| //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the implementation of the scalar evolution expander, |
| // which is used to generate the code corresponding to a given scalar evolution |
| // expression. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/ScalarEvolutionExpander.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/IntrinsicInst.h" |
| #include "llvm/LLVMContext.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/ADT/STLExtras.h" |
| |
| using namespace llvm; |
| |
| /// ReuseOrCreateCast - Arrange for there to be a cast of V to Ty at IP, |
| /// reusing an existing cast if a suitable one exists, moving an existing |
| /// cast if a suitable one exists but isn't in the right place, or |
| /// creating a new one. |
| Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty, |
| Instruction::CastOps Op, |
| BasicBlock::iterator IP) { |
| // Check to see if there is already a cast! |
| for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); |
| UI != E; ++UI) { |
| User *U = *UI; |
| if (U->getType() == Ty) |
| if (CastInst *CI = dyn_cast<CastInst>(U)) |
| if (CI->getOpcode() == Op) { |
| // If the cast isn't where we want it, fix it. |
| if (BasicBlock::iterator(CI) != IP) { |
| // Create a new cast, and leave the old cast in place in case |
| // it is being used as an insert point. Clear its operand |
| // so that it doesn't hold anything live. |
| Instruction *NewCI = CastInst::Create(Op, V, Ty, "", IP); |
| NewCI->takeName(CI); |
| CI->replaceAllUsesWith(NewCI); |
| CI->setOperand(0, UndefValue::get(V->getType())); |
| rememberInstruction(NewCI); |
| return NewCI; |
| } |
| rememberInstruction(CI); |
| return CI; |
| } |
| } |
| |
| // Create a new cast. |
| Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), IP); |
| rememberInstruction(I); |
| return I; |
| } |
| |
| /// InsertNoopCastOfTo - Insert a cast of V to the specified type, |
| /// which must be possible with a noop cast, doing what we can to share |
| /// the casts. |
| Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) { |
| Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false); |
| assert((Op == Instruction::BitCast || |
| Op == Instruction::PtrToInt || |
| Op == Instruction::IntToPtr) && |
| "InsertNoopCastOfTo cannot perform non-noop casts!"); |
| assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) && |
| "InsertNoopCastOfTo cannot change sizes!"); |
| |
| // Short-circuit unnecessary bitcasts. |
| if (Op == Instruction::BitCast && V->getType() == Ty) |
| return V; |
| |
| // Short-circuit unnecessary inttoptr<->ptrtoint casts. |
| if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) && |
| SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) { |
| if (CastInst *CI = dyn_cast<CastInst>(V)) |
| if ((CI->getOpcode() == Instruction::PtrToInt || |
| CI->getOpcode() == Instruction::IntToPtr) && |
| SE.getTypeSizeInBits(CI->getType()) == |
| SE.getTypeSizeInBits(CI->getOperand(0)->getType())) |
| return CI->getOperand(0); |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| if ((CE->getOpcode() == Instruction::PtrToInt || |
| CE->getOpcode() == Instruction::IntToPtr) && |
| SE.getTypeSizeInBits(CE->getType()) == |
| SE.getTypeSizeInBits(CE->getOperand(0)->getType())) |
| return CE->getOperand(0); |
| } |
| |
| // Fold a cast of a constant. |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(Op, C, Ty); |
| |
| // Cast the argument at the beginning of the entry block, after |
| // any bitcasts of other arguments. |
| if (Argument *A = dyn_cast<Argument>(V)) { |
| BasicBlock::iterator IP = A->getParent()->getEntryBlock().begin(); |
| while ((isa<BitCastInst>(IP) && |
| isa<Argument>(cast<BitCastInst>(IP)->getOperand(0)) && |
| cast<BitCastInst>(IP)->getOperand(0) != A) || |
| isa<DbgInfoIntrinsic>(IP)) |
| ++IP; |
| return ReuseOrCreateCast(A, Ty, Op, IP); |
| } |
| |
| // Cast the instruction immediately after the instruction. |
| Instruction *I = cast<Instruction>(V); |
| BasicBlock::iterator IP = I; ++IP; |
| if (InvokeInst *II = dyn_cast<InvokeInst>(I)) |
| IP = II->getNormalDest()->begin(); |
| while (isa<PHINode>(IP) || isa<DbgInfoIntrinsic>(IP)) ++IP; |
| return ReuseOrCreateCast(I, Ty, Op, IP); |
| } |
| |
| /// InsertBinop - Insert the specified binary operator, doing a small amount |
| /// of work to avoid inserting an obviously redundant operation. |
| Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, |
| Value *LHS, Value *RHS) { |
| // Fold a binop with constant operands. |
| if (Constant *CLHS = dyn_cast<Constant>(LHS)) |
| if (Constant *CRHS = dyn_cast<Constant>(RHS)) |
| return ConstantExpr::get(Opcode, CLHS, CRHS); |
| |
| // Do a quick scan to see if we have this binop nearby. If so, reuse it. |
| unsigned ScanLimit = 6; |
| BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin(); |
| // Scanning starts from the last instruction before the insertion point. |
| BasicBlock::iterator IP = Builder.GetInsertPoint(); |
| if (IP != BlockBegin) { |
| --IP; |
| for (; ScanLimit; --IP, --ScanLimit) { |
| // Don't count dbg.value against the ScanLimit, to avoid perturbing the |
| // generated code. |
| if (isa<DbgInfoIntrinsic>(IP)) |
| ScanLimit++; |
| if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS && |
| IP->getOperand(1) == RHS) |
| return IP; |
| if (IP == BlockBegin) break; |
| } |
| } |
| |
| // Save the original insertion point so we can restore it when we're done. |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| |
| // Move the insertion point out of as many loops as we can. |
| while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) { |
| if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break; |
| BasicBlock *Preheader = L->getLoopPreheader(); |
| if (!Preheader) break; |
| |
| // Ok, move up a level. |
| Builder.SetInsertPoint(Preheader, Preheader->getTerminator()); |
| } |
| |
| // If we haven't found this binop, insert it. |
| Instruction *BO = cast<Instruction>(Builder.CreateBinOp(Opcode, LHS, RHS, "tmp")); |
| BO->setDebugLoc(SaveInsertPt->getDebugLoc()); |
| rememberInstruction(BO); |
| |
| // Restore the original insert point. |
| if (SaveInsertBB) |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| |
| return BO; |
| } |
| |
| /// FactorOutConstant - Test if S is divisible by Factor, using signed |
| /// division. If so, update S with Factor divided out and return true. |
| /// S need not be evenly divisible if a reasonable remainder can be |
| /// computed. |
| /// TODO: When ScalarEvolution gets a SCEVSDivExpr, this can be made |
| /// unnecessary; in its place, just signed-divide Ops[i] by the scale and |
| /// check to see if the divide was folded. |
| static bool FactorOutConstant(const SCEV *&S, |
| const SCEV *&Remainder, |
| const SCEV *Factor, |
| ScalarEvolution &SE, |
| const TargetData *TD) { |
| // Everything is divisible by one. |
| if (Factor->isOne()) |
| return true; |
| |
| // x/x == 1. |
| if (S == Factor) { |
| S = SE.getConstant(S->getType(), 1); |
| return true; |
| } |
| |
| // For a Constant, check for a multiple of the given factor. |
| if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) { |
| // 0/x == 0. |
| if (C->isZero()) |
| return true; |
| // Check for divisibility. |
| if (const SCEVConstant *FC = dyn_cast<SCEVConstant>(Factor)) { |
| ConstantInt *CI = |
| ConstantInt::get(SE.getContext(), |
| C->getValue()->getValue().sdiv( |
| FC->getValue()->getValue())); |
| // If the quotient is zero and the remainder is non-zero, reject |
| // the value at this scale. It will be considered for subsequent |
| // smaller scales. |
| if (!CI->isZero()) { |
| const SCEV *Div = SE.getConstant(CI); |
| S = Div; |
| Remainder = |
| SE.getAddExpr(Remainder, |
| SE.getConstant(C->getValue()->getValue().srem( |
| FC->getValue()->getValue()))); |
| return true; |
| } |
| } |
| } |
| |
| // In a Mul, check if there is a constant operand which is a multiple |
| // of the given factor. |
| if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) { |
| if (TD) { |
| // With TargetData, the size is known. Check if there is a constant |
| // operand which is a multiple of the given factor. If so, we can |
| // factor it. |
| const SCEVConstant *FC = cast<SCEVConstant>(Factor); |
| if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0))) |
| if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) { |
| SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end()); |
| NewMulOps[0] = |
| SE.getConstant(C->getValue()->getValue().sdiv( |
| FC->getValue()->getValue())); |
| S = SE.getMulExpr(NewMulOps); |
| return true; |
| } |
| } else { |
| // Without TargetData, check if Factor can be factored out of any of the |
| // Mul's operands. If so, we can just remove it. |
| for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { |
| const SCEV *SOp = M->getOperand(i); |
| const SCEV *Remainder = SE.getConstant(SOp->getType(), 0); |
| if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) && |
| Remainder->isZero()) { |
| SmallVector<const SCEV *, 4> NewMulOps(M->op_begin(), M->op_end()); |
| NewMulOps[i] = SOp; |
| S = SE.getMulExpr(NewMulOps); |
| return true; |
| } |
| } |
| } |
| } |
| |
| // In an AddRec, check if both start and step are divisible. |
| if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) { |
| const SCEV *Step = A->getStepRecurrence(SE); |
| const SCEV *StepRem = SE.getConstant(Step->getType(), 0); |
| if (!FactorOutConstant(Step, StepRem, Factor, SE, TD)) |
| return false; |
| if (!StepRem->isZero()) |
| return false; |
| const SCEV *Start = A->getStart(); |
| if (!FactorOutConstant(Start, Remainder, Factor, SE, TD)) |
| return false; |
| // FIXME: can use A->getNoWrapFlags(FlagNW) |
| S = SE.getAddRecExpr(Start, Step, A->getLoop(), SCEV::FlagAnyWrap); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /// SimplifyAddOperands - Sort and simplify a list of add operands. NumAddRecs |
| /// is the number of SCEVAddRecExprs present, which are kept at the end of |
| /// the list. |
| /// |
| static void SimplifyAddOperands(SmallVectorImpl<const SCEV *> &Ops, |
| Type *Ty, |
| ScalarEvolution &SE) { |
| unsigned NumAddRecs = 0; |
| for (unsigned i = Ops.size(); i > 0 && isa<SCEVAddRecExpr>(Ops[i-1]); --i) |
| ++NumAddRecs; |
| // Group Ops into non-addrecs and addrecs. |
| SmallVector<const SCEV *, 8> NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs); |
| SmallVector<const SCEV *, 8> AddRecs(Ops.end() - NumAddRecs, Ops.end()); |
| // Let ScalarEvolution sort and simplify the non-addrecs list. |
| const SCEV *Sum = NoAddRecs.empty() ? |
| SE.getConstant(Ty, 0) : |
| SE.getAddExpr(NoAddRecs); |
| // If it returned an add, use the operands. Otherwise it simplified |
| // the sum into a single value, so just use that. |
| Ops.clear(); |
| if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Sum)) |
| Ops.append(Add->op_begin(), Add->op_end()); |
| else if (!Sum->isZero()) |
| Ops.push_back(Sum); |
| // Then append the addrecs. |
| Ops.append(AddRecs.begin(), AddRecs.end()); |
| } |
| |
| /// SplitAddRecs - Flatten a list of add operands, moving addrec start values |
| /// out to the top level. For example, convert {a + b,+,c} to a, b, {0,+,d}. |
| /// This helps expose more opportunities for folding parts of the expressions |
| /// into GEP indices. |
| /// |
| static void SplitAddRecs(SmallVectorImpl<const SCEV *> &Ops, |
| Type *Ty, |
| ScalarEvolution &SE) { |
| // Find the addrecs. |
| SmallVector<const SCEV *, 8> AddRecs; |
| for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Ops[i])) { |
| const SCEV *Start = A->getStart(); |
| if (Start->isZero()) break; |
| const SCEV *Zero = SE.getConstant(Ty, 0); |
| AddRecs.push_back(SE.getAddRecExpr(Zero, |
| A->getStepRecurrence(SE), |
| A->getLoop(), |
| // FIXME: A->getNoWrapFlags(FlagNW) |
| SCEV::FlagAnyWrap)); |
| if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Start)) { |
| Ops[i] = Zero; |
| Ops.append(Add->op_begin(), Add->op_end()); |
| e += Add->getNumOperands(); |
| } else { |
| Ops[i] = Start; |
| } |
| } |
| if (!AddRecs.empty()) { |
| // Add the addrecs onto the end of the list. |
| Ops.append(AddRecs.begin(), AddRecs.end()); |
| // Resort the operand list, moving any constants to the front. |
| SimplifyAddOperands(Ops, Ty, SE); |
| } |
| } |
| |
| /// expandAddToGEP - Expand an addition expression with a pointer type into |
| /// a GEP instead of using ptrtoint+arithmetic+inttoptr. This helps |
| /// BasicAliasAnalysis and other passes analyze the result. See the rules |
| /// for getelementptr vs. inttoptr in |
| /// http://llvm.org/docs/LangRef.html#pointeraliasing |
| /// for details. |
| /// |
| /// Design note: The correctness of using getelementptr here depends on |
| /// ScalarEvolution not recognizing inttoptr and ptrtoint operators, as |
| /// they may introduce pointer arithmetic which may not be safely converted |
| /// into getelementptr. |
| /// |
| /// Design note: It might seem desirable for this function to be more |
| /// loop-aware. If some of the indices are loop-invariant while others |
| /// aren't, it might seem desirable to emit multiple GEPs, keeping the |
| /// loop-invariant portions of the overall computation outside the loop. |
| /// However, there are a few reasons this is not done here. Hoisting simple |
| /// arithmetic is a low-level optimization that often isn't very |
| /// important until late in the optimization process. In fact, passes |
| /// like InstructionCombining will combine GEPs, even if it means |
| /// pushing loop-invariant computation down into loops, so even if the |
| /// GEPs were split here, the work would quickly be undone. The |
| /// LoopStrengthReduction pass, which is usually run quite late (and |
| /// after the last InstructionCombining pass), takes care of hoisting |
| /// loop-invariant portions of expressions, after considering what |
| /// can be folded using target addressing modes. |
| /// |
| Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, |
| const SCEV *const *op_end, |
| PointerType *PTy, |
| Type *Ty, |
| Value *V) { |
| Type *ElTy = PTy->getElementType(); |
| SmallVector<Value *, 4> GepIndices; |
| SmallVector<const SCEV *, 8> Ops(op_begin, op_end); |
| bool AnyNonZeroIndices = false; |
| |
| // Split AddRecs up into parts as either of the parts may be usable |
| // without the other. |
| SplitAddRecs(Ops, Ty, SE); |
| |
| // Descend down the pointer's type and attempt to convert the other |
| // operands into GEP indices, at each level. The first index in a GEP |
| // indexes into the array implied by the pointer operand; the rest of |
| // the indices index into the element or field type selected by the |
| // preceding index. |
| for (;;) { |
| // If the scale size is not 0, attempt to factor out a scale for |
| // array indexing. |
| SmallVector<const SCEV *, 8> ScaledOps; |
| if (ElTy->isSized()) { |
| const SCEV *ElSize = SE.getSizeOfExpr(ElTy); |
| if (!ElSize->isZero()) { |
| SmallVector<const SCEV *, 8> NewOps; |
| for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| const SCEV *Op = Ops[i]; |
| const SCEV *Remainder = SE.getConstant(Ty, 0); |
| if (FactorOutConstant(Op, Remainder, ElSize, SE, SE.TD)) { |
| // Op now has ElSize factored out. |
| ScaledOps.push_back(Op); |
| if (!Remainder->isZero()) |
| NewOps.push_back(Remainder); |
| AnyNonZeroIndices = true; |
| } else { |
| // The operand was not divisible, so add it to the list of operands |
| // we'll scan next iteration. |
| NewOps.push_back(Ops[i]); |
| } |
| } |
| // If we made any changes, update Ops. |
| if (!ScaledOps.empty()) { |
| Ops = NewOps; |
| SimplifyAddOperands(Ops, Ty, SE); |
| } |
| } |
| } |
| |
| // Record the scaled array index for this level of the type. If |
| // we didn't find any operands that could be factored, tentatively |
| // assume that element zero was selected (since the zero offset |
| // would obviously be folded away). |
| Value *Scaled = ScaledOps.empty() ? |
| Constant::getNullValue(Ty) : |
| expandCodeFor(SE.getAddExpr(ScaledOps), Ty); |
| GepIndices.push_back(Scaled); |
| |
| // Collect struct field index operands. |
| while (StructType *STy = dyn_cast<StructType>(ElTy)) { |
| bool FoundFieldNo = false; |
| // An empty struct has no fields. |
| if (STy->getNumElements() == 0) break; |
| if (SE.TD) { |
| // With TargetData, field offsets are known. See if a constant offset |
| // falls within any of the struct fields. |
| if (Ops.empty()) break; |
| if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0])) |
| if (SE.getTypeSizeInBits(C->getType()) <= 64) { |
| const StructLayout &SL = *SE.TD->getStructLayout(STy); |
| uint64_t FullOffset = C->getValue()->getZExtValue(); |
| if (FullOffset < SL.getSizeInBytes()) { |
| unsigned ElIdx = SL.getElementContainingOffset(FullOffset); |
| GepIndices.push_back( |
| ConstantInt::get(Type::getInt32Ty(Ty->getContext()), ElIdx)); |
| ElTy = STy->getTypeAtIndex(ElIdx); |
| Ops[0] = |
| SE.getConstant(Ty, FullOffset - SL.getElementOffset(ElIdx)); |
| AnyNonZeroIndices = true; |
| FoundFieldNo = true; |
| } |
| } |
| } else { |
| // Without TargetData, just check for an offsetof expression of the |
| // appropriate struct type. |
| for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
| if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) { |
| Type *CTy; |
| Constant *FieldNo; |
| if (U->isOffsetOf(CTy, FieldNo) && CTy == STy) { |
| GepIndices.push_back(FieldNo); |
| ElTy = |
| STy->getTypeAtIndex(cast<ConstantInt>(FieldNo)->getZExtValue()); |
| Ops[i] = SE.getConstant(Ty, 0); |
| AnyNonZeroIndices = true; |
| FoundFieldNo = true; |
| break; |
| } |
| } |
| } |
| // If no struct field offsets were found, tentatively assume that |
| // field zero was selected (since the zero offset would obviously |
| // be folded away). |
| if (!FoundFieldNo) { |
| ElTy = STy->getTypeAtIndex(0u); |
| GepIndices.push_back( |
| Constant::getNullValue(Type::getInt32Ty(Ty->getContext()))); |
| } |
| } |
| |
| if (ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) |
| ElTy = ATy->getElementType(); |
| else |
| break; |
| } |
| |
| // If none of the operands were convertible to proper GEP indices, cast |
| // the base to i8* and do an ugly getelementptr with that. It's still |
| // better than ptrtoint+arithmetic+inttoptr at least. |
| if (!AnyNonZeroIndices) { |
| // Cast the base to i8*. |
| V = InsertNoopCastOfTo(V, |
| Type::getInt8PtrTy(Ty->getContext(), PTy->getAddressSpace())); |
| |
| // Expand the operands for a plain byte offset. |
| Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty); |
| |
| // Fold a GEP with constant operands. |
| if (Constant *CLHS = dyn_cast<Constant>(V)) |
| if (Constant *CRHS = dyn_cast<Constant>(Idx)) |
| return ConstantExpr::getGetElementPtr(CLHS, CRHS); |
| |
| // Do a quick scan to see if we have this GEP nearby. If so, reuse it. |
| unsigned ScanLimit = 6; |
| BasicBlock::iterator BlockBegin = Builder.GetInsertBlock()->begin(); |
| // Scanning starts from the last instruction before the insertion point. |
| BasicBlock::iterator IP = Builder.GetInsertPoint(); |
| if (IP != BlockBegin) { |
| --IP; |
| for (; ScanLimit; --IP, --ScanLimit) { |
| // Don't count dbg.value against the ScanLimit, to avoid perturbing the |
| // generated code. |
| if (isa<DbgInfoIntrinsic>(IP)) |
| ScanLimit++; |
| if (IP->getOpcode() == Instruction::GetElementPtr && |
| IP->getOperand(0) == V && IP->getOperand(1) == Idx) |
| return IP; |
| if (IP == BlockBegin) break; |
| } |
| } |
| |
| // Save the original insertion point so we can restore it when we're done. |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| |
| // Move the insertion point out of as many loops as we can. |
| while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) { |
| if (!L->isLoopInvariant(V) || !L->isLoopInvariant(Idx)) break; |
| BasicBlock *Preheader = L->getLoopPreheader(); |
| if (!Preheader) break; |
| |
| // Ok, move up a level. |
| Builder.SetInsertPoint(Preheader, Preheader->getTerminator()); |
| } |
| |
| // Emit a GEP. |
| Value *GEP = Builder.CreateGEP(V, Idx, "uglygep"); |
| rememberInstruction(GEP); |
| |
| // Restore the original insert point. |
| if (SaveInsertBB) |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| |
| return GEP; |
| } |
| |
| // Save the original insertion point so we can restore it when we're done. |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| |
| // Move the insertion point out of as many loops as we can. |
| while (const Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock())) { |
| if (!L->isLoopInvariant(V)) break; |
| |
| bool AnyIndexNotLoopInvariant = false; |
| for (SmallVectorImpl<Value *>::const_iterator I = GepIndices.begin(), |
| E = GepIndices.end(); I != E; ++I) |
| if (!L->isLoopInvariant(*I)) { |
| AnyIndexNotLoopInvariant = true; |
| break; |
| } |
| if (AnyIndexNotLoopInvariant) |
| break; |
| |
| BasicBlock *Preheader = L->getLoopPreheader(); |
| if (!Preheader) break; |
| |
| // Ok, move up a level. |
| Builder.SetInsertPoint(Preheader, Preheader->getTerminator()); |
| } |
| |
| // Insert a pretty getelementptr. Note that this GEP is not marked inbounds, |
| // because ScalarEvolution may have changed the address arithmetic to |
| // compute a value which is beyond the end of the allocated object. |
| Value *Casted = V; |
| if (V->getType() != PTy) |
| Casted = InsertNoopCastOfTo(Casted, PTy); |
| Value *GEP = Builder.CreateGEP(Casted, |
| GepIndices.begin(), |
| GepIndices.end(), |
| "scevgep"); |
| Ops.push_back(SE.getUnknown(GEP)); |
| rememberInstruction(GEP); |
| |
| // Restore the original insert point. |
| if (SaveInsertBB) |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| |
| return expand(SE.getAddExpr(Ops)); |
| } |
| |
| /// isNonConstantNegative - Return true if the specified scev is negated, but |
| /// not a constant. |
| static bool isNonConstantNegative(const SCEV *F) { |
| const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(F); |
| if (!Mul) return false; |
| |
| // If there is a constant factor, it will be first. |
| const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); |
| if (!SC) return false; |
| |
| // Return true if the value is negative, this matches things like (-42 * V). |
| return SC->getValue()->getValue().isNegative(); |
| } |
| |
| /// PickMostRelevantLoop - Given two loops pick the one that's most relevant for |
| /// SCEV expansion. If they are nested, this is the most nested. If they are |
| /// neighboring, pick the later. |
| static const Loop *PickMostRelevantLoop(const Loop *A, const Loop *B, |
| DominatorTree &DT) { |
| if (!A) return B; |
| if (!B) return A; |
| if (A->contains(B)) return B; |
| if (B->contains(A)) return A; |
| if (DT.dominates(A->getHeader(), B->getHeader())) return B; |
| if (DT.dominates(B->getHeader(), A->getHeader())) return A; |
| return A; // Arbitrarily break the tie. |
| } |
| |
| /// getRelevantLoop - Get the most relevant loop associated with the given |
| /// expression, according to PickMostRelevantLoop. |
| const Loop *SCEVExpander::getRelevantLoop(const SCEV *S) { |
| // Test whether we've already computed the most relevant loop for this SCEV. |
| std::pair<DenseMap<const SCEV *, const Loop *>::iterator, bool> Pair = |
| RelevantLoops.insert(std::make_pair(S, static_cast<const Loop *>(0))); |
| if (!Pair.second) |
| return Pair.first->second; |
| |
| if (isa<SCEVConstant>(S)) |
| // A constant has no relevant loops. |
| return 0; |
| if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
| if (const Instruction *I = dyn_cast<Instruction>(U->getValue())) |
| return Pair.first->second = SE.LI->getLoopFor(I->getParent()); |
| // A non-instruction has no relevant loops. |
| return 0; |
| } |
| if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S)) { |
| const Loop *L = 0; |
| if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) |
| L = AR->getLoop(); |
| for (SCEVNAryExpr::op_iterator I = N->op_begin(), E = N->op_end(); |
| I != E; ++I) |
| L = PickMostRelevantLoop(L, getRelevantLoop(*I), *SE.DT); |
| return RelevantLoops[N] = L; |
| } |
| if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) { |
| const Loop *Result = getRelevantLoop(C->getOperand()); |
| return RelevantLoops[C] = Result; |
| } |
| if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) { |
| const Loop *Result = |
| PickMostRelevantLoop(getRelevantLoop(D->getLHS()), |
| getRelevantLoop(D->getRHS()), |
| *SE.DT); |
| return RelevantLoops[D] = Result; |
| } |
| llvm_unreachable("Unexpected SCEV type!"); |
| return 0; |
| } |
| |
| namespace { |
| |
| /// LoopCompare - Compare loops by PickMostRelevantLoop. |
| class LoopCompare { |
| DominatorTree &DT; |
| public: |
| explicit LoopCompare(DominatorTree &dt) : DT(dt) {} |
| |
| bool operator()(std::pair<const Loop *, const SCEV *> LHS, |
| std::pair<const Loop *, const SCEV *> RHS) const { |
| // Keep pointer operands sorted at the end. |
| if (LHS.second->getType()->isPointerTy() != |
| RHS.second->getType()->isPointerTy()) |
| return LHS.second->getType()->isPointerTy(); |
| |
| // Compare loops with PickMostRelevantLoop. |
| if (LHS.first != RHS.first) |
| return PickMostRelevantLoop(LHS.first, RHS.first, DT) != LHS.first; |
| |
| // If one operand is a non-constant negative and the other is not, |
| // put the non-constant negative on the right so that a sub can |
| // be used instead of a negate and add. |
| if (isNonConstantNegative(LHS.second)) { |
| if (!isNonConstantNegative(RHS.second)) |
| return false; |
| } else if (isNonConstantNegative(RHS.second)) |
| return true; |
| |
| // Otherwise they are equivalent according to this comparison. |
| return false; |
| } |
| }; |
| |
| } |
| |
| Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| |
| // Collect all the add operands in a loop, along with their associated loops. |
| // Iterate in reverse so that constants are emitted last, all else equal, and |
| // so that pointer operands are inserted first, which the code below relies on |
| // to form more involved GEPs. |
| SmallVector<std::pair<const Loop *, const SCEV *>, 8> OpsAndLoops; |
| for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(S->op_end()), |
| E(S->op_begin()); I != E; ++I) |
| OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I)); |
| |
| // Sort by loop. Use a stable sort so that constants follow non-constants and |
| // pointer operands precede non-pointer operands. |
| std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(*SE.DT)); |
| |
| // Emit instructions to add all the operands. Hoist as much as possible |
| // out of loops, and form meaningful getelementptrs where possible. |
| Value *Sum = 0; |
| for (SmallVectorImpl<std::pair<const Loop *, const SCEV *> >::iterator |
| I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E; ) { |
| const Loop *CurLoop = I->first; |
| const SCEV *Op = I->second; |
| if (!Sum) { |
| // This is the first operand. Just expand it. |
| Sum = expand(Op); |
| ++I; |
| } else if (PointerType *PTy = dyn_cast<PointerType>(Sum->getType())) { |
| // The running sum expression is a pointer. Try to form a getelementptr |
| // at this level with that as the base. |
| SmallVector<const SCEV *, 4> NewOps; |
| for (; I != E && I->first == CurLoop; ++I) { |
| // If the operand is SCEVUnknown and not instructions, peek through |
| // it, to enable more of it to be folded into the GEP. |
| const SCEV *X = I->second; |
| if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(X)) |
| if (!isa<Instruction>(U->getValue())) |
| X = SE.getSCEV(U->getValue()); |
| NewOps.push_back(X); |
| } |
| Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum); |
| } else if (PointerType *PTy = dyn_cast<PointerType>(Op->getType())) { |
| // The running sum is an integer, and there's a pointer at this level. |
| // Try to form a getelementptr. If the running sum is instructions, |
| // use a SCEVUnknown to avoid re-analyzing them. |
| SmallVector<const SCEV *, 4> NewOps; |
| NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) : |
| SE.getSCEV(Sum)); |
| for (++I; I != E && I->first == CurLoop; ++I) |
| NewOps.push_back(I->second); |
| Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op)); |
| } else if (isNonConstantNegative(Op)) { |
| // Instead of doing a negate and add, just do a subtract. |
| Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty); |
| Sum = InsertNoopCastOfTo(Sum, Ty); |
| Sum = InsertBinop(Instruction::Sub, Sum, W); |
| ++I; |
| } else { |
| // A simple add. |
| Value *W = expandCodeFor(Op, Ty); |
| Sum = InsertNoopCastOfTo(Sum, Ty); |
| // Canonicalize a constant to the RHS. |
| if (isa<Constant>(Sum)) std::swap(Sum, W); |
| Sum = InsertBinop(Instruction::Add, Sum, W); |
| ++I; |
| } |
| } |
| |
| return Sum; |
| } |
| |
| Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) { |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| |
| // Collect all the mul operands in a loop, along with their associated loops. |
| // Iterate in reverse so that constants are emitted last, all else equal. |
| SmallVector<std::pair<const Loop *, const SCEV *>, 8> OpsAndLoops; |
| for (std::reverse_iterator<SCEVMulExpr::op_iterator> I(S->op_end()), |
| E(S->op_begin()); I != E; ++I) |
| OpsAndLoops.push_back(std::make_pair(getRelevantLoop(*I), *I)); |
| |
| // Sort by loop. Use a stable sort so that constants follow non-constants. |
| std::stable_sort(OpsAndLoops.begin(), OpsAndLoops.end(), LoopCompare(*SE.DT)); |
| |
| // Emit instructions to mul all the operands. Hoist as much as possible |
| // out of loops. |
| Value *Prod = 0; |
| for (SmallVectorImpl<std::pair<const Loop *, const SCEV *> >::iterator |
| I = OpsAndLoops.begin(), E = OpsAndLoops.end(); I != E; ) { |
| const SCEV *Op = I->second; |
| if (!Prod) { |
| // This is the first operand. Just expand it. |
| Prod = expand(Op); |
| ++I; |
| } else if (Op->isAllOnesValue()) { |
| // Instead of doing a multiply by negative one, just do a negate. |
| Prod = InsertNoopCastOfTo(Prod, Ty); |
| Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod); |
| ++I; |
| } else { |
| // A simple mul. |
| Value *W = expandCodeFor(Op, Ty); |
| Prod = InsertNoopCastOfTo(Prod, Ty); |
| // Canonicalize a constant to the RHS. |
| if (isa<Constant>(Prod)) std::swap(Prod, W); |
| Prod = InsertBinop(Instruction::Mul, Prod, W); |
| ++I; |
| } |
| } |
| |
| return Prod; |
| } |
| |
| Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) { |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| |
| Value *LHS = expandCodeFor(S->getLHS(), Ty); |
| if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) { |
| const APInt &RHS = SC->getValue()->getValue(); |
| if (RHS.isPowerOf2()) |
| return InsertBinop(Instruction::LShr, LHS, |
| ConstantInt::get(Ty, RHS.logBase2())); |
| } |
| |
| Value *RHS = expandCodeFor(S->getRHS(), Ty); |
| return InsertBinop(Instruction::UDiv, LHS, RHS); |
| } |
| |
| /// Move parts of Base into Rest to leave Base with the minimal |
| /// expression that provides a pointer operand suitable for a |
| /// GEP expansion. |
| static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest, |
| ScalarEvolution &SE) { |
| while (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(Base)) { |
| Base = A->getStart(); |
| Rest = SE.getAddExpr(Rest, |
| SE.getAddRecExpr(SE.getConstant(A->getType(), 0), |
| A->getStepRecurrence(SE), |
| A->getLoop(), |
| // FIXME: A->getNoWrapFlags(FlagNW) |
| SCEV::FlagAnyWrap)); |
| } |
| if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(Base)) { |
| Base = A->getOperand(A->getNumOperands()-1); |
| SmallVector<const SCEV *, 8> NewAddOps(A->op_begin(), A->op_end()); |
| NewAddOps.back() = Rest; |
| Rest = SE.getAddExpr(NewAddOps); |
| ExposePointerBase(Base, Rest, SE); |
| } |
| } |
| |
| /// getAddRecExprPHILiterally - Helper for expandAddRecExprLiterally. Expand |
| /// the base addrec, which is the addrec without any non-loop-dominating |
| /// values, and return the PHI. |
| PHINode * |
| SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized, |
| const Loop *L, |
| Type *ExpandTy, |
| Type *IntTy) { |
| assert((!IVIncInsertLoop||IVIncInsertPos) && "Uninitialized insert position"); |
| |
| // Reuse a previously-inserted PHI, if present. |
| for (BasicBlock::iterator I = L->getHeader()->begin(); |
| PHINode *PN = dyn_cast<PHINode>(I); ++I) |
| if (SE.isSCEVable(PN->getType()) && |
| (SE.getEffectiveSCEVType(PN->getType()) == |
| SE.getEffectiveSCEVType(Normalized->getType())) && |
| SE.getSCEV(PN) == Normalized) |
| if (BasicBlock *LatchBlock = L->getLoopLatch()) { |
| Instruction *IncV = |
| cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock)); |
| |
| // Determine if this is a well-behaved chain of instructions leading |
| // back to the PHI. It probably will be, if we're scanning an inner |
| // loop already visited by LSR for example, but it wouldn't have |
| // to be. |
| do { |
| if (IncV->getNumOperands() == 0 || isa<PHINode>(IncV) || |
| (isa<CastInst>(IncV) && !isa<BitCastInst>(IncV))) { |
| IncV = 0; |
| break; |
| } |
| // If any of the operands don't dominate the insert position, bail. |
| // Addrec operands are always loop-invariant, so this can only happen |
| // if there are instructions which haven't been hoisted. |
| if (L == IVIncInsertLoop) { |
| for (User::op_iterator OI = IncV->op_begin()+1, |
| OE = IncV->op_end(); OI != OE; ++OI) |
| if (Instruction *OInst = dyn_cast<Instruction>(OI)) |
| if (!SE.DT->dominates(OInst, IVIncInsertPos)) { |
| IncV = 0; |
| break; |
| } |
| } |
| if (!IncV) |
| break; |
| // Advance to the next instruction. |
| IncV = dyn_cast<Instruction>(IncV->getOperand(0)); |
| if (!IncV) |
| break; |
| if (IncV->mayHaveSideEffects()) { |
| IncV = 0; |
| break; |
| } |
| } while (IncV != PN); |
| |
| if (IncV) { |
| // Ok, the add recurrence looks usable. |
| // Remember this PHI, even in post-inc mode. |
| InsertedValues.insert(PN); |
| // Remember the increment. |
| IncV = cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock)); |
| rememberInstruction(IncV); |
| if (L == IVIncInsertLoop) |
| do { |
| if (SE.DT->dominates(IncV, IVIncInsertPos)) |
| break; |
| // Make sure the increment is where we want it. But don't move it |
| // down past a potential existing post-inc user. |
| IncV->moveBefore(IVIncInsertPos); |
| IVIncInsertPos = IncV; |
| IncV = cast<Instruction>(IncV->getOperand(0)); |
| } while (IncV != PN); |
| return PN; |
| } |
| } |
| |
| // Save the original insertion point so we can restore it when we're done. |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| |
| // Expand code for the start value. |
| Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy, |
| L->getHeader()->begin()); |
| |
| // StartV must be hoisted into L's preheader to dominate the new phi. |
| assert(!isa<Instruction>(StartV) || |
| SE.DT->properlyDominates(cast<Instruction>(StartV)->getParent(), |
| L->getHeader())); |
| |
| // Expand code for the step value. Insert instructions right before the |
| // terminator corresponding to the back-edge. Do this before creating the PHI |
| // so that PHI reuse code doesn't see an incomplete PHI. If the stride is |
| // negative, insert a sub instead of an add for the increment (unless it's a |
| // constant, because subtracts of constants are canonicalized to adds). |
| const SCEV *Step = Normalized->getStepRecurrence(SE); |
| bool isPointer = ExpandTy->isPointerTy(); |
| bool isNegative = !isPointer && isNonConstantNegative(Step); |
| if (isNegative) |
| Step = SE.getNegativeSCEV(Step); |
| Value *StepV = expandCodeFor(Step, IntTy, L->getHeader()->begin()); |
| |
| // Create the PHI. |
| BasicBlock *Header = L->getHeader(); |
| Builder.SetInsertPoint(Header, Header->begin()); |
| pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header); |
| PHINode *PN = Builder.CreatePHI(ExpandTy, std::distance(HPB, HPE), |
| Twine(IVName) + ".iv"); |
| rememberInstruction(PN); |
| |
| // Create the step instructions and populate the PHI. |
| for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) { |
| BasicBlock *Pred = *HPI; |
| |
| // Add a start value. |
| if (!L->contains(Pred)) { |
| PN->addIncoming(StartV, Pred); |
| continue; |
| } |
| |
| // Create a step value and add it to the PHI. If IVIncInsertLoop is |
| // non-null and equal to the addrec's loop, insert the instructions |
| // at IVIncInsertPos. |
| Instruction *InsertPos = L == IVIncInsertLoop ? |
| IVIncInsertPos : Pred->getTerminator(); |
| Builder.SetInsertPoint(InsertPos); |
| Value *IncV; |
| // If the PHI is a pointer, use a GEP, otherwise use an add or sub. |
| if (isPointer) { |
| PointerType *GEPPtrTy = cast<PointerType>(ExpandTy); |
| // If the step isn't constant, don't use an implicitly scaled GEP, because |
| // that would require a multiply inside the loop. |
| if (!isa<ConstantInt>(StepV)) |
| GEPPtrTy = PointerType::get(Type::getInt1Ty(SE.getContext()), |
| GEPPtrTy->getAddressSpace()); |
| const SCEV *const StepArray[1] = { SE.getSCEV(StepV) }; |
| IncV = expandAddToGEP(StepArray, StepArray+1, GEPPtrTy, IntTy, PN); |
| if (IncV->getType() != PN->getType()) { |
| IncV = Builder.CreateBitCast(IncV, PN->getType(), "tmp"); |
| rememberInstruction(IncV); |
| } |
| } else { |
| IncV = isNegative ? |
| Builder.CreateSub(PN, StepV, Twine(IVName) + ".iv.next") : |
| Builder.CreateAdd(PN, StepV, Twine(IVName) + ".iv.next"); |
| rememberInstruction(IncV); |
| } |
| PN->addIncoming(IncV, Pred); |
| } |
| |
| // Restore the original insert point. |
| if (SaveInsertBB) |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| |
| // Remember this PHI, even in post-inc mode. |
| InsertedValues.insert(PN); |
| |
| return PN; |
| } |
| |
| Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) { |
| Type *STy = S->getType(); |
| Type *IntTy = SE.getEffectiveSCEVType(STy); |
| const Loop *L = S->getLoop(); |
| |
| // Determine a normalized form of this expression, which is the expression |
| // before any post-inc adjustment is made. |
| const SCEVAddRecExpr *Normalized = S; |
| if (PostIncLoops.count(L)) { |
| PostIncLoopSet Loops; |
| Loops.insert(L); |
| Normalized = |
| cast<SCEVAddRecExpr>(TransformForPostIncUse(Normalize, S, 0, 0, |
| Loops, SE, *SE.DT)); |
| } |
| |
| // Strip off any non-loop-dominating component from the addrec start. |
| const SCEV *Start = Normalized->getStart(); |
| const SCEV *PostLoopOffset = 0; |
| if (!SE.properlyDominates(Start, L->getHeader())) { |
| PostLoopOffset = Start; |
| Start = SE.getConstant(Normalized->getType(), 0); |
| Normalized = cast<SCEVAddRecExpr>( |
| SE.getAddRecExpr(Start, Normalized->getStepRecurrence(SE), |
| Normalized->getLoop(), |
| // FIXME: Normalized->getNoWrapFlags(FlagNW) |
| SCEV::FlagAnyWrap)); |
| } |
| |
| // Strip off any non-loop-dominating component from the addrec step. |
| const SCEV *Step = Normalized->getStepRecurrence(SE); |
| const SCEV *PostLoopScale = 0; |
| if (!SE.dominates(Step, L->getHeader())) { |
| PostLoopScale = Step; |
| Step = SE.getConstant(Normalized->getType(), 1); |
| Normalized = |
| cast<SCEVAddRecExpr>(SE.getAddRecExpr(Start, Step, |
| Normalized->getLoop(), |
| // FIXME: Normalized |
| // ->getNoWrapFlags(FlagNW) |
| SCEV::FlagAnyWrap)); |
| } |
| |
| // Expand the core addrec. If we need post-loop scaling, force it to |
| // expand to an integer type to avoid the need for additional casting. |
| Type *ExpandTy = PostLoopScale ? IntTy : STy; |
| PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy); |
| |
| // Accommodate post-inc mode, if necessary. |
| Value *Result; |
| if (!PostIncLoops.count(L)) |
| Result = PN; |
| else { |
| // In PostInc mode, use the post-incremented value. |
| BasicBlock *LatchBlock = L->getLoopLatch(); |
| assert(LatchBlock && "PostInc mode requires a unique loop latch!"); |
| Result = PN->getIncomingValueForBlock(LatchBlock); |
| } |
| |
| // Re-apply any non-loop-dominating scale. |
| if (PostLoopScale) { |
| Result = InsertNoopCastOfTo(Result, IntTy); |
| Result = Builder.CreateMul(Result, |
| expandCodeFor(PostLoopScale, IntTy)); |
| rememberInstruction(Result); |
| } |
| |
| // Re-apply any non-loop-dominating offset. |
| if (PostLoopOffset) { |
| if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) { |
| const SCEV *const OffsetArray[1] = { PostLoopOffset }; |
| Result = expandAddToGEP(OffsetArray, OffsetArray+1, PTy, IntTy, Result); |
| } else { |
| Result = InsertNoopCastOfTo(Result, IntTy); |
| Result = Builder.CreateAdd(Result, |
| expandCodeFor(PostLoopOffset, IntTy)); |
| rememberInstruction(Result); |
| } |
| } |
| |
| return Result; |
| } |
| |
| Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { |
| if (!CanonicalMode) return expandAddRecExprLiterally(S); |
| |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| const Loop *L = S->getLoop(); |
| |
| // First check for an existing canonical IV in a suitable type. |
| PHINode *CanonicalIV = 0; |
| if (PHINode *PN = L->getCanonicalInductionVariable()) |
| if (SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty)) |
| CanonicalIV = PN; |
| |
| // Rewrite an AddRec in terms of the canonical induction variable, if |
| // its type is more narrow. |
| if (CanonicalIV && |
| SE.getTypeSizeInBits(CanonicalIV->getType()) > |
| SE.getTypeSizeInBits(Ty)) { |
| SmallVector<const SCEV *, 4> NewOps(S->getNumOperands()); |
| for (unsigned i = 0, e = S->getNumOperands(); i != e; ++i) |
| NewOps[i] = SE.getAnyExtendExpr(S->op_begin()[i], CanonicalIV->getType()); |
| Value *V = expand(SE.getAddRecExpr(NewOps, S->getLoop(), |
| // FIXME: S->getNoWrapFlags(FlagNW) |
| SCEV::FlagAnyWrap)); |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| BasicBlock::iterator NewInsertPt = |
| llvm::next(BasicBlock::iterator(cast<Instruction>(V))); |
| while (isa<PHINode>(NewInsertPt) || isa<DbgInfoIntrinsic>(NewInsertPt)) |
| ++NewInsertPt; |
| V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0, |
| NewInsertPt); |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| return V; |
| } |
| |
| // {X,+,F} --> X + {0,+,F} |
| if (!S->getStart()->isZero()) { |
| SmallVector<const SCEV *, 4> NewOps(S->op_begin(), S->op_end()); |
| NewOps[0] = SE.getConstant(Ty, 0); |
| // FIXME: can use S->getNoWrapFlags() |
| const SCEV *Rest = SE.getAddRecExpr(NewOps, L, SCEV::FlagAnyWrap); |
| |
| // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the |
| // comments on expandAddToGEP for details. |
| const SCEV *Base = S->getStart(); |
| const SCEV *RestArray[1] = { Rest }; |
| // Dig into the expression to find the pointer base for a GEP. |
| ExposePointerBase(Base, RestArray[0], SE); |
| // If we found a pointer, expand the AddRec with a GEP. |
| if (PointerType *PTy = dyn_cast<PointerType>(Base->getType())) { |
| // Make sure the Base isn't something exotic, such as a multiplied |
| // or divided pointer value. In those cases, the result type isn't |
| // actually a pointer type. |
| if (!isa<SCEVMulExpr>(Base) && !isa<SCEVUDivExpr>(Base)) { |
| Value *StartV = expand(Base); |
| assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!"); |
| return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV); |
| } |
| } |
| |
| // Just do a normal add. Pre-expand the operands to suppress folding. |
| return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())), |
| SE.getUnknown(expand(Rest)))); |
| } |
| |
| // If we don't yet have a canonical IV, create one. |
| if (!CanonicalIV) { |
| // Create and insert the PHI node for the induction variable in the |
| // specified loop. |
| BasicBlock *Header = L->getHeader(); |
| pred_iterator HPB = pred_begin(Header), HPE = pred_end(Header); |
| CanonicalIV = PHINode::Create(Ty, std::distance(HPB, HPE), "indvar", |
| Header->begin()); |
| rememberInstruction(CanonicalIV); |
| |
| Constant *One = ConstantInt::get(Ty, 1); |
| for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) { |
| BasicBlock *HP = *HPI; |
| if (L->contains(HP)) { |
| // Insert a unit add instruction right before the terminator |
| // corresponding to the back-edge. |
| Instruction *Add = BinaryOperator::CreateAdd(CanonicalIV, One, |
| "indvar.next", |
| HP->getTerminator()); |
| Add->setDebugLoc(HP->getTerminator()->getDebugLoc()); |
| rememberInstruction(Add); |
| CanonicalIV->addIncoming(Add, HP); |
| } else { |
| CanonicalIV->addIncoming(Constant::getNullValue(Ty), HP); |
| } |
| } |
| } |
| |
| // {0,+,1} --> Insert a canonical induction variable into the loop! |
| if (S->isAffine() && S->getOperand(1)->isOne()) { |
| assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) && |
| "IVs with types different from the canonical IV should " |
| "already have been handled!"); |
| return CanonicalIV; |
| } |
| |
| // {0,+,F} --> {0,+,1} * F |
| |
| // If this is a simple linear addrec, emit it now as a special case. |
| if (S->isAffine()) // {0,+,F} --> i*F |
| return |
| expand(SE.getTruncateOrNoop( |
| SE.getMulExpr(SE.getUnknown(CanonicalIV), |
| SE.getNoopOrAnyExtend(S->getOperand(1), |
| CanonicalIV->getType())), |
| Ty)); |
| |
| // If this is a chain of recurrences, turn it into a closed form, using the |
| // folders, then expandCodeFor the closed form. This allows the folders to |
| // simplify the expression without having to build a bunch of special code |
| // into this folder. |
| const SCEV *IH = SE.getUnknown(CanonicalIV); // Get I as a "symbolic" SCEV. |
| |
| // Promote S up to the canonical IV type, if the cast is foldable. |
| const SCEV *NewS = S; |
| const SCEV *Ext = SE.getNoopOrAnyExtend(S, CanonicalIV->getType()); |
| if (isa<SCEVAddRecExpr>(Ext)) |
| NewS = Ext; |
| |
| const SCEV *V = cast<SCEVAddRecExpr>(NewS)->evaluateAtIteration(IH, SE); |
| //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n"; |
| |
| // Truncate the result down to the original type, if needed. |
| const SCEV *T = SE.getTruncateOrNoop(V, Ty); |
| return expand(T); |
| } |
| |
| Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) { |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expandCodeFor(S->getOperand(), |
| SE.getEffectiveSCEVType(S->getOperand()->getType())); |
| Value *I = Builder.CreateTrunc(V, Ty, "tmp"); |
| rememberInstruction(I); |
| return I; |
| } |
| |
| Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) { |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expandCodeFor(S->getOperand(), |
| SE.getEffectiveSCEVType(S->getOperand()->getType())); |
| Value *I = Builder.CreateZExt(V, Ty, "tmp"); |
| rememberInstruction(I); |
| return I; |
| } |
| |
| Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) { |
| Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expandCodeFor(S->getOperand(), |
| SE.getEffectiveSCEVType(S->getOperand()->getType())); |
| Value *I = Builder.CreateSExt(V, Ty, "tmp"); |
| rememberInstruction(I); |
| return I; |
| } |
| |
| Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) { |
| Value *LHS = expand(S->getOperand(S->getNumOperands()-1)); |
| Type *Ty = LHS->getType(); |
| for (int i = S->getNumOperands()-2; i >= 0; --i) { |
| // In the case of mixed integer and pointer types, do the |
| // rest of the comparisons as integer. |
| if (S->getOperand(i)->getType() != Ty) { |
| Ty = SE.getEffectiveSCEVType(Ty); |
| LHS = InsertNoopCastOfTo(LHS, Ty); |
| } |
| Value *RHS = expandCodeFor(S->getOperand(i), Ty); |
| Value *ICmp = Builder.CreateICmpSGT(LHS, RHS, "tmp"); |
| rememberInstruction(ICmp); |
| Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax"); |
| rememberInstruction(Sel); |
| LHS = Sel; |
| } |
| // In the case of mixed integer and pointer types, cast the |
| // final result back to the pointer type. |
| if (LHS->getType() != S->getType()) |
| LHS = InsertNoopCastOfTo(LHS, S->getType()); |
| return LHS; |
| } |
| |
| Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) { |
| Value *LHS = expand(S->getOperand(S->getNumOperands()-1)); |
| Type *Ty = LHS->getType(); |
| for (int i = S->getNumOperands()-2; i >= 0; --i) { |
| // In the case of mixed integer and pointer types, do the |
| // rest of the comparisons as integer. |
| if (S->getOperand(i)->getType() != Ty) { |
| Ty = SE.getEffectiveSCEVType(Ty); |
| LHS = InsertNoopCastOfTo(LHS, Ty); |
| } |
| Value *RHS = expandCodeFor(S->getOperand(i), Ty); |
| Value *ICmp = Builder.CreateICmpUGT(LHS, RHS, "tmp"); |
| rememberInstruction(ICmp); |
| Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax"); |
| rememberInstruction(Sel); |
| LHS = Sel; |
| } |
| // In the case of mixed integer and pointer types, cast the |
| // final result back to the pointer type. |
| if (LHS->getType() != S->getType()) |
| LHS = InsertNoopCastOfTo(LHS, S->getType()); |
| return LHS; |
| } |
| |
| Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty, |
| Instruction *I) { |
| BasicBlock::iterator IP = I; |
| while (isInsertedInstruction(IP) || isa<DbgInfoIntrinsic>(IP)) |
| ++IP; |
| Builder.SetInsertPoint(IP->getParent(), IP); |
| return expandCodeFor(SH, Ty); |
| } |
| |
| Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) { |
| // Expand the code for this SCEV. |
| Value *V = expand(SH); |
| if (Ty) { |
| assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) && |
| "non-trivial casts should be done with the SCEVs directly!"); |
| V = InsertNoopCastOfTo(V, Ty); |
| } |
| return V; |
| } |
| |
| Value *SCEVExpander::expand(const SCEV *S) { |
| // Compute an insertion point for this SCEV object. Hoist the instructions |
| // as far out in the loop nest as possible. |
| Instruction *InsertPt = Builder.GetInsertPoint(); |
| for (Loop *L = SE.LI->getLoopFor(Builder.GetInsertBlock()); ; |
| L = L->getParentLoop()) |
| if (SE.isLoopInvariant(S, L)) { |
| if (!L) break; |
| if (BasicBlock *Preheader = L->getLoopPreheader()) |
| InsertPt = Preheader->getTerminator(); |
| } else { |
| // If the SCEV is computable at this level, insert it into the header |
| // after the PHIs (and after any other instructions that we've inserted |
| // there) so that it is guaranteed to dominate any user inside the loop. |
| if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L)) |
| InsertPt = L->getHeader()->getFirstNonPHI(); |
| while (isInsertedInstruction(InsertPt) || isa<DbgInfoIntrinsic>(InsertPt)) |
| InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); |
| break; |
| } |
| |
| // Check to see if we already expanded this here. |
| std::map<std::pair<const SCEV *, Instruction *>, |
| AssertingVH<Value> >::iterator I = |
| InsertedExpressions.find(std::make_pair(S, InsertPt)); |
| if (I != InsertedExpressions.end()) |
| return I->second; |
| |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| Builder.SetInsertPoint(InsertPt->getParent(), InsertPt); |
| |
| // Expand the expression into instructions. |
| Value *V = visit(S); |
| |
| // Remember the expanded value for this SCEV at this location. |
| if (PostIncLoops.empty()) |
| InsertedExpressions[std::make_pair(S, InsertPt)] = V; |
| |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| return V; |
| } |
| |
| void SCEVExpander::rememberInstruction(Value *I) { |
| if (!PostIncLoops.empty()) |
| InsertedPostIncValues.insert(I); |
| else |
| InsertedValues.insert(I); |
| |
| // If we just claimed an existing instruction and that instruction had |
| // been the insert point, adjust the insert point forward so that |
| // subsequently inserted code will be dominated. |
| if (Builder.GetInsertPoint() == I) { |
| BasicBlock::iterator It = cast<Instruction>(I); |
| do { ++It; } while (isInsertedInstruction(It) || |
| isa<DbgInfoIntrinsic>(It)); |
| Builder.SetInsertPoint(Builder.GetInsertBlock(), It); |
| } |
| } |
| |
| void SCEVExpander::restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I) { |
| // If we acquired more instructions since the old insert point was saved, |
| // advance past them. |
| while (isInsertedInstruction(I) || isa<DbgInfoIntrinsic>(I)) ++I; |
| |
| Builder.SetInsertPoint(BB, I); |
| } |
| |
| /// getOrInsertCanonicalInductionVariable - This method returns the |
| /// canonical induction variable of the specified type for the specified |
| /// loop (inserting one if there is none). A canonical induction variable |
| /// starts at zero and steps by one on each iteration. |
| PHINode * |
| SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L, |
| Type *Ty) { |
| assert(Ty->isIntegerTy() && "Can only insert integer induction variables!"); |
| |
| // Build a SCEV for {0,+,1}<L>. |
| // Conservatively use FlagAnyWrap for now. |
| const SCEV *H = SE.getAddRecExpr(SE.getConstant(Ty, 0), |
| SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap); |
| |
| // Emit code for it. |
| BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); |
| BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); |
| PHINode *V = cast<PHINode>(expandCodeFor(H, 0, L->getHeader()->begin())); |
| if (SaveInsertBB) |
| restoreInsertPoint(SaveInsertBB, SaveInsertPt); |
| |
| return V; |
| } |