X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FScalarEvolutionExpander.cpp;h=e55ca53c9505770d9249ecfd0d8e2765a4e18ebe;hb=faa75f6e47350f491a44d5e8773acd9457185d51;hp=80b47d89240a7919d5a25f090033e10fd9895497;hpb=e2a17468d1e47ef430933b7a91c5c1c4669d7d8d;p=oota-llvm.git diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp index 80b47d89240..e55ca53c950 100644 --- a/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/lib/Analysis/ScalarEvolutionExpander.cpp @@ -15,50 +15,75 @@ #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; -/// InsertCastOfTo - Insert a cast of V to the specified type, doing what -/// we can to share the casts. -Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V, - const Type *Ty) { +/// 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, const 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 (opcode == Instruction::BitCast && V->getType() == Ty) + if (Op == Instruction::BitCast && V->getType() == Ty) return V; // Short-circuit unnecessary inttoptr<->ptrtoint casts. - if ((opcode == Instruction::PtrToInt || opcode == Instruction::IntToPtr) && - SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) + if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) && + SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) { if (CastInst *CI = dyn_cast(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(V)) + if ((CE->getOpcode() == Instruction::PtrToInt || + CE->getOpcode() == Instruction::IntToPtr) && + SE.getTypeSizeInBits(CE->getType()) == + SE.getTypeSizeInBits(CE->getOperand(0)->getType())) + return CE->getOperand(0); + } - // FIXME: keep track of the cast instruction. if (Constant *C = dyn_cast(V)) - return ConstantExpr::getCast(opcode, C, Ty); - + return ConstantExpr::getCast(Op, C, Ty); + if (Argument *A = dyn_cast(V)) { // Check to see if there is already a cast! for (Value::use_iterator UI = A->use_begin(), E = A->use_end(); - UI != E; ++UI) { + UI != E; ++UI) if ((*UI)->getType() == Ty) if (CastInst *CI = dyn_cast(cast(*UI))) - if (CI->getOpcode() == opcode) { + if (CI->getOpcode() == Op) { // If the cast isn't the first instruction of the function, move it. - if (BasicBlock::iterator(CI) != + if (BasicBlock::iterator(CI) != A->getParent()->getEntryBlock().begin()) { - // If the CastInst is the insert point, change the insert point. - if (CI == InsertPt) ++InsertPt; - // Splice the cast at the beginning of the entry block. - CI->moveBefore(A->getParent()->getEntryBlock().begin()); + // Recreate the cast at the beginning of the entry block. + // The old cast is left in place in case it is being used + // as an insert point. + Instruction *NewCI = + CastInst::Create(Op, V, Ty, "", + A->getParent()->getEntryBlock().begin()); + NewCI->takeName(CI); + CI->replaceAllUsesWith(NewCI); + return NewCI; } return CI; } - } - return CastInst::Create(opcode, V, Ty, V->getName(), - A->getParent()->getEntryBlock().begin()); + + Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), + A->getParent()->getEntryBlock().begin()); + rememberInstruction(I); + return I; } Instruction *I = cast(V); @@ -68,17 +93,22 @@ Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V, UI != E; ++UI) { if ((*UI)->getType() == Ty) if (CastInst *CI = dyn_cast(cast(*UI))) - if (CI->getOpcode() == opcode) { + if (CI->getOpcode() == Op) { BasicBlock::iterator It = I; ++It; if (isa(I)) It = cast(I)->getNormalDest()->begin(); while (isa(It)) ++It; if (It != BasicBlock::iterator(CI)) { - // If the CastInst is the insert point, change the insert point. - if (CI == InsertPt) ++InsertPt; - // Splice the cast immediately after the operand in question. - CI->moveBefore(It); + // Recreate the cast after the user. + // The old cast is left in place in case it is being used + // as an insert point. + Instruction *NewCI = CastInst::Create(Op, V, Ty, "", It); + NewCI->takeName(CI); + CI->replaceAllUsesWith(NewCI); + rememberInstruction(NewCI); + return NewCI; } + rememberInstruction(CI); return CI; } } @@ -86,26 +116,15 @@ Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V, if (InvokeInst *II = dyn_cast(I)) IP = II->getNormalDest()->begin(); while (isa(IP)) ++IP; - return CastInst::Create(opcode, V, Ty, V->getName(), IP); -} - -/// InsertNoopCastOfTo - Insert a cast of V to the specified type, -/// which must be possible with a noop cast. -Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const 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!"); - return InsertCastOfTo(Op, V, Ty); + Instruction *CI = CastInst::Create(Op, V, Ty, V->getName(), IP); + rememberInstruction(CI); + return CI; } /// 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, BasicBlock::iterator InsertPt) { +Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, + Value *LHS, Value *RHS) { // Fold a binop with constant operands. if (Constant *CLHS = dyn_cast(LHS)) if (Constant *CRHS = dyn_cast(RHS)) @@ -113,242 +132,1217 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, // Do a quick scan to see if we have this binop nearby. If so, reuse it. unsigned ScanLimit = 6; - BasicBlock::iterator BlockBegin = InsertPt->getParent()->begin(); - if (InsertPt != BlockBegin) { - // Scanning starts from the last instruction before InsertPt. - BasicBlock::iterator IP = InsertPt; + 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) { - if (BinaryOperator *BinOp = dyn_cast(IP)) - if (BinOp->getOpcode() == Opcode && BinOp->getOperand(0) == LHS && - BinOp->getOperand(1) == RHS) - return BinOp; + // Don't count dbg.value against the ScanLimit, to avoid perturbing the + // generated code. + if (isa(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. - return BinaryOperator::Create(Opcode, LHS, RHS, "tmp", InsertPt); + Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp"); + 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.getIntegerSCEV(1, S->getType()); + return true; + } + + // For a Constant, check for a multiple of the given factor. + if (const SCEVConstant *C = dyn_cast(S)) { + // 0/x == 0. + if (C->isZero()) + return true; + // Check for divisibility. + if (const SCEVConstant *FC = dyn_cast(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(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(Factor); + if (const SCEVConstant *C = dyn_cast(M->getOperand(0))) + if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) { + SmallVector 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.getIntegerSCEV(0, SOp->getType()); + if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) && + Remainder->isZero()) { + SmallVector 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(S)) { + const SCEV *Step = A->getStepRecurrence(SE); + const SCEV *StepRem = SE.getIntegerSCEV(0, Step->getType()); + 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; + S = SE.getAddRecExpr(Start, Step, A->getLoop()); + 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 &Ops, + const Type *Ty, + ScalarEvolution &SE) { + unsigned NumAddRecs = 0; + for (unsigned i = Ops.size(); i > 0 && isa(Ops[i-1]); --i) + ++NumAddRecs; + // Group Ops into non-addrecs and addrecs. + SmallVector NoAddRecs(Ops.begin(), Ops.end() - NumAddRecs); + SmallVector AddRecs(Ops.end() - NumAddRecs, Ops.end()); + // Let ScalarEvolution sort and simplify the non-addrecs list. + const SCEV *Sum = NoAddRecs.empty() ? + SE.getIntegerSCEV(0, Ty) : + 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(Sum)) + Ops.insert(Ops.end(), Add->op_begin(), Add->op_end()); + else if (!Sum->isZero()) + Ops.push_back(Sum); + // Then append the addrecs. + Ops.insert(Ops.end(), 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 &Ops, + const Type *Ty, + ScalarEvolution &SE) { + // Find the addrecs. + SmallVector AddRecs; + for (unsigned i = 0, e = Ops.size(); i != e; ++i) + while (const SCEVAddRecExpr *A = dyn_cast(Ops[i])) { + const SCEV *Start = A->getStart(); + if (Start->isZero()) break; + const SCEV *Zero = SE.getIntegerSCEV(0, Ty); + AddRecs.push_back(SE.getAddRecExpr(Zero, + A->getStepRecurrence(SE), + A->getLoop())); + if (const SCEVAddExpr *Add = dyn_cast(Start)) { + Ops[i] = Zero; + Ops.insert(Ops.end(), 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.insert(Ops.end(), 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, + const PointerType *PTy, + const Type *Ty, + Value *V) { + const Type *ElTy = PTy->getElementType(); + SmallVector GepIndices; + SmallVector 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 ScaledOps; + if (ElTy->isSized()) { + const SCEV *ElSize = SE.getSizeOfExpr(ElTy); + if (!ElSize->isZero()) { + SmallVector NewOps; + for (unsigned i = 0, e = Ops.size(); i != e; ++i) { + const SCEV *Op = Ops[i]; + const SCEV *Remainder = SE.getIntegerSCEV(0, Ty); + 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 (const StructType *STy = dyn_cast(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(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(Ops[i])) { + const Type *CTy; + Constant *FieldNo; + if (U->isOffsetOf(CTy, FieldNo) && CTy == STy) { + GepIndices.push_back(FieldNo); + ElTy = + STy->getTypeAtIndex(cast(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 (const ArrayType *ATy = dyn_cast(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(V)) + if (Constant *CRHS = dyn_cast(Idx)) + return ConstantExpr::getGetElementPtr(CLHS, &CRHS, 1); + + // 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(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::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(F); + if (!Mul) return false; + + // If there is a constant factor, it will be first. + const SCEVConstant *SC = dyn_cast(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. +static const Loop *GetRelevantLoop(const SCEV *S, LoopInfo &LI, + DominatorTree &DT) { + if (isa(S)) + return 0; + if (const SCEVUnknown *U = dyn_cast(S)) { + if (const Instruction *I = dyn_cast(U->getValue())) + return LI.getLoopFor(I->getParent()); + return 0; + } + if (const SCEVNAryExpr *N = dyn_cast(S)) { + const Loop *L = 0; + if (const SCEVAddRecExpr *AR = dyn_cast(S)) + L = AR->getLoop(); + for (SCEVNAryExpr::op_iterator I = N->op_begin(), E = N->op_end(); + I != E; ++I) + L = PickMostRelevantLoop(L, GetRelevantLoop(*I, LI, DT), DT); + return L; + } + if (const SCEVCastExpr *C = dyn_cast(S)) + return GetRelevantLoop(C->getOperand(), LI, DT); + if (const SCEVUDivExpr *D = dyn_cast(S)) + return PickMostRelevantLoop(GetRelevantLoop(D->getLHS(), LI, DT), + GetRelevantLoop(D->getRHS(), LI, DT), + DT); + llvm_unreachable("Unexpected SCEV type!"); } +/// LoopCompare - Compare loops by PickMostRelevantLoop. +class LoopCompare { + DominatorTree &DT; +public: + explicit LoopCompare(DominatorTree &dt) : DT(dt) {} + + bool operator()(std::pair LHS, + std::pair RHS) const { + // 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) { const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *V = expand(S->getOperand(S->getNumOperands()-1)); - V = InsertNoopCastOfTo(V, Ty); - // Emit a bunch of add instructions - for (int i = S->getNumOperands()-2; i >= 0; --i) { - Value *W = expand(S->getOperand(i)); - W = InsertNoopCastOfTo(W, Ty); - V = InsertBinop(Instruction::Add, V, W, InsertPt); + // 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, 8> OpsAndLoops; + for (std::reverse_iterator I(S->op_end()), + E(S->op_begin()); I != E; ++I) + OpsAndLoops.push_back(std::make_pair(GetRelevantLoop(*I, *SE.LI, *SE.DT), + *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 >::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 (const PointerType *PTy = dyn_cast(Sum->getType())) { + // The running sum expression is a pointer. Try to form a getelementptr + // at this level with that as the base. + SmallVector NewOps; + for (; I != E && I->first == CurLoop; ++I) + NewOps.push_back(I->second); + Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum); + } else if (const PointerType *PTy = dyn_cast(Op->getType())) { + // The running sum is an integer, and there's a pointer at this level. + // Try to form a getelementptr. + SmallVector NewOps; + NewOps.push_back(SE.getUnknown(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(Sum)) std::swap(Sum, W); + Sum = InsertBinop(Instruction::Add, Sum, W); + ++I; + } } - return V; + + return Sum; } - + Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) { const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - int FirstOp = 0; // Set if we should emit a subtract. - if (const SCEVConstant *SC = dyn_cast(S->getOperand(0))) - if (SC->getValue()->isAllOnesValue()) - FirstOp = 1; - int i = S->getNumOperands()-2; - Value *V = expand(S->getOperand(i+1)); - V = InsertNoopCastOfTo(V, Ty); + // 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, 8> OpsAndLoops; + for (std::reverse_iterator I(S->op_end()), + E(S->op_begin()); I != E; ++I) + OpsAndLoops.push_back(std::make_pair(GetRelevantLoop(*I, *SE.LI, *SE.DT), + *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 a bunch of multiply instructions - for (; i >= FirstOp; --i) { - Value *W = expand(S->getOperand(i)); - W = InsertNoopCastOfTo(W, Ty); - V = InsertBinop(Instruction::Mul, V, W, InsertPt); + // Emit instructions to mul all the operands. Hoist as much as possible + // out of loops. + Value *Prod = 0; + for (SmallVectorImpl >::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(Prod)) std::swap(Prod, W); + Prod = InsertBinop(Instruction::Mul, Prod, W); + ++I; + } } - // -1 * ... ---> 0 - ... - if (FirstOp == 1) - V = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), V, InsertPt); - return V; + return Prod; } Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) { const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *LHS = expand(S->getLHS()); - LHS = InsertNoopCastOfTo(LHS, Ty); + Value *LHS = expandCodeFor(S->getLHS(), Ty); if (const SCEVConstant *SC = dyn_cast(S->getRHS())) { const APInt &RHS = SC->getValue()->getValue(); if (RHS.isPowerOf2()) return InsertBinop(Instruction::LShr, LHS, - ConstantInt::get(Ty, RHS.logBase2()), - InsertPt); + 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(Base)) { + Base = A->getStart(); + Rest = SE.getAddExpr(Rest, + SE.getAddRecExpr(SE.getIntegerSCEV(0, A->getType()), + A->getStepRecurrence(SE), + A->getLoop())); + } + if (const SCEVAddExpr *A = dyn_cast(Base)) { + Base = A->getOperand(A->getNumOperands()-1); + SmallVector 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, + const Type *ExpandTy, + const Type *IntTy) { + // Reuse a previously-inserted PHI, if present. + for (BasicBlock::iterator I = L->getHeader()->begin(); + PHINode *PN = dyn_cast(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(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(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. + for (User::op_iterator OI = IncV->op_begin()+1, + OE = IncV->op_end(); OI != OE; ++OI) + if (Instruction *OInst = dyn_cast(OI)) + if (!SE.DT->dominates(OInst, IVIncInsertPos)) { + IncV = 0; + break; + } + if (!IncV) + break; + // Advance to the next instruction. + IncV = dyn_cast(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(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(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()); + + // 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. + Builder.SetInsertPoint(L->getHeader(), L->getHeader()->begin()); + PHINode *PN = Builder.CreatePHI(ExpandTy, "lsr.iv"); + rememberInstruction(PN); + + // Create the step instructions and populate the PHI. + BasicBlock *Header = L->getHeader(); + for (pred_iterator HPI = pred_begin(Header), HPE = pred_end(Header); + 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->getParent(), InsertPos); + Value *IncV; + // If the PHI is a pointer, use a GEP, otherwise use an add or sub. + if (isPointer) { + const PointerType *GEPPtrTy = cast(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(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, "lsr.iv.next") : + Builder.CreateAdd(PN, StepV, "lsr.iv.next"); + rememberInstruction(IncV); + } + PN->addIncoming(IncV, Pred); } - Value *RHS = expand(S->getRHS()); - RHS = InsertNoopCastOfTo(RHS, Ty); - return InsertBinop(Instruction::UDiv, LHS, RHS, InsertPt); + // 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) { + const Type *STy = S->getType(); + const 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 (L == PostIncLoop) { + const SCEV *Step = S->getStepRecurrence(SE); + Normalized = cast(SE.getMinusSCEV(S, Step)); + } + + // Strip off any non-loop-dominating component from the addrec start. + const SCEV *Start = Normalized->getStart(); + const SCEV *PostLoopOffset = 0; + if (!Start->properlyDominates(L->getHeader(), SE.DT)) { + PostLoopOffset = Start; + Start = SE.getIntegerSCEV(0, Normalized->getType()); + Normalized = + cast(SE.getAddRecExpr(Start, + Normalized->getStepRecurrence(SE), + Normalized->getLoop())); + } + + // Strip off any non-loop-dominating component from the addrec step. + const SCEV *Step = Normalized->getStepRecurrence(SE); + const SCEV *PostLoopScale = 0; + if (!Step->hasComputableLoopEvolution(L) && + !Step->dominates(L->getHeader(), SE.DT)) { + PostLoopScale = Step; + Step = SE.getIntegerSCEV(1, Normalized->getType()); + Normalized = + cast(SE.getAddRecExpr(Start, Step, + Normalized->getLoop())); + } + + // 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. + const Type *ExpandTy = PostLoopScale ? IntTy : STy; + PHINode *PN = getAddRecExprPHILiterally(Normalized, L, ExpandTy, IntTy); + + // Accommodate post-inc mode, if necessary. + Value *Result; + if (L != PostIncLoop) + 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 (const PointerType *PTy = dyn_cast(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); + const 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.isSCEVable(PN->getType()) && + SE.getEffectiveSCEVType(PN->getType())->isIntegerTy() && + 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 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())); + BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); + BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); + BasicBlock::iterator NewInsertPt = + llvm::next(BasicBlock::iterator(cast(V))); + while (isa(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()) { - Value *Start = expand(S->getStart()); - Start = InsertNoopCastOfTo(Start, Ty); - std::vector NewOps(S->op_begin(), S->op_end()); + SmallVector NewOps(S->op_begin(), S->op_end()); NewOps[0] = SE.getIntegerSCEV(0, Ty); - Value *Rest = expand(SE.getAddRecExpr(NewOps, L)); - Rest = InsertNoopCastOfTo(Rest, Ty); + const SCEV *Rest = SE.getAddRecExpr(NewOps, L); + + // 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 (const PointerType *PTy = dyn_cast(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(Base) && !isa(Base)) { + Value *StartV = expand(Base); + assert(StartV->getType() == PTy && "Pointer type mismatch for GEP!"); + return expandAddToGEP(RestArray, RestArray+1, PTy, Ty, StartV); + } + } - // FIXME: look for an existing add to use. - return InsertBinop(Instruction::Add, Rest, Start, InsertPt); + // 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)))); } // {0,+,1} --> Insert a canonical induction variable into the loop! if (S->isAffine() && S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) { + // If there's a canonical IV, just use it. + if (CanonicalIV) { + assert(Ty == SE.getEffectiveSCEVType(CanonicalIV->getType()) && + "IVs with types different from the canonical IV should " + "already have been handled!"); + return CanonicalIV; + } + // Create and insert the PHI node for the induction variable in the // specified loop. BasicBlock *Header = L->getHeader(); PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin()); - PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader()); + rememberInstruction(PN); - pred_iterator HPI = pred_begin(Header); - assert(HPI != pred_end(Header) && "Loop with zero preds???"); - if (!L->contains(*HPI)) ++HPI; - assert(HPI != pred_end(Header) && L->contains(*HPI) && - "No backedge in loop?"); - - // Insert a unit add instruction right before the terminator corresponding - // to the back-edge. Constant *One = ConstantInt::get(Ty, 1); - Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next", - (*HPI)->getTerminator()); - - pred_iterator PI = pred_begin(Header); - if (*PI == L->getLoopPreheader()) - ++PI; - PN->addIncoming(Add, *PI); - return PN; + for (pred_iterator HPI = pred_begin(Header), HPE = pred_end(Header); + HPI != HPE; ++HPI) + if (L->contains(*HPI)) { + // Insert a unit add instruction right before the terminator + // corresponding to the back-edge. + Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next", + (*HPI)->getTerminator()); + rememberInstruction(Add); + PN->addIncoming(Add, *HPI); + } else { + PN->addIncoming(Constant::getNullValue(Ty), *HPI); + } } + // {0,+,F} --> {0,+,1} * F // Get the canonical induction variable I for this loop. - Value *I = getOrInsertCanonicalInductionVariable(L, Ty); + Value *I = CanonicalIV ? + CanonicalIV : + getOrInsertCanonicalInductionVariable(L, Ty); // If this is a simple linear addrec, emit it now as a special case. - if (S->isAffine()) { // {0,+,F} --> i*F - Value *F = expand(S->getOperand(1)); - F = InsertNoopCastOfTo(F, Ty); - - // IF the step is by one, just return the inserted IV. - if (ConstantInt *CI = dyn_cast(F)) - if (CI->getValue() == 1) - return I; - - // If the insert point is directly inside of the loop, emit the multiply at - // the insert point. Otherwise, L is a loop that is a parent of the insert - // point loop. If we can, move the multiply to the outer most loop that it - // is safe to be in. - BasicBlock::iterator MulInsertPt = getInsertionPoint(); - Loop *InsertPtLoop = LI.getLoopFor(MulInsertPt->getParent()); - if (InsertPtLoop != L && InsertPtLoop && - L->contains(InsertPtLoop->getHeader())) { - do { - // If we cannot hoist the multiply out of this loop, don't. - if (!InsertPtLoop->isLoopInvariant(F)) break; - - BasicBlock *InsertPtLoopPH = InsertPtLoop->getLoopPreheader(); - - // If this loop hasn't got a preheader, we aren't able to hoist the - // multiply. - if (!InsertPtLoopPH) - break; - - // Otherwise, move the insert point to the preheader. - MulInsertPt = InsertPtLoopPH->getTerminator(); - InsertPtLoop = InsertPtLoop->getParentLoop(); - } while (InsertPtLoop != L); - } - - return InsertBinop(Instruction::Mul, I, F, MulInsertPt); - } + if (S->isAffine()) // {0,+,F} --> i*F + return + expand(SE.getTruncateOrNoop( + SE.getMulExpr(SE.getUnknown(I), + SE.getNoopOrAnyExtend(S->getOperand(1), + I->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. - SCEVHandle IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV. + const SCEV *IH = SE.getUnknown(I); // 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, I->getType()); + if (isa(Ext)) + NewS = Ext; - SCEVHandle V = S->evaluateAtIteration(IH, SE); + const SCEV *V = cast(NewS)->evaluateAtIteration(IH, SE); //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n"; - return expand(V); + // 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) { const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *V = expand(S->getOperand()); - V = InsertNoopCastOfTo(V, SE.getEffectiveSCEVType(V->getType())); - return new TruncInst(V, Ty, "tmp.", InsertPt); + 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) { const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *V = expand(S->getOperand()); - V = InsertNoopCastOfTo(V, SE.getEffectiveSCEVType(V->getType())); - return new ZExtInst(V, Ty, "tmp.", InsertPt); + 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) { const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *V = expand(S->getOperand()); - V = InsertNoopCastOfTo(V, SE.getEffectiveSCEVType(V->getType())); - return new SExtInst(V, Ty, "tmp.", InsertPt); + 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) { - const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *LHS = expand(S->getOperand(0)); - LHS = InsertNoopCastOfTo(LHS, Ty); - for (unsigned i = 1; i < S->getNumOperands(); ++i) { - Value *RHS = expand(S->getOperand(i)); - RHS = InsertNoopCastOfTo(RHS, Ty); - Value *ICmp = new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS, "tmp", InsertPt); - LHS = SelectInst::Create(ICmp, LHS, RHS, "smax", InsertPt); + Value *LHS = expand(S->getOperand(S->getNumOperands()-1)); + const 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) { - const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *LHS = expand(S->getOperand(0)); - LHS = InsertNoopCastOfTo(LHS, Ty); - for (unsigned i = 1; i < S->getNumOperands(); ++i) { - Value *RHS = expand(S->getOperand(i)); - RHS = InsertNoopCastOfTo(RHS, Ty); - Value *ICmp = new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS, "tmp", InsertPt); - LHS = SelectInst::Create(ICmp, LHS, RHS, "umax", InsertPt); + Value *LHS = expand(S->getOperand(S->getNumOperands()-1)); + const 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(SCEVHandle SH, const Type *Ty, - BasicBlock::iterator IP) { +Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) { // Expand the code for this SCEV. - assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) && - "non-trivial casts should be done with the SCEVs directly!"); - InsertPt = IP; Value *V = expand(SH); - return InsertNoopCastOfTo(V, Ty); + 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) { - // Check to see if we already expanded this. - std::map::iterator I = InsertedExpressions.find(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 (S->isLoopInvariant(L)) { + if (!L) break; + if (BasicBlock *Preheader = L->getLoopPreheader()) { + InsertPt = Preheader->getTerminator(); + BasicBlock::iterator IP = InsertPt; + // Back past any debug info instructions. Sometimes we inserted + // something earlier before debug info but after any real instructions. + // This should behave the same as if debug info was not present. + while (IP != Preheader->begin()) { + --IP; + if (!isa(IP)) + break; + InsertPt = IP; + } + } + } 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 && S->hasComputableLoopEvolution(L) && L != PostIncLoop) + InsertPt = L->getHeader()->getFirstNonPHI(); + while (isa(InsertPt)) + InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); + while (isInsertedInstruction(InsertPt)) + InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); + break; + } + + // Check to see if we already expanded this here. + std::map, + AssertingVH >::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); - InsertedExpressions[S] = V; + + // Remember the expanded value for this SCEV at this location. + if (!PostIncLoop) + InsertedExpressions[std::make_pair(S, InsertPt)] = V; + + restoreInsertPoint(SaveInsertBB, SaveInsertPt); + return V; +} + +void SCEVExpander::rememberInstruction(Value *I) { + if (!PostIncLoop) + 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(I); + do { ++It; } while (isInsertedInstruction(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)) ++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. +Value * +SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L, + const Type *Ty) { + assert(Ty->isIntegerTy() && "Can only insert integer induction variables!"); + const SCEV *H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty), + SE.getIntegerSCEV(1, Ty), L); + BasicBlock *SaveInsertBB = Builder.GetInsertBlock(); + BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint(); + Value *V = expandCodeFor(H, 0, L->getHeader()->begin()); + if (SaveInsertBB) + restoreInsertPoint(SaveInsertBB, SaveInsertPt); return V; }