X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FScalarEvolutionExpander.cpp;h=e55ca53c9505770d9249ecfd0d8e2765a4e18ebe;hb=faa75f6e47350f491a44d5e8773acd9457185d51;hp=34724709b0fd5eff17f06f7ece4e9504dd2f31ce;hpb=4c0d5d5db876b0628bdf6a2174263a1c0a9130e2;p=oota-llvm.git diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp index 34724709b0f..e55ca53c950 100644 --- a/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/lib/Analysis/ScalarEvolutionExpander.cpp @@ -15,6 +15,7 @@ #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" @@ -81,7 +82,7 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) { Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), A->getParent()->getEntryBlock().begin()); - InsertedValues.insert(I); + rememberInstruction(I); return I; } @@ -98,14 +99,16 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) { It = cast(I)->getNormalDest()->begin(); while (isa(It)) ++It; if (It != BasicBlock::iterator(CI)) { - // Recreate the cast at the beginning of the entry block. + // 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; } } @@ -114,7 +117,7 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) { IP = II->getNormalDest()->begin(); while (isa(IP)) ++IP; Instruction *CI = CastInst::Create(Op, V, Ty, V->getName(), IP); - InsertedValues.insert(CI); + rememberInstruction(CI); return CI; } @@ -135,6 +138,10 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, 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() == (unsigned)Opcode && IP->getOperand(0) == LHS && IP->getOperand(1) == RHS) return IP; @@ -142,15 +149,34 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, } } + // 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. Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp"); - InsertedValues.insert(BO); + 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 divisble if a reasonable remainder can be +/// 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 @@ -206,9 +232,7 @@ static bool FactorOutConstant(const SCEV *&S, const SCEVConstant *FC = cast(Factor); if (const SCEVConstant *C = dyn_cast(M->getOperand(0))) if (!C->getValue()->getValue().srem(FC->getValue()->getValue())) { - const SmallVectorImpl &MOperands = M->getOperands(); - SmallVector NewMulOps(MOperands.begin(), - MOperands.end()); + SmallVector NewMulOps(M->op_begin(), M->op_end()); NewMulOps[0] = SE.getConstant(C->getValue()->getValue().sdiv( FC->getValue()->getValue())); @@ -223,9 +247,7 @@ static bool FactorOutConstant(const SCEV *&S, const SCEV *Remainder = SE.getIntegerSCEV(0, SOp->getType()); if (FactorOutConstant(SOp, Remainder, Factor, SE, TD) && Remainder->isZero()) { - const SmallVectorImpl &MOperands = M->getOperands(); - SmallVector NewMulOps(MOperands.begin(), - MOperands.end()); + SmallVector NewMulOps(M->op_begin(), M->op_end()); NewMulOps[i] = SOp; S = SE.getMulExpr(NewMulOps); return true; @@ -271,13 +293,11 @@ static void SimplifyAddOperands(SmallVectorImpl &Ops, 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 = Add->getOperands(); - else { - Ops.clear(); - if (!Sum->isZero()) - Ops.push_back(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()); } @@ -323,7 +343,7 @@ static void SplitAddRecs(SmallVectorImpl &Ops, /// http://llvm.org/docs/LangRef.html#pointeraliasing /// for details. /// -/// Design note: The correctness of using getelmeentptr here depends on +/// 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. @@ -357,37 +377,39 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, // without the other. SplitAddRecs(Ops, Ty, SE); - // Decend down the pointer's type and attempt to convert the other + // 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 (;;) { - const SCEV *ElSize = SE.getAllocSizeExpr(ElTy); // If the scale size is not 0, attempt to factor out a scale for // array indexing. SmallVector ScaledOps; - if (ElTy->isSized() && !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 (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); } - } - // If we made any changes, update Ops. - if (!ScaledOps.empty()) { - Ops = NewOps; - SimplifyAddOperands(Ops, Ty, SE); } } @@ -425,22 +447,22 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, } } } else { - // Without TargetData, just check for a SCEVFieldOffsetExpr of the + // 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 SCEVFieldOffsetExpr *FO = - dyn_cast(Ops[i])) - if (FO->getStructType() == STy) { - unsigned FieldNo = FO->getFieldNo(); - GepIndices.push_back( - ConstantInt::get(Type::getInt32Ty(Ty->getContext()), - FieldNo)); - ElTy = STy->getTypeAtIndex(FieldNo); + 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 @@ -458,13 +480,13 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, break; } - // If none of the operands were convertable to proper GEP indices, cast + // 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::getInt8Ty(Ty->getContext())->getPointerTo(PTy->getAddressSpace())); + Type::getInt8PtrTy(Ty->getContext(), PTy->getAddressSpace())); // Expand the operands for a plain byte offset. Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty); @@ -482,6 +504,10 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, 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; @@ -489,65 +515,263 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, } } + // 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"); - InsertedValues.insert(GEP); + 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 *GEP = Builder.CreateGEP(V, + 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)); - InsertedValues.insert(GEP); + rememberInstruction(GEP); + + // Restore the original insert point. + if (SaveInsertBB) + restoreInsertPoint(SaveInsertBB, SaveInsertPt); + return expand(SE.getAddExpr(Ops)); } -Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { - const Type *Ty = SE.getEffectiveSCEVType(S->getType()); - Value *V = expand(S->getOperand(S->getNumOperands()-1)); +/// 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. +} - // Turn things like ptrtoint+arithmetic+inttoptr into GEP. See the - // comments on expandAddToGEP for details. - if (const PointerType *PTy = dyn_cast(V->getType())) { - const SmallVectorImpl &Ops = S->getOperands(); - return expandAddToGEP(&Ops[0], &Ops[Ops.size() - 1], PTy, Ty, V); +/// 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!"); +} - V = InsertNoopCastOfTo(V, Ty); +/// 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; - // Emit a bunch of add instructions - for (int i = S->getNumOperands()-2; i >= 0; --i) { - Value *W = expandCodeFor(S->getOperand(i), Ty); - V = InsertBinop(Instruction::Add, V, W); + // Otherwise they are equivalent according to this comparison. + return false; } - return V; +}; + +Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { + const 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, 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 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 = expandCodeFor(S->getOperand(i+1), Ty); - - // Emit a bunch of multiply instructions - for (; i >= FirstOp; --i) { - Value *W = expandCodeFor(S->getOperand(i), Ty); - V = InsertBinop(Instruction::Mul, V, W); + // 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 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); - return V; + return Prod; } Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) { @@ -586,7 +810,234 @@ static void ExposePointerBase(const SCEV *&Base, const SCEV *&Rest, } } +/// 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); + } + + // 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(); @@ -594,7 +1045,7 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { PHINode *CanonicalIV = 0; if (PHINode *PN = L->getCanonicalInductionVariable()) if (SE.isSCEVable(PN->getType()) && - isa(SE.getEffectiveSCEVType(PN->getType())) && + SE.getEffectiveSCEVType(PN->getType())->isIntegerTy() && SE.getTypeSizeInBits(PN->getType()) >= SE.getTypeSizeInBits(Ty)) CanonicalIV = PN; @@ -603,26 +1054,24 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { if (CanonicalIV && SE.getTypeSizeInBits(CanonicalIV->getType()) > SE.getTypeSizeInBits(Ty)) { - const SCEV *Start = SE.getAnyExtendExpr(S->getStart(), - CanonicalIV->getType()); - const SCEV *Step = SE.getAnyExtendExpr(S->getStepRecurrence(SE), - CanonicalIV->getType()); - Value *V = expand(SE.getAddRecExpr(Start, Step, S->getLoop())); + 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 = - next(BasicBlock::iterator(cast(V))); + llvm::next(BasicBlock::iterator(cast(V))); while (isa(NewInsertPt)) ++NewInsertPt; V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), 0, NewInsertPt); - Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt); + restoreInsertPoint(SaveInsertBB, SaveInsertPt); return V; } // {X,+,F} --> X + {0,+,F} if (!S->getStart()->isZero()) { - const SmallVectorImpl &SOperands = S->getOperands(); - SmallVector NewOps(SOperands.begin(), SOperands.end()); + SmallVector NewOps(S->op_begin(), S->op_end()); NewOps[0] = SE.getIntegerSCEV(0, Ty); const SCEV *Rest = SE.getAddRecExpr(NewOps, L); @@ -663,29 +1112,22 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { // Create and insert the PHI node for the induction variable in the // specified loop. BasicBlock *Header = L->getHeader(); - BasicBlock *Preheader = L->getLoopPreheader(); PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin()); - InsertedValues.insert(PN); - PN->addIncoming(Constant::getNullValue(Ty), Preheader); - - 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?"); + rememberInstruction(PN); - // 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()); - InsertedValues.insert(Add); - - pred_iterator PI = pred_begin(Header); - if (*PI == Preheader) - ++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 @@ -728,7 +1170,7 @@ Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) { Value *V = expandCodeFor(S->getOperand(), SE.getEffectiveSCEVType(S->getOperand()->getType())); Value *I = Builder.CreateTrunc(V, Ty, "tmp"); - InsertedValues.insert(I); + rememberInstruction(I); return I; } @@ -737,7 +1179,7 @@ Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) { Value *V = expandCodeFor(S->getOperand(), SE.getEffectiveSCEVType(S->getOperand()->getType())); Value *I = Builder.CreateZExt(V, Ty, "tmp"); - InsertedValues.insert(I); + rememberInstruction(I); return I; } @@ -746,7 +1188,7 @@ Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) { Value *V = expandCodeFor(S->getOperand(), SE.getEffectiveSCEVType(S->getOperand()->getType())); Value *I = Builder.CreateSExt(V, Ty, "tmp"); - InsertedValues.insert(I); + rememberInstruction(I); return I; } @@ -762,9 +1204,9 @@ Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) { } Value *RHS = expandCodeFor(S->getOperand(i), Ty); Value *ICmp = Builder.CreateICmpSGT(LHS, RHS, "tmp"); - InsertedValues.insert(ICmp); + rememberInstruction(ICmp); Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax"); - InsertedValues.insert(Sel); + rememberInstruction(Sel); LHS = Sel; } // In the case of mixed integer and pointer types, cast the @@ -786,9 +1228,9 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) { } Value *RHS = expandCodeFor(S->getOperand(i), Ty); Value *ICmp = Builder.CreateICmpUGT(LHS, RHS, "tmp"); - InsertedValues.insert(ICmp); + rememberInstruction(ICmp); Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax"); - InsertedValues.insert(Sel); + rememberInstruction(Sel); LHS = Sel; } // In the case of mixed integer and pointer types, cast the @@ -798,14 +1240,6 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) { return LHS; } -Value *SCEVExpander::visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S) { - return ConstantExpr::getOffsetOf(S->getStructType(), S->getFieldNo()); -} - -Value *SCEVExpander::visitAllocSizeExpr(const SCEVAllocSizeExpr *S) { - return ConstantExpr::getSizeOf(S->getAllocType()); -} - Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) { // Expand the code for this SCEV. Value *V = expand(SH); @@ -825,16 +1259,29 @@ Value *SCEVExpander::expand(const SCEV *S) { L = L->getParentLoop()) if (S->isLoopInvariant(L)) { if (!L) break; - if (BasicBlock *Preheader = L->getLoopPreheader()) + 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)) + if (L && S->hasComputableLoopEvolution(L) && L != PostIncLoop) InsertPt = L->getHeader()->getFirstNonPHI(); + while (isa(InsertPt)) + InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); while (isInsertedInstruction(InsertPt)) - InsertPt = next(BasicBlock::iterator(InsertPt)); + InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); break; } @@ -853,12 +1300,35 @@ Value *SCEVExpander::expand(const SCEV *S) { Value *V = visit(S); // Remember the expanded value for this SCEV at this location. - InsertedExpressions[std::make_pair(S, InsertPt)] = V; + if (!PostIncLoop) + InsertedExpressions[std::make_pair(S, InsertPt)] = V; - Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt); + 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 @@ -866,13 +1336,13 @@ Value *SCEVExpander::expand(const SCEV *S) { Value * SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty) { - assert(Ty->isInteger() && "Can only insert integer induction variables!"); + 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) - Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt); + restoreInsertPoint(SaveInsertBB, SaveInsertPt); return V; }