#ifndef LLVM_TRANSFORMS_UTILS_LOOPUTILS_H
#define LLVM_TRANSFORMS_UTILS_LOOPUTILS_H
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IRBuilder.h"
+
namespace llvm {
-class AliasAnalysis;
+class AliasSet;
+class AliasSetTracker;
+class AssumptionCache;
class BasicBlock;
+class DataLayout;
class DominatorTree;
class Loop;
class LoopInfo;
class Pass;
+class PredIteratorCache;
class ScalarEvolution;
+class TargetLibraryInfo;
+
+/// \brief Captures loop safety information.
+/// It keep information for loop & its header may throw exception.
+struct LICMSafetyInfo {
+ bool MayThrow; // The current loop contains an instruction which
+ // may throw.
+ bool HeaderMayThrow; // Same as previous, but specific to loop header
+ LICMSafetyInfo() : MayThrow(false), HeaderMayThrow(false)
+ {}
+};
+
+/// The RecurrenceDescriptor is used to identify recurrences variables in a
+/// loop. Reduction is a special case of recurrence that has uses of the
+/// recurrence variable outside the loop. The method isReductionPHI identifies
+/// reductions that are basic recurrences.
+///
+/// Basic recurrences are defined as the summation, product, OR, AND, XOR, min,
+/// or max of a set of terms. For example: for(i=0; i<n; i++) { total +=
+/// array[i]; } is a summation of array elements. Basic recurrences are a
+/// special case of chains of recurrences (CR). See ScalarEvolution for CR
+/// references.
+
+/// This struct holds information about recurrence variables.
+class RecurrenceDescriptor {
+
+public:
+ /// This enum represents the kinds of recurrences that we support.
+ enum RecurrenceKind {
+ RK_NoRecurrence, ///< Not a recurrence.
+ RK_IntegerAdd, ///< Sum of integers.
+ RK_IntegerMult, ///< Product of integers.
+ RK_IntegerOr, ///< Bitwise or logical OR of numbers.
+ RK_IntegerAnd, ///< Bitwise or logical AND of numbers.
+ RK_IntegerXor, ///< Bitwise or logical XOR of numbers.
+ RK_IntegerMinMax, ///< Min/max implemented in terms of select(cmp()).
+ RK_FloatAdd, ///< Sum of floats.
+ RK_FloatMult, ///< Product of floats.
+ RK_FloatMinMax ///< Min/max implemented in terms of select(cmp()).
+ };
+
+ // This enum represents the kind of minmax recurrence.
+ enum MinMaxRecurrenceKind {
+ MRK_Invalid,
+ MRK_UIntMin,
+ MRK_UIntMax,
+ MRK_SIntMin,
+ MRK_SIntMax,
+ MRK_FloatMin,
+ MRK_FloatMax
+ };
+
+ RecurrenceDescriptor()
+ : StartValue(nullptr), LoopExitInstr(nullptr), Kind(RK_NoRecurrence),
+ MinMaxKind(MRK_Invalid), UnsafeAlgebraInst(nullptr),
+ RecurrenceType(nullptr), IsSigned(false) {}
+
+ RecurrenceDescriptor(Value *Start, Instruction *Exit, RecurrenceKind K,
+ MinMaxRecurrenceKind MK, Instruction *UAI, Type *RT,
+ bool Signed, SmallPtrSetImpl<Instruction *> &CI)
+ : StartValue(Start), LoopExitInstr(Exit), Kind(K), MinMaxKind(MK),
+ UnsafeAlgebraInst(UAI), RecurrenceType(RT), IsSigned(Signed) {
+ CastInsts.insert(CI.begin(), CI.end());
+ }
+
+ /// This POD struct holds information about a potential recurrence operation.
+ class InstDesc {
+
+ public:
+ InstDesc(bool IsRecur, Instruction *I, Instruction *UAI = nullptr)
+ : IsRecurrence(IsRecur), PatternLastInst(I), MinMaxKind(MRK_Invalid),
+ UnsafeAlgebraInst(UAI) {}
+
+ InstDesc(Instruction *I, MinMaxRecurrenceKind K, Instruction *UAI = nullptr)
+ : IsRecurrence(true), PatternLastInst(I), MinMaxKind(K),
+ UnsafeAlgebraInst(UAI) {}
+
+ bool isRecurrence() { return IsRecurrence; }
+
+ bool hasUnsafeAlgebra() { return UnsafeAlgebraInst != nullptr; }
+
+ Instruction *getUnsafeAlgebraInst() { return UnsafeAlgebraInst; }
+
+ MinMaxRecurrenceKind getMinMaxKind() { return MinMaxKind; }
+
+ Instruction *getPatternInst() { return PatternLastInst; }
+
+ private:
+ // Is this instruction a recurrence candidate.
+ bool IsRecurrence;
+ // The last instruction in a min/max pattern (select of the select(icmp())
+ // pattern), or the current recurrence instruction otherwise.
+ Instruction *PatternLastInst;
+ // If this is a min/max pattern the comparison predicate.
+ MinMaxRecurrenceKind MinMaxKind;
+ // Recurrence has unsafe algebra.
+ Instruction *UnsafeAlgebraInst;
+ };
+
+ /// Returns a struct describing if the instruction 'I' can be a recurrence
+ /// variable of type 'Kind'. If the recurrence is a min/max pattern of
+ /// select(icmp()) this function advances the instruction pointer 'I' from the
+ /// compare instruction to the select instruction and stores this pointer in
+ /// 'PatternLastInst' member of the returned struct.
+ static InstDesc isRecurrenceInstr(Instruction *I, RecurrenceKind Kind,
+ InstDesc &Prev, bool HasFunNoNaNAttr);
+
+ /// Returns true if instruction I has multiple uses in Insts
+ static bool hasMultipleUsesOf(Instruction *I,
+ SmallPtrSetImpl<Instruction *> &Insts);
+
+ /// Returns true if all uses of the instruction I is within the Set.
+ static bool areAllUsesIn(Instruction *I, SmallPtrSetImpl<Instruction *> &Set);
+
+ /// Returns a struct describing if the instruction if the instruction is a
+ /// Select(ICmp(X, Y), X, Y) instruction pattern corresponding to a min(X, Y)
+ /// or max(X, Y).
+ static InstDesc isMinMaxSelectCmpPattern(Instruction *I, InstDesc &Prev);
+
+ /// Returns identity corresponding to the RecurrenceKind.
+ static Constant *getRecurrenceIdentity(RecurrenceKind K, Type *Tp);
+
+ /// Returns the opcode of binary operation corresponding to the
+ /// RecurrenceKind.
+ static unsigned getRecurrenceBinOp(RecurrenceKind Kind);
+
+ /// Returns a Min/Max operation corresponding to MinMaxRecurrenceKind.
+ static Value *createMinMaxOp(IRBuilder<> &Builder, MinMaxRecurrenceKind RK,
+ Value *Left, Value *Right);
+
+ /// Returns true if Phi is a reduction of type Kind and adds it to the
+ /// RecurrenceDescriptor.
+ static bool AddReductionVar(PHINode *Phi, RecurrenceKind Kind, Loop *TheLoop,
+ bool HasFunNoNaNAttr,
+ RecurrenceDescriptor &RedDes);
+
+ /// Returns true if Phi is a reduction in TheLoop. The RecurrenceDescriptor is
+ /// returned in RedDes.
+ static bool isReductionPHI(PHINode *Phi, Loop *TheLoop,
+ RecurrenceDescriptor &RedDes);
+
+ RecurrenceKind getRecurrenceKind() { return Kind; }
-BasicBlock *InsertPreheaderForLoop(Loop *L, Pass *P);
+ MinMaxRecurrenceKind getMinMaxRecurrenceKind() { return MinMaxKind; }
+
+ TrackingVH<Value> getRecurrenceStartValue() { return StartValue; }
+
+ Instruction *getLoopExitInstr() { return LoopExitInstr; }
+
+ /// Returns true if the recurrence has unsafe algebra which requires a relaxed
+ /// floating-point model.
+ bool hasUnsafeAlgebra() { return UnsafeAlgebraInst != nullptr; }
+
+ /// Returns first unsafe algebra instruction in the PHI node's use-chain.
+ Instruction *getUnsafeAlgebraInst() { return UnsafeAlgebraInst; }
+
+ /// Returns true if the recurrence kind is an integer kind.
+ static bool isIntegerRecurrenceKind(RecurrenceKind Kind);
+
+ /// Returns true if the recurrence kind is a floating point kind.
+ static bool isFloatingPointRecurrenceKind(RecurrenceKind Kind);
+
+ /// Returns true if the recurrence kind is an arithmetic kind.
+ static bool isArithmeticRecurrenceKind(RecurrenceKind Kind);
+
+ /// Determines if Phi may have been type-promoted. If Phi has a single user
+ /// that ANDs the Phi with a type mask, return the user. RT is updated to
+ /// account for the narrower bit width represented by the mask, and the AND
+ /// instruction is added to CI.
+ static Instruction *lookThroughAnd(PHINode *Phi, Type *&RT,
+ SmallPtrSetImpl<Instruction *> &Visited,
+ SmallPtrSetImpl<Instruction *> &CI);
+
+ /// Returns true if all the source operands of a recurrence are either
+ /// SExtInsts or ZExtInsts. This function is intended to be used with
+ /// lookThroughAnd to determine if the recurrence has been type-promoted. The
+ /// source operands are added to CI, and IsSigned is updated to indicate if
+ /// all source operands are SExtInsts.
+ static bool getSourceExtensionKind(Instruction *Start, Instruction *Exit,
+ Type *RT, bool &IsSigned,
+ SmallPtrSetImpl<Instruction *> &Visited,
+ SmallPtrSetImpl<Instruction *> &CI);
+
+ /// Returns the type of the recurrence. This type can be narrower than the
+ /// actual type of the Phi if the recurrence has been type-promoted.
+ Type *getRecurrenceType() { return RecurrenceType; }
+
+ /// Returns a reference to the instructions used for type-promoting the
+ /// recurrence.
+ SmallPtrSet<Instruction *, 8> &getCastInsts() { return CastInsts; }
+
+ /// Returns true if all source operands of the recurrence are SExtInsts.
+ bool isSigned() { return IsSigned; }
+
+private:
+ // The starting value of the recurrence.
+ // It does not have to be zero!
+ TrackingVH<Value> StartValue;
+ // The instruction who's value is used outside the loop.
+ Instruction *LoopExitInstr;
+ // The kind of the recurrence.
+ RecurrenceKind Kind;
+ // If this a min/max recurrence the kind of recurrence.
+ MinMaxRecurrenceKind MinMaxKind;
+ // First occurance of unasfe algebra in the PHI's use-chain.
+ Instruction *UnsafeAlgebraInst;
+ // The type of the recurrence.
+ Type *RecurrenceType;
+ // True if all source operands of the recurrence are SExtInsts.
+ bool IsSigned;
+ // Instructions used for type-promoting the recurrence.
+ SmallPtrSet<Instruction *, 8> CastInsts;
+};
+
+/// A struct for saving information about induction variables.
+class InductionDescriptor {
+public:
+ /// This enum represents the kinds of inductions that we support.
+ enum InductionKind {
+ IK_NoInduction, ///< Not an induction variable.
+ IK_IntInduction, ///< Integer induction variable. Step = C.
+ IK_PtrInduction ///< Pointer induction var. Step = C / sizeof(elem).
+ };
+
+public:
+ /// Default constructor - creates an invalid induction.
+ InductionDescriptor()
+ : StartValue(nullptr), IK(IK_NoInduction), StepValue(nullptr) {}
+
+ /// Get the consecutive direction. Returns:
+ /// 0 - unknown or non-consecutive.
+ /// 1 - consecutive and increasing.
+ /// -1 - consecutive and decreasing.
+ int getConsecutiveDirection() const;
+
+ /// Compute the transformed value of Index at offset StartValue using step
+ /// StepValue.
+ /// For integer induction, returns StartValue + Index * StepValue.
+ /// For pointer induction, returns StartValue[Index * StepValue].
+ /// FIXME: The newly created binary instructions should contain nsw/nuw
+ /// flags, which can be found from the original scalar operations.
+ Value *transform(IRBuilder<> &B, Value *Index) const;
+
+ Value *getStartValue() const { return StartValue; }
+ InductionKind getKind() const { return IK; }
+ ConstantInt *getStepValue() const { return StepValue; }
+
+ static bool isInductionPHI(PHINode *Phi, ScalarEvolution *SE,
+ InductionDescriptor &D);
+
+private:
+ /// Private constructor - used by \c isInductionPHI.
+ InductionDescriptor(Value *Start, InductionKind K, ConstantInt *Step);
+
+ /// Start value.
+ TrackingVH<Value> StartValue;
+ /// Induction kind.
+ InductionKind IK;
+ /// Step value.
+ ConstantInt *StepValue;
+};
+
+BasicBlock *InsertPreheaderForLoop(Loop *L, DominatorTree *DT, LoopInfo *LI,
+ bool PreserveLCSSA);
/// \brief Simplify each loop in a loop nest recursively.
///
/// This takes a potentially un-simplified loop L (and its children) and turns
-/// it into a simplified loop nest with preheaders and single backedges. It
-/// will optionally update \c AliasAnalysis and \c ScalarEvolution analyses if
-/// passed into it.
-bool simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI, Pass *PP,
- AliasAnalysis *AA = nullptr, ScalarEvolution *SE = nullptr);
+/// it into a simplified loop nest with preheaders and single backedges. It will
+/// update \c AliasAnalysis and \c ScalarEvolution analyses if they're non-null.
+bool simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI, ScalarEvolution *SE,
+ AssumptionCache *AC, bool PreserveLCSSA);
/// \brief Put loop into LCSSA form.
///
/// If ScalarEvolution is passed in, it will be preserved.
///
/// Returns true if any modifications are made to the loop.
-bool formLCSSA(Loop &L, DominatorTree &DT, ScalarEvolution *SE = nullptr);
+bool formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI,
+ ScalarEvolution *SE);
/// \brief Put a loop nest into LCSSA form.
///
/// If ScalarEvolution is passed in, it will be preserved.
///
/// Returns true if any modifications are made to the loop.
-bool formLCSSARecursively(Loop &L, DominatorTree &DT,
- ScalarEvolution *SE = nullptr);
+bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
+ ScalarEvolution *SE);
+
+/// \brief Walk the specified region of the CFG (defined by all blocks
+/// dominated by the specified block, and that are in the current loop) in
+/// reverse depth first order w.r.t the DominatorTree. This allows us to visit
+/// uses before definitions, allowing us to sink a loop body in one pass without
+/// iteration. Takes DomTreeNode, AliasAnalysis, LoopInfo, DominatorTree,
+/// DataLayout, TargetLibraryInfo, Loop, AliasSet information for all
+/// instructions of the loop and loop safety information as arguments.
+/// It returns changed status.
+bool sinkRegion(DomTreeNode *, AliasAnalysis *, LoopInfo *, DominatorTree *,
+ TargetLibraryInfo *, Loop *, AliasSetTracker *,
+ LICMSafetyInfo *);
+
+/// \brief Walk the specified region of the CFG (defined by all blocks
+/// dominated by the specified block, and that are in the current loop) in depth
+/// first order w.r.t the DominatorTree. This allows us to visit definitions
+/// before uses, allowing us to hoist a loop body in one pass without iteration.
+/// Takes DomTreeNode, AliasAnalysis, LoopInfo, DominatorTree, DataLayout,
+/// TargetLibraryInfo, Loop, AliasSet information for all instructions of the
+/// loop and loop safety information as arguments. It returns changed status.
+bool hoistRegion(DomTreeNode *, AliasAnalysis *, LoopInfo *, DominatorTree *,
+ TargetLibraryInfo *, Loop *, AliasSetTracker *,
+ LICMSafetyInfo *);
+
+/// \brief Try to promote memory values to scalars by sinking stores out of
+/// the loop and moving loads to before the loop. We do this by looping over
+/// the stores in the loop, looking for stores to Must pointers which are
+/// loop invariant. It takes AliasSet, Loop exit blocks vector, loop exit blocks
+/// insertion point vector, PredIteratorCache, LoopInfo, DominatorTree, Loop,
+/// AliasSet information for all instructions of the loop and loop safety
+/// information as arguments. It returns changed status.
+bool promoteLoopAccessesToScalars(AliasSet &, SmallVectorImpl<BasicBlock*> &,
+ SmallVectorImpl<Instruction*> &,
+ PredIteratorCache &, LoopInfo *,
+ DominatorTree *, Loop *, AliasSetTracker *,
+ LICMSafetyInfo *);
+
+/// \brief Computes safety information for a loop
+/// checks loop body & header for the possibility of may throw
+/// exception, it takes LICMSafetyInfo and loop as argument.
+/// Updates safety information in LICMSafetyInfo argument.
+void computeLICMSafetyInfo(LICMSafetyInfo *, Loop *);
+
+/// \brief Returns the instructions that use values defined in the loop.
+SmallVector<Instruction *, 8> findDefsUsedOutsideOfLoop(Loop *L);
}
#endif
projects / oota-llvm.git / blobdiff