//===----------------------------------------------------------------------===//
//
// 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.
#include "llvm/Pass.h"
#include "llvm/Instructions.h"
#include "llvm/Function.h"
-#include "llvm/System/DataTypes.h"
+#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/ConstantRange.h"
class Loop;
class LoopInfo;
class Operator;
+ class SCEVUnknown;
+ class SCEV;
+ template<> struct FoldingSetTrait<SCEV>;
/// 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 : public FastFoldingSetNode {
+ 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.
+ 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 miscelaneous information.
+ /// subclasses to store miscellaneous information.
unsigned short SubclassData;
private:
SCEV(const SCEV &); // DO NOT IMPLEMENT
void operator=(const SCEV &); // DO NOT IMPLEMENT
- protected:
- virtual ~SCEV();
+
public:
- explicit SCEV(const FoldingSetNodeID &ID, unsigned SCEVTy) :
- FastFoldingSetNode(ID), SCEVType(SCEVTy), SubclassData(0) {}
+ 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;
-
- /// 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;
-
/// getType - Return the LLVM type of this SCEV expression.
///
- virtual const Type *getType() const = 0;
+ const Type *getType() const;
/// isZero - Return true if the expression is a constant zero.
///
///
bool isAllOnesValue() const;
- /// hasOperand - Test whether this SCEV has Op as a direct or
- /// indirect operand.
- virtual bool hasOperand(const SCEV *Op) 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;
-
- /// properlyDominates - Return true if elements that makes up this SCEV
- /// properly dominate the specified basic block.
- virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const = 0;
-
/// 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(raw_ostream &OS) const;
/// dump - This method is used for debugging.
///
void dump() const;
};
+ // 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,
+ FoldingSetNodeID &TempID) {
+ return ID == X.FastID;
+ }
+ static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) {
+ return X.FastID.ComputeHash();
+ }
+ };
+
inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
S.print(OS);
return OS;
struct SCEVCouldNotCompute : public SCEV {
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 bool hasOperand(const SCEV *Op) const;
-
- virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
- return true;
- }
-
- virtual bool properlyDominates(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);
/// they must ask this class for services.
///
class ScalarEvolution : public FunctionPass {
+ public:
+ /// LoopDisposition - 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.
+ enum BlockDisposition {
+ DoesNotDominateBlock, ///< The SCEV does not dominate the block.
+ DominatesBlock, ///< The SCEV dominates the block.
+ ProperlyDominatesBlock ///< The SCEV properly dominates the block.
+ };
+
+ private:
/// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
/// notified whenever a Value is deleted.
class SCEVCallbackVH : public CallbackVH {
friend class SCEVCallbackVH;
friend class SCEVExpander;
+ friend class SCEVUnknown;
/// F - The function we are analyzing.
///
///
LoopInfo *LI;
- /// TD - The target data information for the target we are targetting.
+ /// TD - The target data information for the target we are targeting.
///
TargetData *TD;
/// counts and things.
SCEVCouldNotCompute CouldNotCompute;
- /// Scalars - This is a cache of the scalars we have analyzed so far.
+ /// ValueExprMapType - The typedef for ValueExprMap.
///
- std::map<SCEVCallbackVH, const SCEV *> Scalars;
+ typedef DenseMap<SCEVCallbackVH, const SCEV *, DenseMapInfo<Value *> >
+ ValueExprMapType;
+
+ /// ValueExprMap - This is a cache of the values we have analyzed so far.
+ ///
+ ValueExprMapType ValueExprMap;
/// BackedgeTakenInfo - Information about the backedge-taken count
- /// of a loop. This currently inclues an exact count and a maximum count.
+ /// of a loop. This currently includes an exact count and a maximum count.
///
struct BackedgeTakenInfo {
/// Exact - An expression indicating the exact backedge-taken count of
std::map<const SCEV *,
std::map<const Loop *, const SCEV *> > ValuesAtScopes;
+ /// LoopDispositions - Memoized computeLoopDisposition results.
+ std::map<const SCEV *,
+ std::map<const Loop *, LoopDisposition> > LoopDispositions;
+
+ /// computeLoopDisposition - Compute a LoopDisposition value.
+ LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L);
+
+ /// BlockDispositions - Memoized computeBlockDisposition results.
+ std::map<const SCEV *,
+ std::map<const BasicBlock *, BlockDisposition> > BlockDispositions;
+
+ /// computeBlockDisposition - Compute a BlockDisposition value.
+ BlockDisposition computeBlockDisposition(const SCEV *S, const BasicBlock *BB);
+
+ /// UnsignedRanges - Memoized results from getUnsignedRange
+ DenseMap<const SCEV *, ConstantRange> UnsignedRanges;
+
+ /// SignedRanges - Memoized results from getSignedRange
+ 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;
+ }
+
+ /// 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));
+ 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.
const SCEV *createSCEV(Value *V);
/// ForgetSymbolicValue - This looks up computed SCEV values for all
/// instructions that depend on the given instruction and removes them from
- /// the Scalars map if they reference SymName. This is used during PHI
+ /// the ValueExprMap map if they reference SymName. This is used during PHI
/// resolution.
void ForgetSymbolicName(Instruction *I, const SCEV *SymName);
BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
const Loop *L, bool isSigned);
- /// getLoopPredecessor - If the given loop's header has exactly one unique
- /// predecessor outside the loop, return it. Otherwise return null.
- BasicBlock *getLoopPredecessor(const Loop *L);
-
/// 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);
+ std::pair<BasicBlock *, BasicBlock *>
+ getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
- /// isImpliedCond - Test whether the condition described by Pred, LHS,
- /// and RHS is true whenever the given Cond value evaluates to true.
- bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred,
+ /// isImpliedCond - 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 desribed by Pred, FoundLHS,
+ /// 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 desribed by Pred,
+ /// 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,
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.
+ ///
+ bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
+ const SCEV *LHS, const SCEV *RHS);
+
+ /// forgetMemoizedResults - Drop memoized information computed for S.
+ void forgetMemoizedResults(const SCEV *S);
+
public:
static char ID; // Pass identification, replacement for typeid
ScalarEvolution();
///
const SCEV *getNotSCEV(const SCEV *V);
- /// getMinusSCEV - Return LHS-RHS.
- ///
- const SCEV *getMinusSCEV(const SCEV *LHS,
- const SCEV *RHS);
+ /// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1,
+ /// and thus the HasNUW and HasNSW bits apply to the resultant add, not
+ /// whether the sub would have overflowed.
+ const SCEV *getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
+ bool HasNUW = false, bool HasNSW = false);
/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
/// of the input value to the specified type. If the type must be
/// widening.
const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty);
- /// getIntegerSCEV - Given a SCEVable type, create a constant for the
- /// specified signed integer value and return a SCEV for the constant.
- const SCEV *getIntegerSCEV(int64_t Val, const Type *Ty);
-
/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
/// the types using zero-extension, and then perform a umax operation
/// with them.
/// getSCEVAtScope(getSCEV(V), L).
const SCEV *getSCEVAtScope(Value *V, const Loop *L);
- /// isLoopGuardedByCond - Test whether entry to the loop is protected by
- /// a conditional between LHS and RHS. This is used to help avoid max
+ /// 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.
- bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS);
+ 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
///
bool isKnownNonZero(const SCEV *S);
- /// isKnownNonZero - Test if the given expression is known to satisfy
+ /// isKnownPredicate - 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.
+ ///
+ bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
+ const SCEV *&LHS,
+ const SCEV *&RHS);
+
+ /// getLoopDisposition - 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.
+ 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.
+ bool hasComputableLoopEvolution(const SCEV *S, const Loop *L);
+
+ /// getLoopDisposition - 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.
+ 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.
+ bool properlyDominates(const SCEV *S, const BasicBlock *BB);
+
+ /// hasOperand - 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;
private:
FoldingSet<SCEV> UniqueSCEVs;
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.
+ SCEVUnknown *FirstUnknown;
};
}
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