *CRHS = dyn_cast<Constant>(Idx)) 47982749Sdillon return ConstantExpr::getGetElementPtr(CLHS, &CRHS, 1); 48082749Sdillon 48175893Sjhb // Do a quick scan to see if we have this GEP nearby. If so, reuse it. 48282749Sdillon unsigned ScanLimit = 6; 4831541Srgrimes BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin(); 48482749Sdillon // Scanning starts from the last instruction before the insertion point. 4851541Srgrimes BasicBlock::iterator IP = Builder.GetInsertPoint(); 48675893Sjhb if (IP != BlockBegin) { 48775893Sjhb --IP; 48882749Sdillon for (; ScanLimit; --IP, --ScanLimit) { 48982749Sdillon if (IP->getOpcode() == Instruction::GetElementPtr && 49075893Sjhb IP->getOperand(0) == V && IP->getOperand(1) == Idx) 49182749Sdillon return IP; 49275893Sjhb if (IP == BlockBegin) break; 49375893Sjhb } 49482749Sdillon } 49582749Sdillon 49686304Sjhb // Emit a GEP. 49782749Sdillon Value *GEP = Builder.CreateGEP(V, Idx, "uglygep"); 49882749Sdillon rememberInstruction(GEP); 4991541Srgrimes return GEP; 5001541Srgrimes } 50124448Speter 50224448Speter // Insert a pretty getelementptr. Note that this GEP is not marked inbounds, 50372093Sasmodai // because ScalarEvolution may have changed the address arithmetic to 50424448Speter // compute a value which is beyond the end of the allocated object. 50524448Speter Value *Casted = V; 50624448Speter if (V->getType() != PTy) 50724448Speter Casted = InsertNoopCastOfTo(Casted, PTy); 50824448Speter Value *GEP = Builder.CreateGEP(Casted, 50924448Speter GepIndices.begin(), 51024448Speter GepIndices.end(), 51124448Speter "scevgep"); 51224448Speter Ops.push_back(SE.getUnknown(GEP)); 51312221Sbde rememberInstruction(GEP); 5141541Srgrimes return expand(SE.getAddExpr(Ops)); 5151541Srgrimes} 5161541Srgrimes 51712221Sbde/// isNonConstantNegative - Return true if the specified scev is negated, but 51882749Sdillon/// not a constant. 51982749Sdillonstatic bool isNonConstantNegative(const SCEV *F) { 52082749Sdillon const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(F); 5211541Srgrimes if (!Mul) return false; 5221549Srgrimes 52383366Sjulian // If there is a constant factor, it will be first. 52483366Sjulian const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); 5251541Srgrimes if (!SC) return false; 5261541Srgrimes 52783366Sjulian // Return true if the value is negative, this matches things like (-42 * V). 52877183Srwatson return SC->getValue()->getValue().isNegative(); 52977183Srwatson} 53082749Sdillon 5311541SrgrimesValue *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { 53277183Srwatson int NumOperands = S->getNumOperands(); 53377183Srwatson const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 53482749Sdillon 53582749Sdillon // Find the index of an operand to start with. Choose the operand with 53624448Speter // pointer type, if there is one, or the last operand otherwise. 53724448Speter int PIdx = 0; 53824448Speter for (; PIdx != NumOperands - 1; ++PIdx) 53924448Speter if (isa<PointerType>(S->getOperand(PIdx)->getType())) break; 54024448Speter 54172093Sasmodai // Expand code for the operand that we chose. 54224448Speter Value *V = expand(S->getOperand(PIdx)); 54324448Speter 54424448Speter // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the 54524448Speter // comments on expandAddToGEP for details. 54624448Speter if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) { 54724448Speter // Take the operand at PIdx out of the list. 54824448Speter const SmallVectorImpl<const SCEV *> &Ops = S->getOperands(); 54924448Speter SmallVector<const SCEV *, 8> NewOps; 55024448Speter NewOps.insert(NewOps.end(), Ops.begin(), Ops.begin() + PIdx); 55124448Speter NewOps.insert(NewOps.end(), Ops.begin() + PIdx + 1, Ops.end()); 55224448Speter // Make a GEP. 55377183Srwatson return expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, V); 55417994Sache } 55577183Srwatson 55617994Sache // Otherwise, we'll expand the rest of the SCEVAddExpr as plain integer 55724448Speter // arithmetic. 55877183Srwatson V = InsertNoopCastOfTo(V, Ty); 55924448Speter 56077183Srwatson // Emit a bunch of add instructions 56182749Sdillon for (int i = NumOperands-1; i >= 0; --i) { 56224448Speter if (i == PIdx) continue; 56377183Srwatson const SCEV *Op = S->getOperand(i); 56424448Speter if (isNonConstantNegative(Op)) { 5651541Srgrimes Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty); 56624448Speter V = InsertBinop(Instruction::Sub, V, W); 56724448Speter } else { 5681541Srgrimes Value *W = expandCodeFor(Op, Ty); 56917994Sache V = InsertBinop(Instruction::Add, V, W); 57024448Speter } 57177183Srwatson } 57217994Sache return V; 57377183Srwatson} 57417994Sache 57524448SpeterValue *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) { 57624448Speter const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 57765495Struckman int FirstOp = 0; // Set if we should emit a subtract. 57824448Speter if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0))) 57977183Srwatson if (SC->getValue()->isAllOnesValue()) 58077183Srwatson FirstOp = 1; 58165495Struckman 58224448Speter int i = S->getNumOperands()-2; 58324448Speter Value *V = expandCodeFor(S->getOperand(i+1), Ty); 58424448Speter 58524448Speter // Emit a bunch of multiply instructions 58624448Speter for (; i >= FirstOp; --i) { 58724448Speter Value *W = expandCodeFor(S->getOperand(i), Ty); 58824448Speter V = InsertBinop(Instruction::Mul, V, W); 58924448Speter } 59077183Srwatson 59177183Srwatson // -1 * ... ---> 0 - ... 59231891Ssef if (FirstOp == 1) 59324448Speter V = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), V); 5948141Sache return V; 59524448Speter} 59624448Speter 59724448SpeterValue *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) { 59824448Speter const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 59924448Speter 60077183Srwatson Value *LHS = expandCodeFor(S->getLHS(), Ty); 60177183Srwatson if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) { 60231891Ssef const APInt &RHS = SC->getValue()->getValue(); 60324448Speter if (RHS.isPowerOf2()) 60477183Srwatson return InsertBinop(Instruction::LShr, LHS, 60577183Srwatson ConstantInt::get(Ty, RHS.logBase2())); 60682749Sdillon } 60782749Sdillon 60882749Sdillon Value *RHS = expandCodeFor(S->getRHS(), Ty); 6091541Srgrimes return InsertBinop(Instruction::UDiv, LHS, RHS); 6101541Srgrimes} 61112221Sbde 6121541Srgrimes/// Move parts of Base into Rest to leave Base with the minimal 6131541Srgrimes/// expression that provides a pointer operand suitable for a 6141541Srgrimes/// GEP expansion. 61512221Sbdestatic void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest, 61682749Sdillon ScalarEvolution &SE) { 61782749Sdillon while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) { 61882749Sdillon Base = A->getStart(); 6191541Srgrimes Rest = SE.getAddExpr(Rest, 6201549Srgrimes SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()), 62183366Sjulian A->getStepRecurrence(SE), 62283366Sjulian A->getLoop())); 6231541Srgrimes } 6241541Srgrimes if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) { 62583366Sjulian Base = A->getOperand(A->getNumOperands()-1); 62677183Srwatson SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end()); 62777183Srwatson NewAddOps.back() = Rest; 62882749Sdillon Rest = SE.getAddExpr(NewAddOps); 6291541Srgrimes ExposePointerBase(Base, Rest, SE); 6301541Srgrimes } 63182749Sdillon} 63282749Sdillon 63377183Srwatson/// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand 63477183Srwatson/// the base addrec, which is the addrec without any non-loop-dominating 63577183Srwatson/// values, and return the PHI. 63682749SdillonPHINode * 63782749SdillonSCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized, 63882749Sdillon const Loop *L, 6391541Srgrimes const Type *ExpandTy, 6401541Srgrimes const Type *IntTy) { 6411541Srgrimes // Reuse a previously-inserted PHI, if present. 6421541Srgrimes for (BasicBlock::iterator I = L->getHeader()->begin(); 64377183Srwatson PHINode *PN = dyn_cast<PHINode>(I); ++I) 64477183Srwatson if (SE.isSCEVable(PN->getType()) && 64577183Srwatson (SE.getEffectiveSCEVType(PN->getType()) == 64631891Ssef SE.getEffectiveSCEVType(Normalized->getType())) && 64724449Speter SE.getSCEV(PN) == Normalized) 64877183Srwatson if (BasicBlock *LatchBlock = L->getLoopLatch()) { 64977183Srwatson Instruction *IncV = 65082749Sdillon cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock)); 65182749Sdillon 65282749Sdillon // Determine if this is a well-behaved chain of instructions leading 6531541Srgrimes // back to the PHI. It probably will be, if we're scanning an inner 6541541Srgrimes // loop already visited by LSR for example, but it wouldn't have 65512221Sbde // to be. 6561541Srgrimes do { 6571541Srgrimes if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV)) { 6581541Srgrimes IncV = 0; 65912221Sbde break; 66082749Sdillon } 66182749Sdillon IncV = dyn_cast<Instruction>(IncV->getOperand(0)); 66282749Sdillon if (!IncV) 6631541Srgrimes break; 6641549Srgrimes if (IncV->mayHaveSideEffects()) { 66583366Sjulian IncV = 0; 66683366Sjulian break; 6671541Srgrimes } 6681541Srgrimes } while (IncV != PN); 66983366Sjulian 67077183Srwatson if (IncV) { 67177183Srwatson // Ok, the add recurrence looks usable. 67282749Sdillon // Remember this PHI, even in post-inc mode. 6731541Srgrimes InsertedValues.insert(PN); 67477183Srwatson // Remember the increment. 67582749Sdillon IncV = cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock)); 67682749Sdillon rememberInstruction(IncV); 67777183Srwatson if (L == IVIncInsertLoop) 67824448Speter do { 67924448Speter if (SE.DT->dominates(IncV, IVIncInsertPos)) 68024448Speter break; 68124448Speter // Make sure the increment is where we want it. But don't move it 68224448Speter // down past a potential existing post-inc user. 68372093Sasmodai IncV->moveBefore(IVIncInsertPos); 68424448Speter IVIncInsertPos = IncV; 68524448Speter IncV = cast<Instruction>(IncV->getOperand(0)); 68624448Speter } while (IncV != PN); 68724448Speter return PN; 68824448Speter } 68977183Srwatson } 69017994Sache 69177183Srwatson // Save the original insertion point so we can restore it when we're done. 69217994Sache BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); 69324448Speter BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); 69477183Srwatson 69524448Speter // Expand code for the start value. 69682749Sdillon Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy, 69782749Sdillon L->getHeader()->begin()); 69882749Sdillon 69924448Speter // Expand code for the step value. Insert instructions right before the 70077183Srwatson // terminator corresponding to the back-edge. Do this before creating the PHI 70117994Sache // so that PHI reuse code doesn't see an incomplete PHI. If the stride is 70224448Speter // negative, insert a sub instead of an add for the increment (unless it's a 70324448Speter // constant, because subtracts of constants are canonicalized to adds). 70424448Speter const SCEV *Step = Normalized->getStepRecurrence(SE); 70524448Speter bool isPointer = isa<PointerType>(ExpandTy); 70624448Speter bool isNegative = !isPointer && isNonConstantNegative(Step); 70724448Speter if (isNegative) 70877183Srwatson Step = SE.getNegativeSCEV(Step); 70917994Sache Value *StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin()); 71077183Srwatson 71124448Speter // Create the PHI. 71224448Speter Builder.SetInsertPoint(L->getHeader(), L->getHeader()->begin()); 71324448Speter PHINode *PN = Builder.CreatePHI(ExpandTy, "lsr.iv"); 71424448Speter rememberInstruction(PN); 71524448Speter 71677183Srwatson // Create the step instructions and populate the PHI. 71777183Srwatson BasicBlock *Header = L->getHeader(); 71831891Ssef for (pred_iterator HPI = pred_begin(Header), HPE = pred_end(Header); 71924448Speter HPI != HPE; ++HPI) { 72024448Speter BasicBlock *Pred = *HPI; 72124448Speter 72224448Speter // Add a start value. 72324448Speter if (!L->contains(Pred)) { 72424448Speter PN->addIncoming(StartV, Pred); 72524448Speter continue; 72624448Speter } 72777183Srwatson 72877183Srwatson // Create a step value and add it to the PHI. If IVIncInsertLoop is 72931891Ssef // non-null and equal to the addrec's loop, insert the instructions 73024448Speter // at IVIncInsertPos. 7318141Sache Instruction *InsertPos = L == IVIncInsertLoop ? 73224448Speter IVIncInsertPos : Pred->getTerminator(); 73324448Speter Builder.SetInsertPoint(InsertPos->getParent(), InsertPos); 73424448Speter Value *IncV; 73524448Speter // If the PHI is a pointer, use a GEP, otherwise use an add or sub. 73677183Srwatson if (isPointer) { 73777183Srwatson const PointerType *GEPPtrTy = cast<PointerType>(ExpandTy); 73831891Ssef // If the step isn't constant, don't use an implicitly scaled GEP, because 73924448Speter // that would require a multiply inside the loop. 74077183Srwatson if (!isa<ConstantInt>(StepV)) 74177183Srwatson GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()), 74282749Sdillon GEPPtrTy->getAddressSpace()); 74382749Sdillon const SCEV *const StepArray[1] = { SE.getSCEV(StepV) }; 74482749Sdillon IncV = expandAddToGEP(StepArray, StepArray+1, GEPPtrTy, IntTy, PN); 7451541Srgrimes if (IncV->getType() != PN->getType()) { 7461541Srgrimes IncV = Builder.CreateBitCast(IncV, PN->getType(), "tmp"); 74712221Sbde rememberInstruction(IncV); 7481541Srgrimes } 7491541Srgrimes } else { 7501541Srgrimes IncV = isNegative ? 75112221Sbde Builder.CreateSub(PN, StepV, "lsr.iv.next") : 75282749Sdillon Builder.CreateAdd(PN, StepV, "lsr.iv.next"); 75382749Sdillon rememberInstruction(IncV); 75482749Sdillon } 7551541Srgrimes PN->addIncoming(IncV, Pred); 7561549Srgrimes } 75783366Sjulian 75883366Sjulian // Restore the original insert point. 7591541Srgrimes if (SaveInsertBB) 7601541Srgrimes restoreInsertPoint(SaveInsertBB, SaveInsertPt); 76183366Sjulian 76277183Srwatson // Remember this PHI, even in post-inc mode. 76377183Srwatson InsertedValues.insert(PN); 76482749Sdillon 7651541Srgrimes return PN; 7661541Srgrimes} 76782749Sdillon 76882749SdillonValue *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) { 76977183Srwatson const Type *STy = S->getType(); 77077183Srwatson const Type *IntTy = SE.getEffectiveSCEVType(STy); 77177183Srwatson const Loop *L = S->getLoop(); 77282749Sdillon 77382749Sdillon // Determine a normalized form of this expression, which is the expression 77482749Sdillon // before any post-inc adjustment is made. 77577183Srwatson const SCEVAddRecExpr *Normalized = S; 77677183Srwatson if (L == PostIncLoop) { 77777183Srwatson const SCEV *Step = S->getStepRecurrence(SE); 77831891Ssef Normalized = cast<SCEVAddRecExpr>(SE.getMinusSCEV(S, Step)); 77924449Speter } 78077183Srwatson 78177183Srwatson // Strip off any non-loop-dominating component from the addrec start. 78282749Sdillon const SCEV *Start = Normalized->getStart(); 78382749Sdillon const SCEV *PostLoopOffset = 0; 78482749Sdillon if (!Start->properlyDominates(L->getHeader(), SE.DT)) { 7851541Srgrimes PostLoopOffset = Start; 7861541Srgrimes Start = SE.getIntegerSCEV(0, Normalized->getType()); 78712221Sbde Normalized = 7881541Srgrimes cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, 7891541Srgrimes Normalized->getStepRecurrence(SE), 7901541Srgrimes Normalized->getLoop())); 7911541Srgrimes } 79212221Sbde 79382749Sdillon // Strip off any non-loop-dominating component from the addrec step. 79482749Sdillon const SCEV *Step = Normalized->getStepRecurrence(SE); 79582749Sdillon const SCEV *PostLoopScale = 0; 7961541Srgrimes if (!Step->hasComputableLoopEvolution(L) && 7971549Srgrimes !Step->dominates(L->getHeader(), SE.DT)) { 79883366Sjulian PostLoopScale = Step; 79983366Sjulian Step = SE.getIntegerSCEV(1, Normalized->getType()); 8001541Srgrimes Normalized = 8011541Srgrimes cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, Step, 80283366Sjulian Normalized->getLoop())); 80377183Srwatson } 80477183Srwatson 8051541Srgrimes // Expand the core addrec. If we need post-loop scaling, force it to 8061541Srgrimes // expand to an integer type to avoid the need for additional casting. 80782749Sdillon const Type *ExpandTy = PostLoopScale ? IntTy : STy; 80882749Sdillon PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy); 80977183Srwatson 81077183Srwatson // Accomodate post-inc mode, if necessary. 81177183Srwatson Value *Result; 81282749Sdillon if (L != PostIncLoop) 81382749Sdillon Result = PN; 81482749Sdillon else { 81582749Sdillon // In PostInc mode, use the post-incremented value. 81682749Sdillon BasicBlock *LatchBlock = L->getLoopLatch(); 81724447Speter assert(LatchBlock && "PostInc mode requires a unique loop latch!"); 81824447Speter Result = PN->getIncomingValueForBlock(LatchBlock); 81924447Speter } 82024447Speter 82177183Srwatson // Re-apply any non-loop-dominating scale. 82224447Speter if (PostLoopScale) { 82324447Speter Result = InsertNoopCastOfTo(Result, IntTy); 82424447Speter Result = Builder.CreateMul(Result, 82524447Speter expandCodeFor(PostLoopScale, IntTy)); 82624447Speter rememberInstruction(Result); 82724447Speter } 82824447Speter 82977183Srwatson // Re-apply any non-loop-dominating offset. 83024447Speter if (PostLoopOffset) { 83124447Speter if (const PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) { 83277183Srwatson const SCEV *const OffsetArray[1] = { PostLoopOffset }; 83377183Srwatson Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result); 83482749Sdillon } else { 83577183Srwatson Result = InsertNoopCastOfTo(Result, IntTy); 83677183Srwatson Result = Builder.CreateAdd(Result, 83724447Speter expandCodeFor(PostLoopOffset, IntTy)); 83831891Ssef rememberInstruction(Result); 83977183Srwatson } 84077183Srwatson } 84182749Sdillon 84282749Sdillon return Result; 84382749Sdillon} 8441541Srgrimes 8451541SrgrimesValue *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { 84612221Sbde if (!CanonicalMode) return expandAddRecExprLiterally(S); 8471541Srgrimes 8489238Sache const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 8499238Sache const Loop *L = S->getLoop(); 8501541Srgrimes 85112221Sbde // First check for an existing canonical IV in a suitable type. 85282749Sdillon PHINode *CanonicalIV = 0; 85382749Sdillon if (PHINode *PN = L->getCanonicalInductionVariable()) 85482749Sdillon if (SE.isSCEVable(PN->getType()) && 8551541Srgrimes isa<IntegerType>(SE.getEffectiveSCEVType(PN->getType())) && 8561549Srgrimes SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty)) 85783366Sjulian CanonicalIV = PN; 85883366Sjulian 8591541Srgrimes // Rewrite an AddRec in terms of the canonical induction variable, if 8601541Srgrimes // its type is more narrow. 86183366Sjulian if (CanonicalIV && 86277183Srwatson SE.getTypeSizeInBits(CanonicalIV->getType()) > 86377183Srwatson SE.getTypeSizeInBits(Ty)) { 86482749Sdillon const SmallVectorImpl<const SCEV *> &Ops = S->getOperands(); 8651541Srgrimes SmallVector<const SCEV *, 4> NewOps(Ops.size()); 8669238Sache for (unsigned i = 0, e = Ops.size(); i != e; ++i) 8679238Sache NewOps[i] = SE.getAnyExtendExpr(Ops[i], CanonicalIV->getType()); 86882749Sdillon Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop())); 86982749Sdillon BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); 87082749Sdillon BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); 87177183Srwatson BasicBlock::iterator NewInsertPt = 87277183Srwatson llvm::next(BasicBlock::iterator(cast<Instruction>(V))); 87377183Srwatson while (isa<PHINode>(NewInsertPt)) ++NewInsertPt; 87477183Srwatson V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0, 87577183Srwatson NewInsertPt); 87682749Sdillon restoreInsertPoint(SaveInsertBB, SaveInsertPt); 87782749Sdillon return V; 87882749Sdillon } 87977183Srwatson 88077183Srwatson // {X,+,F} --> X + {0,+,F} 88177183Srwatson if (!S->getStart()->isZero()) { 88231891Ssef const SmallVectorImpl<const SCEV *> &SOperands = S->getOperands(); 88324450Speter SmallVector<const SCEV *, 4> NewOps(SOperands.begin(), SOperands.end()); 88477183Srwatson NewOps[0] = SE.getIntegerSCEV(0, Ty); 88577183Srwatson const SCEV *Rest = SE.getAddRecExpr(NewOps, L); 88631891Ssef 8878135Sache // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the 88877183Srwatson // comments on expandAddToGEP for details. 88977183Srwatson const SCEV *Base = S->getStart(); 89077183Srwatson const SCEV *RestArray[1] = { Rest }; 89131891Ssef // Dig into the expression to find the pointer base for a GEP. 89224450Speter ExposePointerBase(Base, RestArray[0], SE); 89377183Srwatson // If we found a pointer, expand the AddRec with a GEP. 89477183Srwatson if (const PointerType *PTy = dyn_cast<PointerType>(Base->getType())) { 89582749Sdillon // Make sure the Base isn't something exotic, such as a multiplied 89682749Sdillon // or divided pointer value. In those cases, the result type isn't 89782749Sdillon // actually a pointer type. 8981541Srgrimes if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) { 8991541Srgrimes Value *StartV = expand(Base); 90012221Sbde assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!"); 9011541Srgrimes return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV); 9029238Sache } 9039238Sache } 9041541Srgrimes 90512221Sbde // Just do a normal add. Pre-expand the operands to suppress folding. 90682749Sdillon return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())), 90782749Sdillon SE.getUnknown(expand(Rest)))); 90882749Sdillon } 9091541Srgrimes 9101549Srgrimes // {0,+,1} --> Insert a canonical induction variable into the loop! 91183366Sjulian if (S->isAffine() && 91283366Sjulian S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) { 9131541Srgrimes // If there's a canonical IV, just use it. 9141541Srgrimes if (CanonicalIV) { 91583366Sjulian assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) && 91677183Srwatson "IVs with types different from the canonical IV should " 91777183Srwatson "already have been handled!"); 91882749Sdillon return CanonicalIV; 9191541Srgrimes } 9209238Sache 9219238Sache // Create and insert the PHI node for the induction variable in the 92282749Sdillon // specified loop. 92382749Sdillon BasicBlock *Header = L->getHeader(); 92482749Sdillon PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin()); 92577183Srwatson rememberInstruction(PN); 92677183Srwatson 92777183Srwatson Constant *One = ConstantInt::get(Ty, 1); 92877183Srwatson for (pred_iterator HPI = pred_begin(Header), HPE = pred_end(Header); 92977183Srwatson HPI != HPE; ++HPI) 93082749Sdillon if (L->contains(*HPI)) { 93182749Sdillon // Insert a unit add instruction right before the terminator 93282749Sdillon // corresponding to the back-edge. 9339238Sache Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next", 93477183Srwatson (*HPI)->getTerminator()); 93577183Srwatson rememberInstruction(Add); 93677183Srwatson PN->addIncoming(Add, *HPI); 93731891Ssef } else { 93824450Speter PN->addIncoming(Constant::getNullValue(Ty), *HPI); 93977183Srwatson } 94077183Srwatson } 94131891Ssef 94224450Speter // {0,+,F} --> {0,+,1} * F 94377183Srwatson // Get the canonical induction variable I for this loop. 94477183Srwatson Value *I = CanonicalIV ? 94577183Srwatson CanonicalIV : 94631891Ssef getOrInsertCanonicalInductionVariable(L, Ty); 94724450Speter 94877812Sru // If this is a simple linear addrec, emit it now as a special case. 94977812Sru if (S->isAffine()) // {0,+,F} --> i*F 95082749Sdillon return 95182749Sdillon expand(SE.getTruncateOrNoop( 95282749Sdillon SE.getMulExpr(SE.getUnknown(I), 9531541Srgrimes SE.getNoopOrAnyExtend(S->getOperand(1), 9541541Srgrimes I->getType())), 95556115Speter Ty)); 95656115Speter 95756115Speter // If this is a chain of recurrences, turn it into a closed form, using the 95856115Speter // folders, then expandCodeFor the closed form. This allows the folders to 95956115Speter // simplify the expression without having to build a bunch of special code 96024453Speter // into this folder. 96156115Speter const SCEV *IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV. 96256115Speter 96356115Speter // Promote S up to the canonical IV type, if the cast is foldable. 96456115Speter const SCEV *NewS = S; 96556115Speter const SCEV *Ext = SE.getNoopOrAnyExtend(S, I->getType()); 96656115Speter if (isa<SCEVAddRecExpr>(Ext)) 96782749Sdillon NewS = Ext; 96882749Sdillon 96982749Sdillon const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE); 97056115Speter //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n"; 97156115Speter 97283366Sjulian // Truncate the result down to the original type, if needed. 97383366Sjulian const SCEV *T = SE.getTruncateOrNoop(V, Ty); 97456115Speter return expand(T); 97556115Speter} 97683366Sjulian 97777183SrwatsonValue *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) { 97877183Srwatson const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 97956115Speter Value *V = expandCodeFor(S->getOperand(), 98056115Speter SE.getEffectiveSCEVType(S->getOperand()->getType())); 98156115Speter Value *I = Builder.CreateTrunc(V, Ty, "tmp"); 98256115Speter rememberInstruction(I); 98356115Speter return I; 98482749Sdillon} 98582749Sdillon 98677183SrwatsonValue *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) { 98777183Srwatson const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 98877183Srwatson Value *V = expandCodeFor(S->getOperand(), 98977183Srwatson SE.getEffectiveSCEVType(S->getOperand()->getType())); 99077183Srwatson Value *I = Builder.CreateZExt(V, Ty, "tmp"); 99177183Srwatson rememberInstruction(I); 99277183Srwatson return I; 99377183Srwatson} 99477183Srwatson 99577183SrwatsonValue *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) { 99682749Sdillon const Type *Ty = SE.getEffectiveSCEVType(S->getType()); 99782749Sdillon Value *V = expandCodeFor(S->getOperand(), 99882749Sdillon SE.getEffectiveSCEVType(S->getOperand()->getType())); 99977183Srwatson Value *I = Builder.CreateSExt(V, Ty, "tmp"); 100077183Srwatson rememberInstruction(I); 100177183Srwatson return I; 100277183Srwatson} 100356115Speter 100456115SpeterValue *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) { 100577183Srwatson Value *LHS = expand(S->getOperand(S->getNumOperands()-1)); 100677183Srwatson const Type *Ty = LHS->getType(); 100756115Speter for (int i = S->getNumOperands()-2; i >= 0; --i) { 100856115Speter // In the case of mixed integer and pointer types, do the 100977183Srwatson // rest of the comparisons as integer. 101077183Srwatson if (S->getOperand(i)->getType() != Ty) { 101156115Speter Ty = SE.getEffectiveSCEVType(Ty); 101256115Speter LHS = InsertNoopCastOfTo(LHS, Ty); 101377183Srwatson } 101477183Srwatson Value *RHS = expandCodeFor(S->getOperand(i), Ty); 101582749Sdillon Value *ICmp = Builder.CreateICmpSGT(LHS, RHS, "tmp"); 101682749Sdillon rememberInstruction(ICmp); 101782749Sdillon Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax"); 101882749Sdillon rememberInstruction(Sel); 101956115Speter LHS = Sel; 102056115Speter } 102156115Speter // In the case of mixed integer and pointer types, cast the 102256115Speter // final result back to the pointer type. 102356115Speter if (LHS->getType() != S->getType()) 102456115Speter LHS = InsertNoopCastOfTo(LHS, S->getType()); 102556115Speter return LHS; 102656115Speter} 102756115Speter 102856115SpeterValue *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) { 102956115Speter Value *LHS = expand(S->getOperand(S->getNumOperands()-1)); 103056115Speter const Type *Ty = LHS->getType(); 103156115Speter for (int i = S->getNumOperands()-2; i >= 0; --i) { 103256115Speter // In the case of mixed integer and pointer types, do the 103382749Sdillon // rest of the comparisons as integer. 103482749Sdillon if (S->getOperand(i)->getType() != Ty) { 103582749Sdillon Ty = SE.getEffectiveSCEVType(Ty); 103656115Speter LHS = InsertNoopCastOfTo(LHS, Ty); 103756115Speter } 103883366Sjulian Value *RHS = expandCodeFor(S->getOperand(i), Ty); 103983366Sjulian Value *ICmp = Builder.CreateICmpUGT(LHS, RHS, "tmp"); 104056115Speter rememberInstruction(ICmp); 104156115Speter Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax"); 104283366Sjulian rememberInstruction(Sel); 104377183Srwatson LHS = Sel; 104477183Srwatson } 104556115Speter // In the case of mixed integer and pointer types, cast the 104656115Speter // final result back to the pointer type. 104756115Speter if (LHS->getType() != S->getType()) 104856115Speter LHS = InsertNoopCastOfTo(LHS, S->getType()); 104956115Speter return LHS; 105082749Sdillon} 105182749Sdillon 105277183SrwatsonValue *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) { 105377183Srwatson // Expand the code for this SCEV. 105477183Srwatson Value *V = expand(SH); 105577183Srwatson if (Ty) { 105677183Srwatson assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) && 105777183Srwatson "non-trivial casts should be done with the SCEVs directly!"); 105877183Srwatson V = InsertNoopCastOfTo(V, Ty); 105977183Srwatson } 106077183Srwatson return V; 106177183Srwatson} 106282749Sdillon 106382749SdillonValue *SCEVExpander::expand(const SCEV *S) { 106482749Sdillon // Compute an insertion point for this SCEV object. Hoist the instructions 106577183Srwatson // as far out in the loop nest as possible. 106677183Srwatson Instruction *InsertPt = Builder.GetInsertPoint(); 106777183Srwatson for (Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock()); ; 106856115Speter L = L->getParentLoop()) 106956115Speter if (S->isLoopInvariant(L)) { 107077183Srwatson if (!L) break; 107177183Srwatson if (BasicBlock *Preheader = L->getLoopPreheader()) 107256115Speter InsertPt = Preheader->getTerminator(); 107356115Speter } else { 107477183Srwatson // If the SCEV is computable at this level, insert it into the header 107577183Srwatson // after the PHIs (and after any other instructions that we've inserted 107656115Speter // there) so that it is guaranteed to dominate any user inside the loop. 107756115Speter if (L && S->hasComputableLoopEvolution(L)) 107877183Srwatson InsertPt = L->getHeader()->getFirstNonPHI(); 107977183Srwatson while (isInsertedInstruction(InsertPt)) 108082749Sdillon InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); 108182749Sdillon break; 108282749Sdillon } 108382749Sdillon 108456115Speter // Check to see if we already expanded this here. 108556115Speter std::map<std::pair<const SCEV *, Instruction *>, 108656115Speter AssertingVH<Value> >::iterator I = 108756115Speter InsertedExpressions.find(std::make_pair(S, InsertPt)); 108856115Speter if (I != InsertedExpressions.end()) 108956115Speter return I->second; 109056115Speter 109156115Speter BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); 109256115Speter BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); 109382749Sdillon Builder.SetInsertPoint(InsertPt->getParent(), InsertPt); 109482749Sdillon 109582749Sdillon // Expand the expression into instructions. 109656115Speter Value *V = visit(S); 109756115Speter 109883366Sjulian // Remember the expanded value for this SCEV at this location. 109983366Sjulian if (!PostIncLoop) 110056115Speter InsertedExpressions[std::make_pair(S, InsertPt)] = V; 110156115Speter 110282749Sdillon restoreInsertPoint(SaveInsertBB, SaveInsertPt); 110383366Sjulian return V; 110456115Speter} 110556115Speter 110682749Sdillonvoid SCEVExpander::rememberInstruction(Value *I) { 110782749Sdillon if (!PostIncLoop) 110882749Sdillon InsertedValues.insert(I); 110956115Speter 111077183Srwatson // If we just claimed an existing instruction and that instruction had 111177183Srwatson // been the insert point, adjust the insert point forward so that 111256115Speter // subsequently inserted code will be dominated. 111377183Srwatson if (Builder.GetInsertPoint() == I) { 111477183Srwatson BasicBlock::iterator It = cast<Instruction>(I); 111556115Speter do { ++It; } while (isInsertedInstruction(It)); 111677183Srwatson Builder.SetInsertPoint(Builder.GetInsertBlock(), It); 111777183Srwatson } 111882749Sdillon} 111956115Speter 112056115Spetervoid SCEVExpander::restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I) { 112156115Speter // If we aquired more instructions since the old insert point was saved, 112256115Speter // advance past them. 112356115Speter while (isInsertedInstruction(I)) ++I; 112456115Speter 112556115Speter Builder.SetInsertPoint(BB, I); 112656115Speter} 112756115Speter 112856115Speter/// getOrInsertCanonicalInductionVariable - This method returns the 112982749Sdillon/// canonical induction variable of the specified type for the specified 113082749Sdillon/// loop (inserting one if there is none). A canonical induction variable 113182749Sdillon/// starts at zero and steps by one on each iteration. 113256115SpeterValue * 113356115SpeterSCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L, 113483366Sjulian const Type *Ty) { 113583366Sjulian assert(Ty->isIntegerTy() && "Can only insert integer induction variables!"); 113656115Speter const SCEV *H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty), 113756115Speter SE.getIntegerSCEV(1, Ty), L); 113882749Sdillon BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); 113983366Sjulian BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); 114056115Speter Value *V = expandCodeFor(H, 0, L->getHeader()->begin()); 114156115Speter if (SaveInsertBB) 114282749Sdillon restoreInsertPoint(SaveInsertBB, SaveInsertPt); 114382749Sdillon return V; 114482749Sdillon} 114556115Speter