diff options
Diffstat (limited to 'contrib/llvm/lib/Analysis/ScalarEvolution.cpp')
| -rw-r--r-- | contrib/llvm/lib/Analysis/ScalarEvolution.cpp | 3265 |
1 files changed, 2236 insertions, 1029 deletions
diff --git a/contrib/llvm/lib/Analysis/ScalarEvolution.cpp b/contrib/llvm/lib/Analysis/ScalarEvolution.cpp index 9c7c175..34074ef 100644 --- a/contrib/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/contrib/llvm/lib/Analysis/ScalarEvolution.cpp @@ -83,11 +83,13 @@ #include "llvm/IR/LLVMContext.h" #include "llvm/IR/Metadata.h" #include "llvm/IR/Operator.h" +#include "llvm/IR/PatternMatch.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/MathExtras.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/Support/SaveAndRestore.h" #include <algorithm> using namespace llvm; @@ -114,16 +116,6 @@ static cl::opt<bool> VerifySCEV("verify-scev", cl::desc("Verify ScalarEvolution's backedge taken counts (slow)")); -INITIALIZE_PASS_BEGIN(ScalarEvolution, "scalar-evolution", - "Scalar Evolution Analysis", false, true) -INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) -INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) -INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) -INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass) -INITIALIZE_PASS_END(ScalarEvolution, "scalar-evolution", - "Scalar Evolution Analysis", false, true) -char ScalarEvolution::ID = 0; - //===----------------------------------------------------------------------===// // SCEV class definitions //===----------------------------------------------------------------------===// @@ -132,12 +124,11 @@ char ScalarEvolution::ID = 0; // Implementation of the SCEV class. // -#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +LLVM_DUMP_METHOD void SCEV::dump() const { print(dbgs()); dbgs() << '\n'; } -#endif void SCEV::print(raw_ostream &OS) const { switch (static_cast<SCEVTypes>(getSCEVType())) { @@ -303,7 +294,7 @@ bool SCEV::isNonConstantNegative() const { if (!SC) return false; // Return true if the value is negative, this matches things like (-42 * V). - return SC->getValue()->getValue().isNegative(); + return SC->getAPInt().isNegative(); } SCEVCouldNotCompute::SCEVCouldNotCompute() : @@ -455,179 +446,179 @@ bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const { //===----------------------------------------------------------------------===// namespace { - /// SCEVComplexityCompare - Return true if the complexity of the LHS is less - /// than the complexity of the RHS. This comparator is used to canonicalize - /// expressions. - class SCEVComplexityCompare { - const LoopInfo *const LI; - public: - explicit SCEVComplexityCompare(const LoopInfo *li) : LI(li) {} - - // Return true or false if LHS is less than, or at least RHS, respectively. - bool operator()(const SCEV *LHS, const SCEV *RHS) const { - return compare(LHS, RHS) < 0; - } - - // Return negative, zero, or positive, if LHS is less than, equal to, or - // greater than RHS, respectively. A three-way result allows recursive - // comparisons to be more efficient. - int compare(const SCEV *LHS, const SCEV *RHS) const { - // Fast-path: SCEVs are uniqued so we can do a quick equality check. - if (LHS == RHS) - return 0; - - // Primarily, sort the SCEVs by their getSCEVType(). - unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType(); - if (LType != RType) - return (int)LType - (int)RType; - - // Aside from the getSCEVType() ordering, the particular ordering - // isn't very important except that it's beneficial to be consistent, - // so that (a + b) and (b + a) don't end up as different expressions. - switch (static_cast<SCEVTypes>(LType)) { - case scUnknown: { - const SCEVUnknown *LU = cast<SCEVUnknown>(LHS); - const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); - - // Sort SCEVUnknown values with some loose heuristics. TODO: This is - // not as complete as it could be. - const Value *LV = LU->getValue(), *RV = RU->getValue(); - - // Order pointer values after integer values. This helps SCEVExpander - // form GEPs. - bool LIsPointer = LV->getType()->isPointerTy(), - RIsPointer = RV->getType()->isPointerTy(); - if (LIsPointer != RIsPointer) - return (int)LIsPointer - (int)RIsPointer; - - // Compare getValueID values. - unsigned LID = LV->getValueID(), - RID = RV->getValueID(); - if (LID != RID) - return (int)LID - (int)RID; - - // Sort arguments by their position. - if (const Argument *LA = dyn_cast<Argument>(LV)) { - const Argument *RA = cast<Argument>(RV); - unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo(); - return (int)LArgNo - (int)RArgNo; - } - - // For instructions, compare their loop depth, and their operand - // count. This is pretty loose. - if (const Instruction *LInst = dyn_cast<Instruction>(LV)) { - const Instruction *RInst = cast<Instruction>(RV); - - // Compare loop depths. - const BasicBlock *LParent = LInst->getParent(), - *RParent = RInst->getParent(); - if (LParent != RParent) { - unsigned LDepth = LI->getLoopDepth(LParent), - RDepth = LI->getLoopDepth(RParent); - if (LDepth != RDepth) - return (int)LDepth - (int)RDepth; - } - - // Compare the number of operands. - unsigned LNumOps = LInst->getNumOperands(), - RNumOps = RInst->getNumOperands(); - return (int)LNumOps - (int)RNumOps; - } +/// SCEVComplexityCompare - Return true if the complexity of the LHS is less +/// than the complexity of the RHS. This comparator is used to canonicalize +/// expressions. +class SCEVComplexityCompare { + const LoopInfo *const LI; +public: + explicit SCEVComplexityCompare(const LoopInfo *li) : LI(li) {} - return 0; - } + // Return true or false if LHS is less than, or at least RHS, respectively. + bool operator()(const SCEV *LHS, const SCEV *RHS) const { + return compare(LHS, RHS) < 0; + } - case scConstant: { - const SCEVConstant *LC = cast<SCEVConstant>(LHS); - const SCEVConstant *RC = cast<SCEVConstant>(RHS); - - // Compare constant values. - const APInt &LA = LC->getValue()->getValue(); - const APInt &RA = RC->getValue()->getValue(); - unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth(); - if (LBitWidth != RBitWidth) - return (int)LBitWidth - (int)RBitWidth; - return LA.ult(RA) ? -1 : 1; + // Return negative, zero, or positive, if LHS is less than, equal to, or + // greater than RHS, respectively. A three-way result allows recursive + // comparisons to be more efficient. + int compare(const SCEV *LHS, const SCEV *RHS) const { + // Fast-path: SCEVs are uniqued so we can do a quick equality check. + if (LHS == RHS) + return 0; + + // Primarily, sort the SCEVs by their getSCEVType(). + unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType(); + if (LType != RType) + return (int)LType - (int)RType; + + // Aside from the getSCEVType() ordering, the particular ordering + // isn't very important except that it's beneficial to be consistent, + // so that (a + b) and (b + a) don't end up as different expressions. + switch (static_cast<SCEVTypes>(LType)) { + case scUnknown: { + const SCEVUnknown *LU = cast<SCEVUnknown>(LHS); + const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); + + // Sort SCEVUnknown values with some loose heuristics. TODO: This is + // not as complete as it could be. + const Value *LV = LU->getValue(), *RV = RU->getValue(); + + // Order pointer values after integer values. This helps SCEVExpander + // form GEPs. + bool LIsPointer = LV->getType()->isPointerTy(), + RIsPointer = RV->getType()->isPointerTy(); + if (LIsPointer != RIsPointer) + return (int)LIsPointer - (int)RIsPointer; + + // Compare getValueID values. + unsigned LID = LV->getValueID(), + RID = RV->getValueID(); + if (LID != RID) + return (int)LID - (int)RID; + + // Sort arguments by their position. + if (const Argument *LA = dyn_cast<Argument>(LV)) { + const Argument *RA = cast<Argument>(RV); + unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo(); + return (int)LArgNo - (int)RArgNo; } - case scAddRecExpr: { - const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS); - const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS); - - // Compare addrec loop depths. - const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop(); - if (LLoop != RLoop) { - unsigned LDepth = LLoop->getLoopDepth(), - RDepth = RLoop->getLoopDepth(); + // For instructions, compare their loop depth, and their operand + // count. This is pretty loose. + if (const Instruction *LInst = dyn_cast<Instruction>(LV)) { + const Instruction *RInst = cast<Instruction>(RV); + + // Compare loop depths. + const BasicBlock *LParent = LInst->getParent(), + *RParent = RInst->getParent(); + if (LParent != RParent) { + unsigned LDepth = LI->getLoopDepth(LParent), + RDepth = LI->getLoopDepth(RParent); if (LDepth != RDepth) return (int)LDepth - (int)RDepth; } - // Addrec complexity grows with operand count. - unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands(); - if (LNumOps != RNumOps) - return (int)LNumOps - (int)RNumOps; + // Compare the number of operands. + unsigned LNumOps = LInst->getNumOperands(), + RNumOps = RInst->getNumOperands(); + return (int)LNumOps - (int)RNumOps; + } - // Lexicographically compare. - for (unsigned i = 0; i != LNumOps; ++i) { - long X = compare(LA->getOperand(i), RA->getOperand(i)); - if (X != 0) - return X; - } + return 0; + } - return 0; + case scConstant: { + const SCEVConstant *LC = cast<SCEVConstant>(LHS); + const SCEVConstant *RC = cast<SCEVConstant>(RHS); + + // Compare constant values. + const APInt &LA = LC->getAPInt(); + const APInt &RA = RC->getAPInt(); + unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth(); + if (LBitWidth != RBitWidth) + return (int)LBitWidth - (int)RBitWidth; + return LA.ult(RA) ? -1 : 1; + } + + case scAddRecExpr: { + const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS); + const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS); + + // Compare addrec loop depths. + const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop(); + if (LLoop != RLoop) { + unsigned LDepth = LLoop->getLoopDepth(), + RDepth = RLoop->getLoopDepth(); + if (LDepth != RDepth) + return (int)LDepth - (int)RDepth; } - case scAddExpr: - case scMulExpr: - case scSMaxExpr: - case scUMaxExpr: { - const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS); - const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS); - - // Lexicographically compare n-ary expressions. - unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands(); - if (LNumOps != RNumOps) - return (int)LNumOps - (int)RNumOps; - - for (unsigned i = 0; i != LNumOps; ++i) { - if (i >= RNumOps) - return 1; - long X = compare(LC->getOperand(i), RC->getOperand(i)); - if (X != 0) - return X; - } + // Addrec complexity grows with operand count. + unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands(); + if (LNumOps != RNumOps) return (int)LNumOps - (int)RNumOps; + + // Lexicographically compare. + for (unsigned i = 0; i != LNumOps; ++i) { + long X = compare(LA->getOperand(i), RA->getOperand(i)); + if (X != 0) + return X; } - case scUDivExpr: { - const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS); - const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); + return 0; + } + + case scAddExpr: + case scMulExpr: + case scSMaxExpr: + case scUMaxExpr: { + const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS); + const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS); - // Lexicographically compare udiv expressions. - long X = compare(LC->getLHS(), RC->getLHS()); + // Lexicographically compare n-ary expressions. + unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands(); + if (LNumOps != RNumOps) + return (int)LNumOps - (int)RNumOps; + + for (unsigned i = 0; i != LNumOps; ++i) { + if (i >= RNumOps) + return 1; + long X = compare(LC->getOperand(i), RC->getOperand(i)); if (X != 0) return X; - return compare(LC->getRHS(), RC->getRHS()); } + return (int)LNumOps - (int)RNumOps; + } - case scTruncate: - case scZeroExtend: - case scSignExtend: { - const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS); - const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); + case scUDivExpr: { + const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS); + const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); - // Compare cast expressions by operand. - return compare(LC->getOperand(), RC->getOperand()); - } + // Lexicographically compare udiv expressions. + long X = compare(LC->getLHS(), RC->getLHS()); + if (X != 0) + return X; + return compare(LC->getRHS(), RC->getRHS()); + } - case scCouldNotCompute: - llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!"); - } - llvm_unreachable("Unknown SCEV kind!"); + case scTruncate: + case scZeroExtend: + case scSignExtend: { + const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS); + const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); + + // Compare cast expressions by operand. + return compare(LC->getOperand(), RC->getOperand()); } - }; -} + + case scCouldNotCompute: + llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!"); + } + llvm_unreachable("Unknown SCEV kind!"); + } +}; +} // end anonymous namespace /// GroupByComplexity - Given a list of SCEV objects, order them by their /// complexity, and group objects of the same complexity together by value. @@ -675,24 +666,22 @@ static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops, } } -namespace { -struct FindSCEVSize { - int Size; - FindSCEVSize() : Size(0) {} - - bool follow(const SCEV *S) { - ++Size; - // Keep looking at all operands of S. - return true; - } - bool isDone() const { - return false; - } -}; -} - // Returns the size of the SCEV S. static inline int sizeOfSCEV(const SCEV *S) { + struct FindSCEVSize { + int Size; + FindSCEVSize() : Size(0) {} + + bool follow(const SCEV *S) { + ++Size; + // Keep looking at all operands of S. + return true; + } + bool isDone() const { + return false; + } + }; + FindSCEVSize F; SCEVTraversal<FindSCEVSize> ST(F); ST.visitAll(S); @@ -771,8 +760,8 @@ public: void visitConstant(const SCEVConstant *Numerator) { if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) { - APInt NumeratorVal = Numerator->getValue()->getValue(); - APInt DenominatorVal = D->getValue()->getValue(); + APInt NumeratorVal = Numerator->getAPInt(); + APInt DenominatorVal = D->getAPInt(); uint32_t NumeratorBW = NumeratorVal.getBitWidth(); uint32_t DenominatorBW = DenominatorVal.getBitWidth(); @@ -792,17 +781,15 @@ public: void visitAddRecExpr(const SCEVAddRecExpr *Numerator) { const SCEV *StartQ, *StartR, *StepQ, *StepR; - assert(Numerator->isAffine() && "Numerator should be affine"); + if (!Numerator->isAffine()) + return cannotDivide(Numerator); divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR); divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR); // Bail out if the types do not match. Type *Ty = Denominator->getType(); if (Ty != StartQ->getType() || Ty != StartR->getType() || - Ty != StepQ->getType() || Ty != StepR->getType()) { - Quotient = Zero; - Remainder = Numerator; - return; - } + Ty != StepQ->getType() || Ty != StepR->getType()) + return cannotDivide(Numerator); Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(), Numerator->getNoWrapFlags()); Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(), @@ -818,11 +805,8 @@ public: divide(SE, Op, Denominator, &Q, &R); // Bail out if types do not match. - if (Ty != Q->getType() || Ty != R->getType()) { - Quotient = Zero; - Remainder = Numerator; - return; - } + if (Ty != Q->getType() || Ty != R->getType()) + return cannotDivide(Numerator); Qs.push_back(Q); Rs.push_back(R); @@ -845,11 +829,8 @@ public: bool FoundDenominatorTerm = false; for (const SCEV *Op : Numerator->operands()) { // Bail out if types do not match. - if (Ty != Op->getType()) { - Quotient = Zero; - Remainder = Numerator; - return; - } + if (Ty != Op->getType()) + return cannotDivide(Numerator); if (FoundDenominatorTerm) { Qs.push_back(Op); @@ -865,11 +846,8 @@ public: } // Bail out if types do not match. - if (Ty != Q->getType()) { - Quotient = Zero; - Remainder = Numerator; - return; - } + if (Ty != Q->getType()) + return cannotDivide(Numerator); FoundDenominatorTerm = true; Qs.push_back(Q); @@ -884,11 +862,8 @@ public: return; } - if (!isa<SCEVUnknown>(Denominator)) { - Quotient = Zero; - Remainder = Numerator; - return; - } + if (!isa<SCEVUnknown>(Denominator)) + return cannotDivide(Numerator); // The Remainder is obtained by replacing Denominator by 0 in Numerator. ValueToValueMap RewriteMap; @@ -908,15 +883,12 @@ public: // Quotient is (Numerator - Remainder) divided by Denominator. const SCEV *Q, *R; const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder); - if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator)) { - // This SCEV does not seem to simplify: fail the division here. - Quotient = Zero; - Remainder = Numerator; - return; - } + // This SCEV does not seem to simplify: fail the division here. + if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator)) + return cannotDivide(Numerator); divide(SE, Diff, Denominator, &Q, &R); - assert(R == Zero && - "(Numerator - Remainder) should evenly divide Denominator"); + if (R != Zero) + return cannotDivide(Numerator); Quotient = Q; } @@ -924,11 +896,18 @@ private: SCEVDivision(ScalarEvolution &S, const SCEV *Numerator, const SCEV *Denominator) : SE(S), Denominator(Denominator) { - Zero = SE.getConstant(Denominator->getType(), 0); - One = SE.getConstant(Denominator->getType(), 1); + Zero = SE.getZero(Denominator->getType()); + One = SE.getOne(Denominator->getType()); + + // We generally do not know how to divide Expr by Denominator. We + // initialize the division to a "cannot divide" state to simplify the rest + // of the code. + cannotDivide(Numerator); + } - // By default, we don't know how to divide Expr by Denominator. - // Providing the default here simplifies the rest of the code. + // Convenience function for giving up on the division. We set the quotient to + // be equal to zero and the remainder to be equal to the numerator. + void cannotDivide(const SCEV *Numerator) { Quotient = Zero; Remainder = Numerator; } @@ -1151,8 +1130,8 @@ const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, // If the input value is a chrec scev, truncate the chrec's operands. if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { SmallVector<const SCEV *, 4> Operands; - for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) - Operands.push_back(getTruncateExpr(AddRec->getOperand(i), Ty)); + for (const SCEV *Op : AddRec->operands()) + Operands.push_back(getTruncateExpr(Op, Ty)); return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap); } @@ -1287,7 +1266,9 @@ static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty, // `Step`: // 1. NSW/NUW flags on the step increment. - const SCEV *PreStart = SE->getAddExpr(DiffOps, SA->getNoWrapFlags()); + auto PreStartFlags = + ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW); + const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags); const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>( SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap)); @@ -1322,9 +1303,9 @@ static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty, ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE); if (OverflowLimit && - SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) { + SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) return PreStart; - } + return nullptr; } @@ -1390,24 +1371,22 @@ bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start, if (!StartC) return false; - APInt StartAI = StartC->getValue()->getValue(); + APInt StartAI = StartC->getAPInt(); for (unsigned Delta : {-2, -1, 1, 2}) { const SCEV *PreStart = getConstant(StartAI - Delta); + FoldingSetNodeID ID; + ID.AddInteger(scAddRecExpr); + ID.AddPointer(PreStart); + ID.AddPointer(Step); + ID.AddPointer(L); + void *IP = nullptr; + const auto *PreAR = + static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); + // Give up if we don't already have the add recurrence we need because // actually constructing an add recurrence is relatively expensive. - const SCEVAddRecExpr *PreAR = [&]() { - FoldingSetNodeID ID; - ID.AddInteger(scAddRecExpr); - ID.AddPointer(PreStart); - ID.AddPointer(Step); - ID.AddPointer(L); - void *IP = nullptr; - return static_cast<SCEVAddRecExpr *>( - this->UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); - }(); - if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2) const SCEV *DeltaS = getConstant(StartC->getType(), Delta); ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE; @@ -1578,6 +1557,18 @@ const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op, } } + if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { + // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw> + if (SA->getNoWrapFlags(SCEV::FlagNUW)) { + // If the addition does not unsign overflow then we can, by definition, + // commute the zero extension with the addition operation. + SmallVector<const SCEV *, 4> Ops; + for (const auto *Op : SA->operands()) + Ops.push_back(getZeroExtendExpr(Op, Ty)); + return getAddExpr(Ops, SCEV::FlagNUW); + } + } + // The cast wasn't folded; create an explicit cast node. // Recompute the insert position, as it may have been invalidated. if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; @@ -1635,14 +1626,14 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, } // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2 - if (auto SA = dyn_cast<SCEVAddExpr>(Op)) { + if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { if (SA->getNumOperands() == 2) { - auto SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0)); - auto SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1)); + auto *SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0)); + auto *SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1)); if (SMul && SC1) { - if (auto SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) { - const APInt &C1 = SC1->getValue()->getValue(); - const APInt &C2 = SC2->getValue()->getValue(); + if (auto *SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) { + const APInt &C1 = SC1->getAPInt(); + const APInt &C2 = SC2->getAPInt(); if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) && C2.isPowerOf2()) return getAddExpr(getSignExtendExpr(SC1, Ty), @@ -1650,6 +1641,16 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, } } } + + // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw> + if (SA->getNoWrapFlags(SCEV::FlagNSW)) { + // If the addition does not sign overflow then we can, by definition, + // commute the sign extension with the addition operation. + SmallVector<const SCEV *, 4> Ops; + for (const auto *Op : SA->operands()) + Ops.push_back(getSignExtendExpr(Op, Ty)); + return getAddExpr(Ops, SCEV::FlagNSW); + } } // If the input value is a chrec scev, and we can prove that the value // did not overflow the old, smaller, value, we can sign extend all of the @@ -1754,16 +1755,16 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, // If Start and Step are constants, check if we can apply this // transformation: // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2 - auto SC1 = dyn_cast<SCEVConstant>(Start); - auto SC2 = dyn_cast<SCEVConstant>(Step); + auto *SC1 = dyn_cast<SCEVConstant>(Start); + auto *SC2 = dyn_cast<SCEVConstant>(Step); if (SC1 && SC2) { - const APInt &C1 = SC1->getValue()->getValue(); - const APInt &C2 = SC2->getValue()->getValue(); + const APInt &C1 = SC1->getAPInt(); + const APInt &C2 = SC2->getAPInt(); if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) && C2.isPowerOf2()) { Start = getSignExtendExpr(Start, Ty); - const SCEV *NewAR = getAddRecExpr(getConstant(AR->getType(), 0), Step, - L, AR->getNoWrapFlags()); + const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L, + AR->getNoWrapFlags()); return getAddExpr(Start, getSignExtendExpr(NewAR, Ty)); } } @@ -1798,7 +1799,7 @@ const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op, // Sign-extend negative constants. if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) - if (SC->getValue()->getValue().isNegative()) + if (SC->getAPInt().isNegative()) return getSignExtendExpr(Op, Ty); // Peel off a truncate cast. @@ -1876,7 +1877,7 @@ CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, // Pull a buried constant out to the outside. if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero()) Interesting = true; - AccumulatedConstant += Scale * C->getValue()->getValue(); + AccumulatedConstant += Scale * C->getAPInt(); } // Next comes everything else. We're especially interested in multiplies @@ -1885,7 +1886,7 @@ CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]); if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) { APInt NewScale = - Scale * cast<SCEVConstant>(Mul->getOperand(0))->getValue()->getValue(); + Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt(); if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) { // A multiplication of a constant with another add; recurse. const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1)); @@ -1898,8 +1899,7 @@ CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, // the map. SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end()); const SCEV *Key = SE.getMulExpr(MulOps); - std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair = - M.insert(std::make_pair(Key, NewScale)); + auto Pair = M.insert(std::make_pair(Key, NewScale)); if (Pair.second) { NewOps.push_back(Pair.first->first); } else { @@ -1927,22 +1927,15 @@ CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, return Interesting; } -namespace { - struct APIntCompare { - bool operator()(const APInt &LHS, const APInt &RHS) const { - return LHS.ult(RHS); - } - }; -} - // We're trying to construct a SCEV of type `Type' with `Ops' as operands and // `OldFlags' as can't-wrap behavior. Infer a more aggressive set of // can't-overflow flags for the operation if possible. static SCEV::NoWrapFlags StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type, const SmallVectorImpl<const SCEV *> &Ops, - SCEV::NoWrapFlags OldFlags) { + SCEV::NoWrapFlags Flags) { using namespace std::placeholders; + typedef OverflowingBinaryOperator OBO; bool CanAnalyze = Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr; @@ -1951,18 +1944,42 @@ StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type, int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; SCEV::NoWrapFlags SignOrUnsignWrap = - ScalarEvolution::maskFlags(OldFlags, SignOrUnsignMask); + ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. - auto IsKnownNonNegative = - std::bind(std::mem_fn(&ScalarEvolution::isKnownNonNegative), SE, _1); + auto IsKnownNonNegative = [&](const SCEV *S) { + return SE->isKnownNonNegative(S); + }; + + if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative)) + Flags = + ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); - if (SignOrUnsignWrap == SCEV::FlagNSW && - std::all_of(Ops.begin(), Ops.end(), IsKnownNonNegative)) - return ScalarEvolution::setFlags(OldFlags, - (SCEV::NoWrapFlags)SignOrUnsignMask); + SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); + + if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr && + Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) { + + // (A + C) --> (A + C)<nsw> if the addition does not sign overflow + // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow + + const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt(); + if (!(SignOrUnsignWrap & SCEV::FlagNSW)) { + auto NSWRegion = + ConstantRange::makeNoWrapRegion(Instruction::Add, C, OBO::NoSignedWrap); + if (NSWRegion.contains(SE->getSignedRange(Ops[1]))) + Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); + } + if (!(SignOrUnsignWrap & SCEV::FlagNUW)) { + auto NUWRegion = + ConstantRange::makeNoWrapRegion(Instruction::Add, C, + OBO::NoUnsignedWrap); + if (NUWRegion.contains(SE->getUnsignedRange(Ops[1]))) + Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); + } + } - return OldFlags; + return Flags; } /// getAddExpr - Get a canonical add expression, or something simpler if @@ -1980,10 +1997,10 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, "SCEVAddExpr operand types don't match!"); #endif - Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags); - // Sort by complexity, this groups all similar expression types together. - GroupByComplexity(Ops, LI); + GroupByComplexity(Ops, &LI); + + Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags); // If there are any constants, fold them together. unsigned Idx = 0; @@ -1992,8 +2009,7 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, assert(Idx < Ops.size()); while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { // We found two constants, fold them together! - Ops[0] = getConstant(LHSC->getValue()->getValue() + - RHSC->getValue()->getValue()); + Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt()); if (Ops.size() == 2) return Ops[0]; Ops.erase(Ops.begin()+1); // Erase the folded element LHSC = cast<SCEVConstant>(Ops[0]); @@ -2063,8 +2079,7 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, break; } LargeMulOps.push_back(T->getOperand()); - } else if (const SCEVConstant *C = - dyn_cast<SCEVConstant>(M->getOperand(j))) { + } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) { LargeMulOps.push_back(getAnyExtendExpr(C, SrcType)); } else { Ok = false; @@ -2123,24 +2138,28 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, Ops.data(), Ops.size(), APInt(BitWidth, 1), *this)) { + struct APIntCompare { + bool operator()(const APInt &LHS, const APInt &RHS) const { + return LHS.ult(RHS); + } + }; + // Some interesting folding opportunity is present, so its worthwhile to // re-generate the operands list. Group the operands by constant scale, // to avoid multiplying by the same constant scale multiple times. std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists; - for (SmallVectorImpl<const SCEV *>::const_iterator I = NewOps.begin(), - E = NewOps.end(); I != E; ++I) - MulOpLists[M.find(*I)->second].push_back(*I); + for (const SCEV *NewOp : NewOps) + MulOpLists[M.find(NewOp)->second].push_back(NewOp); // Re-generate the operands list. Ops.clear(); if (AccumulatedConstant != 0) Ops.push_back(getConstant(AccumulatedConstant)); - for (std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare>::iterator - I = MulOpLists.begin(), E = MulOpLists.end(); I != E; ++I) - if (I->first != 0) - Ops.push_back(getMulExpr(getConstant(I->first), - getAddExpr(I->second))); + for (auto &MulOp : MulOpLists) + if (MulOp.first != 0) + Ops.push_back(getMulExpr(getConstant(MulOp.first), + getAddExpr(MulOp.second))); if (Ops.empty()) - return getConstant(Ty, 0); + return getZero(Ty); if (Ops.size() == 1) return Ops[0]; return getAddExpr(Ops); @@ -2168,7 +2187,7 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); InnerMul = getMulExpr(MulOps); } - const SCEV *One = getConstant(Ty, 1); + const SCEV *One = getOne(Ty); const SCEV *AddOne = getAddExpr(One, InnerMul); const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV); if (Ops.size() == 2) return OuterMul; @@ -2279,8 +2298,7 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, AddRec->op_end()); for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); ++OtherIdx) - if (const SCEVAddRecExpr *OtherAddRec = - dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx])) + if (const auto *OtherAddRec = dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx])) if (OtherAddRec->getLoop() == AddRecLoop) { for (unsigned i = 0, e = OtherAddRec->getNumOperands(); i != e; ++i) { @@ -2388,10 +2406,10 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, "SCEVMulExpr operand types don't match!"); #endif - Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags); - // Sort by complexity, this groups all similar expression types together. - GroupByComplexity(Ops, LI); + GroupByComplexity(Ops, &LI); + + Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags); // If there are any constants, fold them together. unsigned Idx = 0; @@ -2410,9 +2428,8 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, ++Idx; while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { // We found two constants, fold them together! - ConstantInt *Fold = ConstantInt::get(getContext(), - LHSC->getValue()->getValue() * - RHSC->getValue()->getValue()); + ConstantInt *Fold = + ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt()); Ops[0] = getConstant(Fold); Ops.erase(Ops.begin()+1); // Erase the folded element if (Ops.size() == 1) return Ops[0]; @@ -2433,23 +2450,19 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) { SmallVector<const SCEV *, 4> NewOps; bool AnyFolded = false; - for (SCEVAddRecExpr::op_iterator I = Add->op_begin(), - E = Add->op_end(); I != E; ++I) { - const SCEV *Mul = getMulExpr(Ops[0], *I); + for (const SCEV *AddOp : Add->operands()) { + const SCEV *Mul = getMulExpr(Ops[0], AddOp); if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true; NewOps.push_back(Mul); } if (AnyFolded) return getAddExpr(NewOps); - } - else if (const SCEVAddRecExpr * - AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) { + } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) { // Negation preserves a recurrence's no self-wrap property. SmallVector<const SCEV *, 4> Operands; - for (SCEVAddRecExpr::op_iterator I = AddRec->op_begin(), - E = AddRec->op_end(); I != E; ++I) { - Operands.push_back(getMulExpr(Ops[0], *I)); - } + for (const SCEV *AddRecOp : AddRec->operands()) + Operands.push_back(getMulExpr(Ops[0], AddRecOp)); + return getAddRecExpr(Operands, AddRec->getLoop(), AddRec->getNoWrapFlags(SCEV::FlagNW)); } @@ -2560,7 +2573,7 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, SmallVector<const SCEV*, 7> AddRecOps; for (int x = 0, xe = AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) { - const SCEV *Term = getConstant(Ty, 0); + const SCEV *Term = getZero(Ty); for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) { uint64_t Coeff1 = Choose(x, 2*x - y, Overflow); for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1), @@ -2638,11 +2651,11 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, // its operands. // TODO: Generalize this to non-constants by using known-bits information. Type *Ty = LHS->getType(); - unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros(); + unsigned LZ = RHSC->getAPInt().countLeadingZeros(); unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1; // For non-power-of-two values, effectively round the value up to the // nearest power of two. - if (!RHSC->getValue()->getValue().isPowerOf2()) + if (!RHSC->getAPInt().isPowerOf2()) ++MaxShiftAmt; IntegerType *ExtTy = IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt); @@ -2650,18 +2663,17 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, if (const SCEVConstant *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) { // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded. - const APInt &StepInt = Step->getValue()->getValue(); - const APInt &DivInt = RHSC->getValue()->getValue(); + const APInt &StepInt = Step->getAPInt(); + const APInt &DivInt = RHSC->getAPInt(); if (!StepInt.urem(DivInt) && getZeroExtendExpr(AR, ExtTy) == getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), getZeroExtendExpr(Step, ExtTy), AR->getLoop(), SCEV::FlagAnyWrap)) { SmallVector<const SCEV *, 4> Operands; - for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i) - Operands.push_back(getUDivExpr(AR->getOperand(i), RHS)); - return getAddRecExpr(Operands, AR->getLoop(), - SCEV::FlagNW); + for (const SCEV *Op : AR->operands()) + Operands.push_back(getUDivExpr(Op, RHS)); + return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW); } /// Get a canonical UDivExpr for a recurrence. /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0. @@ -2672,7 +2684,7 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), getZeroExtendExpr(Step, ExtTy), AR->getLoop(), SCEV::FlagAnyWrap)) { - const APInt &StartInt = StartC->getValue()->getValue(); + const APInt &StartInt = StartC->getAPInt(); const APInt &StartRem = StartInt.urem(StepInt); if (StartRem != 0) LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step, @@ -2682,8 +2694,8 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, // (A*B)/C --> A*(B/C) if safe and B/C can be folded. if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) { SmallVector<const SCEV *, 4> Operands; - for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) - Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy)); + for (const SCEV *Op : M->operands()) + Operands.push_back(getZeroExtendExpr(Op, ExtTy)); if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands)) // Find an operand that's safely divisible. for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { @@ -2700,8 +2712,8 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded. if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) { SmallVector<const SCEV *, 4> Operands; - for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) - Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy)); + for (const SCEV *Op : A->operands()) + Operands.push_back(getZeroExtendExpr(Op, ExtTy)); if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) { Operands.clear(); for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) { @@ -2739,8 +2751,8 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, } static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) { - APInt A = C1->getValue()->getValue().abs(); - APInt B = C2->getValue()->getValue().abs(); + APInt A = C1->getAPInt().abs(); + APInt B = C2->getAPInt().abs(); uint32_t ABW = A.getBitWidth(); uint32_t BBW = B.getBitWidth(); @@ -2769,8 +2781,7 @@ const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS, if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) { // If the mulexpr multiplies by a constant, then that constant must be the // first element of the mulexpr. - if (const SCEVConstant *LHSCst = - dyn_cast<SCEVConstant>(Mul->getOperand(0))) { + if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) { if (LHSCst == RHSCst) { SmallVector<const SCEV *, 2> Operands; Operands.append(Mul->op_begin() + 1, Mul->op_end()); @@ -2782,10 +2793,10 @@ const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS, // check. APInt Factor = gcd(LHSCst, RHSCst); if (!Factor.isIntN(1)) { - LHSCst = cast<SCEVConstant>( - getConstant(LHSCst->getValue()->getValue().udiv(Factor))); - RHSCst = cast<SCEVConstant>( - getConstant(RHSCst->getValue()->getValue().udiv(Factor))); + LHSCst = + cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor))); + RHSCst = + cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor))); SmallVector<const SCEV *, 2> Operands; Operands.push_back(LHSCst); Operands.append(Mul->op_begin() + 1, Mul->op_end()); @@ -2859,22 +2870,19 @@ ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, // Canonicalize nested AddRecs in by nesting them in order of loop depth. if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) { const Loop *NestedLoop = NestedAR->getLoop(); - if (L->contains(NestedLoop) ? - (L->getLoopDepth() < NestedLoop->getLoopDepth()) : - (!NestedLoop->contains(L) && - DT->dominates(L->getHeader(), NestedLoop->getHeader()))) { + if (L->contains(NestedLoop) + ? (L->getLoopDepth() < NestedLoop->getLoopDepth()) + : (!NestedLoop->contains(L) && + DT.dominates(L->getHeader(), NestedLoop->getHeader()))) { SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(), NestedAR->op_end()); Operands[0] = NestedAR->getStart(); // AddRecs require their operands be loop-invariant with respect to their // loops. Don't perform this transformation if it would break this // requirement. - bool AllInvariant = true; - for (unsigned i = 0, e = Operands.size(); i != e; ++i) - if (!isLoopInvariant(Operands[i], L)) { - AllInvariant = false; - break; - } + bool AllInvariant = all_of( + Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); }); + if (AllInvariant) { // Create a recurrence for the outer loop with the same step size. // @@ -2884,12 +2892,10 @@ ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags()); NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags); - AllInvariant = true; - for (unsigned i = 0, e = NestedOperands.size(); i != e; ++i) - if (!isLoopInvariant(NestedOperands[i], NestedLoop)) { - AllInvariant = false; - break; - } + AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) { + return isLoopInvariant(Op, NestedLoop); + }); + if (AllInvariant) { // Ok, both add recurrences are valid after the transformation. // @@ -2936,10 +2942,11 @@ ScalarEvolution::getGEPExpr(Type *PointeeType, const SCEV *BaseExpr, // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP // instruction to its SCEV, because the Instruction may be guarded by control // flow and the no-overflow bits may not be valid for the expression in any - // context. + // context. This can be fixed similarly to how these flags are handled for + // adds. SCEV::NoWrapFlags Wrap = InBounds ? SCEV::FlagNSW : SCEV::FlagAnyWrap; - const SCEV *TotalOffset = getConstant(IntPtrTy, 0); + const SCEV *TotalOffset = getZero(IntPtrTy); // The address space is unimportant. The first thing we do on CurTy is getting // its element type. Type *CurTy = PointerType::getUnqual(PointeeType); @@ -2996,7 +3003,7 @@ ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { #endif // Sort by complexity, this groups all similar expression types together. - GroupByComplexity(Ops, LI); + GroupByComplexity(Ops, &LI); // If there are any constants, fold them together. unsigned Idx = 0; @@ -3005,9 +3012,8 @@ ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { assert(Idx < Ops.size()); while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { // We found two constants, fold them together! - ConstantInt *Fold = ConstantInt::get(getContext(), - APIntOps::smax(LHSC->getValue()->getValue(), - RHSC->getValue()->getValue())); + ConstantInt *Fold = ConstantInt::get( + getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt())); Ops[0] = getConstant(Fold); Ops.erase(Ops.begin()+1); // Erase the folded element if (Ops.size() == 1) return Ops[0]; @@ -3100,7 +3106,7 @@ ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { #endif // Sort by complexity, this groups all similar expression types together. - GroupByComplexity(Ops, LI); + GroupByComplexity(Ops, &LI); // If there are any constants, fold them together. unsigned Idx = 0; @@ -3109,9 +3115,8 @@ ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { assert(Idx < Ops.size()); while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { // We found two constants, fold them together! - ConstantInt *Fold = ConstantInt::get(getContext(), - APIntOps::umax(LHSC->getValue()->getValue(), - RHSC->getValue()->getValue())); + ConstantInt *Fold = ConstantInt::get( + getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt())); Ops[0] = getConstant(Fold); Ops.erase(Ops.begin()+1); // Erase the folded element if (Ops.size() == 1) return Ops[0]; @@ -3200,8 +3205,7 @@ const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) { // We can bypass creating a target-independent // constant expression and then folding it back into a ConstantInt. // This is just a compile-time optimization. - return getConstant(IntTy, - F->getParent()->getDataLayout().getTypeAllocSize(AllocTy)); + return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy)); } const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy, @@ -3211,9 +3215,7 @@ const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy, // constant expression and then folding it back into a ConstantInt. // This is just a compile-time optimization. return getConstant( - IntTy, - F->getParent()->getDataLayout().getStructLayout(STy)->getElementOffset( - FieldNo)); + IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo)); } const SCEV *ScalarEvolution::getUnknown(Value *V) { @@ -3255,7 +3257,7 @@ bool ScalarEvolution::isSCEVable(Type *Ty) const { /// for which isSCEVable must return true. uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const { assert(isSCEVable(Ty) && "Type is not SCEVable!"); - return F->getParent()->getDataLayout().getTypeSizeInBits(Ty); + return getDataLayout().getTypeSizeInBits(Ty); } /// getEffectiveSCEVType - Return a type with the same bitwidth as @@ -3265,20 +3267,20 @@ uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const { Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const { assert(isSCEVable(Ty) && "Type is not SCEVable!"); - if (Ty->isIntegerTy()) { + if (Ty->isIntegerTy()) return Ty; - } // The only other support type is pointer. assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!"); - return F->getParent()->getDataLayout().getIntPtrType(Ty); + return getDataLayout().getIntPtrType(Ty); } const SCEV *ScalarEvolution::getCouldNotCompute() { - return &CouldNotCompute; + return CouldNotCompute.get(); } -namespace { + +bool ScalarEvolution::checkValidity(const SCEV *S) const { // Helper class working with SCEVTraversal to figure out if a SCEV contains // a SCEVUnknown with null value-pointer. FindInvalidSCEVUnknown::FindOne // is set iff if find such SCEVUnknown. @@ -3300,9 +3302,7 @@ namespace { } bool isDone() const { return FindOne; } }; -} -bool ScalarEvolution::checkValidity(const SCEV *S) const { FindInvalidSCEVUnknown F; SCEVTraversal<FindInvalidSCEVUnknown> ST(F); ST.visitAll(S); @@ -3315,35 +3315,39 @@ bool ScalarEvolution::checkValidity(const SCEV *S) const { const SCEV *ScalarEvolution::getSCEV(Value *V) { assert(isSCEVable(V->getType()) && "Value is not SCEVable!"); + const SCEV *S = getExistingSCEV(V); + if (S == nullptr) { + S = createSCEV(V); + ValueExprMap.insert(std::make_pair(SCEVCallbackVH(V, this), S)); + } + return S; +} + +const SCEV *ScalarEvolution::getExistingSCEV(Value *V) { + assert(isSCEVable(V->getType()) && "Value is not SCEVable!"); + ValueExprMapType::iterator I = ValueExprMap.find_as(V); if (I != ValueExprMap.end()) { const SCEV *S = I->second; if (checkValidity(S)) return S; - else - ValueExprMap.erase(I); + ValueExprMap.erase(I); } - const SCEV *S = createSCEV(V); - - // The process of creating a SCEV for V may have caused other SCEVs - // to have been created, so it's necessary to insert the new entry - // from scratch, rather than trying to remember the insert position - // above. - ValueExprMap.insert(std::make_pair(SCEVCallbackVH(V, this), S)); - return S; + return nullptr; } /// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V /// -const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V) { +const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V, + SCEV::NoWrapFlags Flags) { if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) return getConstant( cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue()))); Type *Ty = V->getType(); Ty = getEffectiveSCEVType(Ty); - return getMulExpr(V, - getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)))); + return getMulExpr( + V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags); } /// getNotSCEV - Return a SCEV corresponding to ~V = -1-V @@ -3362,15 +3366,40 @@ const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { /// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1. const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS, SCEV::NoWrapFlags Flags) { - assert(!maskFlags(Flags, SCEV::FlagNUW) && "subtraction does not have NUW"); - // Fast path: X - X --> 0. if (LHS == RHS) - return getConstant(LHS->getType(), 0); + return getZero(LHS->getType()); + + // We represent LHS - RHS as LHS + (-1)*RHS. This transformation + // makes it so that we cannot make much use of NUW. + auto AddFlags = SCEV::FlagAnyWrap; + const bool RHSIsNotMinSigned = + !getSignedRange(RHS).getSignedMin().isMinSignedValue(); + if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) { + // Let M be the minimum representable signed value. Then (-1)*RHS + // signed-wraps if and only if RHS is M. That can happen even for + // a NSW subtraction because e.g. (-1)*M signed-wraps even though + // -1 - M does not. So to transfer NSW from LHS - RHS to LHS + + // (-1)*RHS, we need to prove that RHS != M. + // + // If LHS is non-negative and we know that LHS - RHS does not + // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap + // either by proving that RHS > M or that LHS >= 0. + if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) { + AddFlags = SCEV::FlagNSW; + } + } + + // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS - + // RHS is NSW and LHS >= 0. + // + // The difficulty here is that the NSW flag may have been proven + // relative to a loop that is to be found in a recurrence in LHS and + // not in RHS. Applying NSW to (-1)*M may then let the NSW have a + // larger scope than intended. + auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap; - // X - Y --> X + -Y. - // X -(nsw || nuw) Y --> X + -Y. - return getAddExpr(LHS, getNegativeSCEV(RHS)); + return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags); } /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion of the @@ -3513,16 +3542,14 @@ const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) { if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) { return getPointerBase(Cast->getOperand()); - } - else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) { + } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) { const SCEV *PtrOp = nullptr; - for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); - I != E; ++I) { - if ((*I)->getType()->isPointerTy()) { + for (const SCEV *NAryOp : NAry->operands()) { + if (NAryOp->getType()->isPointerTy()) { // Cannot find the base of an expression with multiple pointer operands. if (PtrOp) return V; - PtrOp = *I; + PtrOp = NAryOp; } } if (!PtrOp) @@ -3558,8 +3585,7 @@ ScalarEvolution::ForgetSymbolicName(Instruction *PN, const SCEV *SymName) { if (!Visited.insert(I).second) continue; - ValueExprMapType::iterator It = - ValueExprMap.find_as(static_cast<Value *>(I)); + auto It = ValueExprMap.find_as(static_cast<Value *>(I)); if (It != ValueExprMap.end()) { const SCEV *Old = It->second; @@ -3587,165 +3613,476 @@ ScalarEvolution::ForgetSymbolicName(Instruction *PN, const SCEV *SymName) { } } -/// createNodeForPHI - PHI nodes have two cases. Either the PHI node exists in -/// a loop header, making it a potential recurrence, or it doesn't. -/// -const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { - if (const Loop *L = LI->getLoopFor(PN->getParent())) - if (L->getHeader() == PN->getParent()) { - // The loop may have multiple entrances or multiple exits; we can analyze - // this phi as an addrec if it has a unique entry value and a unique - // backedge value. - Value *BEValueV = nullptr, *StartValueV = nullptr; - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { - Value *V = PN->getIncomingValue(i); - if (L->contains(PN->getIncomingBlock(i))) { - if (!BEValueV) { - BEValueV = V; - } else if (BEValueV != V) { - BEValueV = nullptr; - break; - } - } else if (!StartValueV) { - StartValueV = V; - } else if (StartValueV != V) { - StartValueV = nullptr; - break; - } - } - if (BEValueV && StartValueV) { - // While we are analyzing this PHI node, handle its value symbolically. - const SCEV *SymbolicName = getUnknown(PN); - assert(ValueExprMap.find_as(PN) == ValueExprMap.end() && - "PHI node already processed?"); - ValueExprMap.insert(std::make_pair(SCEVCallbackVH(PN, this), SymbolicName)); - - // Using this symbolic name for the PHI, analyze the value coming around - // the back-edge. - const SCEV *BEValue = getSCEV(BEValueV); - - // NOTE: If BEValue is loop invariant, we know that the PHI node just - // has a special value for the first iteration of the loop. - - // If the value coming around the backedge is an add with the symbolic - // value we just inserted, then we found a simple induction variable! - if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) { - // If there is a single occurrence of the symbolic value, replace it - // with a recurrence. - unsigned FoundIndex = Add->getNumOperands(); - for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) - if (Add->getOperand(i) == SymbolicName) - if (FoundIndex == e) { - FoundIndex = i; - break; - } +namespace { +class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> { +public: + static const SCEV *rewrite(const SCEV *Scev, const Loop *L, + ScalarEvolution &SE) { + SCEVInitRewriter Rewriter(L, SE); + const SCEV *Result = Rewriter.visit(Scev); + return Rewriter.isValid() ? Result : SE.getCouldNotCompute(); + } - if (FoundIndex != Add->getNumOperands()) { - // Create an add with everything but the specified operand. - SmallVector<const SCEV *, 8> Ops; - for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) - if (i != FoundIndex) - Ops.push_back(Add->getOperand(i)); - const SCEV *Accum = getAddExpr(Ops); - - // This is not a valid addrec if the step amount is varying each - // loop iteration, but is not itself an addrec in this loop. - if (isLoopInvariant(Accum, L) || - (isa<SCEVAddRecExpr>(Accum) && - cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) { - SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; - - // If the increment doesn't overflow, then neither the addrec nor - // the post-increment will overflow. - if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) { - if (OBO->getOperand(0) == PN) { - if (OBO->hasNoUnsignedWrap()) - Flags = setFlags(Flags, SCEV::FlagNUW); - if (OBO->hasNoSignedWrap()) - Flags = setFlags(Flags, SCEV::FlagNSW); - } - } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { - // If the increment is an inbounds GEP, then we know the address - // space cannot be wrapped around. We cannot make any guarantee - // about signed or unsigned overflow because pointers are - // unsigned but we may have a negative index from the base - // pointer. We can guarantee that no unsigned wrap occurs if the - // indices form a positive value. - if (GEP->isInBounds() && GEP->getOperand(0) == PN) { - Flags = setFlags(Flags, SCEV::FlagNW); - - const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); - if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) - Flags = setFlags(Flags, SCEV::FlagNUW); - } + SCEVInitRewriter(const Loop *L, ScalarEvolution &SE) + : SCEVRewriteVisitor(SE), L(L), Valid(true) {} - // We cannot transfer nuw and nsw flags from subtraction - // operations -- sub nuw X, Y is not the same as add nuw X, -Y - // for instance. - } + const SCEV *visitUnknown(const SCEVUnknown *Expr) { + if (!(SE.getLoopDisposition(Expr, L) == ScalarEvolution::LoopInvariant)) + Valid = false; + return Expr; + } - const SCEV *StartVal = getSCEV(StartValueV); - const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); - - // Since the no-wrap flags are on the increment, they apply to the - // post-incremented value as well. - if (isLoopInvariant(Accum, L)) - (void)getAddRecExpr(getAddExpr(StartVal, Accum), - Accum, L, Flags); - - // Okay, for the entire analysis of this edge we assumed the PHI - // to be symbolic. We now need to go back and purge all of the - // entries for the scalars that use the symbolic expression. - ForgetSymbolicName(PN, SymbolicName); - ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; - return PHISCEV; - } + const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { + // Only allow AddRecExprs for this loop. + if (Expr->getLoop() == L) + return Expr->getStart(); + Valid = false; + return Expr; + } + + bool isValid() { return Valid; } + +private: + const Loop *L; + bool Valid; +}; + +class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> { +public: + static const SCEV *rewrite(const SCEV *Scev, const Loop *L, + ScalarEvolution &SE) { + SCEVShiftRewriter Rewriter(L, SE); + const SCEV *Result = Rewriter.visit(Scev); + return Rewriter.isValid() ? Result : SE.getCouldNotCompute(); + } + + SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE) + : SCEVRewriteVisitor(SE), L(L), Valid(true) {} + + const SCEV *visitUnknown(const SCEVUnknown *Expr) { + // Only allow AddRecExprs for this loop. + if (!(SE.getLoopDisposition(Expr, L) == ScalarEvolution::LoopInvariant)) + Valid = false; + return Expr; + } + + const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { + if (Expr->getLoop() == L && Expr->isAffine()) + return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE)); + Valid = false; + return Expr; + } + bool isValid() { return Valid; } + +private: + const Loop *L; + bool Valid; +}; +} // end anonymous namespace + +const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) { + const Loop *L = LI.getLoopFor(PN->getParent()); + if (!L || L->getHeader() != PN->getParent()) + return nullptr; + + // The loop may have multiple entrances or multiple exits; we can analyze + // this phi as an addrec if it has a unique entry value and a unique + // backedge value. + Value *BEValueV = nullptr, *StartValueV = nullptr; + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { + Value *V = PN->getIncomingValue(i); + if (L->contains(PN->getIncomingBlock(i))) { + if (!BEValueV) { + BEValueV = V; + } else if (BEValueV != V) { + BEValueV = nullptr; + break; + } + } else if (!StartValueV) { + StartValueV = V; + } else if (StartValueV != V) { + StartValueV = nullptr; + break; + } + } + if (BEValueV && StartValueV) { + // While we are analyzing this PHI node, handle its value symbolically. + const SCEV *SymbolicName = getUnknown(PN); + assert(ValueExprMap.find_as(PN) == ValueExprMap.end() && + "PHI node already processed?"); + ValueExprMap.insert(std::make_pair(SCEVCallbackVH(PN, this), SymbolicName)); + + // Using this symbolic name for the PHI, analyze the value coming around + // the back-edge. + const SCEV *BEValue = getSCEV(BEValueV); + + // NOTE: If BEValue is loop invariant, we know that the PHI node just + // has a special value for the first iteration of the loop. + + // If the value coming around the backedge is an add with the symbolic + // value we just inserted, then we found a simple induction variable! + if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) { + // If there is a single occurrence of the symbolic value, replace it + // with a recurrence. + unsigned FoundIndex = Add->getNumOperands(); + for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) + if (Add->getOperand(i) == SymbolicName) + if (FoundIndex == e) { + FoundIndex = i; + break; } - } else if (const SCEVAddRecExpr *AddRec = - dyn_cast<SCEVAddRecExpr>(BEValue)) { - // Otherwise, this could be a loop like this: - // i = 0; for (j = 1; ..; ++j) { .... i = j; } - // In this case, j = {1,+,1} and BEValue is j. - // Because the other in-value of i (0) fits the evolution of BEValue - // i really is an addrec evolution. - if (AddRec->getLoop() == L && AddRec->isAffine()) { - const SCEV *StartVal = getSCEV(StartValueV); - - // If StartVal = j.start - j.stride, we can use StartVal as the - // initial step of the addrec evolution. - if (StartVal == getMinusSCEV(AddRec->getOperand(0), - AddRec->getOperand(1))) { - // FIXME: For constant StartVal, we should be able to infer - // no-wrap flags. - const SCEV *PHISCEV = - getAddRecExpr(StartVal, AddRec->getOperand(1), L, - SCEV::FlagAnyWrap); - - // Okay, for the entire analysis of this edge we assumed the PHI - // to be symbolic. We now need to go back and purge all of the - // entries for the scalars that use the symbolic expression. - ForgetSymbolicName(PN, SymbolicName); - ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; - return PHISCEV; + + if (FoundIndex != Add->getNumOperands()) { + // Create an add with everything but the specified operand. + SmallVector<const SCEV *, 8> Ops; + for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) + if (i != FoundIndex) + Ops.push_back(Add->getOperand(i)); + const SCEV *Accum = getAddExpr(Ops); + + // This is not a valid addrec if the step amount is varying each + // loop iteration, but is not itself an addrec in this loop. + if (isLoopInvariant(Accum, L) || + (isa<SCEVAddRecExpr>(Accum) && + cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) { + SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; + + // If the increment doesn't overflow, then neither the addrec nor + // the post-increment will overflow. + if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) { + if (OBO->getOperand(0) == PN) { + if (OBO->hasNoUnsignedWrap()) + Flags = setFlags(Flags, SCEV::FlagNUW); + if (OBO->hasNoSignedWrap()) + Flags = setFlags(Flags, SCEV::FlagNSW); + } + } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { + // If the increment is an inbounds GEP, then we know the address + // space cannot be wrapped around. We cannot make any guarantee + // about signed or unsigned overflow because pointers are + // unsigned but we may have a negative index from the base + // pointer. We can guarantee that no unsigned wrap occurs if the + // indices form a positive value. + if (GEP->isInBounds() && GEP->getOperand(0) == PN) { + Flags = setFlags(Flags, SCEV::FlagNW); + + const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); + if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) + Flags = setFlags(Flags, SCEV::FlagNUW); } + + // We cannot transfer nuw and nsw flags from subtraction + // operations -- sub nuw X, Y is not the same as add nuw X, -Y + // for instance. } + + const SCEV *StartVal = getSCEV(StartValueV); + const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); + + // Since the no-wrap flags are on the increment, they apply to the + // post-incremented value as well. + if (isLoopInvariant(Accum, L)) + (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); + + // Okay, for the entire analysis of this edge we assumed the PHI + // to be symbolic. We now need to go back and purge all of the + // entries for the scalars that use the symbolic expression. + ForgetSymbolicName(PN, SymbolicName); + ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; + return PHISCEV; + } + } + } else { + // Otherwise, this could be a loop like this: + // i = 0; for (j = 1; ..; ++j) { .... i = j; } + // In this case, j = {1,+,1} and BEValue is j. + // Because the other in-value of i (0) fits the evolution of BEValue + // i really is an addrec evolution. + // + // We can generalize this saying that i is the shifted value of BEValue + // by one iteration: + // PHI(f(0), f({1,+,1})) --> f({0,+,1}) + const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this); + const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this); + if (Shifted != getCouldNotCompute() && + Start != getCouldNotCompute()) { + const SCEV *StartVal = getSCEV(StartValueV); + if (Start == StartVal) { + // Okay, for the entire analysis of this edge we assumed the PHI + // to be symbolic. We now need to go back and purge all of the + // entries for the scalars that use the symbolic expression. + ForgetSymbolicName(PN, SymbolicName); + ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted; + return Shifted; } } } + } + + return nullptr; +} + +// Checks if the SCEV S is available at BB. S is considered available at BB +// if S can be materialized at BB without introducing a fault. +static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S, + BasicBlock *BB) { + struct CheckAvailable { + bool TraversalDone = false; + bool Available = true; + + const Loop *L = nullptr; // The loop BB is in (can be nullptr) + BasicBlock *BB = nullptr; + DominatorTree &DT; + + CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT) + : L(L), BB(BB), DT(DT) {} + + bool setUnavailable() { + TraversalDone = true; + Available = false; + return false; + } + + bool follow(const SCEV *S) { + switch (S->getSCEVType()) { + case scConstant: case scTruncate: case scZeroExtend: case scSignExtend: + case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr: + // These expressions are available if their operand(s) is/are. + return true; + + case scAddRecExpr: { + // We allow add recurrences that are on the loop BB is in, or some + // outer loop. This guarantees availability because the value of the + // add recurrence at BB is simply the "current" value of the induction + // variable. We can relax this in the future; for instance an add + // recurrence on a sibling dominating loop is also available at BB. + const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop(); + if (L && (ARLoop == L || ARLoop->contains(L))) + return true; + + return setUnavailable(); + } + + case scUnknown: { + // For SCEVUnknown, we check for simple dominance. + const auto *SU = cast<SCEVUnknown>(S); + Value *V = SU->getValue(); + + if (isa<Argument>(V)) + return false; + + if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB)) + return false; + + return setUnavailable(); + } + + case scUDivExpr: + case scCouldNotCompute: + // We do not try to smart about these at all. + return setUnavailable(); + } + llvm_unreachable("switch should be fully covered!"); + } + + bool isDone() { return TraversalDone; } + }; + + CheckAvailable CA(L, BB, DT); + SCEVTraversal<CheckAvailable> ST(CA); + + ST.visitAll(S); + return CA.Available; +} + +// Try to match a control flow sequence that branches out at BI and merges back +// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful +// match. +static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge, + Value *&C, Value *&LHS, Value *&RHS) { + C = BI->getCondition(); + + BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0)); + BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1)); + + if (!LeftEdge.isSingleEdge()) + return false; + + assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()"); + + Use &LeftUse = Merge->getOperandUse(0); + Use &RightUse = Merge->getOperandUse(1); + + if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) { + LHS = LeftUse; + RHS = RightUse; + return true; + } + + if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) { + LHS = RightUse; + RHS = LeftUse; + return true; + } + + return false; +} + +const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) { + if (PN->getNumIncomingValues() == 2) { + const Loop *L = LI.getLoopFor(PN->getParent()); + + // We don't want to break LCSSA, even in a SCEV expression tree. + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (LI.getLoopFor(PN->getIncomingBlock(i)) != L) + return nullptr; + + // Try to match + // + // br %cond, label %left, label %right + // left: + // br label %merge + // right: + // br label %merge + // merge: + // V = phi [ %x, %left ], [ %y, %right ] + // + // as "select %cond, %x, %y" + + BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock(); + assert(IDom && "At least the entry block should dominate PN"); + + auto *BI = dyn_cast<BranchInst>(IDom->getTerminator()); + Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr; + + if (BI && BI->isConditional() && + BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) && + IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) && + IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent())) + return createNodeForSelectOrPHI(PN, Cond, LHS, RHS); + } + + return nullptr; +} + +const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { + if (const SCEV *S = createAddRecFromPHI(PN)) + return S; + + if (const SCEV *S = createNodeFromSelectLikePHI(PN)) + return S; // If the PHI has a single incoming value, follow that value, unless the // PHI's incoming blocks are in a different loop, in which case doing so // risks breaking LCSSA form. Instcombine would normally zap these, but // it doesn't have DominatorTree information, so it may miss cases. - if (Value *V = - SimplifyInstruction(PN, F->getParent()->getDataLayout(), TLI, DT, AC)) - if (LI->replacementPreservesLCSSAForm(PN, V)) + if (Value *V = SimplifyInstruction(PN, getDataLayout(), &TLI, &DT, &AC)) + if (LI.replacementPreservesLCSSAForm(PN, V)) return getSCEV(V); // If it's not a loop phi, we can't handle it yet. return getUnknown(PN); } +const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I, + Value *Cond, + Value *TrueVal, + Value *FalseVal) { + // Handle "constant" branch or select. This can occur for instance when a + // loop pass transforms an inner loop and moves on to process the outer loop. + if (auto *CI = dyn_cast<ConstantInt>(Cond)) + return getSCEV(CI->isOne() ? TrueVal : FalseVal); + + // Try to match some simple smax or umax patterns. + auto *ICI = dyn_cast<ICmpInst>(Cond); + if (!ICI) + return getUnknown(I); + + Value *LHS = ICI->getOperand(0); + Value *RHS = ICI->getOperand(1); + + switch (ICI->getPredicate()) { + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_SLE: + std::swap(LHS, RHS); + // fall through + case ICmpInst::ICMP_SGT: + case ICmpInst::ICMP_SGE: + // a >s b ? a+x : b+x -> smax(a, b)+x + // a >s b ? b+x : a+x -> smin(a, b)+x + if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { + const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType()); + const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType()); + const SCEV *LA = getSCEV(TrueVal); + const SCEV *RA = getSCEV(FalseVal); + const SCEV *LDiff = getMinusSCEV(LA, LS); + const SCEV *RDiff = getMinusSCEV(RA, RS); + if (LDiff == RDiff) + return getAddExpr(getSMaxExpr(LS, RS), LDiff); + LDiff = getMinusSCEV(LA, RS); + RDiff = getMinusSCEV(RA, LS); + if (LDiff == RDiff) + return getAddExpr(getSMinExpr(LS, RS), LDiff); + } + break; + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_ULE: + std::swap(LHS, RHS); + // fall through + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_UGE: + // a >u b ? a+x : b+x -> umax(a, b)+x + // a >u b ? b+x : a+x -> umin(a, b)+x + if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { + const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); + const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType()); + const SCEV *LA = getSCEV(TrueVal); + const SCEV *RA = getSCEV(FalseVal); + const SCEV *LDiff = getMinusSCEV(LA, LS); + const SCEV *RDiff = getMinusSCEV(RA, RS); + if (LDiff == RDiff) + return getAddExpr(getUMaxExpr(LS, RS), LDiff); + LDiff = getMinusSCEV(LA, RS); + RDiff = getMinusSCEV(RA, LS); + if (LDiff == RDiff) + return getAddExpr(getUMinExpr(LS, RS), LDiff); + } + break; + case ICmpInst::ICMP_NE: + // n != 0 ? n+x : 1+x -> umax(n, 1)+x + if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && + isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { + const SCEV *One = getOne(I->getType()); + const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); + const SCEV *LA = getSCEV(TrueVal); + const SCEV *RA = getSCEV(FalseVal); + const SCEV *LDiff = getMinusSCEV(LA, LS); + const SCEV *RDiff = getMinusSCEV(RA, One); + if (LDiff == RDiff) + return getAddExpr(getUMaxExpr(One, LS), LDiff); + } + break; + case ICmpInst::ICMP_EQ: + // n == 0 ? 1+x : n+x -> umax(n, 1)+x + if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && + isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { + const SCEV *One = getOne(I->getType()); + const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); + const SCEV *LA = getSCEV(TrueVal); + const SCEV *RA = getSCEV(FalseVal); + const SCEV *LDiff = getMinusSCEV(LA, One); + const SCEV *RDiff = getMinusSCEV(RA, LS); + if (LDiff == RDiff) + return getAddExpr(getUMaxExpr(One, LS), LDiff); + } + break; + default: + break; + } + + return getUnknown(I); +} + /// createNodeForGEP - Expand GEP instructions into add and multiply /// operations. This allows them to be analyzed by regular SCEV code. /// @@ -3769,7 +4106,7 @@ const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) { uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) - return C->getValue()->getValue().countTrailingZeros(); + return C->getAPInt().countTrailingZeros(); if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S)) return std::min(GetMinTrailingZeros(T->getOperand()), @@ -3834,8 +4171,8 @@ ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { // For a SCEVUnknown, ask ValueTracking. unsigned BitWidth = getTypeSizeInBits(U->getType()); APInt Zeros(BitWidth, 0), Ones(BitWidth, 0); - computeKnownBits(U->getValue(), Zeros, Ones, - F->getParent()->getDataLayout(), 0, AC, nullptr, DT); + computeKnownBits(U->getValue(), Zeros, Ones, getDataLayout(), 0, &AC, + nullptr, &DT); return Zeros.countTrailingOnes(); } @@ -3846,26 +4183,9 @@ ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { /// GetRangeFromMetadata - Helper method to assign a range to V from /// metadata present in the IR. static Optional<ConstantRange> GetRangeFromMetadata(Value *V) { - if (Instruction *I = dyn_cast<Instruction>(V)) { - if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) { - ConstantRange TotalRange( - cast<IntegerType>(I->getType())->getBitWidth(), false); - - unsigned NumRanges = MD->getNumOperands() / 2; - assert(NumRanges >= 1); - - for (unsigned i = 0; i < NumRanges; ++i) { - ConstantInt *Lower = - mdconst::extract<ConstantInt>(MD->getOperand(2 * i + 0)); - ConstantInt *Upper = - mdconst::extract<ConstantInt>(MD->getOperand(2 * i + 1)); - ConstantRange Range(Lower->getValue(), Upper->getValue()); - TotalRange = TotalRange.unionWith(Range); - } - - return TotalRange; - } - } + if (Instruction *I = dyn_cast<Instruction>(V)) + if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) + return getConstantRangeFromMetadata(*MD); return None; } @@ -3887,7 +4207,7 @@ ScalarEvolution::getRange(const SCEV *S, return I->second; if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) - return setRange(C, SignHint, ConstantRange(C->getValue()->getValue())); + return setRange(C, SignHint, ConstantRange(C->getAPInt())); unsigned BitWidth = getTypeSizeInBits(S->getType()); ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true); @@ -3965,9 +4285,8 @@ ScalarEvolution::getRange(const SCEV *S, if (AddRec->getNoWrapFlags(SCEV::FlagNUW)) if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart())) if (!C->getValue()->isZero()) - ConservativeResult = - ConservativeResult.intersectWith( - ConstantRange(C->getValue()->getValue(), APInt(BitWidth, 0))); + ConservativeResult = ConservativeResult.intersectWith( + ConstantRange(C->getAPInt(), APInt(BitWidth, 0))); // If there's no signed wrap, and all the operands have the same sign or // zero, the value won't ever change sign. @@ -4065,18 +4384,18 @@ ScalarEvolution::getRange(const SCEV *S, // Split here to avoid paying the compile-time cost of calling both // computeKnownBits and ComputeNumSignBits. This restriction can be lifted // if needed. - const DataLayout &DL = F->getParent()->getDataLayout(); + const DataLayout &DL = getDataLayout(); if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) { // For a SCEVUnknown, ask ValueTracking. APInt Zeros(BitWidth, 0), Ones(BitWidth, 0); - computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, AC, nullptr, DT); + computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, &AC, nullptr, &DT); if (Ones != ~Zeros + 1) ConservativeResult = ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1)); } else { assert(SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!"); - unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, AC, nullptr, DT); + unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT); if (NS > 1) ConservativeResult = ConservativeResult.intersectWith( ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1), @@ -4089,8 +4408,64 @@ ScalarEvolution::getRange(const SCEV *S, return setRange(S, SignHint, ConservativeResult); } -/// createSCEV - We know that there is no SCEV for the specified value. -/// Analyze the expression. +SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) { + if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap; + const BinaryOperator *BinOp = cast<BinaryOperator>(V); + + // Return early if there are no flags to propagate to the SCEV. + SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; + if (BinOp->hasNoUnsignedWrap()) + Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); + if (BinOp->hasNoSignedWrap()) + Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); + if (Flags == SCEV::FlagAnyWrap) { + return SCEV::FlagAnyWrap; + } + + // Here we check that BinOp is in the header of the innermost loop + // containing BinOp, since we only deal with instructions in the loop + // header. The actual loop we need to check later will come from an add + // recurrence, but getting that requires computing the SCEV of the operands, + // which can be expensive. This check we can do cheaply to rule out some + // cases early. + Loop *innermostContainingLoop = LI.getLoopFor(BinOp->getParent()); + if (innermostContainingLoop == nullptr || + innermostContainingLoop->getHeader() != BinOp->getParent()) + return SCEV::FlagAnyWrap; + + // Only proceed if we can prove that BinOp does not yield poison. + if (!isKnownNotFullPoison(BinOp)) return SCEV::FlagAnyWrap; + + // At this point we know that if V is executed, then it does not wrap + // according to at least one of NSW or NUW. If V is not executed, then we do + // not know if the calculation that V represents would wrap. Multiple + // instructions can map to the same SCEV. If we apply NSW or NUW from V to + // the SCEV, we must guarantee no wrapping for that SCEV also when it is + // derived from other instructions that map to the same SCEV. We cannot make + // that guarantee for cases where V is not executed. So we need to find the + // loop that V is considered in relation to and prove that V is executed for + // every iteration of that loop. That implies that the value that V + // calculates does not wrap anywhere in the loop, so then we can apply the + // flags to the SCEV. + // + // We check isLoopInvariant to disambiguate in case we are adding two + // recurrences from different loops, so that we know which loop to prove + // that V is executed in. + for (int OpIndex = 0; OpIndex < 2; ++OpIndex) { + const SCEV *Op = getSCEV(BinOp->getOperand(OpIndex)); + if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { + const int OtherOpIndex = 1 - OpIndex; + const SCEV *OtherOp = getSCEV(BinOp->getOperand(OtherOpIndex)); + if (isLoopInvariant(OtherOp, AddRec->getLoop()) && + isGuaranteedToExecuteForEveryIteration(BinOp, AddRec->getLoop())) + return Flags; + } + } + return SCEV::FlagAnyWrap; +} + +/// createSCEV - We know that there is no SCEV for the specified value. Analyze +/// the expression. /// const SCEV *ScalarEvolution::createSCEV(Value *V) { if (!isSCEVable(V->getType())) @@ -4104,14 +4479,14 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) { // reachable. Such instructions don't matter, and they aren't required // to obey basic rules for definitions dominating uses which this // analysis depends on. - if (!DT->isReachableFromEntry(I->getParent())) + if (!DT.isReachableFromEntry(I->getParent())) return getUnknown(V); } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) Opcode = CE->getOpcode(); else if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) return getConstant(CI); else if (isa<ConstantPointerNull>(V)) - return getConstant(V->getType(), 0); + return getZero(V->getType()); else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) return GA->mayBeOverridden() ? getUnknown(V) : getSCEV(GA->getAliasee()); else @@ -4126,47 +4501,79 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) { // because it leads to N-1 getAddExpr calls for N ultimate operands. // Instead, gather up all the operands and make a single getAddExpr call. // LLVM IR canonical form means we need only traverse the left operands. - // - // Don't apply this instruction's NSW or NUW flags to the new - // expression. The instruction may be guarded by control flow that the - // no-wrap behavior depends on. Non-control-equivalent instructions can be - // mapped to the same SCEV expression, and it would be incorrect to transfer - // NSW/NUW semantics to those operations. SmallVector<const SCEV *, 4> AddOps; - AddOps.push_back(getSCEV(U->getOperand(1))); - for (Value *Op = U->getOperand(0); ; Op = U->getOperand(0)) { - unsigned Opcode = Op->getValueID() - Value::InstructionVal; - if (Opcode != Instruction::Add && Opcode != Instruction::Sub) + for (Value *Op = U;; Op = U->getOperand(0)) { + U = dyn_cast<Operator>(Op); + unsigned Opcode = U ? U->getOpcode() : 0; + if (!U || (Opcode != Instruction::Add && Opcode != Instruction::Sub)) { + assert(Op != V && "V should be an add"); + AddOps.push_back(getSCEV(Op)); + break; + } + + if (auto *OpSCEV = getExistingSCEV(U)) { + AddOps.push_back(OpSCEV); + break; + } + + // If a NUW or NSW flag can be applied to the SCEV for this + // addition, then compute the SCEV for this addition by itself + // with a separate call to getAddExpr. We need to do that + // instead of pushing the operands of the addition onto AddOps, + // since the flags are only known to apply to this particular + // addition - they may not apply to other additions that can be + // formed with operands from AddOps. + const SCEV *RHS = getSCEV(U->getOperand(1)); + SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(U); + if (Flags != SCEV::FlagAnyWrap) { + const SCEV *LHS = getSCEV(U->getOperand(0)); + if (Opcode == Instruction::Sub) + AddOps.push_back(getMinusSCEV(LHS, RHS, Flags)); + else + AddOps.push_back(getAddExpr(LHS, RHS, Flags)); break; - U = cast<Operator>(Op); - const SCEV *Op1 = getSCEV(U->getOperand(1)); + } + if (Opcode == Instruction::Sub) - AddOps.push_back(getNegativeSCEV(Op1)); + AddOps.push_back(getNegativeSCEV(RHS)); else - AddOps.push_back(Op1); + AddOps.push_back(RHS); } - AddOps.push_back(getSCEV(U->getOperand(0))); return getAddExpr(AddOps); } + case Instruction::Mul: { - // Don't transfer NSW/NUW for the same reason as AddExpr. SmallVector<const SCEV *, 4> MulOps; - MulOps.push_back(getSCEV(U->getOperand(1))); - for (Value *Op = U->getOperand(0); - Op->getValueID() == Instruction::Mul + Value::InstructionVal; - Op = U->getOperand(0)) { - U = cast<Operator>(Op); + for (Value *Op = U;; Op = U->getOperand(0)) { + U = dyn_cast<Operator>(Op); + if (!U || U->getOpcode() != Instruction::Mul) { + assert(Op != V && "V should be a mul"); + MulOps.push_back(getSCEV(Op)); + break; + } + + if (auto *OpSCEV = getExistingSCEV(U)) { + MulOps.push_back(OpSCEV); + break; + } + + SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(U); + if (Flags != SCEV::FlagAnyWrap) { + MulOps.push_back(getMulExpr(getSCEV(U->getOperand(0)), + getSCEV(U->getOperand(1)), Flags)); + break; + } + MulOps.push_back(getSCEV(U->getOperand(1))); } - MulOps.push_back(getSCEV(U->getOperand(0))); return getMulExpr(MulOps); } case Instruction::UDiv: return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1))); case Instruction::Sub: - return getMinusSCEV(getSCEV(U->getOperand(0)), - getSCEV(U->getOperand(1))); + return getMinusSCEV(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1)), + getNoWrapFlagsFromUB(U)); case Instruction::And: // For an expression like x&255 that merely masks off the high bits, // use zext(trunc(x)) as the SCEV expression. @@ -4185,8 +4592,8 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) { unsigned TZ = A.countTrailingZeros(); unsigned BitWidth = A.getBitWidth(); APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); - computeKnownBits(U->getOperand(0), KnownZero, KnownOne, - F->getParent()->getDataLayout(), 0, AC, nullptr, DT); + computeKnownBits(U->getOperand(0), KnownZero, KnownOne, getDataLayout(), + 0, &AC, nullptr, &DT); APInt EffectiveMask = APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ); @@ -4286,9 +4693,18 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) { if (SA->getValue().uge(BitWidth)) break; + // It is currently not resolved how to interpret NSW for left + // shift by BitWidth - 1, so we avoid applying flags in that + // case. Remove this check (or this comment) once the situation + // is resolved. See + // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html + // and http://reviews.llvm.org/D8890 . + auto Flags = SCEV::FlagAnyWrap; + if (SA->getValue().ult(BitWidth - 1)) Flags = getNoWrapFlagsFromUB(U); + Constant *X = ConstantInt::get(getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue())); - return getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X)); + return getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X), Flags); } break; @@ -4363,94 +4779,13 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) { return createNodeForPHI(cast<PHINode>(U)); case Instruction::Select: - // This could be a smax or umax that was lowered earlier. - // Try to recover it. - if (ICmpInst *ICI = dyn_cast<ICmpInst>(U->getOperand(0))) { - Value *LHS = ICI->getOperand(0); - Value *RHS = ICI->getOperand(1); - switch (ICI->getPredicate()) { - case ICmpInst::ICMP_SLT: - case ICmpInst::ICMP_SLE: - std::swap(LHS, RHS); - // fall through - case ICmpInst::ICMP_SGT: - case ICmpInst::ICMP_SGE: - // a >s b ? a+x : b+x -> smax(a, b)+x - // a >s b ? b+x : a+x -> smin(a, b)+x - if (getTypeSizeInBits(LHS->getType()) <= - getTypeSizeInBits(U->getType())) { - const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), U->getType()); - const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), U->getType()); - const SCEV *LA = getSCEV(U->getOperand(1)); - const SCEV *RA = getSCEV(U->getOperand(2)); - const SCEV *LDiff = getMinusSCEV(LA, LS); - const SCEV *RDiff = getMinusSCEV(RA, RS); - if (LDiff == RDiff) - return getAddExpr(getSMaxExpr(LS, RS), LDiff); - LDiff = getMinusSCEV(LA, RS); - RDiff = getMinusSCEV(RA, LS); - if (LDiff == RDiff) - return getAddExpr(getSMinExpr(LS, RS), LDiff); - } - break; - case ICmpInst::ICMP_ULT: - case ICmpInst::ICMP_ULE: - std::swap(LHS, RHS); - // fall through - case ICmpInst::ICMP_UGT: - case ICmpInst::ICMP_UGE: - // a >u b ? a+x : b+x -> umax(a, b)+x - // a >u b ? b+x : a+x -> umin(a, b)+x - if (getTypeSizeInBits(LHS->getType()) <= - getTypeSizeInBits(U->getType())) { - const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), U->getType()); - const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), U->getType()); - const SCEV *LA = getSCEV(U->getOperand(1)); - const SCEV *RA = getSCEV(U->getOperand(2)); - const SCEV *LDiff = getMinusSCEV(LA, LS); - const SCEV *RDiff = getMinusSCEV(RA, RS); - if (LDiff == RDiff) - return getAddExpr(getUMaxExpr(LS, RS), LDiff); - LDiff = getMinusSCEV(LA, RS); - RDiff = getMinusSCEV(RA, LS); - if (LDiff == RDiff) - return getAddExpr(getUMinExpr(LS, RS), LDiff); - } - break; - case ICmpInst::ICMP_NE: - // n != 0 ? n+x : 1+x -> umax(n, 1)+x - if (getTypeSizeInBits(LHS->getType()) <= - getTypeSizeInBits(U->getType()) && - isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { - const SCEV *One = getConstant(U->getType(), 1); - const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), U->getType()); - const SCEV *LA = getSCEV(U->getOperand(1)); - const SCEV *RA = getSCEV(U->getOperand(2)); - const SCEV *LDiff = getMinusSCEV(LA, LS); - const SCEV *RDiff = getMinusSCEV(RA, One); - if (LDiff == RDiff) - return getAddExpr(getUMaxExpr(One, LS), LDiff); - } - break; - case ICmpInst::ICMP_EQ: - // n == 0 ? 1+x : n+x -> umax(n, 1)+x - if (getTypeSizeInBits(LHS->getType()) <= - getTypeSizeInBits(U->getType()) && - isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { - const SCEV *One = getConstant(U->getType(), 1); - const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), U->getType()); - const SCEV *LA = getSCEV(U->getOperand(1)); - const SCEV *RA = getSCEV(U->getOperand(2)); - const SCEV *LDiff = getMinusSCEV(LA, One); - const SCEV *RDiff = getMinusSCEV(RA, LS); - if (LDiff == RDiff) - return getAddExpr(getUMaxExpr(One, LS), LDiff); - } - break; - default: - break; - } - } + // U can also be a select constant expr, which let fall through. Since + // createNodeForSelect only works for a condition that is an `ICmpInst`, and + // constant expressions cannot have instructions as operands, we'd have + // returned getUnknown for a select constant expressions anyway. + if (isa<Instruction>(U)) + return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0), + U->getOperand(1), U->getOperand(2)); default: // We cannot analyze this expression. break; @@ -4534,8 +4869,7 @@ ScalarEvolution::getSmallConstantTripMultiple(Loop *L, return 1; // Get the trip count from the BE count by adding 1. - const SCEV *TCMul = getAddExpr(ExitCount, - getConstant(ExitCount->getType(), 1)); + const SCEV *TCMul = getAddExpr(ExitCount, getOne(ExitCount->getType())); // FIXME: SCEV distributes multiplication as V1*C1 + V2*C1. We could attempt // to factor simple cases. if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(TCMul)) @@ -4610,10 +4944,10 @@ ScalarEvolution::getBackedgeTakenInfo(const Loop *L) { if (!Pair.second) return Pair.first->second; - // ComputeBackedgeTakenCount may allocate memory for its result. Inserting it + // computeBackedgeTakenCount may allocate memory for its result. Inserting it // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result // must be cleared in this scope. - BackedgeTakenInfo Result = ComputeBackedgeTakenCount(L); + BackedgeTakenInfo Result = computeBackedgeTakenCount(L); if (Result.getExact(this) != getCouldNotCompute()) { assert(isLoopInvariant(Result.getExact(this), L) && @@ -4666,7 +5000,7 @@ ScalarEvolution::getBackedgeTakenInfo(const Loop *L) { } // Re-lookup the insert position, since the call to - // ComputeBackedgeTakenCount above could result in a + // computeBackedgeTakenCount above could result in a // recusive call to getBackedgeTakenInfo (on a different // loop), which would invalidate the iterator computed // earlier. @@ -4744,12 +5078,12 @@ void ScalarEvolution::forgetValue(Value *V) { } /// getExact - Get the exact loop backedge taken count considering all loop -/// exits. A computable result can only be return for loops with a single exit. -/// Returning the minimum taken count among all exits is incorrect because one -/// of the loop's exit limit's may have been skipped. HowFarToZero assumes that -/// the limit of each loop test is never skipped. This is a valid assumption as -/// long as the loop exits via that test. For precise results, it is the -/// caller's responsibility to specify the relevant loop exit using +/// exits. A computable result can only be returned for loops with a single +/// exit. Returning the minimum taken count among all exits is incorrect +/// because one of the loop's exit limit's may have been skipped. HowFarToZero +/// assumes that the limit of each loop test is never skipped. This is a valid +/// assumption as long as the loop exits via that test. For precise results, it +/// is the caller's responsibility to specify the relevant loop exit using /// getExact(ExitingBlock, SE). const SCEV * ScalarEvolution::BackedgeTakenInfo::getExact(ScalarEvolution *SE) const { @@ -4847,10 +5181,10 @@ void ScalarEvolution::BackedgeTakenInfo::clear() { delete[] ExitNotTaken.getNextExit(); } -/// ComputeBackedgeTakenCount - Compute the number of times the backedge +/// computeBackedgeTakenCount - Compute the number of times the backedge /// of the specified loop will execute. ScalarEvolution::BackedgeTakenInfo -ScalarEvolution::ComputeBackedgeTakenCount(const Loop *L) { +ScalarEvolution::computeBackedgeTakenCount(const Loop *L) { SmallVector<BasicBlock *, 8> ExitingBlocks; L->getExitingBlocks(ExitingBlocks); @@ -4864,7 +5198,7 @@ ScalarEvolution::ComputeBackedgeTakenCount(const Loop *L) { // and compute maxBECount. for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) { BasicBlock *ExitBB = ExitingBlocks[i]; - ExitLimit EL = ComputeExitLimit(L, ExitBB); + ExitLimit EL = computeExitLimit(L, ExitBB); // 1. For each exit that can be computed, add an entry to ExitCounts. // CouldComputeBECount is true only if all exits can be computed. @@ -4885,7 +5219,7 @@ ScalarEvolution::ComputeBackedgeTakenCount(const Loop *L) { // MaxBECount is conservatively the maximum EL.Max, where CouldNotCompute is // considered greater than any computable EL.Max. if (EL.Max != getCouldNotCompute() && Latch && - DT->dominates(ExitBB, Latch)) { + DT.dominates(ExitBB, Latch)) { if (!MustExitMaxBECount) MustExitMaxBECount = EL.Max; else { @@ -4906,13 +5240,11 @@ ScalarEvolution::ComputeBackedgeTakenCount(const Loop *L) { return BackedgeTakenInfo(ExitCounts, CouldComputeBECount, MaxBECount); } -/// ComputeExitLimit - Compute the number of times the backedge of the specified -/// loop will execute if it exits via the specified block. ScalarEvolution::ExitLimit -ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) { +ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock) { - // Okay, we've chosen an exiting block. See what condition causes us to - // exit at this block and remember the exit block and whether all other targets + // Okay, we've chosen an exiting block. See what condition causes us to exit + // at this block and remember the exit block and whether all other targets // lead to the loop header. bool MustExecuteLoopHeader = true; BasicBlock *Exit = nullptr; @@ -4952,8 +5284,7 @@ ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) { if (!Pred) return getCouldNotCompute(); TerminatorInst *PredTerm = Pred->getTerminator(); - for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) { - BasicBlock *PredSucc = PredTerm->getSuccessor(i); + for (const BasicBlock *PredSucc : PredTerm->successors()) { if (PredSucc == BB) continue; // If the predecessor has a successor that isn't BB and isn't @@ -4976,19 +5307,19 @@ ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) { if (BranchInst *BI = dyn_cast<BranchInst>(Term)) { assert(BI->isConditional() && "If unconditional, it can't be in loop!"); // Proceed to the next level to examine the exit condition expression. - return ComputeExitLimitFromCond(L, BI->getCondition(), BI->getSuccessor(0), + return computeExitLimitFromCond(L, BI->getCondition(), BI->getSuccessor(0), BI->getSuccessor(1), /*ControlsExit=*/IsOnlyExit); } if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) - return ComputeExitLimitFromSingleExitSwitch(L, SI, Exit, + return computeExitLimitFromSingleExitSwitch(L, SI, Exit, /*ControlsExit=*/IsOnlyExit); return getCouldNotCompute(); } -/// ComputeExitLimitFromCond - Compute the number of times the +/// computeExitLimitFromCond - Compute the number of times the /// backedge of the specified loop will execute if its exit condition /// were a conditional branch of ExitCond, TBB, and FBB. /// @@ -4997,7 +5328,7 @@ ScalarEvolution::ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock) { /// condition is true and can infer that failing to meet the condition prior to /// integer wraparound results in undefined behavior. ScalarEvolution::ExitLimit -ScalarEvolution::ComputeExitLimitFromCond(const Loop *L, +ScalarEvolution::computeExitLimitFromCond(const Loop *L, Value *ExitCond, BasicBlock *TBB, BasicBlock *FBB, @@ -5007,9 +5338,9 @@ ScalarEvolution::ComputeExitLimitFromCond(const Loop *L, if (BO->getOpcode() == Instruction::And) { // Recurse on the operands of the and. bool EitherMayExit = L->contains(TBB); - ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB, + ExitLimit EL0 = computeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB, ControlsExit && !EitherMayExit); - ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB, + ExitLimit EL1 = computeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB, ControlsExit && !EitherMayExit); const SCEV *BECount = getCouldNotCompute(); const SCEV *MaxBECount = getCouldNotCompute(); @@ -5042,9 +5373,9 @@ ScalarEvolution::ComputeExitLimitFromCond(const Loop *L, if (BO->getOpcode() == Instruction::Or) { // Recurse on the operands of the or. bool EitherMayExit = L->contains(FBB); - ExitLimit EL0 = ComputeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB, + ExitLimit EL0 = computeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB, ControlsExit && !EitherMayExit); - ExitLimit EL1 = ComputeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB, + ExitLimit EL1 = computeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB, ControlsExit && !EitherMayExit); const SCEV *BECount = getCouldNotCompute(); const SCEV *MaxBECount = getCouldNotCompute(); @@ -5079,7 +5410,7 @@ ScalarEvolution::ComputeExitLimitFromCond(const Loop *L, // With an icmp, it may be feasible to compute an exact backedge-taken count. // Proceed to the next level to examine the icmp. if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) - return ComputeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit); + return computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit); // Check for a constant condition. These are normally stripped out by // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to @@ -5091,18 +5422,15 @@ ScalarEvolution::ComputeExitLimitFromCond(const Loop *L, return getCouldNotCompute(); else // The backedge is never taken. - return getConstant(CI->getType(), 0); + return getZero(CI->getType()); } // If it's not an integer or pointer comparison then compute it the hard way. - return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB)); + return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB)); } -/// ComputeExitLimitFromICmp - Compute the number of times the -/// backedge of the specified loop will execute if its exit condition -/// were a conditional branch of the ICmpInst ExitCond, TBB, and FBB. ScalarEvolution::ExitLimit -ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L, +ScalarEvolution::computeExitLimitFromICmp(const Loop *L, ICmpInst *ExitCond, BasicBlock *TBB, BasicBlock *FBB, @@ -5119,11 +5447,16 @@ ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L, if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0))) if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) { ExitLimit ItCnt = - ComputeLoadConstantCompareExitLimit(LI, RHS, L, Cond); + computeLoadConstantCompareExitLimit(LI, RHS, L, Cond); if (ItCnt.hasAnyInfo()) return ItCnt; } + ExitLimit ShiftEL = computeShiftCompareExitLimit( + ExitCond->getOperand(0), ExitCond->getOperand(1), L, Cond); + if (ShiftEL.hasAnyInfo()) + return ShiftEL; + const SCEV *LHS = getSCEV(ExitCond->getOperand(0)); const SCEV *RHS = getSCEV(ExitCond->getOperand(1)); @@ -5149,7 +5482,7 @@ ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L, if (AddRec->getLoop() == L) { // Form the constant range. ConstantRange CompRange( - ICmpInst::makeConstantRange(Cond, RHSC->getValue()->getValue())); + ICmpInst::makeConstantRange(Cond, RHSC->getAPInt())); const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this); if (!isa<SCEVCouldNotCompute>(Ret)) return Ret; @@ -5183,21 +5516,13 @@ ScalarEvolution::ComputeExitLimitFromICmp(const Loop *L, break; } default: -#if 0 - dbgs() << "ComputeBackedgeTakenCount "; - if (ExitCond->getOperand(0)->getType()->isUnsigned()) - dbgs() << "[unsigned] "; - dbgs() << *LHS << " " - << Instruction::getOpcodeName(Instruction::ICmp) - << " " << *RHS << "\n"; -#endif break; } - return ComputeExitCountExhaustively(L, ExitCond, !L->contains(TBB)); + return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB)); } ScalarEvolution::ExitLimit -ScalarEvolution::ComputeExitLimitFromSingleExitSwitch(const Loop *L, +ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L, SwitchInst *Switch, BasicBlock *ExitingBlock, bool ControlsExit) { @@ -5230,11 +5555,11 @@ EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C, return cast<SCEVConstant>(Val)->getValue(); } -/// ComputeLoadConstantCompareExitLimit - Given an exit condition of +/// computeLoadConstantCompareExitLimit - Given an exit condition of /// 'icmp op load X, cst', try to see if we can compute the backedge /// execution count. ScalarEvolution::ExitLimit -ScalarEvolution::ComputeLoadConstantCompareExitLimit( +ScalarEvolution::computeLoadConstantCompareExitLimit( LoadInst *LI, Constant *RHS, const Loop *L, @@ -5303,11 +5628,6 @@ ScalarEvolution::ComputeLoadConstantCompareExitLimit( Result = ConstantExpr::getICmp(predicate, Result, RHS); if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure if (cast<ConstantInt>(Result)->getValue().isMinValue()) { -#if 0 - dbgs() << "\n***\n*** Computed loop count " << *ItCst - << "\n*** From global " << *GV << "*** BB: " << *L->getHeader() - << "***\n"; -#endif ++NumArrayLenItCounts; return getConstant(ItCst); // Found terminating iteration! } @@ -5315,6 +5635,149 @@ ScalarEvolution::ComputeLoadConstantCompareExitLimit( return getCouldNotCompute(); } +ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit( + Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) { + ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV); + if (!RHS) + return getCouldNotCompute(); + + const BasicBlock *Latch = L->getLoopLatch(); + if (!Latch) + return getCouldNotCompute(); + + const BasicBlock *Predecessor = L->getLoopPredecessor(); + if (!Predecessor) + return getCouldNotCompute(); + + // Return true if V is of the form "LHS `shift_op` <positive constant>". + // Return LHS in OutLHS and shift_opt in OutOpCode. + auto MatchPositiveShift = + [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) { + + using namespace PatternMatch; + + ConstantInt *ShiftAmt; + if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) + OutOpCode = Instruction::LShr; + else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) + OutOpCode = Instruction::AShr; + else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) + OutOpCode = Instruction::Shl; + else + return false; + + return ShiftAmt->getValue().isStrictlyPositive(); + }; + + // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in + // + // loop: + // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ] + // %iv.shifted = lshr i32 %iv, <positive constant> + // + // Return true on a succesful match. Return the corresponding PHI node (%iv + // above) in PNOut and the opcode of the shift operation in OpCodeOut. + auto MatchShiftRecurrence = + [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) { + Optional<Instruction::BinaryOps> PostShiftOpCode; + + { + Instruction::BinaryOps OpC; + Value *V; + + // If we encounter a shift instruction, "peel off" the shift operation, + // and remember that we did so. Later when we inspect %iv's backedge + // value, we will make sure that the backedge value uses the same + // operation. + // + // Note: the peeled shift operation does not have to be the same + // instruction as the one feeding into the PHI's backedge value. We only + // really care about it being the same *kind* of shift instruction -- + // that's all that is required for our later inferences to hold. + if (MatchPositiveShift(LHS, V, OpC)) { + PostShiftOpCode = OpC; + LHS = V; + } + } + + PNOut = dyn_cast<PHINode>(LHS); + if (!PNOut || PNOut->getParent() != L->getHeader()) + return false; + + Value *BEValue = PNOut->getIncomingValueForBlock(Latch); + Value *OpLHS; + + return + // The backedge value for the PHI node must be a shift by a positive + // amount + MatchPositiveShift(BEValue, OpLHS, OpCodeOut) && + + // of the PHI node itself + OpLHS == PNOut && + + // and the kind of shift should be match the kind of shift we peeled + // off, if any. + (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut); + }; + + PHINode *PN; + Instruction::BinaryOps OpCode; + if (!MatchShiftRecurrence(LHS, PN, OpCode)) + return getCouldNotCompute(); + + const DataLayout &DL = getDataLayout(); + + // The key rationale for this optimization is that for some kinds of shift + // recurrences, the value of the recurrence "stabilizes" to either 0 or -1 + // within a finite number of iterations. If the condition guarding the + // backedge (in the sense that the backedge is taken if the condition is true) + // is false for the value the shift recurrence stabilizes to, then we know + // that the backedge is taken only a finite number of times. + + ConstantInt *StableValue = nullptr; + switch (OpCode) { + default: + llvm_unreachable("Impossible case!"); + + case Instruction::AShr: { + // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most + // bitwidth(K) iterations. + Value *FirstValue = PN->getIncomingValueForBlock(Predecessor); + bool KnownZero, KnownOne; + ComputeSignBit(FirstValue, KnownZero, KnownOne, DL, 0, nullptr, + Predecessor->getTerminator(), &DT); + auto *Ty = cast<IntegerType>(RHS->getType()); + if (KnownZero) + StableValue = ConstantInt::get(Ty, 0); + else if (KnownOne) + StableValue = ConstantInt::get(Ty, -1, true); + else + return getCouldNotCompute(); + + break; + } + case Instruction::LShr: + case Instruction::Shl: + // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>} + // stabilize to 0 in at most bitwidth(K) iterations. + StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0); + break; + } + + auto *Result = + ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI); + assert(Result->getType()->isIntegerTy(1) && + "Otherwise cannot be an operand to a branch instruction"); + + if (Result->isZeroValue()) { + unsigned BitWidth = getTypeSizeInBits(RHS->getType()); + const SCEV *UpperBound = + getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth); + return ExitLimit(getCouldNotCompute(), UpperBound); + } + + return getCouldNotCompute(); +} /// CanConstantFold - Return true if we can constant fold an instruction of the /// specified type, assuming that all operands were constants. @@ -5356,12 +5819,10 @@ getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L, // Otherwise, we can evaluate this instruction if all of its operands are // constant or derived from a PHI node themselves. PHINode *PHI = nullptr; - for (Instruction::op_iterator OpI = UseInst->op_begin(), - OpE = UseInst->op_end(); OpI != OpE; ++OpI) { - - if (isa<Constant>(*OpI)) continue; + for (Value *Op : UseInst->operands()) { + if (isa<Constant>(Op)) continue; - Instruction *OpInst = dyn_cast<Instruction>(*OpI); + Instruction *OpInst = dyn_cast<Instruction>(Op); if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr; PHINode *P = dyn_cast<PHINode>(OpInst); @@ -5395,9 +5856,8 @@ static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) { Instruction *I = dyn_cast<Instruction>(V); if (!I || !canConstantEvolve(I, L)) return nullptr; - if (PHINode *PN = dyn_cast<PHINode>(I)) { + if (PHINode *PN = dyn_cast<PHINode>(I)) return PN; - } // Record non-constant instructions contained by the loop. DenseMap<Instruction *, PHINode *> PHIMap; @@ -5454,6 +5914,30 @@ static Constant *EvaluateExpression(Value *V, const Loop *L, TLI); } + +// If every incoming value to PN except the one for BB is a specific Constant, +// return that, else return nullptr. +static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) { + Constant *IncomingVal = nullptr; + + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { + if (PN->getIncomingBlock(i) == BB) + continue; + + auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i)); + if (!CurrentVal) + return nullptr; + + if (IncomingVal != CurrentVal) { + if (IncomingVal) + return nullptr; + IncomingVal = CurrentVal; + } + } + + return IncomingVal; +} + /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is /// in the header of its containing loop, we know the loop executes a /// constant number of times, and the PHI node is just a recurrence @@ -5462,8 +5946,7 @@ Constant * ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, const APInt &BEs, const Loop *L) { - DenseMap<PHINode*, Constant*>::const_iterator I = - ConstantEvolutionLoopExitValue.find(PN); + auto I = ConstantEvolutionLoopExitValue.find(PN); if (I != ConstantEvolutionLoopExitValue.end()) return I->second; @@ -5476,22 +5959,21 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, BasicBlock *Header = L->getHeader(); assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!"); - // Since the loop is canonicalized, the PHI node must have two entries. One - // entry must be a constant (coming in from outside of the loop), and the - // second must be derived from the same PHI. - bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1)); - PHINode *PHI = nullptr; - for (BasicBlock::iterator I = Header->begin(); - (PHI = dyn_cast<PHINode>(I)); ++I) { - Constant *StartCST = - dyn_cast<Constant>(PHI->getIncomingValue(!SecondIsBackedge)); + BasicBlock *Latch = L->getLoopLatch(); + if (!Latch) + return nullptr; + + for (auto &I : *Header) { + PHINode *PHI = dyn_cast<PHINode>(&I); + if (!PHI) break; + auto *StartCST = getOtherIncomingValue(PHI, Latch); if (!StartCST) continue; CurrentIterVals[PHI] = StartCST; } if (!CurrentIterVals.count(PN)) return RetVal = nullptr; - Value *BEValue = PN->getIncomingValue(SecondIsBackedge); + Value *BEValue = PN->getIncomingValueForBlock(Latch); // Execute the loop symbolically to determine the exit value. if (BEs.getActiveBits() >= 32) @@ -5499,7 +5981,7 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, unsigned NumIterations = BEs.getZExtValue(); // must be in range unsigned IterationNum = 0; - const DataLayout &DL = F->getParent()->getDataLayout(); + const DataLayout &DL = getDataLayout(); for (; ; ++IterationNum) { if (IterationNum == NumIterations) return RetVal = CurrentIterVals[PN]; // Got exit value! @@ -5508,7 +5990,7 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, // EvaluateExpression adds non-phi values to the CurrentIterVals map. DenseMap<Instruction *, Constant *> NextIterVals; Constant *NextPHI = - EvaluateExpression(BEValue, L, CurrentIterVals, DL, TLI); + EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); if (!NextPHI) return nullptr; // Couldn't evaluate! NextIterVals[PN] = NextPHI; @@ -5519,23 +6001,21 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, // cease to be able to evaluate one of them or if they stop evolving, // because that doesn't necessarily prevent us from computing PN. SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute; - for (DenseMap<Instruction *, Constant *>::const_iterator - I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){ - PHINode *PHI = dyn_cast<PHINode>(I->first); + for (const auto &I : CurrentIterVals) { + PHINode *PHI = dyn_cast<PHINode>(I.first); if (!PHI || PHI == PN || PHI->getParent() != Header) continue; - PHIsToCompute.push_back(std::make_pair(PHI, I->second)); + PHIsToCompute.emplace_back(PHI, I.second); } // We use two distinct loops because EvaluateExpression may invalidate any // iterators into CurrentIterVals. - for (SmallVectorImpl<std::pair<PHINode *, Constant*> >::const_iterator - I = PHIsToCompute.begin(), E = PHIsToCompute.end(); I != E; ++I) { - PHINode *PHI = I->first; + for (const auto &I : PHIsToCompute) { + PHINode *PHI = I.first; Constant *&NextPHI = NextIterVals[PHI]; if (!NextPHI) { // Not already computed. - Value *BEValue = PHI->getIncomingValue(SecondIsBackedge); - NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, TLI); + Value *BEValue = PHI->getIncomingValueForBlock(Latch); + NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); } - if (NextPHI != I->second) + if (NextPHI != I.second) StoppedEvolving = false; } @@ -5548,12 +6028,7 @@ ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, } } -/// ComputeExitCountExhaustively - If the loop is known to execute a -/// constant number of times (the condition evolves only from constants), -/// try to evaluate a few iterations of the loop until we get the exit -/// condition gets a value of ExitWhen (true or false). If we cannot -/// evaluate the trip count of the loop, return getCouldNotCompute(). -const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L, +const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L, Value *Cond, bool ExitWhen) { PHINode *PN = getConstantEvolvingPHI(Cond, L); @@ -5567,14 +6042,14 @@ const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L, BasicBlock *Header = L->getHeader(); assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!"); - // One entry must be a constant (coming in from outside of the loop), and the - // second must be derived from the same PHI. - bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1)); - PHINode *PHI = nullptr; - for (BasicBlock::iterator I = Header->begin(); - (PHI = dyn_cast<PHINode>(I)); ++I) { - Constant *StartCST = - dyn_cast<Constant>(PHI->getIncomingValue(!SecondIsBackedge)); + BasicBlock *Latch = L->getLoopLatch(); + assert(Latch && "Should follow from NumIncomingValues == 2!"); + + for (auto &I : *Header) { + PHINode *PHI = dyn_cast<PHINode>(&I); + if (!PHI) + break; + auto *StartCST = getOtherIncomingValue(PHI, Latch); if (!StartCST) continue; CurrentIterVals[PHI] = StartCST; } @@ -5585,10 +6060,10 @@ const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L, // the loop symbolically to determine when the condition gets a value of // "ExitWhen". unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis. - const DataLayout &DL = F->getParent()->getDataLayout(); + const DataLayout &DL = getDataLayout(); for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){ - ConstantInt *CondVal = dyn_cast_or_null<ConstantInt>( - EvaluateExpression(Cond, L, CurrentIterVals, DL, TLI)); + auto *CondVal = dyn_cast_or_null<ConstantInt>( + EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI)); // Couldn't symbolically evaluate. if (!CondVal) return getCouldNotCompute(); @@ -5605,20 +6080,17 @@ const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L, // calling EvaluateExpression on them because that may invalidate iterators // into CurrentIterVals. SmallVector<PHINode *, 8> PHIsToCompute; - for (DenseMap<Instruction *, Constant *>::const_iterator - I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){ - PHINode *PHI = dyn_cast<PHINode>(I->first); + for (const auto &I : CurrentIterVals) { + PHINode *PHI = dyn_cast<PHINode>(I.first); if (!PHI || PHI->getParent() != Header) continue; PHIsToCompute.push_back(PHI); } - for (SmallVectorImpl<PHINode *>::const_iterator I = PHIsToCompute.begin(), - E = PHIsToCompute.end(); I != E; ++I) { - PHINode *PHI = *I; + for (PHINode *PHI : PHIsToCompute) { Constant *&NextPHI = NextIterVals[PHI]; if (NextPHI) continue; // Already computed! - Value *BEValue = PHI->getIncomingValue(SecondIsBackedge); - NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, TLI); + Value *BEValue = PHI->getIncomingValueForBlock(Latch); + NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); } CurrentIterVals.swap(NextIterVals); } @@ -5638,22 +6110,22 @@ const SCEV *ScalarEvolution::ComputeExitCountExhaustively(const Loop *L, /// In the case that a relevant loop exit value cannot be computed, the /// original value V is returned. const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) { + SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values = + ValuesAtScopes[V]; // Check to see if we've folded this expression at this loop before. - SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values = ValuesAtScopes[V]; - for (unsigned u = 0; u < Values.size(); u++) { - if (Values[u].first == L) - return Values[u].second ? Values[u].second : V; - } - Values.push_back(std::make_pair(L, static_cast<const SCEV *>(nullptr))); + for (auto &LS : Values) + if (LS.first == L) + return LS.second ? LS.second : V; + + Values.emplace_back(L, nullptr); + // Otherwise compute it. const SCEV *C = computeSCEVAtScope(V, L); - SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values2 = ValuesAtScopes[V]; - for (unsigned u = Values2.size(); u > 0; u--) { - if (Values2[u - 1].first == L) { - Values2[u - 1].second = C; + for (auto &LS : reverse(ValuesAtScopes[V])) + if (LS.first == L) { + LS.second = C; break; } - } return C; } @@ -5763,7 +6235,7 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { // exit value from the loop without using SCEVs. if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) { if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) { - const Loop *LI = (*this->LI)[I->getParent()]; + const Loop *LI = this->LI[I->getParent()]; if (LI && LI->getParentLoop() == L) // Looking for loop exit value. if (PHINode *PN = dyn_cast<PHINode>(I)) if (PN->getParent() == LI->getHeader()) { @@ -5777,9 +6249,8 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { // Okay, we know how many times the containing loop executes. If // this is a constant evolving PHI node, get the final value at // the specified iteration number. - Constant *RV = getConstantEvolutionLoopExitValue(PN, - BTCC->getValue()->getValue(), - LI); + Constant *RV = + getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI); if (RV) return getSCEV(RV); } } @@ -5791,8 +6262,7 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { if (CanConstantFold(I)) { SmallVector<Constant *, 4> Operands; bool MadeImprovement = false; - for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { - Value *Op = I->getOperand(i); + for (Value *Op : I->operands()) { if (Constant *C = dyn_cast<Constant>(Op)) { Operands.push_back(C); continue; @@ -5821,16 +6291,16 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { // Check to see if getSCEVAtScope actually made an improvement. if (MadeImprovement) { Constant *C = nullptr; - const DataLayout &DL = F->getParent()->getDataLayout(); + const DataLayout &DL = getDataLayout(); if (const CmpInst *CI = dyn_cast<CmpInst>(I)) C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0], - Operands[1], DL, TLI); + Operands[1], DL, &TLI); else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) { if (!LI->isVolatile()) C = ConstantFoldLoadFromConstPtr(Operands[0], DL); } else C = ConstantFoldInstOperands(I->getOpcode(), I->getType(), Operands, - DL, TLI); + DL, &TLI); if (!C) return V; return getSCEV(C); } @@ -6021,10 +6491,10 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { return std::make_pair(CNC, CNC); } - uint32_t BitWidth = LC->getValue()->getValue().getBitWidth(); - const APInt &L = LC->getValue()->getValue(); - const APInt &M = MC->getValue()->getValue(); - const APInt &N = NC->getValue()->getValue(); + uint32_t BitWidth = LC->getAPInt().getBitWidth(); + const APInt &L = LC->getAPInt(); + const APInt &M = MC->getAPInt(); + const APInt &N = NC->getAPInt(); APInt Two(BitWidth, 2); APInt Four(BitWidth, 4); @@ -6103,10 +6573,6 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit) { const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first); const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second); if (R1 && R2) { -#if 0 - dbgs() << "HFTZ: " << *V << " - sol#1: " << *R1 - << " sol#2: " << *R2 << "\n"; -#endif // Pick the smallest positive root value. if (ConstantInt *CB = dyn_cast<ConstantInt>(ConstantExpr::getICmp(CmpInst::ICMP_ULT, @@ -6160,7 +6626,7 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit) { // For negative steps (counting down to zero): // N = Start/-Step // First compute the unsigned distance from zero in the direction of Step. - bool CountDown = StepC->getValue()->getValue().isNegative(); + bool CountDown = StepC->getAPInt().isNegative(); const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start); // Handle unitary steps, which cannot wraparound. @@ -6185,13 +6651,53 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit) { // done by counting and comparing the number of trailing zeros of Step and // Distance. if (!CountDown) { - const APInt &StepV = StepC->getValue()->getValue(); + const APInt &StepV = StepC->getAPInt(); // StepV.isPowerOf2() returns true if StepV is an positive power of two. It // also returns true if StepV is maximally negative (eg, INT_MIN), but that // case is not handled as this code is guarded by !CountDown. if (StepV.isPowerOf2() && - GetMinTrailingZeros(Distance) >= StepV.countTrailingZeros()) - return getUDivExactExpr(Distance, Step); + GetMinTrailingZeros(Distance) >= StepV.countTrailingZeros()) { + // Here we've constrained the equation to be of the form + // + // 2^(N + k) * Distance' = (StepV == 2^N) * X (mod 2^W) ... (0) + // + // where we're operating on a W bit wide integer domain and k is + // non-negative. The smallest unsigned solution for X is the trip count. + // + // (0) is equivalent to: + // + // 2^(N + k) * Distance' - 2^N * X = L * 2^W + // <=> 2^N(2^k * Distance' - X) = L * 2^(W - N) * 2^N + // <=> 2^k * Distance' - X = L * 2^(W - N) + // <=> 2^k * Distance' = L * 2^(W - N) + X ... (1) + // + // The smallest X satisfying (1) is unsigned remainder of dividing the LHS + // by 2^(W - N). + // + // <=> X = 2^k * Distance' URem 2^(W - N) ... (2) + // + // E.g. say we're solving + // + // 2 * Val = 2 * X (in i8) ... (3) + // + // then from (2), we get X = Val URem i8 128 (k = 0 in this case). + // + // Note: It is tempting to solve (3) by setting X = Val, but Val is not + // necessarily the smallest unsigned value of X that satisfies (3). + // E.g. if Val is i8 -127 then the smallest value of X that satisfies (3) + // is i8 1, not i8 -127 + + const auto *ModuloResult = getUDivExactExpr(Distance, Step); + + // Since SCEV does not have a URem node, we construct one using a truncate + // and a zero extend. + + unsigned NarrowWidth = StepV.getBitWidth() - StepV.countTrailingZeros(); + auto *NarrowTy = IntegerType::get(getContext(), NarrowWidth); + auto *WideTy = Distance->getType(); + + return getZeroExtendExpr(getTruncateExpr(ModuloResult, NarrowTy), WideTy); + } } // If the condition controls loop exit (the loop exits only if the expression @@ -6207,8 +6713,7 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit) { // Then, try to solve the above equation provided that Start is constant. if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start)) - return SolveLinEquationWithOverflow(StepC->getValue()->getValue(), - -StartC->getValue()->getValue(), + return SolveLinEquationWithOverflow(StepC->getAPInt(), -StartC->getAPInt(), *this); return getCouldNotCompute(); } @@ -6226,7 +6731,7 @@ ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) { // already. If so, the backedge will execute zero times. if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { if (!C->getValue()->isNullValue()) - return getConstant(C->getType(), 0); + return getZero(C->getType()); return getCouldNotCompute(); // Otherwise it will loop infinitely. } @@ -6251,7 +6756,7 @@ ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) { // A loop's header is defined to be a block that dominates the loop. // If the header has a unique predecessor outside the loop, it must be // a block that has exactly one successor that can reach the loop. - if (Loop *L = LI->getLoopFor(BB)) + if (Loop *L = LI.getLoopFor(BB)) return std::make_pair(L->getLoopPredecessor(), L->getHeader()); return std::pair<BasicBlock *, BasicBlock *>(); @@ -6267,13 +6772,20 @@ static bool HasSameValue(const SCEV *A, const SCEV *B) { // Quick check to see if they are the same SCEV. if (A == B) return true; + auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) { + // Not all instructions that are "identical" compute the same value. For + // instance, two distinct alloca instructions allocating the same type are + // identical and do not read memory; but compute distinct values. + return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A)); + }; + // Otherwise, if they're both SCEVUnknown, it's possible that they hold // two different instructions with the same value. Check for this case. if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A)) if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B)) if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue())) if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue())) - if (AI->isIdenticalTo(BI) && !AI->mayReadFromMemory()) + if (ComputesEqualValues(AI, BI)) return true; // Otherwise assume they may have a different value. @@ -6324,7 +6836,7 @@ bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred, // If there's a constant operand, canonicalize comparisons with boundary // cases, and canonicalize *-or-equal comparisons to regular comparisons. if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) { - const APInt &RA = RC->getValue()->getValue(); + const APInt &RA = RC->getAPInt(); switch (Pred) { default: llvm_unreachable("Unexpected ICmpInst::Predicate value!"); case ICmpInst::ICMP_EQ: @@ -6515,16 +7027,14 @@ bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred, Pred = ICmpInst::ICMP_ULT; Changed = true; } else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) { - LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS, - SCEV::FlagNUW); + LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS); Pred = ICmpInst::ICMP_ULT; Changed = true; } break; case ICmpInst::ICMP_UGE: if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) { - RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS, - SCEV::FlagNUW); + RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS); Pred = ICmpInst::ICMP_UGT; Changed = true; } else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) { @@ -6612,10 +7122,140 @@ bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred, if (LeftGuarded && RightGuarded) return true; + if (isKnownPredicateViaSplitting(Pred, LHS, RHS)) + return true; + // Otherwise see what can be done with known constant ranges. return isKnownPredicateWithRanges(Pred, LHS, RHS); } +bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS, + ICmpInst::Predicate Pred, + bool &Increasing) { + bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing); + +#ifndef NDEBUG + // Verify an invariant: inverting the predicate should turn a monotonically + // increasing change to a monotonically decreasing one, and vice versa. + bool IncreasingSwapped; + bool ResultSwapped = isMonotonicPredicateImpl( + LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped); + + assert(Result == ResultSwapped && "should be able to analyze both!"); + if (ResultSwapped) + assert(Increasing == !IncreasingSwapped && + "monotonicity should flip as we flip the predicate"); +#endif + + return Result; +} + +bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS, + ICmpInst::Predicate Pred, + bool &Increasing) { + + // A zero step value for LHS means the induction variable is essentially a + // loop invariant value. We don't really depend on the predicate actually + // flipping from false to true (for increasing predicates, and the other way + // around for decreasing predicates), all we care about is that *if* the + // predicate changes then it only changes from false to true. + // + // A zero step value in itself is not very useful, but there may be places + // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be + // as general as possible. + + switch (Pred) { + default: + return false; // Conservative answer + + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_UGE: + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_ULE: + if (!LHS->getNoWrapFlags(SCEV::FlagNUW)) + return false; + + Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE; + return true; + + case ICmpInst::ICMP_SGT: + case ICmpInst::ICMP_SGE: + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_SLE: { + if (!LHS->getNoWrapFlags(SCEV::FlagNSW)) + return false; + + const SCEV *Step = LHS->getStepRecurrence(*this); + + if (isKnownNonNegative(Step)) { + Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE; + return true; + } + + if (isKnownNonPositive(Step)) { + Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE; + return true; + } + + return false; + } + + } + + llvm_unreachable("switch has default clause!"); +} + +bool ScalarEvolution::isLoopInvariantPredicate( + ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L, + ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS, + const SCEV *&InvariantRHS) { + + // If there is a loop-invariant, force it into the RHS, otherwise bail out. + if (!isLoopInvariant(RHS, L)) { + if (!isLoopInvariant(LHS, L)) + return false; + + std::swap(LHS, RHS); + Pred = ICmpInst::getSwappedPredicate(Pred); + } + + const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS); + if (!ArLHS || ArLHS->getLoop() != L) + return false; + + bool Increasing; + if (!isMonotonicPredicate(ArLHS, Pred, Increasing)) + return false; + + // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to + // true as the loop iterates, and the backedge is control dependent on + // "ArLHS `Pred` RHS" == true then we can reason as follows: + // + // * if the predicate was false in the first iteration then the predicate + // is never evaluated again, since the loop exits without taking the + // backedge. + // * if the predicate was true in the first iteration then it will + // continue to be true for all future iterations since it is + // monotonically increasing. + // + // For both the above possibilities, we can replace the loop varying + // predicate with its value on the first iteration of the loop (which is + // loop invariant). + // + // A similar reasoning applies for a monotonically decreasing predicate, by + // replacing true with false and false with true in the above two bullets. + + auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred); + + if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS)) + return false; + + InvariantPred = Pred; + InvariantLHS = ArLHS->getStart(); + InvariantRHS = RHS; + return true; +} + bool ScalarEvolution::isKnownPredicateWithRanges(ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) { @@ -6690,6 +7330,84 @@ ScalarEvolution::isKnownPredicateWithRanges(ICmpInst::Predicate Pred, return false; } +bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred, + const SCEV *LHS, + const SCEV *RHS) { + + // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer. + // Return Y via OutY. + auto MatchBinaryAddToConst = + [this](const SCEV *Result, const SCEV *X, APInt &OutY, + SCEV::NoWrapFlags ExpectedFlags) { + const SCEV *NonConstOp, *ConstOp; + SCEV::NoWrapFlags FlagsPresent; + + if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) || + !isa<SCEVConstant>(ConstOp) || NonConstOp != X) + return false; + + OutY = cast<SCEVConstant>(ConstOp)->getAPInt(); + return (FlagsPresent & ExpectedFlags) == ExpectedFlags; + }; + + APInt C; + + switch (Pred) { + default: + break; + + case ICmpInst::ICMP_SGE: + std::swap(LHS, RHS); + case ICmpInst::ICMP_SLE: + // X s<= (X + C)<nsw> if C >= 0 + if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative()) + return true; + + // (X + C)<nsw> s<= X if C <= 0 + if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && + !C.isStrictlyPositive()) + return true; + break; + + case ICmpInst::ICMP_SGT: + std::swap(LHS, RHS); + case ICmpInst::ICMP_SLT: + // X s< (X + C)<nsw> if C > 0 + if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && + C.isStrictlyPositive()) + return true; + + // (X + C)<nsw> s< X if C < 0 + if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative()) + return true; + break; + } + + return false; +} + +bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred, + const SCEV *LHS, + const SCEV *RHS) { + if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate) + return false; + + // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on + // the stack can result in exponential time complexity. + SaveAndRestore<bool> Restore(ProvingSplitPredicate, true); + + // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L + // + // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use + // isKnownPredicate. isKnownPredicate is more powerful, but also more + // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the + // interesting cases seen in practice. We can consider "upgrading" L >= 0 to + // use isKnownPredicate later if needed. + return isKnownNonNegative(RHS) && + isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) && + isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS); +} + /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is /// protected by a conditional between LHS and RHS. This is used to /// to eliminate casts. @@ -6715,46 +7433,49 @@ ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L, LoopContinuePredicate->getSuccessor(0) != L->getHeader())) return true; + // We don't want more than one activation of the following loops on the stack + // -- that can lead to O(n!) time complexity. + if (WalkingBEDominatingConds) + return false; + + SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true); + + // See if we can exploit a trip count to prove the predicate. + const auto &BETakenInfo = getBackedgeTakenInfo(L); + const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this); + if (LatchBECount != getCouldNotCompute()) { + // We know that Latch branches back to the loop header exactly + // LatchBECount times. This means the backdege condition at Latch is + // equivalent to "{0,+,1} u< LatchBECount". + Type *Ty = LatchBECount->getType(); + auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW); + const SCEV *LoopCounter = + getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags); + if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter, + LatchBECount)) + return true; + } + // Check conditions due to any @llvm.assume intrinsics. - for (auto &AssumeVH : AC->assumptions()) { + for (auto &AssumeVH : AC.assumptions()) { if (!AssumeVH) continue; auto *CI = cast<CallInst>(AssumeVH); - if (!DT->dominates(CI, Latch->getTerminator())) + if (!DT.dominates(CI, Latch->getTerminator())) continue; if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false)) return true; } - struct ClearWalkingBEDominatingCondsOnExit { - ScalarEvolution &SE; - - explicit ClearWalkingBEDominatingCondsOnExit(ScalarEvolution &SE) - : SE(SE){}; - - ~ClearWalkingBEDominatingCondsOnExit() { - SE.WalkingBEDominatingConds = false; - } - }; - - // We don't want more than one activation of the following loop on the stack - // -- that can lead to O(n!) time complexity. - if (WalkingBEDominatingConds) - return false; - - WalkingBEDominatingConds = true; - ClearWalkingBEDominatingCondsOnExit ClearOnExit(*this); - // If the loop is not reachable from the entry block, we risk running into an // infinite loop as we walk up into the dom tree. These loops do not matter // anyway, so we just return a conservative answer when we see them. - if (!DT->isReachableFromEntry(L->getHeader())) + if (!DT.isReachableFromEntry(L->getHeader())) return false; - for (DomTreeNode *DTN = (*DT)[Latch], *HeaderDTN = (*DT)[L->getHeader()]; - DTN != HeaderDTN; - DTN = DTN->getIDom()) { + for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()]; + DTN != HeaderDTN; DTN = DTN->getIDom()) { assert(DTN && "should reach the loop header before reaching the root!"); @@ -6778,7 +7499,7 @@ ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L, // We're constructively (and conservatively) enumerating edges within the // loop body that dominate the latch. The dominator tree better agree // with us on this: - assert(DT->dominates(DominatingEdge, Latch) && "should be!"); + assert(DT.dominates(DominatingEdge, Latch) && "should be!"); if (isImpliedCond(Pred, LHS, RHS, Condition, BB != ContinuePredicate->getSuccessor(0))) @@ -6823,11 +7544,11 @@ ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L, } // Check conditions due to any @llvm.assume intrinsics. - for (auto &AssumeVH : AC->assumptions()) { + for (auto &AssumeVH : AC.assumptions()) { if (!AssumeVH) continue; auto *CI = cast<CallInst>(AssumeVH); - if (!DT->dominates(CI, L->getHeader())) + if (!DT.dominates(CI, L->getHeader())) continue; if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false)) @@ -6837,6 +7558,7 @@ ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L, return false; } +namespace { /// RAII wrapper to prevent recursive application of isImpliedCond. /// ScalarEvolution's PendingLoopPredicates set must be empty unless we are /// currently evaluating isImpliedCond. @@ -6854,6 +7576,7 @@ struct MarkPendingLoopPredicate { LoopPreds.erase(Cond); } }; +} // end anonymous namespace /// isImpliedCond - Test whether the condition described by Pred, LHS, /// and RHS is true whenever the given Cond value evaluates to true. @@ -6892,6 +7615,14 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *FoundLHS = getSCEV(ICI->getOperand(0)); const SCEV *FoundRHS = getSCEV(ICI->getOperand(1)); + return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS); +} + +bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS, + const SCEV *RHS, + ICmpInst::Predicate FoundPred, + const SCEV *FoundLHS, + const SCEV *FoundRHS) { // Balance the types. if (getTypeSizeInBits(LHS->getType()) < getTypeSizeInBits(FoundLHS->getType())) { @@ -6947,6 +7678,13 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, RHS, LHS, FoundLHS, FoundRHS); } + // Unsigned comparison is the same as signed comparison when both the operands + // are non-negative. + if (CmpInst::isUnsigned(FoundPred) && + CmpInst::getSignedPredicate(FoundPred) == Pred && + isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS)) + return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS); + // Check if we can make progress by sharpening ranges. if (FoundPred == ICmpInst::ICMP_NE && (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) { @@ -6970,7 +7708,7 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, APInt Min = ICmpInst::isSigned(Pred) ? getSignedRange(V).getSignedMin() : getUnsignedRange(V).getUnsignedMin(); - if (Min == C->getValue()->getValue()) { + if (Min == C->getAPInt()) { // Given (V >= Min && V != Min) we conclude V >= (Min + 1). // This is true even if (Min + 1) wraps around -- in case of // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)). @@ -7021,6 +7759,149 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, return false; } +bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr, + const SCEV *&L, const SCEV *&R, + SCEV::NoWrapFlags &Flags) { + const auto *AE = dyn_cast<SCEVAddExpr>(Expr); + if (!AE || AE->getNumOperands() != 2) + return false; + + L = AE->getOperand(0); + R = AE->getOperand(1); + Flags = AE->getNoWrapFlags(); + return true; +} + +bool ScalarEvolution::computeConstantDifference(const SCEV *Less, + const SCEV *More, + APInt &C) { + // We avoid subtracting expressions here because this function is usually + // fairly deep in the call stack (i.e. is called many times). + + if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) { + const auto *LAR = cast<SCEVAddRecExpr>(Less); + const auto *MAR = cast<SCEVAddRecExpr>(More); + + if (LAR->getLoop() != MAR->getLoop()) + return false; + + // We look at affine expressions only; not for correctness but to keep + // getStepRecurrence cheap. + if (!LAR->isAffine() || !MAR->isAffine()) + return false; + + if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this)) + return false; + + Less = LAR->getStart(); + More = MAR->getStart(); + + // fall through + } + + if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) { + const auto &M = cast<SCEVConstant>(More)->getAPInt(); + const auto &L = cast<SCEVConstant>(Less)->getAPInt(); + C = M - L; + return true; + } + + const SCEV *L, *R; + SCEV::NoWrapFlags Flags; + if (splitBinaryAdd(Less, L, R, Flags)) + if (const auto *LC = dyn_cast<SCEVConstant>(L)) + if (R == More) { + C = -(LC->getAPInt()); + return true; + } + + if (splitBinaryAdd(More, L, R, Flags)) + if (const auto *LC = dyn_cast<SCEVConstant>(L)) + if (R == Less) { + C = LC->getAPInt(); + return true; + } + + return false; +} + +bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow( + ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, + const SCEV *FoundLHS, const SCEV *FoundRHS) { + if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT) + return false; + + const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS); + if (!AddRecLHS) + return false; + + const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS); + if (!AddRecFoundLHS) + return false; + + // We'd like to let SCEV reason about control dependencies, so we constrain + // both the inequalities to be about add recurrences on the same loop. This + // way we can use isLoopEntryGuardedByCond later. + + const Loop *L = AddRecFoundLHS->getLoop(); + if (L != AddRecLHS->getLoop()) + return false; + + // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1) + // + // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C) + // ... (2) + // + // Informal proof for (2), assuming (1) [*]: + // + // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**] + // + // Then + // + // FoundLHS s< FoundRHS s< INT_MIN - C + // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ] + // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ] + // <=> (FoundLHS + INT_MIN + C + INT_MIN) s< + // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ] + // <=> FoundLHS + C s< FoundRHS + C + // + // [*]: (1) can be proved by ruling out overflow. + // + // [**]: This can be proved by analyzing all the four possibilities: + // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and + // (A s>= 0, B s>= 0). + // + // Note: + // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C" + // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS + // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS + // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is + // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS + + // C)". + + APInt LDiff, RDiff; + if (!computeConstantDifference(FoundLHS, LHS, LDiff) || + !computeConstantDifference(FoundRHS, RHS, RDiff) || + LDiff != RDiff) + return false; + + if (LDiff == 0) + return true; + + APInt FoundRHSLimit; + + if (Pred == CmpInst::ICMP_ULT) { + FoundRHSLimit = -RDiff; + } else { + assert(Pred == CmpInst::ICMP_SLT && "Checked above!"); + FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - RDiff; + } + + // Try to prove (1) or (2), as needed. + return isLoopEntryGuardedByCond(L, Pred, FoundRHS, + getConstant(FoundRHSLimit)); +} + /// isImpliedCondOperands - Test whether the condition described by Pred, /// LHS, and RHS is true whenever the condition described by Pred, FoundLHS, /// and FoundRHS is true. @@ -7031,6 +7912,9 @@ bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred, if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS)) return true; + if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS)) + return true; + return isImpliedCondOperandsHelper(Pred, LHS, RHS, FoundLHS, FoundRHS) || // ~x < ~y --> x > y @@ -7043,17 +7927,13 @@ bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred, /// If Expr computes ~A, return A else return nullptr static const SCEV *MatchNotExpr(const SCEV *Expr) { const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr); - if (!Add || Add->getNumOperands() != 2) return nullptr; - - const SCEVConstant *AddLHS = dyn_cast<SCEVConstant>(Add->getOperand(0)); - if (!(AddLHS && AddLHS->getValue()->getValue().isAllOnesValue())) + if (!Add || Add->getNumOperands() != 2 || + !Add->getOperand(0)->isAllOnesValue()) return nullptr; const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1)); - if (!AddRHS || AddRHS->getNumOperands() != 2) return nullptr; - - const SCEVConstant *MulLHS = dyn_cast<SCEVConstant>(AddRHS->getOperand(0)); - if (!(MulLHS && MulLHS->getValue()->getValue().isAllOnesValue())) + if (!AddRHS || AddRHS->getNumOperands() != 2 || + !AddRHS->getOperand(0)->isAllOnesValue()) return nullptr; return AddRHS->getOperand(1); @@ -7067,8 +7947,7 @@ static bool IsMaxConsistingOf(const SCEV *MaybeMaxExpr, const MaxExprType *MaxExpr = dyn_cast<MaxExprType>(MaybeMaxExpr); if (!MaxExpr) return false; - auto It = std::find(MaxExpr->op_begin(), MaxExpr->op_end(), Candidate); - return It != MaxExpr->op_end(); + return find(MaxExpr->operands(), Candidate) != MaxExpr->op_end(); } @@ -7084,6 +7963,38 @@ static bool IsMinConsistingOf(ScalarEvolution &SE, return IsMaxConsistingOf<MaxExprType>(MaybeMaxExpr, SE.getNotSCEV(Candidate)); } +static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE, + ICmpInst::Predicate Pred, + const SCEV *LHS, const SCEV *RHS) { + + // If both sides are affine addrecs for the same loop, with equal + // steps, and we know the recurrences don't wrap, then we only + // need to check the predicate on the starting values. + + if (!ICmpInst::isRelational(Pred)) + return false; + + const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS); + if (!LAR) + return false; + const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS); + if (!RAR) + return false; + if (LAR->getLoop() != RAR->getLoop()) + return false; + if (!LAR->isAffine() || !RAR->isAffine()) + return false; + + if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE)) + return false; + + SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ? + SCEV::FlagNSW : SCEV::FlagNUW; + if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW)) + return false; + + return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart()); +} /// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max /// expression? @@ -7129,7 +8040,9 @@ ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, auto IsKnownPredicateFull = [this](ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) { return isKnownPredicateWithRanges(Pred, LHS, RHS) || - IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS); + IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) || + IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) || + isKnownPredicateViaNoOverflow(Pred, LHS, RHS); }; switch (Pred) { @@ -7185,7 +8098,7 @@ bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred, !isa<SCEVConstant>(AddLHS->getOperand(0))) return false; - APInt ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getValue()->getValue(); + APInt ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt(); // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the // antecedent "`FoundLHS` `Pred` `FoundRHS`". @@ -7194,13 +8107,12 @@ bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred, // Since `LHS` is `FoundLHS` + `AddLHS->getOperand(0)`, we can compute a range // for `LHS`: - APInt Addend = - cast<SCEVConstant>(AddLHS->getOperand(0))->getValue()->getValue(); + APInt Addend = cast<SCEVConstant>(AddLHS->getOperand(0))->getAPInt(); ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(Addend)); // We can also compute the range of values for `LHS` that satisfy the // consequent, "`LHS` `Pred` `RHS`": - APInt ConstRHS = cast<SCEVConstant>(RHS)->getValue()->getValue(); + APInt ConstRHS = cast<SCEVConstant>(RHS)->getAPInt(); ConstantRange SatisfyingLHSRange = ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS); @@ -7217,7 +8129,7 @@ bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, if (NoWrap) return false; unsigned BitWidth = getTypeSizeInBits(RHS->getType()); - const SCEV *One = getConstant(Stride->getType(), 1); + const SCEV *One = getOne(Stride->getType()); if (IsSigned) { APInt MaxRHS = getSignedRange(RHS).getSignedMax(); @@ -7246,7 +8158,7 @@ bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, if (NoWrap) return false; unsigned BitWidth = getTypeSizeInBits(RHS->getType()); - const SCEV *One = getConstant(Stride->getType(), 1); + const SCEV *One = getOne(Stride->getType()); if (IsSigned) { APInt MinRHS = getSignedRange(RHS).getSignedMin(); @@ -7271,7 +8183,7 @@ bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, // stride and presence of the equality in the comparison. const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step, bool Equality) { - const SCEV *One = getConstant(Step->getType(), 1); + const SCEV *One = getOne(Step->getType()); Delta = Equality ? getAddExpr(Delta, Step) : getAddExpr(Delta, getMinusSCEV(Step, One)); return getUDivExpr(Delta, Step); @@ -7324,7 +8236,7 @@ ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS, // overflow, in which case if RHS - Start is a constant, we don't need to // do a max operation since we can just figure it out statically if (NoWrap && isa<SCEVConstant>(Diff)) { - APInt D = dyn_cast<const SCEVConstant>(Diff)->getValue()->getValue(); + APInt D = dyn_cast<const SCEVConstant>(Diff)->getAPInt(); if (D.isNegative()) End = Start; } else @@ -7405,7 +8317,7 @@ ScalarEvolution::HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS, // overflow, in which case if RHS - Start is a constant, we don't need to // do a max operation since we can just figure it out statically if (NoWrap && isa<SCEVConstant>(Diff)) { - APInt D = dyn_cast<const SCEVConstant>(Diff)->getValue()->getValue(); + APInt D = dyn_cast<const SCEVConstant>(Diff)->getAPInt(); if (!D.isNegative()) End = Start; } else @@ -7460,23 +8372,20 @@ const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart())) if (!SC->getValue()->isZero()) { SmallVector<const SCEV *, 4> Operands(op_begin(), op_end()); - Operands[0] = SE.getConstant(SC->getType(), 0); + Operands[0] = SE.getZero(SC->getType()); const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(), getNoWrapFlags(FlagNW)); - if (const SCEVAddRecExpr *ShiftedAddRec = - dyn_cast<SCEVAddRecExpr>(Shifted)) + if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted)) return ShiftedAddRec->getNumIterationsInRange( - Range.subtract(SC->getValue()->getValue()), SE); + Range.subtract(SC->getAPInt()), SE); // This is strange and shouldn't happen. return SE.getCouldNotCompute(); } // The only time we can solve this is when we have all constant indices. // Otherwise, we cannot determine the overflow conditions. - for (unsigned i = 0, e = getNumOperands(); i != e; ++i) - if (!isa<SCEVConstant>(getOperand(i))) - return SE.getCouldNotCompute(); - + if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); })) + return SE.getCouldNotCompute(); // Okay at this point we know that all elements of the chrec are constants and // that the start element is zero. @@ -7485,7 +8394,7 @@ const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, // iteration exits. unsigned BitWidth = SE.getTypeSizeInBits(getType()); if (!Range.contains(APInt(BitWidth, 0))) - return SE.getConstant(getType(), 0); + return SE.getZero(getType()); if (isAffine()) { // If this is an affine expression then we have this situation: @@ -7496,7 +8405,7 @@ const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, // If A is negative then the lower of the range is the last possible loop // value. Also note that we already checked for a full range. APInt One(BitWidth,1); - APInt A = cast<SCEVConstant>(getOperand(1))->getValue()->getValue(); + APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt(); APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower(); // The exit value should be (End+A)/A. @@ -7528,15 +8437,13 @@ const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, FlagAnyWrap); // Next, solve the constructed addrec - std::pair<const SCEV *,const SCEV *> Roots = - SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE); + auto Roots = SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE); const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first); const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second); if (R1) { // Pick the smallest positive root value. - if (ConstantInt *CB = - dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT, - R1->getValue(), R2->getValue()))) { + if (ConstantInt *CB = dyn_cast<ConstantInt>(ConstantExpr::getICmp( + ICmpInst::ICMP_ULT, R1->getValue(), R2->getValue()))) { if (!CB->getZExtValue()) std::swap(R1, R2); // R1 is the minimum root now. @@ -7549,7 +8456,7 @@ const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, if (Range.contains(R1Val->getValue())) { // The next iteration must be out of the range... ConstantInt *NextVal = - ConstantInt::get(SE.getContext(), R1->getValue()->getValue()+1); + ConstantInt::get(SE.getContext(), R1->getAPInt() + 1); R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE); if (!Range.contains(R1Val->getValue())) @@ -7560,7 +8467,7 @@ const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range, // If R1 was not in the range, then it is a good return value. Make // sure that R1-1 WAS in the range though, just in case. ConstantInt *NextVal = - ConstantInt::get(SE.getContext(), R1->getValue()->getValue()-1); + ConstantInt::get(SE.getContext(), R1->getAPInt() - 1); R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE); if (Range.contains(R1Val->getValue())) return R1; @@ -7644,9 +8551,84 @@ struct SCEVCollectTerms { } bool isDone() const { return false; } }; + +// Check if a SCEV contains an AddRecExpr. +struct SCEVHasAddRec { + bool &ContainsAddRec; + + SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) { + ContainsAddRec = false; + } + + bool follow(const SCEV *S) { + if (isa<SCEVAddRecExpr>(S)) { + ContainsAddRec = true; + + // Stop recursion: once we collected a term, do not walk its operands. + return false; + } + + // Keep looking. + return true; + } + bool isDone() const { return false; } +}; + +// Find factors that are multiplied with an expression that (possibly as a +// subexpression) contains an AddRecExpr. In the expression: +// +// 8 * (100 + %p * %q * (%a + {0, +, 1}_loop)) +// +// "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)" +// that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size +// parameters as they form a product with an induction variable. +// +// This collector expects all array size parameters to be in the same MulExpr. +// It might be necessary to later add support for collecting parameters that are +// spread over different nested MulExpr. +struct SCEVCollectAddRecMultiplies { + SmallVectorImpl<const SCEV *> &Terms; + ScalarEvolution &SE; + + SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE) + : Terms(T), SE(SE) {} + + bool follow(const SCEV *S) { + if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) { + bool HasAddRec = false; + SmallVector<const SCEV *, 0> Operands; + for (auto Op : Mul->operands()) { + if (isa<SCEVUnknown>(Op)) { + Operands.push_back(Op); + } else { + bool ContainsAddRec; + SCEVHasAddRec ContiansAddRec(ContainsAddRec); + visitAll(Op, ContiansAddRec); + HasAddRec |= ContainsAddRec; + } + } + if (Operands.size() == 0) + return true; + + if (!HasAddRec) + return false; + + Terms.push_back(SE.getMulExpr(Operands)); + // Stop recursion: once we collected a term, do not walk its operands. + return false; + } + + // Keep looking. + return true; + } + bool isDone() const { return false; } +}; } -/// Find parametric terms in this SCEVAddRecExpr. +/// Find parametric terms in this SCEVAddRecExpr. We first for parameters in +/// two places: +/// 1) The strides of AddRec expressions. +/// 2) Unknowns that are multiplied with AddRec expressions. void ScalarEvolution::collectParametricTerms(const SCEV *Expr, SmallVectorImpl<const SCEV *> &Terms) { SmallVector<const SCEV *, 4> Strides; @@ -7669,6 +8651,9 @@ void ScalarEvolution::collectParametricTerms(const SCEV *Expr, for (const SCEV *T : Terms) dbgs() << *T << "\n"; }); + + SCEVCollectAddRecMultiplies MulCollector(Terms, *this); + visitAll(Expr, MulCollector); } static bool findArrayDimensionsRec(ScalarEvolution &SE, @@ -7718,30 +8703,28 @@ static bool findArrayDimensionsRec(ScalarEvolution &SE, return true; } -namespace { -struct FindParameter { - bool FoundParameter; - FindParameter() : FoundParameter(false) {} - - bool follow(const SCEV *S) { - if (isa<SCEVUnknown>(S)) { - FoundParameter = true; - // Stop recursion: we found a parameter. - return false; - } - // Keep looking. - return true; - } - bool isDone() const { - // Stop recursion if we have found a parameter. - return FoundParameter; - } -}; -} - // Returns true when S contains at least a SCEVUnknown parameter. static inline bool containsParameters(const SCEV *S) { + struct FindParameter { + bool FoundParameter; + FindParameter() : FoundParameter(false) {} + + bool follow(const SCEV *S) { + if (isa<SCEVUnknown>(S)) { + FoundParameter = true; + // Stop recursion: we found a parameter. + return false; + } + // Keep looking. + return true; + } + bool isDone() const { + // Stop recursion if we have found a parameter. + return FoundParameter; + } + }; + FindParameter F; SCEVTraversal<FindParameter> ST(F); ST.visitAll(S); @@ -7829,11 +8812,13 @@ void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms, ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); - // Divide all terms by the element size. + // Try to divide all terms by the element size. If term is not divisible by + // element size, proceed with the original term. for (const SCEV *&Term : Terms) { const SCEV *Q, *R; SCEVDivision::divide(SE, Term, ElementSize, &Q, &R); - Term = Q; + if (!Q->isZero()) + Term = Q; } SmallVector<const SCEV *, 4> NewTerms; @@ -7875,7 +8860,7 @@ void ScalarEvolution::computeAccessFunctions( if (Sizes.empty()) return; - if (auto AR = dyn_cast<SCEVAddRecExpr>(Expr)) + if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr)) if (!AR->isAffine()) return; @@ -8059,58 +9044,55 @@ ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se) // ScalarEvolution Class Implementation //===----------------------------------------------------------------------===// -ScalarEvolution::ScalarEvolution() - : FunctionPass(ID), WalkingBEDominatingConds(false), ValuesAtScopes(64), - LoopDispositions(64), BlockDispositions(64), FirstUnknown(nullptr) { - initializeScalarEvolutionPass(*PassRegistry::getPassRegistry()); -} - -bool ScalarEvolution::runOnFunction(Function &F) { - this->F = &F; - AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F); - LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); - TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); - DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); - return false; -} - -void ScalarEvolution::releaseMemory() { +ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI, + AssumptionCache &AC, DominatorTree &DT, + LoopInfo &LI) + : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI), + CouldNotCompute(new SCEVCouldNotCompute()), + WalkingBEDominatingConds(false), ProvingSplitPredicate(false), + ValuesAtScopes(64), LoopDispositions(64), BlockDispositions(64), + FirstUnknown(nullptr) {} + +ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg) + : F(Arg.F), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT), LI(Arg.LI), + CouldNotCompute(std::move(Arg.CouldNotCompute)), + ValueExprMap(std::move(Arg.ValueExprMap)), + WalkingBEDominatingConds(false), ProvingSplitPredicate(false), + BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)), + ConstantEvolutionLoopExitValue( + std::move(Arg.ConstantEvolutionLoopExitValue)), + ValuesAtScopes(std::move(Arg.ValuesAtScopes)), + LoopDispositions(std::move(Arg.LoopDispositions)), + BlockDispositions(std::move(Arg.BlockDispositions)), + UnsignedRanges(std::move(Arg.UnsignedRanges)), + SignedRanges(std::move(Arg.SignedRanges)), + UniqueSCEVs(std::move(Arg.UniqueSCEVs)), + UniquePreds(std::move(Arg.UniquePreds)), + SCEVAllocator(std::move(Arg.SCEVAllocator)), + FirstUnknown(Arg.FirstUnknown) { + Arg.FirstUnknown = nullptr; +} + +ScalarEvolution::~ScalarEvolution() { // Iterate through all the SCEVUnknown instances and call their // destructors, so that they release their references to their values. - for (SCEVUnknown *U = FirstUnknown; U; U = U->Next) - U->~SCEVUnknown(); + for (SCEVUnknown *U = FirstUnknown; U;) { + SCEVUnknown *Tmp = U; + U = U->Next; + Tmp->~SCEVUnknown(); + } FirstUnknown = nullptr; ValueExprMap.clear(); // Free any extra memory created for ExitNotTakenInfo in the unlikely event // that a loop had multiple computable exits. - for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I = - BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end(); - I != E; ++I) { - I->second.clear(); - } + for (auto &BTCI : BackedgeTakenCounts) + BTCI.second.clear(); assert(PendingLoopPredicates.empty() && "isImpliedCond garbage"); assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!"); - - BackedgeTakenCounts.clear(); - ConstantEvolutionLoopExitValue.clear(); - ValuesAtScopes.clear(); - LoopDispositions.clear(); - BlockDispositions.clear(); - UnsignedRanges.clear(); - SignedRanges.clear(); - UniqueSCEVs.clear(); - SCEVAllocator.Reset(); -} - -void ScalarEvolution::getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesAll(); - AU.addRequired<AssumptionCacheTracker>(); - AU.addRequiredTransitive<LoopInfoWrapperPass>(); - AU.addRequiredTransitive<DominatorTreeWrapperPass>(); - AU.addRequired<TargetLibraryInfoWrapperPass>(); + assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"); } bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) { @@ -8152,7 +9134,7 @@ static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE, OS << "\n"; } -void ScalarEvolution::print(raw_ostream &OS, const Module *) const { +void ScalarEvolution::print(raw_ostream &OS) const { // ScalarEvolution's implementation of the print method is to print // out SCEV values of all instructions that are interesting. Doing // this potentially causes it to create new SCEV objects though, @@ -8162,13 +9144,13 @@ void ScalarEvolution::print(raw_ostream &OS, const Module *) const { ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); OS << "Classifying expressions for: "; - F->printAsOperand(OS, /*PrintType=*/false); + F.printAsOperand(OS, /*PrintType=*/false); OS << "\n"; - for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) - if (isSCEVable(I->getType()) && !isa<CmpInst>(*I)) { - OS << *I << '\n'; + for (Instruction &I : instructions(F)) + if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) { + OS << I << '\n'; OS << " --> "; - const SCEV *SV = SE.getSCEV(&*I); + const SCEV *SV = SE.getSCEV(&I); SV->print(OS); if (!isa<SCEVCouldNotCompute>(SV)) { OS << " U: "; @@ -8177,7 +9159,7 @@ void ScalarEvolution::print(raw_ostream &OS, const Module *) const { SE.getSignedRange(SV).print(OS); } - const Loop *L = LI->getLoopFor((*I).getParent()); + const Loop *L = LI.getLoopFor(I.getParent()); const SCEV *AtUse = SE.getSCEVAtScope(SV, L); if (AtUse != SV) { @@ -8205,9 +9187,9 @@ void ScalarEvolution::print(raw_ostream &OS, const Module *) const { } OS << "Determining loop execution counts for: "; - F->printAsOperand(OS, /*PrintType=*/false); + F.printAsOperand(OS, /*PrintType=*/false); OS << "\n"; - for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) + for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I) PrintLoopInfo(OS, &SE, *I); } @@ -8260,9 +9242,8 @@ ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) { // This recurrence is variant w.r.t. L if any of its operands // are variant. - for (SCEVAddRecExpr::op_iterator I = AR->op_begin(), E = AR->op_end(); - I != E; ++I) - if (!isLoopInvariant(*I, L)) + for (auto *Op : AR->operands()) + if (!isLoopInvariant(Op, L)) return LoopVariant; // Otherwise it's loop-invariant. @@ -8272,11 +9253,9 @@ ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) { case scMulExpr: case scUMaxExpr: case scSMaxExpr: { - const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S); bool HasVarying = false; - for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); - I != E; ++I) { - LoopDisposition D = getLoopDisposition(*I, L); + for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) { + LoopDisposition D = getLoopDisposition(Op, L); if (D == LoopVariant) return LoopVariant; if (D == LoopComputable) @@ -8300,7 +9279,7 @@ ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) { // invariant if they are not contained in the specified loop. // Instructions are never considered invariant in the function body // (null loop) because they are defined within the "loop". - if (Instruction *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) + if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) return (L && !L->contains(I)) ? LoopInvariant : LoopVariant; return LoopInvariant; case scCouldNotCompute: @@ -8351,7 +9330,7 @@ ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) { // produces the addrec's value is a PHI, and a PHI effectively properly // dominates its entire containing block. const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); - if (!DT->dominates(AR->getLoop()->getHeader(), BB)) + if (!DT.dominates(AR->getLoop()->getHeader(), BB)) return DoesNotDominateBlock; } // FALL THROUGH into SCEVNAryExpr handling. @@ -8361,9 +9340,8 @@ ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) { case scSMaxExpr: { const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S); bool Proper = true; - for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); - I != E; ++I) { - BlockDisposition D = getBlockDisposition(*I, BB); + for (const SCEV *NAryOp : NAry->operands()) { + BlockDisposition D = getBlockDisposition(NAryOp, BB); if (D == DoesNotDominateBlock) return DoesNotDominateBlock; if (D == DominatesBlock) @@ -8388,7 +9366,7 @@ ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) { dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) { if (I->getParent() == BB) return DominatesBlock; - if (DT->properlyDominates(I->getParent(), BB)) + if (DT.properlyDominates(I->getParent(), BB)) return ProperlyDominatesBlock; return DoesNotDominateBlock; } @@ -8407,24 +9385,22 @@ bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) { return getBlockDisposition(S, BB) == ProperlyDominatesBlock; } -namespace { -// Search for a SCEV expression node within an expression tree. -// Implements SCEVTraversal::Visitor. -struct SCEVSearch { - const SCEV *Node; - bool IsFound; +bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const { + // Search for a SCEV expression node within an expression tree. + // Implements SCEVTraversal::Visitor. + struct SCEVSearch { + const SCEV *Node; + bool IsFound; - SCEVSearch(const SCEV *N): Node(N), IsFound(false) {} + SCEVSearch(const SCEV *N): Node(N), IsFound(false) {} - bool follow(const SCEV *S) { - IsFound |= (S == Node); - return !IsFound; - } - bool isDone() const { return IsFound; } -}; -} + bool follow(const SCEV *S) { + IsFound |= (S == Node); + return !IsFound; + } + bool isDone() const { return IsFound; } + }; -bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const { SCEVSearch Search(Op); visitAll(S, Search); return Search.IsFound; @@ -8463,43 +9439,39 @@ static void replaceSubString(std::string &Str, StringRef From, StringRef To) { /// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis. static void getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) { - for (Loop::reverse_iterator I = L->rbegin(), E = L->rend(); I != E; ++I) { - getLoopBackedgeTakenCounts(*I, Map, SE); // recurse. - - std::string &S = Map[L]; - if (S.empty()) { - raw_string_ostream OS(S); - SE.getBackedgeTakenCount(L)->print(OS); + std::string &S = Map[L]; + if (S.empty()) { + raw_string_ostream OS(S); + SE.getBackedgeTakenCount(L)->print(OS); - // false and 0 are semantically equivalent. This can happen in dead loops. - replaceSubString(OS.str(), "false", "0"); - // Remove wrap flags, their use in SCEV is highly fragile. - // FIXME: Remove this when SCEV gets smarter about them. - replaceSubString(OS.str(), "<nw>", ""); - replaceSubString(OS.str(), "<nsw>", ""); - replaceSubString(OS.str(), "<nuw>", ""); - } + // false and 0 are semantically equivalent. This can happen in dead loops. + replaceSubString(OS.str(), "false", "0"); + // Remove wrap flags, their use in SCEV is highly fragile. + // FIXME: Remove this when SCEV gets smarter about them. + replaceSubString(OS.str(), "<nw>", ""); + replaceSubString(OS.str(), "<nsw>", ""); + replaceSubString(OS.str(), "<nuw>", ""); } -} -void ScalarEvolution::verifyAnalysis() const { - if (!VerifySCEV) - return; + for (auto *R : reverse(*L)) + getLoopBackedgeTakenCounts(R, Map, SE); // recurse. +} +void ScalarEvolution::verify() const { ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); // Gather stringified backedge taken counts for all loops using SCEV's caches. // FIXME: It would be much better to store actual values instead of strings, // but SCEV pointers will change if we drop the caches. VerifyMap BackedgeDumpsOld, BackedgeDumpsNew; - for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I) + for (LoopInfo::reverse_iterator I = LI.rbegin(), E = LI.rend(); I != E; ++I) getLoopBackedgeTakenCounts(*I, BackedgeDumpsOld, SE); - // Gather stringified backedge taken counts for all loops without using - // SCEV's caches. - SE.releaseMemory(); - for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I) - getLoopBackedgeTakenCounts(*I, BackedgeDumpsNew, SE); + // Gather stringified backedge taken counts for all loops using a fresh + // ScalarEvolution object. + ScalarEvolution SE2(F, TLI, AC, DT, LI); + for (LoopInfo::reverse_iterator I = LI.rbegin(), E = LI.rend(); I != E; ++I) + getLoopBackedgeTakenCounts(*I, BackedgeDumpsNew, SE2); // Now compare whether they're the same with and without caches. This allows // verifying that no pass changed the cache. @@ -8532,3 +9504,238 @@ void ScalarEvolution::verifyAnalysis() const { // TODO: Verify more things. } + +char ScalarEvolutionAnalysis::PassID; + +ScalarEvolution ScalarEvolutionAnalysis::run(Function &F, + AnalysisManager<Function> *AM) { + return ScalarEvolution(F, AM->getResult<TargetLibraryAnalysis>(F), + AM->getResult<AssumptionAnalysis>(F), + AM->getResult<DominatorTreeAnalysis>(F), + AM->getResult<LoopAnalysis>(F)); +} + +PreservedAnalyses +ScalarEvolutionPrinterPass::run(Function &F, AnalysisManager<Function> *AM) { + AM->getResult<ScalarEvolutionAnalysis>(F).print(OS); + return PreservedAnalyses::all(); +} + +INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution", + "Scalar Evolution Analysis", false, true) +INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) +INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) +INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass) +INITIALIZE_PASS_END(ScalarEvolutionWrapperPass, "scalar-evolution", + "Scalar Evolution Analysis", false, true) +char ScalarEvolutionWrapperPass::ID = 0; + +ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) { + initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry()); +} + +bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) { + SE.reset(new ScalarEvolution( + F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(), + getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F), + getAnalysis<DominatorTreeWrapperPass>().getDomTree(), + getAnalysis<LoopInfoWrapperPass>().getLoopInfo())); + return false; +} + +void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); } + +void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const { + SE->print(OS); +} + +void ScalarEvolutionWrapperPass::verifyAnalysis() const { + if (!VerifySCEV) + return; + + SE->verify(); +} + +void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesAll(); + AU.addRequiredTransitive<AssumptionCacheTracker>(); + AU.addRequiredTransitive<LoopInfoWrapperPass>(); + AU.addRequiredTransitive<DominatorTreeWrapperPass>(); + AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>(); +} + +const SCEVPredicate * +ScalarEvolution::getEqualPredicate(const SCEVUnknown *LHS, + const SCEVConstant *RHS) { + FoldingSetNodeID ID; + // Unique this node based on the arguments + ID.AddInteger(SCEVPredicate::P_Equal); + ID.AddPointer(LHS); + ID.AddPointer(RHS); + void *IP = nullptr; + if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP)) + return S; + SCEVEqualPredicate *Eq = new (SCEVAllocator) + SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS); + UniquePreds.InsertNode(Eq, IP); + return Eq; +} + +namespace { +class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> { +public: + static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE, + SCEVUnionPredicate &A) { + SCEVPredicateRewriter Rewriter(SE, A); + return Rewriter.visit(Scev); + } + + SCEVPredicateRewriter(ScalarEvolution &SE, SCEVUnionPredicate &P) + : SCEVRewriteVisitor(SE), P(P) {} + + const SCEV *visitUnknown(const SCEVUnknown *Expr) { + auto ExprPreds = P.getPredicatesForExpr(Expr); + for (auto *Pred : ExprPreds) + if (const auto *IPred = dyn_cast<const SCEVEqualPredicate>(Pred)) + if (IPred->getLHS() == Expr) + return IPred->getRHS(); + + return Expr; + } + +private: + SCEVUnionPredicate &P; +}; +} // end anonymous namespace + +const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *Scev, + SCEVUnionPredicate &Preds) { + return SCEVPredicateRewriter::rewrite(Scev, *this, Preds); +} + +/// SCEV predicates +SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID, + SCEVPredicateKind Kind) + : FastID(ID), Kind(Kind) {} + +SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID, + const SCEVUnknown *LHS, + const SCEVConstant *RHS) + : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) {} + +bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const { + const auto *Op = dyn_cast<const SCEVEqualPredicate>(N); + + if (!Op) + return false; + + return Op->LHS == LHS && Op->RHS == RHS; +} + +bool SCEVEqualPredicate::isAlwaysTrue() const { return false; } + +const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; } + +void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const { + OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n"; +} + +/// Union predicates don't get cached so create a dummy set ID for it. +SCEVUnionPredicate::SCEVUnionPredicate() + : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {} + +bool SCEVUnionPredicate::isAlwaysTrue() const { + return all_of(Preds, + [](const SCEVPredicate *I) { return I->isAlwaysTrue(); }); +} + +ArrayRef<const SCEVPredicate *> +SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) { + auto I = SCEVToPreds.find(Expr); + if (I == SCEVToPreds.end()) + return ArrayRef<const SCEVPredicate *>(); + return I->second; +} + +bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const { + if (const auto *Set = dyn_cast<const SCEVUnionPredicate>(N)) + return all_of(Set->Preds, + [this](const SCEVPredicate *I) { return this->implies(I); }); + + auto ScevPredsIt = SCEVToPreds.find(N->getExpr()); + if (ScevPredsIt == SCEVToPreds.end()) + return false; + auto &SCEVPreds = ScevPredsIt->second; + + return any_of(SCEVPreds, + [N](const SCEVPredicate *I) { return I->implies(N); }); +} + +const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; } + +void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const { + for (auto Pred : Preds) + Pred->print(OS, Depth); +} + +void SCEVUnionPredicate::add(const SCEVPredicate *N) { + if (const auto *Set = dyn_cast<const SCEVUnionPredicate>(N)) { + for (auto Pred : Set->Preds) + add(Pred); + return; + } + + if (implies(N)) + return; + + const SCEV *Key = N->getExpr(); + assert(Key && "Only SCEVUnionPredicate doesn't have an " + " associated expression!"); + + SCEVToPreds[Key].push_back(N); + Preds.push_back(N); +} + +PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE) + : SE(SE), Generation(0) {} + +const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) { + const SCEV *Expr = SE.getSCEV(V); + RewriteEntry &Entry = RewriteMap[Expr]; + + // If we already have an entry and the version matches, return it. + if (Entry.second && Generation == Entry.first) + return Entry.second; + + // We found an entry but it's stale. Rewrite the stale entry + // acording to the current predicate. + if (Entry.second) + Expr = Entry.second; + + const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, Preds); + Entry = {Generation, NewSCEV}; + + return NewSCEV; +} + +void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) { + if (Preds.implies(&Pred)) + return; + Preds.add(&Pred); + updateGeneration(); +} + +const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const { + return Preds; +} + +void PredicatedScalarEvolution::updateGeneration() { + // If the generation number wrapped recompute everything. + if (++Generation == 0) { + for (auto &II : RewriteMap) { + const SCEV *Rewritten = II.second.second; + II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, Preds)}; + } + } +} |
