//===----------------------------------------------------------------------===//
//
// The ScalarEvolution class is an LLVM pass which can be used to analyze and
-// catagorize scalar expressions in loops. It specializes in recognizing
+// categorize scalar expressions in loops. It specializes in recognizing
// general induction variables, representing them with the abstract and opaque
// SCEV class. Given this analysis, trip counts of loops and other important
// properties can be obtained.
#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_H
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/FoldingSet.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/Analysis/LoopInfo.h"
+#include "llvm/Support/Allocator.h"
#include "llvm/Support/DataTypes.h"
-#include "llvm/Support/ValueHandle.h"
-#include <iosfwd>
+#include <map>
namespace llvm {
class APInt;
+ class AssumptionCache;
+ class Constant;
class ConstantInt;
+ class DominatorTree;
class Type;
- class SCEVHandle;
class ScalarEvolution;
- class TargetData;
-
- /// SCEV - This class represent an analyzed expression in the program. These
- /// are reference counted opaque objects that the client is not allowed to
- /// do much with directly.
+ class DataLayout;
+ class TargetLibraryInfo;
+ class LLVMContext;
+ class Loop;
+ class LoopInfo;
+ class Operator;
+ class SCEVUnknown;
+ class SCEVAddRecExpr;
+ class SCEV;
+ template<> struct FoldingSetTrait<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.
///
- class SCEV {
- const unsigned SCEVType; // The SCEV baseclass this node corresponds to
- mutable unsigned RefCount;
-
- friend class SCEVHandle;
- void addRef() const { ++RefCount; }
- void dropRef() const {
- if (--RefCount == 0)
- delete this;
- }
+ class SCEV : public FoldingSetNode {
+ friend struct FoldingSetTrait<SCEV>;
+
+ /// 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;
- SCEV(const SCEV &); // DO NOT IMPLEMENT
- void operator=(const SCEV &); // DO NOT IMPLEMENT
protected:
- virtual ~SCEV();
+ /// This field is initialized to zero and may be used in subclasses to store
+ /// miscellaneous information.
+ unsigned short SubclassData;
+
+ private:
+ SCEV(const SCEV &) = delete;
+ void operator=(const SCEV &) = delete;
+
public:
- explicit SCEV(unsigned SCEVTy) : SCEVType(SCEVTy), RefCount(0) {}
+ /// NoWrapFlags are bitfield indices into SubclassData.
+ ///
+ /// Add and Mul expressions may have no-unsigned-wrap <NUW> or
+ /// no-signed-wrap <NSW> properties, which are derived from the IR
+ /// operator. NSW is a misnomer that we use to mean no signed overflow or
+ /// underflow.
+ ///
+ /// 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
+ /// whenever either NUW or NSW are set.
+ enum NoWrapFlags { FlagAnyWrap = 0, // No guarantee.
+ FlagNW = (1 << 0), // No self-wrap.
+ FlagNUW = (1 << 1), // No unsigned wrap.
+ FlagNSW = (1 << 2), // No signed wrap.
+ NoWrapMask = (1 << 3) -1 };
+
+ explicit SCEV(const FoldingSetNodeIDRef ID, unsigned SCEVTy) :
+ FastID(ID), SCEVType(SCEVTy), SubclassData(0) {}
unsigned getSCEVType() const { return SCEVType; }
- /// isLoopInvariant - Return true if the value of this SCEV is unchanging in
- /// the specified loop.
- virtual bool isLoopInvariant(const Loop *L) const = 0;
+ /// Return the LLVM type of this SCEV expression.
+ ///
+ Type *getType() const;
- /// hasComputableLoopEvolution - Return true if this 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.
- virtual bool hasComputableLoopEvolution(const Loop *L) const = 0;
+ /// Return true if the expression is a constant zero.
+ ///
+ bool isZero() const;
- /// getType - Return the LLVM type of this SCEV expression.
+ /// Return true if the expression is a constant one.
///
- virtual const Type *getType() const = 0;
+ bool isOne() const;
- /// isZero - Return true if the expression is a constant zero.
+ /// Return true if the expression is a constant all-ones value.
///
- bool isZero() const;
+ bool isAllOnesValue() const;
- /// replaceSymbolicValuesWithConcrete - If this SCEV internally references
- /// the symbolic value "Sym", construct and return a new SCEV that produces
- /// the same value, but which uses the concrete value Conc instead of the
- /// symbolic value. If this SCEV does not use the symbolic value, it
- /// returns itself.
- virtual SCEVHandle
- replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc,
- ScalarEvolution &SE) const = 0;
-
- /// dominates - Return true if elements that makes up this SCEV dominates
- /// the specified basic block.
- virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0;
+ /// 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.
- virtual void print(raw_ostream &OS) const = 0;
- void print(std::ostream &OS) const;
- void print(std::ostream *OS) const { if (OS) print(*OS); }
+ /// 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.
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+ /// This method is used for debugging.
///
void dump() const;
+#endif
};
- inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
- S.print(OS);
- return OS;
- }
+ // Specialize FoldingSetTrait for SCEV to avoid needing to compute
+ // temporary FoldingSetNodeID values.
+ template<> struct FoldingSetTrait<SCEV> : DefaultFoldingSetTrait<SCEV> {
+ static void Profile(const SCEV &X, FoldingSetNodeID& ID) {
+ ID = X.FastID;
+ }
+ static bool Equals(const SCEV &X, const FoldingSetNodeID &ID,
+ unsigned IDHash, FoldingSetNodeID &TempID) {
+ return ID == X.FastID;
+ }
+ static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) {
+ return X.FastID.ComputeHash();
+ }
+ };
- inline std::ostream &operator<<(std::ostream &OS, const SCEV &S) {
+ inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
S.print(OS);
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();
- ~SCEVCouldNotCompute();
-
- // None of these methods are valid for this object.
- virtual bool isLoopInvariant(const Loop *L) const;
- virtual const Type *getType() const;
- virtual bool hasComputableLoopEvolution(const Loop *L) const;
- virtual void print(raw_ostream &OS) const;
- virtual SCEVHandle
- replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
- const SCEVHandle &Conc,
- ScalarEvolution &SE) const;
-
- virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
- return true;
- }
/// 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);
};
- /// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
- /// notified whenever a Value is deleted.
- class SCEVCallbackVH : public CallbackVH {
- ScalarEvolution *SE;
- virtual void deleted();
- virtual void allUsesReplacedWith(Value *New);
+ /// 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:
- SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
- };
-
- /// SCEVHandle - This class is used to maintain the SCEV object's refcounts,
- /// freeing the objects when the last reference is dropped.
- class SCEVHandle {
- const SCEV *S;
- SCEVHandle(); // DO NOT IMPLEMENT
- public:
- SCEVHandle(const SCEV *s) : S(s) {
- assert(S && "Cannot create a handle to a null SCEV!");
- S->addRef();
- }
- SCEVHandle(const SCEVHandle &RHS) : S(RHS.S) {
- S->addRef();
- }
- ~SCEVHandle() { S->dropRef(); }
-
- operator const SCEV*() const { return S; }
-
- const SCEV &operator*() const { return *S; }
- const SCEV *operator->() const { return S; }
+ /// 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.
+ };
- bool operator==(const SCEV *RHS) const { return S == RHS; }
- bool operator!=(const SCEV *RHS) const { return S != RHS; }
+ /// 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.
+ ProperlyDominatesBlock ///< The SCEV properly dominates the block.
+ };
- const SCEVHandle &operator=(SCEV *RHS) {
- if (S != RHS) {
- S->dropRef();
- S = RHS;
- S->addRef();
- }
- return *this;
+ /// Convenient NoWrapFlags manipulation that hides enum casts and is
+ /// visible in the ScalarEvolution name space.
+ static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
+ maskFlags(SCEV::NoWrapFlags Flags, int Mask) {
+ return (SCEV::NoWrapFlags)(Flags & Mask);
}
-
- const SCEVHandle &operator=(const SCEVHandle &RHS) {
- if (S != RHS.S) {
- S->dropRef();
- S = RHS.S;
- S->addRef();
- }
- return *this;
+ static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
+ setFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OnFlags) {
+ return (SCEV::NoWrapFlags)(Flags | OnFlags);
}
- };
-
- template<typename From> struct simplify_type;
- template<> struct simplify_type<const SCEVHandle> {
- typedef const SCEV* SimpleType;
- static SimpleType getSimplifiedValue(const SCEVHandle &Node) {
- return Node;
+ static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
+ clearFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OffFlags) {
+ return (SCEV::NoWrapFlags)(Flags & ~OffFlags);
}
- };
- template<> struct simplify_type<SCEVHandle>
- : public simplify_type<const SCEVHandle> {};
- /// 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 {
+ private:
+ /// A CallbackVH to arrange for ScalarEvolution to be notified whenever a
+ /// Value is deleted.
+ class SCEVCallbackVH final : public CallbackVH {
+ ScalarEvolution *SE;
+ void deleted() override;
+ void allUsesReplacedWith(Value *New) override;
+ public:
+ SCEVCallbackVH(Value *V, ScalarEvolution *SE = nullptr);
+ };
+
friend class SCEVCallbackVH;
+ friend class SCEVExpander;
+ friend class SCEVUnknown;
+
+ /// The function we are analyzing.
+ ///
+ Function &F;
- /// F - The function we are analyzing.
+ /// The target library information for the target we are targeting.
///
- Function *F;
+ TargetLibraryInfo &TLI;
- /// LI - The loop information for the function we are currently analyzing.
+ /// The tracker for @llvm.assume intrinsics in this function.
+ AssumptionCache &AC;
+
+ /// The dominator tree.
///
- LoopInfo *LI;
+ DominatorTree &DT;
- /// TD - The target data information for the target we are targetting.
+ /// The loop information for the function we are currently analyzing.
///
- TargetData *TD;
+ LoopInfo &LI;
- /// UnknownValue - This SCEV is used to represent unknown trip counts and
- /// things.
- SCEVHandle UnknownValue;
+ /// This SCEV is used to represent unknown trip counts and things.
+ std::unique_ptr<SCEVCouldNotCompute> CouldNotCompute;
- /// Scalars - This is a cache of the scalars we have analyzed so far.
+ /// The typedef for ValueExprMap.
///
- std::map<SCEVCallbackVH, SCEVHandle> Scalars;
+ typedef DenseMap<SCEVCallbackVH, const SCEV *, DenseMapInfo<Value *> >
+ ValueExprMapType;
- /// BackedgeTakenInfo - Information about the backedge-taken count
- /// of a loop. This currently inclues an exact count and a maximum count.
+ /// This is a cache of the values we have analyzed so far.
///
- struct BackedgeTakenInfo {
- /// Exact - An expression indicating the exact backedge-taken count of
- /// the loop if it is known, or a SCEVCouldNotCompute otherwise.
- SCEVHandle Exact;
+ ValueExprMapType ValueExprMap;
+
+ /// Mark predicate values currently being processed by isImpliedCond.
+ DenseSet<Value*> PendingLoopPredicates;
- /// Exact - An expression indicating the least maximum backedge-taken
- /// count of the loop that is known, or a SCEVCouldNotCompute.
- SCEVHandle Max;
+ /// Set to true by isLoopBackedgeGuardedByCond when we're walking the set of
+ /// conditions dominating the backedge of a loop.
+ bool WalkingBEDominatingConds;
- /*implicit*/ BackedgeTakenInfo(SCEVHandle exact) :
- Exact(exact), Max(exact) {}
+ /// 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*/ BackedgeTakenInfo(const SCEV *exact) :
- Exact(exact), Max(exact) {}
+ /*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {}
- BackedgeTakenInfo(SCEVHandle exact, SCEVHandle max) :
- Exact(exact), Max(max) {}
+ ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {}
- /// hasAnyInfo - Test whether this BackedgeTakenInfo 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);
+ !isa<SCEVCouldNotCompute>(Max);
+ }
+ };
+
+ /// 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(nullptr), ExactNotTaken(nullptr) {}
+
+ /// Return true if all loop exits are computable.
+ bool isCompleteList() const {
+ return NextExit.getInt() == 0;
+ }
+
+ void setIncomplete() { NextExit.setInt(1); }
+
+ /// Return a pointer to the next exit's not-taken info.
+ ExitNotTakenInfo *getNextExit() const {
+ return NextExit.getPointer();
+ }
+
+ void setNextExit(ExitNotTakenInfo *ENT) { NextExit.setPointer(ENT); }
+ };
+
+ /// Information about the backedge-taken count of a loop. This currently
+ /// includes an exact count and a maximum count.
+ ///
+ class BackedgeTakenInfo {
+ /// A list of computable exits and their not-taken counts. Loops almost
+ /// never have more than one computable exit.
+ ExitNotTakenInfo ExitNotTaken;
+
+ /// An expression indicating the least maximum backedge-taken count of the
+ /// loop that is known, or a SCEVCouldNotCompute.
+ const SCEV *Max;
+
+ public:
+ 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);
+
+ /// Test whether this BackedgeTakenInfo contains any computed information,
+ /// or whether it's all SCEVCouldNotCompute values.
+ bool hasAnyInfo() const {
+ return ExitNotTaken.ExitingBlock || !isa<SCEVCouldNotCompute>(Max);
}
+
+ /// 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;
+
+ /// 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;
+
+ /// Get the max backedge taken count for the loop.
+ const SCEV *getMax(ScalarEvolution *SE) const;
+
+ /// 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.
- std::map<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.
- std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
-
- /// createSCEV - We know that there is no SCEV for the specified value.
- /// Analyze the expression.
- SCEVHandle createSCEV(Value *V);
-
- /// createNodeForPHI - Provide the special handling we need to analyze PHI
- /// SCEVs.
- SCEVHandle createNodeForPHI(PHINode *PN);
-
- /// ReplaceSymbolicValueWithConcrete - This looks up the computed SCEV value
- /// for the specified instruction and replaces any references to the
- /// symbolic value SymName with the specified value. This is used during
- /// PHI resolution.
- void ReplaceSymbolicValueWithConcrete(Instruction *I,
- const SCEVHandle &SymName,
- const SCEVHandle &NewVal);
-
- /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given
- /// loop, lazily computing new values if the loop hasn't been analyzed
- /// yet.
+ /// Cache the backedge-taken count of the loops for this function as they
+ /// are computed.
+ DenseMap<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
+
+ /// 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;
+
+ /// 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 *,
+ SmallVector<std::pair<const Loop *, const SCEV *>, 2> > ValuesAtScopes;
+
+ /// Memoized computeLoopDisposition results.
+ DenseMap<const SCEV *,
+ SmallVector<PointerIntPair<const Loop *, 2, LoopDisposition>, 2>>
+ LoopDispositions;
+
+ /// Compute a LoopDisposition value.
+ LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L);
+
+ /// Memoized computeBlockDisposition results.
+ DenseMap<
+ const SCEV *,
+ SmallVector<PointerIntPair<const BasicBlock *, 2, BlockDisposition>, 2>>
+ BlockDispositions;
+
+ /// Compute a BlockDisposition value.
+ BlockDisposition computeBlockDisposition(const SCEV *S, const BasicBlock *BB);
+
+ /// Memoized results from getRange
+ DenseMap<const SCEV *, ConstantRange> UnsignedRanges;
+
+ /// Memoized results from getRange
+ DenseMap<const SCEV *, ConstantRange> SignedRanges;
+
+ /// 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;
+
+ std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
+ Cache.insert(std::make_pair(S, CR));
+ if (!Pair.second)
+ Pair.first->second = CR;
+ return Pair.first->second;
+ }
+
+ /// 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);
+
+ /// Provide the special handling we need to analyze PHI SCEVs.
+ const SCEV *createNodeForPHI(PHINode *PN);
+
+ /// Provide the special handling we need to analyze GEP SCEVs.
+ const SCEV *createNodeForGEP(GEPOperator *GEP);
+
+ /// Implementation code for getSCEVAtScope; called at most once for each
+ /// SCEV+Loop pair.
+ ///
+ const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
+
+ /// 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);
+
+ /// 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.
+ /// Compute the number of times the specified loop will iterate.
BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
- /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition
- /// of 'icmp op load X, cst', try to see if we can compute the trip count.
- SCEVHandle
- ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI,
- Constant *RHS,
- const Loop *L,
- ICmpInst::Predicate p);
-
- /// ComputeBackedgeTakenCountExhaustively - If the trip 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 UnknownValue.
- SCEVHandle ComputeBackedgeTakenCountExhaustively(const Loop *L, Value *Cond,
- bool ExitWhen);
-
- /// HowFarToZero - Return the number of times a backedge comparing the
- /// specified value to zero will execute. If not computable, return
- /// UnknownValue.
- SCEVHandle HowFarToZero(const SCEV *V, const Loop *L);
-
- /// HowFarToNonZero - Return the number of times a backedge checking the
- /// specified value for nonzero will execute. If not computable, return
- /// UnknownValue.
- SCEVHandle HowFarToNonZero(const SCEV *V, const Loop *L);
-
- /// HowManyLessThans - Return the number of times a backedge containing the
- /// specified less-than comparison will execute. If not computable, return
- /// UnknownValue. isSigned specifies whether the less-than is signed.
- BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
- const Loop *L, bool isSigned);
-
- /// 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.
- BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
-
- /// 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.
+ /// 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 its exit condition were a conditional branch of ExitCond,
+ /// TBB, and FBB.
+ ExitLimit ComputeExitLimitFromCond(const Loop *L,
+ Value *ExitCond,
+ BasicBlock *TBB,
+ BasicBlock *FBB,
+ bool IsSubExpr);
+
+ /// 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,
+ 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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, bool IsSubExpr);
+ ExitLimit HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
+ const Loop *L, bool isSigned, bool IsSubExpr);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
- /// getSCEVAtScope - Compute the value of the specified expression within
- /// the indicated loop (which may be null to indicate in no loop). If the
- /// expression cannot be evaluated, return UnknownValue itself.
- SCEVHandle getSCEVAtScope(const SCEV *S, const Loop *L);
+ /// 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);
+
+ /// 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;
- /// forgetLoopPHIs - Delete the memoized SCEVs associated with the
- /// PHI nodes in the given loop. This is used when the trip count of
- /// the loop may have changed.
- void forgetLoopPHIs(const Loop *L);
+ /// 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();
-
- /// 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.
- bool isSCEVable(const Type *Ty) const;
-
- /// getTypeSizeInBits - Return the size in bits of the specified type,
- /// for which isSCEVable must return true.
- uint64_t getTypeSizeInBits(const 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.
- const Type *getEffectiveSCEVType(const Type *Ty) const;
-
- /// getSCEV - Return a SCEV expression handle for the full generality of the
- /// specified expression.
- SCEVHandle getSCEV(Value *V);
-
- SCEVHandle getConstant(ConstantInt *V);
- SCEVHandle getConstant(const APInt& Val);
- SCEVHandle getTruncateExpr(const SCEVHandle &Op, const Type *Ty);
- SCEVHandle getZeroExtendExpr(const SCEVHandle &Op, const Type *Ty);
- SCEVHandle getSignExtendExpr(const SCEVHandle &Op, const Type *Ty);
- SCEVHandle getAddExpr(std::vector<SCEVHandle> &Ops);
- SCEVHandle getAddExpr(const SCEVHandle &LHS, const SCEVHandle &RHS) {
- std::vector<SCEVHandle> Ops;
+ ScalarEvolution(Function &F, TargetLibraryInfo &TLI, AssumptionCache &AC,
+ DominatorTree &DT, LoopInfo &LI);
+ ~ScalarEvolution();
+ ScalarEvolution(ScalarEvolution &&Arg);
+
+ LLVMContext &getContext() const { return F.getContext(); }
+
+ /// 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;
+
+ /// Return the size in bits of the specified type, for which isSCEVable must
+ /// return true.
+ uint64_t getTypeSizeInBits(Type *Ty) const;
+
+ /// 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;
+
+ /// Return a SCEV expression for the full generality of the specified
+ /// expression.
+ const SCEV *getSCEV(Value *V);
+
+ const SCEV *getConstant(ConstantInt *V);
+ const SCEV *getConstant(const APInt& Val);
+ const SCEV *getConstant(Type *Ty, uint64_t V, bool isSigned = false);
+ const SCEV *getTruncateExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getZeroExtendExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getSignExtendExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getAnyExtendExpr(const SCEV *Op, Type *Ty);
+ const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
+ 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);
- return getAddExpr(Ops);
+ return getAddExpr(Ops, Flags);
}
- SCEVHandle getAddExpr(const SCEVHandle &Op0, const SCEVHandle &Op1,
- const SCEVHandle &Op2) {
- std::vector<SCEVHandle> Ops;
+ 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);
- return getAddExpr(Ops);
+ return getAddExpr(Ops, Flags);
}
- SCEVHandle getMulExpr(std::vector<SCEVHandle> &Ops);
- SCEVHandle getMulExpr(const SCEVHandle &LHS, const SCEVHandle &RHS) {
- std::vector<SCEVHandle> Ops;
+ 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);
- return getMulExpr(Ops);
+ return getMulExpr(Ops, Flags);
}
- SCEVHandle getUDivExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
- SCEVHandle getAddRecExpr(const SCEVHandle &Start, const SCEVHandle &Step,
- const Loop *L);
- SCEVHandle getAddRecExpr(std::vector<SCEVHandle> &Operands,
- const Loop *L);
- SCEVHandle getAddRecExpr(const std::vector<SCEVHandle> &Operands,
- const Loop *L) {
- std::vector<SCEVHandle> NewOp(Operands);
- return getAddRecExpr(NewOp, L);
+ 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);
+ 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,
+ const Loop *L, SCEV::NoWrapFlags Flags);
+ const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
+ const Loop *L, SCEV::NoWrapFlags Flags) {
+ SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
+ return getAddRecExpr(NewOp, L, Flags);
}
- SCEVHandle getSMaxExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
- SCEVHandle getSMaxExpr(std::vector<SCEVHandle> Operands);
- SCEVHandle getUMaxExpr(const SCEVHandle &LHS, const SCEVHandle &RHS);
- SCEVHandle getUMaxExpr(std::vector<SCEVHandle> Operands);
- SCEVHandle getUnknown(Value *V);
- SCEVHandle getCouldNotCompute();
+ /// \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 *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
+ const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
+ const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
+ const SCEV *getUnknown(Value *V);
+ const SCEV *getCouldNotCompute();
+
+ /// \brief Return a SCEV for the constant 0 of a specific type.
+ const SCEV *getZero(Type *Ty) { return getConstant(Ty, 0); }
+
+ /// \brief Return a SCEV for the constant 1 of a specific type.
+ const SCEV *getOne(Type *Ty) { return getConstant(Ty, 1); }
+
+ /// Return an expression for sizeof AllocTy that is type IntTy
+ ///
+ const SCEV *getSizeOfExpr(Type *IntTy, Type *AllocTy);
- /// getNegativeSCEV - Return the SCEV object corresponding to -V.
+ /// Return an expression for offsetof on the given field with type IntTy
///
- SCEVHandle getNegativeSCEV(const SCEVHandle &V);
+ const SCEV *getOffsetOfExpr(Type *IntTy, StructType *STy, unsigned FieldNo);
- /// getNotSCEV - Return the SCEV object corresponding to ~V.
+ /// Return the SCEV object corresponding to -V.
///
- SCEVHandle getNotSCEV(const SCEVHandle &V);
+ const SCEV *getNegativeSCEV(const SCEV *V,
+ SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
- /// getMinusSCEV - Return LHS-RHS.
+ /// Return the SCEV object corresponding to ~V.
+ ///
+ const SCEV *getNotSCEV(const SCEV *V);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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);
+
+ /// 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.
+ ///
+ /// In the case that a relevant loop exit value cannot be computed, the
+ /// original value V is returned.
+ const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
+
+ /// This is a convenience function which does getSCEVAtScope(getSCEV(V), L).
+ const SCEV *getSCEVAtScope(Value *V, const Loop *L);
+
+ /// 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);
+
+ /// 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);
+
+ /// \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);
+
+ /// \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);
+
+ /// 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);
+
+ /// 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
+ /// hasLoopInvariantBackedgeTakenCount).
///
- SCEVHandle getMinusSCEV(const SCEVHandle &LHS,
- const SCEVHandle &RHS);
+ const SCEV *getBackedgeTakenCount(const Loop *L);
- /// 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.
- SCEVHandle getTruncateOrZeroExtend(const SCEVHandle &V, const Type *Ty);
+ /// 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);
- /// 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.
- SCEVHandle getTruncateOrSignExtend(const SCEVHandle &V, const Type *Ty);
+ /// Return true if the specified loop has an analyzable loop-invariant
+ /// backedge-taken count.
+ bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
+
+ /// 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);
- /// getIntegerSCEV - Given an integer or FP type, create a constant for the
- /// specified signed integer value and return a SCEV for the constant.
- SCEVHandle getIntegerSCEV(int Val, const Type *Ty);
+ /// 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);
- /// hasSCEV - Return true if the SCEV for this value has already been
- /// computed.
- bool hasSCEV(Value *V) const;
+ /// \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(); }
- /// setSCEV - Insert the specified SCEV into the map of current SCEVs for
- /// the specified value.
- void setSCEV(Value *V, const SCEVHandle &H);
+ /// 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);
- /// getSCEVAtScope - Return a SCEV expression handle 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.
+ /// Determine the unsigned range for a particular SCEV.
///
- /// 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.
+ ConstantRange getUnsignedRange(const SCEV *S) {
+ return getRange(S, HINT_RANGE_UNSIGNED);
+ }
+
+ /// Determine the signed range for a particular SCEV.
///
- /// If this value is not computable at this scope, a SCEVCouldNotCompute
- /// object is returned.
- SCEVHandle getSCEVAtScope(Value *V, const Loop *L);
+ ConstantRange getSignedRange(const SCEV *S) {
+ return getRange(S, HINT_RANGE_SIGNED);
+ }
- /// isLoopGuardedByCond - 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.
- bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS);
+ /// Test if the given expression is known to be negative.
+ ///
+ bool isKnownNegative(const SCEV *S);
- /// 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.
+ /// Test if the given expression is known to be positive.
///
- /// Note that it is not valid to call this method on a loop without a
- /// loop-invariant backedge-taken count (see
- /// hasLoopInvariantBackedgeTakenCount).
+ bool isKnownPositive(const SCEV *S);
+
+ /// Test if the given expression is known to be non-negative.
///
- SCEVHandle getBackedgeTakenCount(const Loop *L);
+ bool isKnownNonNegative(const SCEV *S);
- /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
- /// return the least SCEV value that is known never to be less than the
- /// actual backedge taken count.
- SCEVHandle getMaxBackedgeTakenCount(const Loop *L);
+ /// Test if the given expression is known to be non-positive.
+ ///
+ bool isKnownNonPositive(const SCEV *S);
- /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
- /// has an analyzable loop-invariant backedge-taken count.
- bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
+ /// Test if the given expression is known to be non-zero.
+ ///
+ bool isKnownNonZero(const SCEV *S);
- /// forgetLoopBackedgeTakenCount - 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.
- void forgetLoopBackedgeTakenCount(const Loop *L);
-
- virtual bool runOnFunction(Function &F);
- virtual void releaseMemory();
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- void print(raw_ostream &OS, const Module* = 0) const;
- virtual void print(std::ostream &OS, const Module* = 0) const;
- void print(std::ostream *OS, const Module* M = 0) const {
- if (OS) print(*OS, M);
- }
+ /// 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);
+
+ /// 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,
+ unsigned Depth = 0);
+
+ /// Return the "disposition" of the given SCEV with respect to the given
+ /// loop.
+ LoopDisposition getLoopDisposition(const SCEV *S, const Loop *L);
+
+ /// Return true if the value of the given SCEV is unchanging in the
+ /// specified loop.
+ bool isLoopInvariant(const SCEV *S, const Loop *L);
+
+ /// 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);
+
+ /// Return the "disposition" of the given SCEV with respect to the given
+ /// block.
+ BlockDisposition getBlockDisposition(const SCEV *S, const BasicBlock *BB);
+
+ /// Return true if elements that makes up the given SCEV dominate the
+ /// specified basic block.
+ bool dominates(const SCEV *S, const BasicBlock *BB);
+
+ /// Return true if elements that makes up the given SCEV properly dominate
+ /// the specified basic block.
+ bool properlyDominates(const SCEV *S, const BasicBlock *BB);
+
+ /// Test whether the given SCEV has Op as a direct or indirect operand.
+ bool hasOperand(const SCEV *S, const SCEV *Op) 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);
+
+ 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;
+ BumpPtrAllocator SCEVAllocator;
+
+ /// 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;
};
}
projects / oota-llvm.git / blobdiff