#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_H
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/ConstantRange.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
-#include "llvm/Instructions.h"
-#include "llvm/Function.h"
-#include "llvm/Operator.h"
-#include "llvm/Support/DataTypes.h"
-#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/Allocator.h"
-#include "llvm/Support/ConstantRange.h"
-#include "llvm/ADT/FoldingSet.h"
-#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/DataTypes.h"
#include <map>
namespace llvm {
class APInt;
+ class AssumptionCache;
class Constant;
class ConstantInt;
class DominatorTree;
class Type;
class ScalarEvolution;
- class TargetData;
+ class DataLayout;
class TargetLibraryInfo;
class LLVMContext;
- class Loop;
- class LoopInfo;
class Operator;
- class SCEVUnknown;
class SCEV;
- template<> struct FoldingSetTrait<SCEV>;
+ class SCEVAddRecExpr;
+ class SCEVConstant;
+ class SCEVExpander;
+ class SCEVPredicate;
+ class SCEVUnknown;
+
+ template <> struct FoldingSetTrait<SCEV>;
+ template <> struct FoldingSetTrait<SCEVPredicate>;
- /// SCEV - This class represents an analyzed expression in the program. These
- /// are opaque objects that the client is not allowed to do much with
- /// directly.
+ /// This class represents an analyzed expression in the program. These are
+ /// opaque objects that the client is not allowed to do much with directly.
///
class SCEV : public FoldingSetNode {
friend struct FoldingSetTrait<SCEV>;
- /// FastID - A reference to an Interned FoldingSetNodeID for this node.
- /// The ScalarEvolution's BumpPtrAllocator holds the data.
+ /// A reference to an Interned FoldingSetNodeID for this node. The
+ /// ScalarEvolution's BumpPtrAllocator holds the data.
FoldingSetNodeIDRef FastID;
// The SCEV baseclass this node corresponds to
const unsigned short SCEVType;
protected:
- /// SubclassData - This field is initialized to zero and may be used in
- /// subclasses to store miscellaneous information.
+ /// This field is initialized to zero and may be used in subclasses to store
+ /// miscellaneous information.
unsigned short SubclassData;
private:
- SCEV(const SCEV &); // DO NOT IMPLEMENT
- void operator=(const SCEV &); // DO NOT IMPLEMENT
+ SCEV(const SCEV &) = delete;
+ void operator=(const SCEV &) = delete;
public:
/// NoWrapFlags are bitfield indices into SubclassData.
/// operator. NSW is a misnomer that we use to mean no signed overflow or
/// underflow.
///
- /// AddRec expression may have a no-self-wraparound <NW> property if the
- /// result can never reach the start value. This property is independent of
- /// the actual start value and step direction. Self-wraparound is defined
- /// purely in terms of the recurrence's loop, step size, and
- /// bitwidth. Formally, a recurrence with no self-wraparound satisfies:
- /// abs(step) * max-iteration(loop) <= unsigned-max(bitwidth).
+ /// AddRec expressions may have a no-self-wraparound <NW> property if, in
+ /// the integer domain, abs(step) * max-iteration(loop) <=
+ /// unsigned-max(bitwidth). This means that the recurrence will never reach
+ /// its start value if the step is non-zero. Computing the same value on
+ /// each iteration is not considered wrapping, and recurrences with step = 0
+ /// are trivially <NW>. <NW> is independent of the sign of step and the
+ /// value the add recurrence starts with.
///
/// Note that NUW and NSW are also valid properties of a recurrence, and
/// either implies NW. For convenience, NW will be set for a recurrence
unsigned getSCEVType() const { return SCEVType; }
- /// getType - Return the LLVM type of this SCEV expression.
+ /// Return the LLVM type of this SCEV expression.
///
Type *getType() const;
- /// isZero - Return true if the expression is a constant zero.
+ /// Return true if the expression is a constant zero.
///
bool isZero() const;
- /// isOne - Return true if the expression is a constant one.
+ /// Return true if the expression is a constant one.
///
bool isOne() const;
- /// isAllOnesValue - Return true if the expression is a constant
- /// all-ones value.
+ /// Return true if the expression is a constant all-ones value.
///
bool isAllOnesValue() const;
- /// isNonConstantNegative - Return true if the specified scev is negated,
- /// but not a constant.
+ /// Return true if the specified scev is negated, but not a constant.
bool isNonConstantNegative() const;
- /// print - Print out the internal representation of this scalar to the
- /// specified stream. This should really only be used for debugging
- /// purposes.
+ /// Print out the internal representation of this scalar to the specified
+ /// stream. This should really only be used for debugging purposes.
void print(raw_ostream &OS) const;
- /// dump - This method is used for debugging.
+ /// This method is used for debugging.
///
void dump() const;
};
ID = X.FastID;
}
static bool Equals(const SCEV &X, const FoldingSetNodeID &ID,
- FoldingSetNodeID &TempID) {
+ unsigned IDHash, FoldingSetNodeID &TempID) {
return ID == X.FastID;
}
static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) {
return OS;
}
- /// SCEVCouldNotCompute - An object of this class is returned by queries that
- /// could not be answered. For example, if you ask for the number of
- /// iterations of a linked-list traversal loop, you will get one of these.
- /// None of the standard SCEV operations are valid on this class, it is just a
- /// marker.
+ /// An object of this class is returned by queries that could not be answered.
+ /// For example, if you ask for the number of iterations of a linked-list
+ /// traversal loop, you will get one of these. None of the standard SCEV
+ /// operations are valid on this class, it is just a marker.
struct SCEVCouldNotCompute : public SCEV {
SCEVCouldNotCompute();
/// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVCouldNotCompute *S) { return true; }
static bool classof(const SCEV *S);
};
- /// ScalarEvolution - This class is the main scalar evolution driver. Because
- /// client code (intentionally) can't do much with the SCEV objects directly,
- /// they must ask this class for services.
- ///
- class ScalarEvolution : public FunctionPass {
+ /// SCEVPredicate - This class represents an assumption made using SCEV
+ /// expressions which can be checked at run-time.
+ class SCEVPredicate : public FoldingSetNode {
+ friend struct FoldingSetTrait<SCEVPredicate>;
+
+ /// A reference to an Interned FoldingSetNodeID for this node. The
+ /// ScalarEvolution's BumpPtrAllocator holds the data.
+ FoldingSetNodeIDRef FastID;
+
+ public:
+ enum SCEVPredicateKind { P_Union, P_Equal };
+
+ protected:
+ SCEVPredicateKind Kind;
+ ~SCEVPredicate() = default;
+ SCEVPredicate(const SCEVPredicate&) = default;
+ SCEVPredicate &operator=(const SCEVPredicate&) = default;
+
+ public:
+ SCEVPredicate(const FoldingSetNodeIDRef ID, SCEVPredicateKind Kind);
+
+ SCEVPredicateKind getKind() const { return Kind; }
+
+ /// \brief Returns the estimated complexity of this predicate.
+ /// This is roughly measured in the number of run-time checks required.
+ virtual unsigned getComplexity() const { return 1; }
+
+ /// \brief Returns true if the predicate is always true. This means that no
+ /// assumptions were made and nothing needs to be checked at run-time.
+ virtual bool isAlwaysTrue() const = 0;
+
+ /// \brief Returns true if this predicate implies \p N.
+ virtual bool implies(const SCEVPredicate *N) const = 0;
+
+ /// \brief Prints a textual representation of this predicate with an
+ /// indentation of \p Depth.
+ virtual void print(raw_ostream &OS, unsigned Depth = 0) const = 0;
+
+ /// \brief Returns the SCEV to which this predicate applies, or nullptr
+ /// if this is a SCEVUnionPredicate.
+ virtual const SCEV *getExpr() const = 0;
+ };
+
+ inline raw_ostream &operator<<(raw_ostream &OS, const SCEVPredicate &P) {
+ P.print(OS);
+ return OS;
+ }
+
+ // Specialize FoldingSetTrait for SCEVPredicate to avoid needing to compute
+ // temporary FoldingSetNodeID values.
+ template <>
+ struct FoldingSetTrait<SCEVPredicate>
+ : DefaultFoldingSetTrait<SCEVPredicate> {
+
+ static void Profile(const SCEVPredicate &X, FoldingSetNodeID &ID) {
+ ID = X.FastID;
+ }
+
+ static bool Equals(const SCEVPredicate &X, const FoldingSetNodeID &ID,
+ unsigned IDHash, FoldingSetNodeID &TempID) {
+ return ID == X.FastID;
+ }
+ static unsigned ComputeHash(const SCEVPredicate &X,
+ FoldingSetNodeID &TempID) {
+ return X.FastID.ComputeHash();
+ }
+ };
+
+ /// SCEVEqualPredicate - This class represents an assumption that two SCEV
+ /// expressions are equal, and this can be checked at run-time. We assume
+ /// that the left hand side is a SCEVUnknown and the right hand side a
+ /// constant.
+ class SCEVEqualPredicate final : public SCEVPredicate {
+ /// We assume that LHS == RHS, where LHS is a SCEVUnknown and RHS a
+ /// constant.
+ const SCEVUnknown *LHS;
+ const SCEVConstant *RHS;
+
public:
- /// LoopDisposition - An enum describing the relationship between a
- /// SCEV and a loop.
+ SCEVEqualPredicate(const FoldingSetNodeIDRef ID, const SCEVUnknown *LHS,
+ const SCEVConstant *RHS);
+
+ /// Implementation of the SCEVPredicate interface
+ bool implies(const SCEVPredicate *N) const override;
+ void print(raw_ostream &OS, unsigned Depth = 0) const override;
+ bool isAlwaysTrue() const override;
+ const SCEV *getExpr() const override;
+
+ /// \brief Returns the left hand side of the equality.
+ const SCEVUnknown *getLHS() const { return LHS; }
+
+ /// \brief Returns the right hand side of the equality.
+ const SCEVConstant *getRHS() const { return RHS; }
+
+ /// Methods for support type inquiry through isa, cast, and dyn_cast:
+ static inline bool classof(const SCEVPredicate *P) {
+ return P->getKind() == P_Equal;
+ }
+ };
+
+ /// SCEVUnionPredicate - This class represents a composition of other
+ /// SCEV predicates, and is the class that most clients will interact with.
+ /// This is equivalent to a logical "AND" of all the predicates in the union.
+ class SCEVUnionPredicate final : public SCEVPredicate {
+ private:
+ typedef DenseMap<const SCEV *, SmallVector<const SCEVPredicate *, 4>>
+ PredicateMap;
+
+ /// Vector with references to all predicates in this union.
+ SmallVector<const SCEVPredicate *, 16> Preds;
+ /// Maps SCEVs to predicates for quick look-ups.
+ PredicateMap SCEVToPreds;
+
+ public:
+ SCEVUnionPredicate();
+
+ const SmallVectorImpl<const SCEVPredicate *> &getPredicates() const {
+ return Preds;
+ }
+
+ /// \brief Adds a predicate to this union.
+ void add(const SCEVPredicate *N);
+
+ /// \brief Returns a reference to a vector containing all predicates
+ /// which apply to \p Expr.
+ ArrayRef<const SCEVPredicate *> getPredicatesForExpr(const SCEV *Expr);
+
+ /// Implementation of the SCEVPredicate interface
+ bool isAlwaysTrue() const override;
+ bool implies(const SCEVPredicate *N) const override;
+ void print(raw_ostream &OS, unsigned Depth) const override;
+ const SCEV *getExpr() const override;
+
+ /// \brief We estimate the complexity of a union predicate as the size
+ /// number of predicates in the union.
+ unsigned getComplexity() const override { return Preds.size(); }
+
+ /// Methods for support type inquiry through isa, cast, and dyn_cast:
+ static inline bool classof(const SCEVPredicate *P) {
+ return P->getKind() == P_Union;
+ }
+ };
+
+ /// The main scalar evolution driver. Because client code (intentionally)
+ /// can't do much with the SCEV objects directly, they must ask this class
+ /// for services.
+ class ScalarEvolution {
+ public:
+ /// An enum describing the relationship between a SCEV and a loop.
enum LoopDisposition {
LoopVariant, ///< The SCEV is loop-variant (unknown).
LoopInvariant, ///< The SCEV is loop-invariant.
LoopComputable ///< The SCEV varies predictably with the loop.
};
- /// BlockDisposition - An enum describing the relationship between a
- /// SCEV and a basic block.
+ /// An enum describing the relationship between a SCEV and a basic block.
enum BlockDisposition {
DoesNotDominateBlock, ///< The SCEV does not dominate the block.
DominatesBlock, ///< The SCEV dominates the block.
/// Convenient NoWrapFlags manipulation that hides enum casts and is
/// visible in the ScalarEvolution name space.
- static SCEV::NoWrapFlags maskFlags(SCEV::NoWrapFlags Flags, int Mask) {
+ static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
+ maskFlags(SCEV::NoWrapFlags Flags, int Mask) {
return (SCEV::NoWrapFlags)(Flags & Mask);
}
- static SCEV::NoWrapFlags setFlags(SCEV::NoWrapFlags Flags,
- SCEV::NoWrapFlags OnFlags) {
+ static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
+ setFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OnFlags) {
return (SCEV::NoWrapFlags)(Flags | OnFlags);
}
- static SCEV::NoWrapFlags clearFlags(SCEV::NoWrapFlags Flags,
- SCEV::NoWrapFlags OffFlags) {
+ static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
+ clearFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OffFlags) {
return (SCEV::NoWrapFlags)(Flags & ~OffFlags);
}
private:
- /// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
- /// notified whenever a Value is deleted.
- class SCEVCallbackVH : public CallbackVH {
+ /// A CallbackVH to arrange for ScalarEvolution to be notified whenever a
+ /// Value is deleted.
+ class SCEVCallbackVH final : public CallbackVH {
ScalarEvolution *SE;
- virtual void deleted();
- virtual void allUsesReplacedWith(Value *New);
+ void deleted() override;
+ void allUsesReplacedWith(Value *New) override;
public:
- SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
+ SCEVCallbackVH(Value *V, ScalarEvolution *SE = nullptr);
};
friend class SCEVCallbackVH;
friend class SCEVExpander;
friend class SCEVUnknown;
- /// F - The function we are analyzing.
+ /// The function we are analyzing.
///
- Function *F;
+ Function &F;
- /// LI - The loop information for the function we are currently analyzing.
+ /// The target library information for the target we are targeting.
///
- LoopInfo *LI;
+ TargetLibraryInfo &TLI;
- /// TD - The target data information for the target we are targeting.
- ///
- TargetData *TD;
+ /// The tracker for @llvm.assume intrinsics in this function.
+ AssumptionCache &AC;
- /// TLI - The target library information for the target we are targeting.
+ /// The dominator tree.
///
- TargetLibraryInfo *TLI;
+ DominatorTree &DT;
- /// DT - The dominator tree.
+ /// The loop information for the function we are currently analyzing.
///
- DominatorTree *DT;
+ LoopInfo &LI;
- /// CouldNotCompute - This SCEV is used to represent unknown trip
- /// counts and things.
- SCEVCouldNotCompute CouldNotCompute;
+ /// This SCEV is used to represent unknown trip counts and things.
+ std::unique_ptr<SCEVCouldNotCompute> CouldNotCompute;
- /// ValueExprMapType - The typedef for ValueExprMap.
+ /// The typedef for ValueExprMap.
///
typedef DenseMap<SCEVCallbackVH, const SCEV *, DenseMapInfo<Value *> >
ValueExprMapType;
- /// ValueExprMap - This is a cache of the values we have analyzed so far.
+ /// This is a cache of the values we have analyzed so far.
///
ValueExprMapType ValueExprMap;
- /// ExitLimit - Information about the number of loop iterations for
- /// which a loop exit's branch condition evaluates to the not-taken path.
- /// This is a temporary pair of exact and max expressions that are
- /// eventually summarized in ExitNotTakenInfo and BackedgeTakenInfo.
+ /// Mark predicate values currently being processed by isImpliedCond.
+ DenseSet<Value*> PendingLoopPredicates;
+
+ /// Set to true by isLoopBackedgeGuardedByCond when we're walking the set of
+ /// conditions dominating the backedge of a loop.
+ bool WalkingBEDominatingConds;
+
+ /// Set to true by isKnownPredicateViaSplitting when we're trying to prove a
+ /// predicate by splitting it into a set of independent predicates.
+ bool ProvingSplitPredicate;
+
+ /// Information about the number of loop iterations for which a loop exit's
+ /// branch condition evaluates to the not-taken path. This is a temporary
+ /// pair of exact and max expressions that are eventually summarized in
+ /// ExitNotTakenInfo and BackedgeTakenInfo.
struct ExitLimit {
const SCEV *Exact;
const SCEV *Max;
/*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {}
- ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {}
+ ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {
+ assert((isa<SCEVCouldNotCompute>(Exact) ||
+ !isa<SCEVCouldNotCompute>(Max)) &&
+ "Exact is not allowed to be less precise than Max");
+ }
- /// hasAnyInfo - Test whether this ExitLimit contains any computed
- /// information, or whether it's all SCEVCouldNotCompute values.
+ /// Test whether this ExitLimit contains any computed information, or
+ /// whether it's all SCEVCouldNotCompute values.
bool hasAnyInfo() const {
return !isa<SCEVCouldNotCompute>(Exact) ||
!isa<SCEVCouldNotCompute>(Max);
}
};
- /// ExitNotTakenInfo - Information about the number of times a particular
- /// loop exit may be reached before exiting the loop.
+ /// Information about the number of times a particular loop exit may be
+ /// reached before exiting the loop.
struct ExitNotTakenInfo {
AssertingVH<BasicBlock> ExitingBlock;
const SCEV *ExactNotTaken;
PointerIntPair<ExitNotTakenInfo*, 1> NextExit;
- ExitNotTakenInfo() : ExitingBlock(0), ExactNotTaken(0) {}
+ ExitNotTakenInfo() : ExitingBlock(nullptr), ExactNotTaken(nullptr) {}
- /// isCompleteList - Return true if all loop exits are computable.
+ /// Return true if all loop exits are computable.
bool isCompleteList() const {
return NextExit.getInt() == 0;
}
void setIncomplete() { NextExit.setInt(1); }
- /// getNextExit - Return a pointer to the next exit's not-taken info.
+ /// Return a pointer to the next exit's not-taken info.
ExitNotTakenInfo *getNextExit() const {
return NextExit.getPointer();
}
void setNextExit(ExitNotTakenInfo *ENT) { NextExit.setPointer(ENT); }
};
- /// BackedgeTakenInfo - Information about the backedge-taken count
- /// of a loop. This currently includes an exact count and a maximum count.
+ /// Information about the backedge-taken count of a loop. This currently
+ /// includes an exact count and a maximum count.
///
class BackedgeTakenInfo {
- /// ExitNotTaken - A list of computable exits and their not-taken counts.
- /// Loops almost never have more than one computable exit.
+ /// A list of computable exits and their not-taken counts. Loops almost
+ /// never have more than one computable exit.
ExitNotTakenInfo ExitNotTaken;
- /// Max - An expression indicating the least maximum backedge-taken
- /// count of the loop that is known, or a SCEVCouldNotCompute.
+ /// An expression indicating the least maximum backedge-taken count of the
+ /// loop that is known, or a SCEVCouldNotCompute.
const SCEV *Max;
public:
- BackedgeTakenInfo() : Max(0) {}
+ BackedgeTakenInfo() : Max(nullptr) {}
/// Initialize BackedgeTakenInfo from a list of exact exit counts.
BackedgeTakenInfo(
SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts,
bool Complete, const SCEV *MaxCount);
- /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
- /// computed information, or whether it's all SCEVCouldNotCompute
- /// values.
+ /// Test whether this BackedgeTakenInfo contains any computed information,
+ /// or whether it's all SCEVCouldNotCompute values.
bool hasAnyInfo() const {
return ExitNotTaken.ExitingBlock || !isa<SCEVCouldNotCompute>(Max);
}
- /// getExact - Return an expression indicating the exact backedge-taken
- /// count of the loop if it is known, or SCEVCouldNotCompute
- /// otherwise. This is the number of times the loop header can be
- /// guaranteed to execute, minus one.
+ /// Return an expression indicating the exact backedge-taken count of the
+ /// loop if it is known, or SCEVCouldNotCompute otherwise. This is the
+ /// number of times the loop header can be guaranteed to execute, minus
+ /// one.
const SCEV *getExact(ScalarEvolution *SE) const;
- /// getExact - Return the number of times this loop exit may fall through
- /// to the back edge, or SCEVCouldNotCompute. The loop is guaranteed not
- /// to exit via this block before this number of iterations, but may exit
- /// via another block.
+ /// Return the number of times this loop exit may fall through to the back
+ /// edge, or SCEVCouldNotCompute. The loop is guaranteed not to exit via
+ /// this block before this number of iterations, but may exit via another
+ /// block.
const SCEV *getExact(BasicBlock *ExitingBlock, ScalarEvolution *SE) const;
- /// getMax - Get the max backedge taken count for the loop.
+ /// Get the max backedge taken count for the loop.
const SCEV *getMax(ScalarEvolution *SE) const;
- /// clear - Invalidate this result and free associated memory.
+ /// Return true if any backedge taken count expressions refer to the given
+ /// subexpression.
+ bool hasOperand(const SCEV *S, ScalarEvolution *SE) const;
+
+ /// Invalidate this result and free associated memory.
void clear();
};
- /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
- /// this function as they are computed.
+ /// Cache the backedge-taken count of the loops for this function as they
+ /// are computed.
DenseMap<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
- /// ConstantEvolutionLoopExitValue - This map contains entries for all of
- /// the PHI instructions that we attempt to compute constant evolutions for.
- /// This allows us to avoid potentially expensive recomputation of these
- /// properties. An instruction maps to null if we are unable to compute its
- /// exit value.
+ /// This map contains entries for all of the PHI instructions that we
+ /// attempt to compute constant evolutions for. This allows us to avoid
+ /// potentially expensive recomputation of these properties. An instruction
+ /// maps to null if we are unable to compute its exit value.
DenseMap<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
- /// ValuesAtScopes - This map contains entries for all the expressions
- /// that we attempt to compute getSCEVAtScope information for, which can
- /// be expensive in extreme cases.
+ /// This map contains entries for all the expressions that we attempt to
+ /// compute getSCEVAtScope information for, which can be expensive in
+ /// extreme cases.
DenseMap<const SCEV *,
- std::map<const Loop *, const SCEV *> > ValuesAtScopes;
+ SmallVector<std::pair<const Loop *, const SCEV *>, 2> > ValuesAtScopes;
- /// LoopDispositions - Memoized computeLoopDisposition results.
+ /// Memoized computeLoopDisposition results.
DenseMap<const SCEV *,
- std::map<const Loop *, LoopDisposition> > LoopDispositions;
+ SmallVector<PointerIntPair<const Loop *, 2, LoopDisposition>, 2>>
+ LoopDispositions;
- /// computeLoopDisposition - Compute a LoopDisposition value.
+ /// Compute a LoopDisposition value.
LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L);
- /// BlockDispositions - Memoized computeBlockDisposition results.
- DenseMap<const SCEV *,
- std::map<const BasicBlock *, BlockDisposition> > BlockDispositions;
+ /// Memoized computeBlockDisposition results.
+ DenseMap<
+ const SCEV *,
+ SmallVector<PointerIntPair<const BasicBlock *, 2, BlockDisposition>, 2>>
+ BlockDispositions;
- /// computeBlockDisposition - Compute a BlockDisposition value.
+ /// Compute a BlockDisposition value.
BlockDisposition computeBlockDisposition(const SCEV *S, const BasicBlock *BB);
- /// UnsignedRanges - Memoized results from getUnsignedRange
+ /// Memoized results from getRange
DenseMap<const SCEV *, ConstantRange> UnsignedRanges;
- /// SignedRanges - Memoized results from getSignedRange
+ /// Memoized results from getRange
DenseMap<const SCEV *, ConstantRange> SignedRanges;
- /// setUnsignedRange - Set the memoized unsigned range for the given SCEV.
- const ConstantRange &setUnsignedRange(const SCEV *S,
- const ConstantRange &CR) {
- std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
- UnsignedRanges.insert(std::make_pair(S, CR));
- if (!Pair.second)
- Pair.first->second = CR;
- return Pair.first->second;
- }
+ /// Used to parameterize getRange
+ enum RangeSignHint { HINT_RANGE_UNSIGNED, HINT_RANGE_SIGNED };
+
+ /// Set the memoized range for the given SCEV.
+ const ConstantRange &setRange(const SCEV *S, RangeSignHint Hint,
+ const ConstantRange &CR) {
+ DenseMap<const SCEV *, ConstantRange> &Cache =
+ Hint == HINT_RANGE_UNSIGNED ? UnsignedRanges : SignedRanges;
- /// setUnsignedRange - Set the memoized signed range for the given SCEV.
- const ConstantRange &setSignedRange(const SCEV *S,
- const ConstantRange &CR) {
std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
- SignedRanges.insert(std::make_pair(S, CR));
+ Cache.insert(std::make_pair(S, CR));
if (!Pair.second)
Pair.first->second = CR;
return Pair.first->second;
}
- /// createSCEV - We know that there is no SCEV for the specified value.
- /// Analyze the expression.
+ /// Determine the range for a particular SCEV.
+ ConstantRange getRange(const SCEV *S, RangeSignHint Hint);
+
+ /// We know that there is no SCEV for the specified value. Analyze the
+ /// expression.
const SCEV *createSCEV(Value *V);
- /// createNodeForPHI - Provide the special handling we need to analyze PHI
- /// SCEVs.
+ /// Provide the special handling we need to analyze PHI SCEVs.
const SCEV *createNodeForPHI(PHINode *PN);
- /// createNodeForGEP - Provide the special handling we need to analyze GEP
- /// SCEVs.
+ /// Helper function called from createNodeForPHI.
+ const SCEV *createAddRecFromPHI(PHINode *PN);
+
+ /// Helper function called from createNodeForPHI.
+ const SCEV *createNodeFromSelectLikePHI(PHINode *PN);
+
+ /// Provide special handling for a select-like instruction (currently this
+ /// is either a select instruction or a phi node). \p I is the instruction
+ /// being processed, and it is assumed equivalent to "Cond ? TrueVal :
+ /// FalseVal".
+ const SCEV *createNodeForSelectOrPHI(Instruction *I, Value *Cond,
+ Value *TrueVal, Value *FalseVal);
+
+ /// Provide the special handling we need to analyze GEP SCEVs.
const SCEV *createNodeForGEP(GEPOperator *GEP);
- /// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
- /// at most once for each SCEV+Loop pair.
+ /// Implementation code for getSCEVAtScope; called at most once for each
+ /// SCEV+Loop pair.
///
const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
- /// ForgetSymbolicValue - This looks up computed SCEV values for all
- /// instructions that depend on the given instruction and removes them from
- /// the ValueExprMap map if they reference SymName. This is used during PHI
- /// resolution.
+ /// This looks up computed SCEV values for all instructions that depend on
+ /// the given instruction and removes them from the ValueExprMap map if they
+ /// reference SymName. This is used during PHI resolution.
void ForgetSymbolicName(Instruction *I, const SCEV *SymName);
- /// getBECount - Subtract the end and start values and divide by the step,
- /// rounding up, to get the number of times the backedge is executed. Return
- /// CouldNotCompute if an intermediate computation overflows.
- const SCEV *getBECount(const SCEV *Start,
- const SCEV *End,
- const SCEV *Step,
- bool NoWrap);
-
- /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given
- /// loop, lazily computing new values if the loop hasn't been analyzed
- /// yet.
+ /// Return the BackedgeTakenInfo for the given loop, lazily computing new
+ /// values if the loop hasn't been analyzed yet.
const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L);
- /// ComputeBackedgeTakenCount - Compute the number of times the specified
- /// loop will iterate.
- BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
+ /// Compute the number of times the specified loop will iterate.
+ BackedgeTakenInfo computeBackedgeTakenCount(const Loop *L);
- /// ComputeExitLimit - Compute the number of times the backedge of the
- /// specified loop will execute if it exits via the specified block.
- ExitLimit ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock);
+ /// Compute the number of times the backedge of the specified loop will
+ /// execute if it exits via the specified block.
+ ExitLimit computeExitLimit(const Loop *L, BasicBlock *ExitingBlock);
- /// 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.
- ExitLimit ComputeExitLimitFromCond(const Loop *L,
+ /// 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.
+ ExitLimit computeExitLimitFromCond(const Loop *L,
Value *ExitCond,
BasicBlock *TBB,
- BasicBlock *FBB);
+ BasicBlock *FBB,
+ bool IsSubExpr);
- /// 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.
- ExitLimit ComputeExitLimitFromICmp(const Loop *L,
+ /// 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.
+ ExitLimit computeExitLimitFromICmp(const Loop *L,
ICmpInst *ExitCond,
BasicBlock *TBB,
- BasicBlock *FBB);
-
- /// ComputeLoadConstantCompareExitLimit - Given an exit condition
- /// of 'icmp op load X, cst', try to see if we can compute the
- /// backedge-taken count.
- ExitLimit ComputeLoadConstantCompareExitLimit(LoadInst *LI,
+ BasicBlock *FBB,
+ bool IsSubExpr);
+
+ /// Compute the number of times the backedge of the specified loop will
+ /// execute if its exit condition were a switch with a single exiting case
+ /// to ExitingBB.
+ ExitLimit
+ computeExitLimitFromSingleExitSwitch(const Loop *L, SwitchInst *Switch,
+ BasicBlock *ExitingBB, bool IsSubExpr);
+
+ /// Given an exit condition of 'icmp op load X, cst', try to see if we can
+ /// compute the backedge-taken count.
+ ExitLimit computeLoadConstantCompareExitLimit(LoadInst *LI,
Constant *RHS,
const Loop *L,
ICmpInst::Predicate p);
- /// 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 exit count of the loop, return CouldNotCompute.
- const SCEV *ComputeExitCountExhaustively(const Loop *L,
+ /// Compute the exit limit of a loop that is controlled by a
+ /// "(IV >> 1) != 0" type comparison. We cannot compute the exact trip
+ /// count in these cases (since SCEV has no way of expressing them), but we
+ /// can still sometimes compute an upper bound.
+ ///
+ /// Return an ExitLimit for a loop whose backedge is guarded by `LHS Pred
+ /// RHS`.
+ ExitLimit computeShiftCompareExitLimit(Value *LHS, Value *RHS,
+ const Loop *L,
+ ICmpInst::Predicate Pred);
+
+ /// 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 exit count of the loop,
+ /// return CouldNotCompute.
+ const SCEV *computeExitCountExhaustively(const Loop *L,
Value *Cond,
bool ExitWhen);
- /// HowFarToZero - Return the number of times an exit condition comparing
- /// the specified value to zero will execute. If not computable, return
- /// CouldNotCompute.
- ExitLimit HowFarToZero(const SCEV *V, const Loop *L);
+ /// Return the number of times an exit condition comparing the specified
+ /// value to zero will execute. If not computable, return CouldNotCompute.
+ ExitLimit HowFarToZero(const SCEV *V, const Loop *L, bool IsSubExpr);
- /// HowFarToNonZero - Return the number of times an exit condition checking
- /// the specified value for nonzero will execute. If not computable, return
+ /// Return the number of times an exit condition checking the specified
+ /// value for nonzero will execute. If not computable, return
/// CouldNotCompute.
ExitLimit HowFarToNonZero(const SCEV *V, const Loop *L);
- /// HowManyLessThans - Return the number of times an exit condition
- /// containing the specified less-than comparison will execute. If not
- /// computable, return CouldNotCompute. isSigned specifies whether the
- /// less-than is signed.
+ /// Return the number of times an exit condition containing the specified
+ /// less-than comparison will execute. If not computable, return
+ /// CouldNotCompute. isSigned specifies whether the less-than is signed.
ExitLimit HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
- const Loop *L, bool isSigned);
+ const Loop *L, bool isSigned, bool IsSubExpr);
+ ExitLimit HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
+ const Loop *L, bool isSigned, bool IsSubExpr);
- /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
- /// (which may not be an immediate predecessor) which has exactly one
- /// successor from which BB is reachable, or null if no such block is
- /// found.
+ /// Return a predecessor of BB (which may not be an immediate predecessor)
+ /// which has exactly one successor from which BB is reachable, or null if
+ /// no such block is found.
std::pair<BasicBlock *, BasicBlock *>
getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
- /// isImpliedCond - Test whether the condition described by Pred, LHS, and
- /// RHS is true whenever the given FoundCondValue value evaluates to true.
+ /// Test whether the condition described by Pred, LHS, and RHS is true
+ /// whenever the given FoundCondValue value evaluates to true.
bool isImpliedCond(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
Value *FoundCondValue,
bool Inverse);
- /// isImpliedCondOperands - Test whether the condition described by Pred,
- /// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
- /// and FoundRHS is true.
+ /// Test whether the condition described by Pred, LHS, and RHS is true
+ /// whenever the condition described by FoundPred, FoundLHS, FoundRHS is
+ /// true.
+ bool isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
+ const SCEV *RHS, ICmpInst::Predicate FoundPred,
+ const SCEV *FoundLHS, const SCEV *FoundRHS);
+
+ /// Test whether the condition described by Pred, LHS, and RHS is true
+ /// whenever the condition described by Pred, FoundLHS, and FoundRHS is
+ /// true.
bool isImpliedCondOperands(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
const SCEV *FoundLHS, const SCEV *FoundRHS);
- /// isImpliedCondOperandsHelper - Test whether the condition described by
- /// Pred, LHS, and RHS is true whenever the condition described by Pred,
- /// FoundLHS, and FoundRHS is true.
+ /// Test whether the condition described by Pred, LHS, and RHS is true
+ /// whenever the condition described by Pred, FoundLHS, and FoundRHS is
+ /// true.
bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
const SCEV *FoundLHS,
const SCEV *FoundRHS);
- /// 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
- /// involving constants, fold it.
+ /// Test whether the condition described by Pred, LHS, and RHS is true
+ /// whenever the condition described by Pred, FoundLHS, and FoundRHS is
+ /// true. Utility function used by isImpliedCondOperands.
+ bool isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS,
+ const SCEV *FoundLHS,
+ const SCEV *FoundRHS);
+
+ /// Test whether the condition described by Pred, LHS, and RHS is true
+ /// whenever the condition described by Pred, FoundLHS, and FoundRHS is
+ /// true.
+ ///
+ /// This routine tries to rule out certain kinds of integer overflow, and
+ /// then tries to reason about arithmetic properties of the predicates.
+ bool isImpliedCondOperandsViaNoOverflow(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS,
+ const SCEV *FoundLHS,
+ const SCEV *FoundRHS);
+
+ /// 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 involving constants, fold it.
Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
const Loop *L);
- /// isKnownPredicateWithRanges - Test if the given expression is known to
- /// satisfy the condition described by Pred and the known constant ranges
- /// of LHS and RHS.
+ /// Test if the given expression is known to satisfy the condition described
+ /// by Pred and the known constant ranges of LHS and RHS.
///
bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
- /// forgetMemoizedResults - Drop memoized information computed for S.
+ /// Try to prove the condition described by "LHS Pred RHS" by ruling out
+ /// integer overflow.
+ ///
+ /// For instance, this will return true for "A s< (A + C)<nsw>" if C is
+ /// positive.
+ bool isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS);
+
+ /// Try to split Pred LHS RHS into logical conjunctions (and's) and try to
+ /// prove them individually.
+ bool isKnownPredicateViaSplitting(ICmpInst::Predicate Pred, const SCEV *LHS,
+ const SCEV *RHS);
+
+ /// Try to match the Expr as "(L + R)<Flags>".
+ bool splitBinaryAdd(const SCEV *Expr, const SCEV *&L, const SCEV *&R,
+ SCEV::NoWrapFlags &Flags);
+
+ /// Return true if More == (Less + C), where C is a constant. This is
+ /// intended to be used as a cheaper substitute for full SCEV subtraction.
+ bool computeConstantDifference(const SCEV *Less, const SCEV *More,
+ APInt &C);
+
+ /// Drop memoized information computed for S.
void forgetMemoizedResults(const SCEV *S);
+ /// Return an existing SCEV for V if there is one, otherwise return nullptr.
+ const SCEV *getExistingSCEV(Value *V);
+
+ /// Return false iff given SCEV contains a SCEVUnknown with NULL value-
+ /// pointer.
+ bool checkValidity(const SCEV *S) const;
+
+ /// Return true if `ExtendOpTy`({`Start`,+,`Step`}) can be proved to be
+ /// equal to {`ExtendOpTy`(`Start`),+,`ExtendOpTy`(`Step`)}. This is
+ /// equivalent to proving no signed (resp. unsigned) wrap in
+ /// {`Start`,+,`Step`} if `ExtendOpTy` is `SCEVSignExtendExpr`
+ /// (resp. `SCEVZeroExtendExpr`).
+ ///
+ template<typename ExtendOpTy>
+ bool proveNoWrapByVaryingStart(const SCEV *Start, const SCEV *Step,
+ const Loop *L);
+
+ bool isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
+ ICmpInst::Predicate Pred, bool &Increasing);
+
+ /// Return true if, for all loop invariant X, the predicate "LHS `Pred` X"
+ /// is monotonically increasing or decreasing. In the former case set
+ /// `Increasing` to true and in the latter case set `Increasing` to false.
+ ///
+ /// A predicate is said to be monotonically increasing if may go from being
+ /// false to being true as the loop iterates, but never the other way
+ /// around. A predicate is said to be monotonically decreasing if may go
+ /// from being true to being false as the loop iterates, but never the other
+ /// way around.
+ bool isMonotonicPredicate(const SCEVAddRecExpr *LHS,
+ ICmpInst::Predicate Pred, bool &Increasing);
+
+ // Return SCEV no-wrap flags that can be proven based on reasoning
+ // about how poison produced from no-wrap flags on this value
+ // (e.g. a nuw add) would trigger undefined behavior on overflow.
+ SCEV::NoWrapFlags getNoWrapFlagsFromUB(const Value *V);
+
public:
- static char ID; // Pass identification, replacement for typeid
- ScalarEvolution();
+ ScalarEvolution(Function &F, TargetLibraryInfo &TLI, AssumptionCache &AC,
+ DominatorTree &DT, LoopInfo &LI);
+ ~ScalarEvolution();
+ ScalarEvolution(ScalarEvolution &&Arg);
- LLVMContext &getContext() const { return F->getContext(); }
+ LLVMContext &getContext() const { return F.getContext(); }
- /// isSCEVable - Test if values of the given type are analyzable within
- /// the SCEV framework. This primarily includes integer types, and it
- /// can optionally include pointer types if the ScalarEvolution class
- /// has access to target-specific information.
+ /// Test if values of the given type are analyzable within the SCEV
+ /// framework. This primarily includes integer types, and it can optionally
+ /// include pointer types if the ScalarEvolution class has access to
+ /// target-specific information.
bool isSCEVable(Type *Ty) const;
- /// getTypeSizeInBits - Return the size in bits of the specified type,
- /// for which isSCEVable must return true.
+ /// Return the size in bits of the specified type, for which isSCEVable must
+ /// return true.
uint64_t getTypeSizeInBits(Type *Ty) const;
- /// getEffectiveSCEVType - Return a type with the same bitwidth as
- /// the given type and which represents how SCEV will treat the given
- /// type, for which isSCEVable must return true. For pointer types,
- /// this is the pointer-sized integer type.
+ /// Return a type with the same bitwidth as the given type and which
+ /// represents how SCEV will treat the given type, for which isSCEVable must
+ /// return true. For pointer types, this is the pointer-sized integer type.
Type *getEffectiveSCEVType(Type *Ty) const;
- /// getSCEV - Return a SCEV expression for the full generality of the
- /// specified expression.
+ /// Return a SCEV expression for the full generality of the specified
+ /// expression.
const SCEV *getSCEV(Value *V);
const SCEV *getConstant(ConstantInt *V);
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
- SmallVector<const SCEV *, 2> Ops;
- Ops.push_back(LHS);
- Ops.push_back(RHS);
+ SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
return getAddExpr(Ops, Flags);
}
const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2,
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
- SmallVector<const SCEV *, 3> Ops;
- Ops.push_back(Op0);
- Ops.push_back(Op1);
- Ops.push_back(Op2);
+ SmallVector<const SCEV *, 3> Ops = {Op0, Op1, Op2};
return getAddExpr(Ops, Flags);
}
const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
- SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap)
- {
- SmallVector<const SCEV *, 2> Ops;
- Ops.push_back(LHS);
- Ops.push_back(RHS);
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
+ SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
return getMulExpr(Ops, Flags);
}
const SCEV *getMulExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2,
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
- SmallVector<const SCEV *, 3> Ops;
- Ops.push_back(Op0);
- Ops.push_back(Op1);
- Ops.push_back(Op2);
+ SmallVector<const SCEV *, 3> Ops = {Op0, Op1, Op2};
return getMulExpr(Ops, Flags);
}
const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
+ const SCEV *getUDivExactExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
const Loop *L, SCEV::NoWrapFlags Flags);
const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
return getAddRecExpr(NewOp, L, Flags);
}
+ /// \brief Returns an expression for a GEP
+ ///
+ /// \p PointeeType The type used as the basis for the pointer arithmetics
+ /// \p BaseExpr The expression for the pointer operand.
+ /// \p IndexExprs The expressions for the indices.
+ /// \p InBounds Whether the GEP is in bounds.
+ const SCEV *getGEPExpr(Type *PointeeType, const SCEV *BaseExpr,
+ const SmallVectorImpl<const SCEV *> &IndexExprs,
+ bool InBounds = false);
const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getUnknown(Value *V);
const SCEV *getCouldNotCompute();
- /// getSizeOfExpr - Return an expression for sizeof on the given type.
- ///
- const SCEV *getSizeOfExpr(Type *AllocTy);
+ /// \brief Return a SCEV for the constant 0 of a specific type.
+ const SCEV *getZero(Type *Ty) { return getConstant(Ty, 0); }
- /// getAlignOfExpr - Return an expression for alignof on the given type.
- ///
- const SCEV *getAlignOfExpr(Type *AllocTy);
+ /// \brief Return a SCEV for the constant 1 of a specific type.
+ const SCEV *getOne(Type *Ty) { return getConstant(Ty, 1); }
- /// getOffsetOfExpr - Return an expression for offsetof on the given field.
+ /// Return an expression for sizeof AllocTy that is type IntTy
///
- const SCEV *getOffsetOfExpr(StructType *STy, unsigned FieldNo);
+ const SCEV *getSizeOfExpr(Type *IntTy, Type *AllocTy);
- /// getOffsetOfExpr - Return an expression for offsetof on the given field.
+ /// Return an expression for offsetof on the given field with type IntTy
///
- const SCEV *getOffsetOfExpr(Type *CTy, Constant *FieldNo);
+ const SCEV *getOffsetOfExpr(Type *IntTy, StructType *STy, unsigned FieldNo);
- /// getNegativeSCEV - Return the SCEV object corresponding to -V.
+ /// Return the SCEV object corresponding to -V.
///
- const SCEV *getNegativeSCEV(const SCEV *V);
+ const SCEV *getNegativeSCEV(const SCEV *V,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
- /// getNotSCEV - Return the SCEV object corresponding to ~V.
+ /// Return the SCEV object corresponding to ~V.
///
const SCEV *getNotSCEV(const SCEV *V);
- /// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1.
+ /// Return LHS-RHS. Minus is represented in SCEV as A+B*-1.
const SCEV *getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
- /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
- /// of the input value to the specified type. If the type must be
- /// extended, it is zero extended.
+ /// Return a SCEV corresponding to a conversion of the input value to the
+ /// specified type. If the type must be extended, it is zero extended.
const SCEV *getTruncateOrZeroExtend(const SCEV *V, Type *Ty);
- /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
- /// of the input value to the specified type. If the type must be
- /// extended, it is sign extended.
+ /// Return a SCEV corresponding to a conversion of the input value to the
+ /// specified type. If the type must be extended, it is sign extended.
const SCEV *getTruncateOrSignExtend(const SCEV *V, Type *Ty);
- /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
- /// the input value to the specified type. If the type must be extended,
- /// it is zero extended. The conversion must not be narrowing.
+ /// Return a SCEV corresponding to a conversion of the input value to the
+ /// specified type. If the type must be extended, it is zero extended. The
+ /// conversion must not be narrowing.
const SCEV *getNoopOrZeroExtend(const SCEV *V, Type *Ty);
- /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
- /// the input value to the specified type. If the type must be extended,
- /// it is sign extended. The conversion must not be narrowing.
+ /// Return a SCEV corresponding to a conversion of the input value to the
+ /// specified type. If the type must be extended, it is sign extended. The
+ /// conversion must not be narrowing.
const SCEV *getNoopOrSignExtend(const SCEV *V, Type *Ty);
- /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
- /// the input value to the specified type. If the type must be extended,
- /// it is extended with unspecified bits. The conversion must not be
- /// narrowing.
+ /// Return a SCEV corresponding to a conversion of the input value to the
+ /// specified type. If the type must be extended, it is extended with
+ /// unspecified bits. The conversion must not be narrowing.
const SCEV *getNoopOrAnyExtend(const SCEV *V, Type *Ty);
- /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
- /// input value to the specified type. The conversion must not be
- /// widening.
+ /// Return a SCEV corresponding to a conversion of the input value to the
+ /// specified type. The conversion must not be widening.
const SCEV *getTruncateOrNoop(const SCEV *V, Type *Ty);
- /// getUMaxFromMismatchedTypes - Promote the operands to the wider of
- /// the types using zero-extension, and then perform a umax operation
- /// with them.
+ /// Promote the operands to the wider of the types using zero-extension, and
+ /// then perform a umax operation with them.
const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
const SCEV *RHS);
- /// getUMinFromMismatchedTypes - Promote the operands to the wider of
- /// the types using zero-extension, and then perform a umin operation
- /// with them.
+ /// Promote the operands to the wider of the types using zero-extension, and
+ /// then perform a umin operation with them.
const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
const SCEV *RHS);
- /// getPointerBase - Transitively follow the chain of pointer-type operands
- /// until reaching a SCEV that does not have a single pointer operand. This
- /// returns a SCEVUnknown pointer for well-formed pointer-type expressions,
- /// but corner cases do exist.
+ /// Transitively follow the chain of pointer-type operands until reaching a
+ /// SCEV that does not have a single pointer operand. This returns a
+ /// SCEVUnknown pointer for well-formed pointer-type expressions, but corner
+ /// cases do exist.
const SCEV *getPointerBase(const SCEV *V);
- /// getSCEVAtScope - Return a SCEV expression for the specified value
- /// at the specified scope in the program. The L value specifies a loop
- /// nest to evaluate the expression at, where null is the top-level or a
- /// specified loop is immediately inside of the loop.
+ /// Return a SCEV expression for the specified value at the specified scope
+ /// in the program. The L value specifies a loop nest to evaluate the
+ /// expression at, where null is the top-level or a specified loop is
+ /// immediately inside of the loop.
///
/// This method can be used to compute the exit value for a variable defined
/// in a loop by querying what the value will hold in the parent loop.
/// original value V is returned.
const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
- /// getSCEVAtScope - This is a convenience function which does
- /// getSCEVAtScope(getSCEV(V), L).
+ /// This is a convenience function which does getSCEVAtScope(getSCEV(V), L).
const SCEV *getSCEVAtScope(Value *V, const Loop *L);
- /// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
- /// by a conditional between LHS and RHS. This is used to help avoid max
- /// expressions in loop trip counts, and to eliminate casts.
+ /// Test whether entry to the loop is protected by a conditional between LHS
+ /// and RHS. This is used to help avoid max expressions in loop trip
+ /// counts, and to eliminate casts.
bool isLoopEntryGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *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.
+ /// Test whether the backedge of the loop is protected by a conditional
+ /// between LHS and RHS. This is used to to eliminate casts.
bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
- /// getSmallConstantTripCount - Returns the maximum trip count of this loop
- /// as a normal unsigned value. Returns 0 if the trip count is unknown or
- /// not constant. This "trip count" assumes that control exits via
- /// ExitingBlock. More precisely, it is the number of times that control may
- /// reach ExitingBlock before taking the branch. For loops with multiple
- /// exits, it may not be the number times that the loop header executes if
- /// the loop exits prematurely via another branch.
+ /// \brief Returns the maximum trip count of the loop if it is a single-exit
+ /// loop and we can compute a small maximum for that loop.
+ ///
+ /// Implemented in terms of the \c getSmallConstantTripCount overload with
+ /// the single exiting block passed to it. See that routine for details.
+ unsigned getSmallConstantTripCount(Loop *L);
+
+ /// Returns the maximum trip count of this loop as a normal unsigned
+ /// value. Returns 0 if the trip count is unknown or not constant. This
+ /// "trip count" assumes that control exits via ExitingBlock. More
+ /// precisely, it is the number of times that control may reach ExitingBlock
+ /// before taking the branch. For loops with multiple exits, it may not be
+ /// the number times that the loop header executes if the loop exits
+ /// prematurely via another branch.
unsigned getSmallConstantTripCount(Loop *L, BasicBlock *ExitingBlock);
- /// getSmallConstantTripMultiple - Returns the largest constant divisor of
- /// the trip count of this loop as a normal unsigned value, if
- /// possible. This means that the actual trip count is always a multiple of
- /// the returned value (don't forget the trip count could very well be zero
- /// as well!). As explained in the comments for getSmallConstantTripCount,
- /// this assumes that control exits the loop via ExitingBlock.
+ /// \brief Returns the largest constant divisor of the trip count of the
+ /// loop if it is a single-exit loop and we can compute a small maximum for
+ /// that loop.
+ ///
+ /// Implemented in terms of the \c getSmallConstantTripMultiple overload with
+ /// the single exiting block passed to it. See that routine for details.
+ unsigned getSmallConstantTripMultiple(Loop *L);
+
+ /// Returns the largest constant divisor of the trip count of this loop as a
+ /// normal unsigned value, if possible. This means that the actual trip
+ /// count is always a multiple of the returned value (don't forget the trip
+ /// count could very well be zero as well!). As explained in the comments
+ /// for getSmallConstantTripCount, this assumes that control exits the loop
+ /// via ExitingBlock.
unsigned getSmallConstantTripMultiple(Loop *L, BasicBlock *ExitingBlock);
- // getExitCount - Get the expression for the number of loop iterations for
- // which this loop is guaranteed not to exit via ExitingBlock. Otherwise
- // return SCEVCouldNotCompute.
+ /// Get the expression for the number of loop iterations for which this loop
+ /// is guaranteed not to exit via ExitingBlock. Otherwise return
+ /// SCEVCouldNotCompute.
const SCEV *getExitCount(Loop *L, BasicBlock *ExitingBlock);
- /// getBackedgeTakenCount - If the specified loop has a predictable
- /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
- /// object. The backedge-taken count is the number of times the loop header
- /// will be branched to from within the loop. This is one less than the
- /// trip count of the loop, since it doesn't count the first iteration,
- /// when the header is branched to from outside the loop.
+ /// If the specified loop has a predictable backedge-taken count, return it,
+ /// otherwise return a SCEVCouldNotCompute object. The backedge-taken count
+ /// is the number of times the loop header will be branched to from within
+ /// the loop. This is one less than the trip count of the loop, since it
+ /// doesn't count the first iteration, when the header is branched to from
+ /// outside the loop.
///
/// Note that it is not valid to call this method on a loop without a
/// loop-invariant backedge-taken count (see
///
const SCEV *getBackedgeTakenCount(const Loop *L);
- /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
- /// return the least SCEV value that is known never to be less than the
- /// actual backedge taken count.
+ /// Similar to getBackedgeTakenCount, except return the least SCEV value
+ /// that is known never to be less than the actual backedge taken count.
const SCEV *getMaxBackedgeTakenCount(const Loop *L);
- /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
- /// has an analyzable loop-invariant backedge-taken count.
+ /// Return true if the specified loop has an analyzable loop-invariant
+ /// backedge-taken count.
bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
- /// forgetLoop - This method should be called by the client when it has
- /// changed a loop in a way that may effect ScalarEvolution's ability to
- /// compute a trip count, or if the loop is deleted.
+ /// This method should be called by the client when it has changed a loop in
+ /// a way that may effect ScalarEvolution's ability to compute a trip count,
+ /// or if the loop is deleted. This call is potentially expensive for large
+ /// loop bodies.
void forgetLoop(const Loop *L);
- /// forgetValue - This method should be called by the client when it has
- /// changed a value in a way that may effect its value, or which may
- /// disconnect it from a def-use chain linking it to a loop.
+ /// This method should be called by the client when it has changed a value
+ /// in a way that may effect its value, or which may disconnect it from a
+ /// def-use chain linking it to a loop.
void forgetValue(Value *V);
- /// GetMinTrailingZeros - Determine the minimum number of zero bits that S
- /// is guaranteed to end in (at every loop iteration). It is, at the same
- /// time, the minimum number of times S is divisible by 2. For example,
- /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
- /// bitwidth of S.
+ /// \brief Called when the client has changed the disposition of values in
+ /// this loop.
+ ///
+ /// We don't have a way to invalidate per-loop dispositions. Clear and
+ /// recompute is simpler.
+ void forgetLoopDispositions(const Loop *L) { LoopDispositions.clear(); }
+
+ /// Determine the minimum number of zero bits that S is guaranteed to end in
+ /// (at every loop iteration). It is, at the same time, the minimum number
+ /// of times S is divisible by 2. For example, given {4,+,8} it returns 2.
+ /// If S is guaranteed to be 0, it returns the bitwidth of S.
uint32_t GetMinTrailingZeros(const SCEV *S);
- /// getUnsignedRange - Determine the unsigned range for a particular SCEV.
+ /// Determine the unsigned range for a particular SCEV.
///
- ConstantRange getUnsignedRange(const SCEV *S);
+ ConstantRange getUnsignedRange(const SCEV *S) {
+ return getRange(S, HINT_RANGE_UNSIGNED);
+ }
- /// getSignedRange - Determine the signed range for a particular SCEV.
+ /// Determine the signed range for a particular SCEV.
///
- ConstantRange getSignedRange(const SCEV *S);
+ ConstantRange getSignedRange(const SCEV *S) {
+ return getRange(S, HINT_RANGE_SIGNED);
+ }
- /// isKnownNegative - Test if the given expression is known to be negative.
+ /// Test if the given expression is known to be negative.
///
bool isKnownNegative(const SCEV *S);
- /// isKnownPositive - Test if the given expression is known to be positive.
+ /// Test if the given expression is known to be positive.
///
bool isKnownPositive(const SCEV *S);
- /// isKnownNonNegative - Test if the given expression is known to be
- /// non-negative.
+ /// Test if the given expression is known to be non-negative.
///
bool isKnownNonNegative(const SCEV *S);
- /// isKnownNonPositive - Test if the given expression is known to be
- /// non-positive.
+ /// Test if the given expression is known to be non-positive.
///
bool isKnownNonPositive(const SCEV *S);
- /// isKnownNonZero - Test if the given expression is known to be
- /// non-zero.
+ /// Test if the given expression is known to be non-zero.
///
bool isKnownNonZero(const SCEV *S);
- /// isKnownPredicate - Test if the given expression is known to satisfy
- /// the condition described by Pred, LHS, and RHS.
+ /// Test if the given expression is known to satisfy the condition described
+ /// by Pred, LHS, and RHS.
///
bool isKnownPredicate(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
- /// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
- /// predicate Pred. Return true iff any changes were made. If the
- /// operands are provably equal or inequal, LHS and RHS are set to
- /// the same value and Pred is set to either ICMP_EQ or ICMP_NE.
+ /// Return true if the result of the predicate LHS `Pred` RHS is loop
+ /// invariant with respect to L. Set InvariantPred, InvariantLHS and
+ /// InvariantLHS so that InvariantLHS `InvariantPred` InvariantRHS is the
+ /// loop invariant form of LHS `Pred` RHS.
+ bool isLoopInvariantPredicate(ICmpInst::Predicate Pred, const SCEV *LHS,
+ const SCEV *RHS, const Loop *L,
+ ICmpInst::Predicate &InvariantPred,
+ const SCEV *&InvariantLHS,
+ const SCEV *&InvariantRHS);
+
+ /// Simplify LHS and RHS in a comparison with predicate Pred. Return true
+ /// iff any changes were made. If the operands are provably equal or
+ /// unequal, LHS and RHS are set to the same value and Pred is set to either
+ /// ICMP_EQ or ICMP_NE.
///
bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
const SCEV *&LHS,
- const SCEV *&RHS);
+ const SCEV *&RHS,
+ unsigned Depth = 0);
- /// getLoopDisposition - Return the "disposition" of the given SCEV with
- /// respect to the given loop.
+ /// Return the "disposition" of the given SCEV with respect to the given
+ /// loop.
LoopDisposition getLoopDisposition(const SCEV *S, const Loop *L);
- /// isLoopInvariant - Return true if the value of the given SCEV is
- /// unchanging in the specified loop.
+ /// Return true if the value of the given SCEV is unchanging in the
+ /// specified loop.
bool isLoopInvariant(const SCEV *S, const Loop *L);
- /// hasComputableLoopEvolution - Return true if the given SCEV changes value
- /// in a known way in the specified loop. This property being true implies
- /// that the value is variant in the loop AND that we can emit an expression
- /// to compute the value of the expression at any particular loop iteration.
+ /// Return true if the given SCEV changes value in a known way in the
+ /// specified loop. This property being true implies that the value is
+ /// variant in the loop AND that we can emit an expression to compute the
+ /// value of the expression at any particular loop iteration.
bool hasComputableLoopEvolution(const SCEV *S, const Loop *L);
- /// getLoopDisposition - Return the "disposition" of the given SCEV with
- /// respect to the given block.
+ /// Return the "disposition" of the given SCEV with respect to the given
+ /// block.
BlockDisposition getBlockDisposition(const SCEV *S, const BasicBlock *BB);
- /// dominates - Return true if elements that makes up the given SCEV
- /// dominate the specified basic block.
+ /// Return true if elements that makes up the given SCEV dominate the
+ /// specified basic block.
bool dominates(const SCEV *S, const BasicBlock *BB);
- /// properlyDominates - Return true if elements that makes up the given SCEV
- /// properly dominate the specified basic block.
+ /// Return true if elements that makes up the given SCEV properly dominate
+ /// the specified basic block.
bool properlyDominates(const SCEV *S, const BasicBlock *BB);
- /// hasOperand - Test whether the given SCEV has Op as a direct or
- /// indirect operand.
+ /// Test whether the given SCEV has Op as a direct or indirect operand.
bool hasOperand(const SCEV *S, const SCEV *Op) const;
- virtual bool runOnFunction(Function &F);
- virtual void releaseMemory();
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- virtual void print(raw_ostream &OS, const Module* = 0) const;
+ /// Return the size of an element read or written by Inst.
+ const SCEV *getElementSize(Instruction *Inst);
+
+ /// Compute the array dimensions Sizes from the set of Terms extracted from
+ /// the memory access function of this SCEVAddRecExpr.
+ void findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
+ SmallVectorImpl<const SCEV *> &Sizes,
+ const SCEV *ElementSize) const;
+
+ void print(raw_ostream &OS) const;
+ void verify() const;
+
+ /// Collect parametric terms occurring in step expressions.
+ void collectParametricTerms(const SCEV *Expr,
+ SmallVectorImpl<const SCEV *> &Terms);
+
+
+
+ /// Return in Subscripts the access functions for each dimension in Sizes.
+ void computeAccessFunctions(const SCEV *Expr,
+ SmallVectorImpl<const SCEV *> &Subscripts,
+ SmallVectorImpl<const SCEV *> &Sizes);
+
+ /// Split this SCEVAddRecExpr into two vectors of SCEVs representing the
+ /// subscripts and sizes of an array access.
+ ///
+ /// The delinearization is a 3 step process: the first two steps compute the
+ /// sizes of each subscript and the third step computes the access functions
+ /// for the delinearized array:
+ ///
+ /// 1. Find the terms in the step functions
+ /// 2. Compute the array size
+ /// 3. Compute the access function: divide the SCEV by the array size
+ /// starting with the innermost dimensions found in step 2. The Quotient
+ /// is the SCEV to be divided in the next step of the recursion. The
+ /// Remainder is the subscript of the innermost dimension. Loop over all
+ /// array dimensions computed in step 2.
+ ///
+ /// To compute a uniform array size for several memory accesses to the same
+ /// object, one can collect in step 1 all the step terms for all the memory
+ /// accesses, and compute in step 2 a unique array shape. This guarantees
+ /// that the array shape will be the same across all memory accesses.
+ ///
+ /// FIXME: We could derive the result of steps 1 and 2 from a description of
+ /// the array shape given in metadata.
+ ///
+ /// Example:
+ ///
+ /// A[][n][m]
+ ///
+ /// for i
+ /// for j
+ /// for k
+ /// A[j+k][2i][5i] =
+ ///
+ /// The initial SCEV:
+ ///
+ /// A[{{{0,+,2*m+5}_i, +, n*m}_j, +, n*m}_k]
+ ///
+ /// 1. Find the different terms in the step functions:
+ /// -> [2*m, 5, n*m, n*m]
+ ///
+ /// 2. Compute the array size: sort and unique them
+ /// -> [n*m, 2*m, 5]
+ /// find the GCD of all the terms = 1
+ /// divide by the GCD and erase constant terms
+ /// -> [n*m, 2*m]
+ /// GCD = m
+ /// divide by GCD -> [n, 2]
+ /// remove constant terms
+ /// -> [n]
+ /// size of the array is A[unknown][n][m]
+ ///
+ /// 3. Compute the access function
+ /// a. Divide {{{0,+,2*m+5}_i, +, n*m}_j, +, n*m}_k by the innermost size m
+ /// Quotient: {{{0,+,2}_i, +, n}_j, +, n}_k
+ /// Remainder: {{{0,+,5}_i, +, 0}_j, +, 0}_k
+ /// The remainder is the subscript of the innermost array dimension: [5i].
+ ///
+ /// b. Divide Quotient: {{{0,+,2}_i, +, n}_j, +, n}_k by next outer size n
+ /// Quotient: {{{0,+,0}_i, +, 1}_j, +, 1}_k
+ /// Remainder: {{{0,+,2}_i, +, 0}_j, +, 0}_k
+ /// The Remainder is the subscript of the next array dimension: [2i].
+ ///
+ /// The subscript of the outermost dimension is the Quotient: [j+k].
+ ///
+ /// Overall, we have: A[][n][m], and the access function: A[j+k][2i][5i].
+ void delinearize(const SCEV *Expr,
+ SmallVectorImpl<const SCEV *> &Subscripts,
+ SmallVectorImpl<const SCEV *> &Sizes,
+ const SCEV *ElementSize);
+
+ /// Return the DataLayout associated with the module this SCEV instance is
+ /// operating on.
+ const DataLayout &getDataLayout() const {
+ return F.getParent()->getDataLayout();
+ }
+
+ const SCEVPredicate *getEqualPredicate(const SCEVUnknown *LHS,
+ const SCEVConstant *RHS);
+
+ /// Re-writes the SCEV according to the Predicates in \p Preds.
+ const SCEV *rewriteUsingPredicate(const SCEV *Scev, SCEVUnionPredicate &A);
+
+ private:
+ /// Compute the backedge taken count knowing the interval difference, the
+ /// stride and presence of the equality in the comparison.
+ const SCEV *computeBECount(const SCEV *Delta, const SCEV *Stride,
+ bool Equality);
+
+ /// Verify if an linear IV with positive stride can overflow when in a
+ /// less-than comparison, knowing the invariant term of the comparison,
+ /// the stride and the knowledge of NSW/NUW flags on the recurrence.
+ bool doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
+ bool IsSigned, bool NoWrap);
+
+ /// Verify if an linear IV with negative stride can overflow when in a
+ /// greater-than comparison, knowing the invariant term of the comparison,
+ /// the stride and the knowledge of NSW/NUW flags on the recurrence.
+ bool doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
+ bool IsSigned, bool NoWrap);
private:
FoldingSet<SCEV> UniqueSCEVs;
+ FoldingSet<SCEVPredicate> UniquePreds;
BumpPtrAllocator SCEVAllocator;
- /// FirstUnknown - The head of a linked list of all SCEVUnknown
- /// values that have been allocated. This is used by releaseMemory
- /// to locate them all and call their destructors.
+ /// The head of a linked list of all SCEVUnknown values that have been
+ /// allocated. This is used by releaseMemory to locate them all and call
+ /// their destructors.
SCEVUnknown *FirstUnknown;
};
+
+ /// \brief Analysis pass that exposes the \c ScalarEvolution for a function.
+ class ScalarEvolutionAnalysis {
+ static char PassID;
+
+ public:
+ typedef ScalarEvolution Result;
+
+ /// \brief Opaque, unique identifier for this analysis pass.
+ static void *ID() { return (void *)&PassID; }
+
+ /// \brief Provide a name for the analysis for debugging and logging.
+ static StringRef name() { return "ScalarEvolutionAnalysis"; }
+
+ ScalarEvolution run(Function &F, AnalysisManager<Function> *AM);
+ };
+
+ /// \brief Printer pass for the \c ScalarEvolutionAnalysis results.
+ class ScalarEvolutionPrinterPass {
+ raw_ostream &OS;
+
+ public:
+ explicit ScalarEvolutionPrinterPass(raw_ostream &OS) : OS(OS) {}
+ PreservedAnalyses run(Function &F, AnalysisManager<Function> *AM);
+
+ static StringRef name() { return "ScalarEvolutionPrinterPass"; }
+ };
+
+ class ScalarEvolutionWrapperPass : public FunctionPass {
+ std::unique_ptr<ScalarEvolution> SE;
+
+ public:
+ static char ID;
+
+ ScalarEvolutionWrapperPass();
+
+ ScalarEvolution &getSE() { return *SE; }
+ const ScalarEvolution &getSE() const { return *SE; }
+
+ bool runOnFunction(Function &F) override;
+ void releaseMemory() override;
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ void print(raw_ostream &OS, const Module * = nullptr) const override;
+ void verifyAnalysis() const override;
+ };
+
+ /// An interface layer with SCEV used to manage how we see SCEV expressions
+ /// for values in the context of existing predicates. We can add new
+ /// predicates, but we cannot remove them.
+ ///
+ /// This layer has multiple purposes:
+ /// - provides a simple interface for SCEV versioning.
+ /// - guarantees that the order of transformations applied on a SCEV
+ /// expression for a single Value is consistent across two different
+ /// getSCEV calls. This means that, for example, once we've obtained
+ /// an AddRec expression for a certain value through expression
+ /// rewriting, we will continue to get an AddRec expression for that
+ /// Value.
+ /// - lowers the number of expression rewrites.
+ class PredicatedScalarEvolution {
+ public:
+ PredicatedScalarEvolution(ScalarEvolution &SE);
+ const SCEVUnionPredicate &getUnionPredicate() const;
+ /// \brief Returns the SCEV expression of V, in the context of the current
+ /// SCEV predicate.
+ /// The order of transformations applied on the expression of V returned
+ /// by ScalarEvolution is guaranteed to be preserved, even when adding new
+ /// predicates.
+ const SCEV *getSCEV(Value *V);
+ /// \brief Adds a new predicate.
+ void addPredicate(const SCEVPredicate &Pred);
+ /// \brief Returns the ScalarEvolution analysis used.
+ ScalarEvolution *getSE() const { return &SE; }
+
+ private:
+ /// \brief Increments the version number of the predicate.
+ /// This needs to be called every time the SCEV predicate changes.
+ void updateGeneration();
+ /// Holds a SCEV and the version number of the SCEV predicate used to
+ /// perform the rewrite of the expression.
+ typedef std::pair<unsigned, const SCEV *> RewriteEntry;
+ /// Maps a SCEV to the rewrite result of that SCEV at a certain version
+ /// number. If this number doesn't match the current Generation, we will
+ /// need to do a rewrite. To preserve the transformation order of previous
+ /// rewrites, we will rewrite the previous result instead of the original
+ /// SCEV.
+ DenseMap<const SCEV *, RewriteEntry> RewriteMap;
+ /// The ScalarEvolution analysis.
+ ScalarEvolution &SE;
+ /// The SCEVPredicate that forms our context. We will rewrite all
+ /// expressions assuming that this predicate true.
+ SCEVUnionPredicate Preds;
+ /// Marks the version of the SCEV predicate used. When rewriting a SCEV
+ /// expression we mark it with the version of the predicate. We use this to
+ /// figure out if the predicate has changed from the last rewrite of the
+ /// SCEV. If so, we need to perform a new rewrite.
+ unsigned Generation;
+ };
}
#endif
projects / oota-llvm.git / blobdiff