X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FScalarEvolutionExpander.cpp;h=a72f58f64faecd231ffaf33c772a3360889d6225;hb=2e369930dc9e36728f7953a238d63925d3660612;hp=fd37d7bc1e35a5f8687115f69797cd01b403ad72;hpb=c70c37794fbff2c615d4f9dc3b6adf9583b855dc;p=oota-llvm.git diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp index fd37d7bc1e3..a72f58f64fa 100644 --- a/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/lib/Analysis/ScalarEvolutionExpander.cpp @@ -81,7 +81,7 @@ 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 +98,16 @@ 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 +116,7 @@ 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; } @@ -144,7 +146,7 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, // If we haven't found this binop, insert it. Value *BO = Builder.CreateBinOp(Opcode, LHS, RHS, "tmp"); - InsertedValues.insert(BO); + rememberInstruction(BO); return BO; } @@ -323,7 +325,7 @@ 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. @@ -357,7 +359,7 @@ 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 @@ -464,7 +466,7 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, 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); @@ -491,22 +493,39 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin, // Emit a GEP. Value *GEP = Builder.CreateGEP(V, Idx, "uglygep"); - InsertedValues.insert(GEP); + rememberInstruction(GEP); return GEP; } // 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); 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(); +} + Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { int NumOperands = S->getNumOperands(); const Type *Ty = SE.getEffectiveSCEVType(S->getType()); @@ -539,8 +558,14 @@ Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { // Emit a bunch of add instructions for (int i = NumOperands-1; i >= 0; --i) { if (i == PIdx) continue; - Value *W = expandCodeFor(S->getOperand(i), Ty); - V = InsertBinop(Instruction::Add, V, W); + const SCEV *Op = S->getOperand(i); + if (isNonConstantNegative(Op)) { + Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty); + V = InsertBinop(Instruction::Sub, V, W); + } else { + Value *W = expandCodeFor(Op, Ty); + V = InsertBinop(Instruction::Add, V, W); + } } return V; } @@ -603,7 +628,175 @@ 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 (isInsertedInstruction(PN) && SE.getSCEV(PN) == Normalized) + 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 = isa(ExpandTy); + 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) + Builder.SetInsertPoint(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); + + // Accomodate 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 = 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 = 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(); @@ -620,15 +813,15 @@ 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())); + const SmallVectorImpl &Ops = S->getOperands(); + SmallVector NewOps(Ops.size()); + for (unsigned i = 0, e = Ops.size(); i != e; ++i) + NewOps[i] = SE.getAnyExtendExpr(Ops[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); @@ -680,29 +873,22 @@ 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); + 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()); - 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 @@ -745,7 +931,7 @@ 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; } @@ -754,7 +940,7 @@ 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; } @@ -763,7 +949,7 @@ 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; } @@ -779,9 +965,9 @@ 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 @@ -803,9 +989,9 @@ 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 @@ -851,7 +1037,7 @@ Value *SCEVExpander::expand(const SCEV *S) { if (L && S->hasComputableLoopEvolution(L)) InsertPt = L->getHeader()->getFirstNonPHI(); while (isInsertedInstruction(InsertPt)) - InsertPt = next(BasicBlock::iterator(InsertPt)); + InsertPt = llvm::next(BasicBlock::iterator(InsertPt)); break; } @@ -870,7 +1056,8 @@ 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); return V;