linux-x64/clang/include/llvm/Analysis/TargetTransformInfo.h

//===- TargetTransformInfo.h ------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
/// This pass exposes codegen information to IR-level passes. Every
/// transformation that uses codegen information is broken into three parts:
/// 1. The IR-level analysis pass.
/// 2. The IR-level transformation interface which provides the needed
///    information.
/// 3. Codegen-level implementation which uses target-specific hooks.
///
/// This file defines #2, which is the interface that IR-level transformations
/// use for querying the codegen.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_TARGETTRANSFORMINFO_H
#define LLVM_ANALYSIS_TARGETTRANSFORMINFO_H

#include "llvm/ADT/Optional.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/AtomicOrdering.h"
#include "llvm/Support/DataTypes.h"
#include <functional>

namespace llvm {

namespace Intrinsic {
enum ID : unsigned;
}

class Function;
class GlobalValue;
class IntrinsicInst;
class LoadInst;
class Loop;
class SCEV;
class ScalarEvolution;
class StoreInst;
class SwitchInst;
class Type;
class User;
class Value;

/// \brief Information about a load/store intrinsic defined by the target.
struct MemIntrinsicInfo {
  /// This is the pointer that the intrinsic is loading from or storing to.
  /// If this is non-null, then analysis/optimization passes can assume that
  /// this intrinsic is functionally equivalent to a load/store from this
  /// pointer.
  Value *PtrVal = nullptr;

  // Ordering for atomic operations.
  AtomicOrdering Ordering = AtomicOrdering::NotAtomic;

  // Same Id is set by the target for corresponding load/store intrinsics.
  unsigned short MatchingId = 0;

  bool ReadMem = false;
  bool WriteMem = false;
  bool IsVolatile = false;

  bool isUnordered() const {
    return (Ordering == AtomicOrdering::NotAtomic ||
            Ordering == AtomicOrdering::Unordered) && !IsVolatile;
  }
};

/// \brief This pass provides access to the codegen interfaces that are needed
/// for IR-level transformations.
class TargetTransformInfo {
public:
  /// \brief Construct a TTI object using a type implementing the \c Concept
  /// API below.
  ///
  /// This is used by targets to construct a TTI wrapping their target-specific
  /// implementaion that encodes appropriate costs for their target.
  template <typename T> TargetTransformInfo(T Impl);

  /// \brief Construct a baseline TTI object using a minimal implementation of
  /// the \c Concept API below.
  ///
  /// The TTI implementation will reflect the information in the DataLayout
  /// provided if non-null.
  explicit TargetTransformInfo(const DataLayout &DL);

  // Provide move semantics.
  TargetTransformInfo(TargetTransformInfo &&Arg);
  TargetTransformInfo &operator=(TargetTransformInfo &&RHS);

  // We need to define the destructor out-of-line to define our sub-classes
  // out-of-line.
  ~TargetTransformInfo();

  /// \brief Handle the invalidation of this information.
  ///
  /// When used as a result of \c TargetIRAnalysis this method will be called
  /// when the function this was computed for changes. When it returns false,
  /// the information is preserved across those changes.
  bool invalidate(Function &, const PreservedAnalyses &,
                  FunctionAnalysisManager::Invalidator &) {
    // FIXME: We should probably in some way ensure that the subtarget
    // information for a function hasn't changed.
    return false;
  }

  /// \name Generic Target Information
  /// @{

  /// \brief The kind of cost model.
  ///
  /// There are several different cost models that can be customized by the
  /// target. The normalization of each cost model may be target specific.
  enum TargetCostKind {
    TCK_RecipThroughput, ///< Reciprocal throughput.
    TCK_Latency,         ///< The latency of instruction.
    TCK_CodeSize         ///< Instruction code size.
  };

  /// \brief Query the cost of a specified instruction.
  ///
  /// Clients should use this interface to query the cost of an existing
  /// instruction. The instruction must have a valid parent (basic block).
  ///
  /// Note, this method does not cache the cost calculation and it
  /// can be expensive in some cases.
  int getInstructionCost(const Instruction *I, enum TargetCostKind kind) const {
    switch (kind){
    case TCK_RecipThroughput:
      return getInstructionThroughput(I);

    case TCK_Latency:
      return getInstructionLatency(I);

    case TCK_CodeSize:
      return getUserCost(I);
    }
    llvm_unreachable("Unknown instruction cost kind");
  }

  /// \brief Underlying constants for 'cost' values in this interface.
  ///
  /// Many APIs in this interface return a cost. This enum defines the
  /// fundamental values that should be used to interpret (and produce) those
  /// costs. The costs are returned as an int rather than a member of this
  /// enumeration because it is expected that the cost of one IR instruction
  /// may have a multiplicative factor to it or otherwise won't fit directly
  /// into the enum. Moreover, it is common to sum or average costs which works
  /// better as simple integral values. Thus this enum only provides constants.
  /// Also note that the returned costs are signed integers to make it natural
  /// to add, subtract, and test with zero (a common boundary condition). It is
  /// not expected that 2^32 is a realistic cost to be modeling at any point.
  ///
  /// Note that these costs should usually reflect the intersection of code-size
  /// cost and execution cost. A free instruction is typically one that folds
  /// into another instruction. For example, reg-to-reg moves can often be
  /// skipped by renaming the registers in the CPU, but they still are encoded
  /// and thus wouldn't be considered 'free' here.
  enum TargetCostConstants {
    TCC_Free = 0,     ///< Expected to fold away in lowering.
    TCC_Basic = 1,    ///< The cost of a typical 'add' instruction.
    TCC_Expensive = 4 ///< The cost of a 'div' instruction on x86.
  };

  /// \brief Estimate the cost of a specific operation when lowered.
  ///
  /// Note that this is designed to work on an arbitrary synthetic opcode, and
  /// thus work for hypothetical queries before an instruction has even been
  /// formed. However, this does *not* work for GEPs, and must not be called
  /// for a GEP instruction. Instead, use the dedicated getGEPCost interface as
  /// analyzing a GEP's cost required more information.
  ///
  /// Typically only the result type is required, and the operand type can be
  /// omitted. However, if the opcode is one of the cast instructions, the
  /// operand type is required.
  ///
  /// The returned cost is defined in terms of \c TargetCostConstants, see its
  /// comments for a detailed explanation of the cost values.
  int getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy = nullptr) const;

  /// \brief Estimate the cost of a GEP operation when lowered.
  ///
  /// The contract for this function is the same as \c getOperationCost except
  /// that it supports an interface that provides extra information specific to
  /// the GEP operation.
  int getGEPCost(Type *PointeeType, const Value *Ptr,
                 ArrayRef<const Value *> Operands) const;

  /// \brief Estimate the cost of a EXT operation when lowered.
  ///
  /// The contract for this function is the same as \c getOperationCost except
  /// that it supports an interface that provides extra information specific to
  /// the EXT operation.
  int getExtCost(const Instruction *I, const Value *Src) const;

  /// \brief Estimate the cost of a function call when lowered.
  ///
  /// The contract for this is the same as \c getOperationCost except that it
  /// supports an interface that provides extra information specific to call
  /// instructions.
  ///
  /// This is the most basic query for estimating call cost: it only knows the
  /// function type and (potentially) the number of arguments at the call site.
  /// The latter is only interesting for varargs function types.
  int getCallCost(FunctionType *FTy, int NumArgs = -1) const;

  /// \brief Estimate the cost of calling a specific function when lowered.
  ///
  /// This overload adds the ability to reason about the particular function
  /// being called in the event it is a library call with special lowering.
  int getCallCost(const Function *F, int NumArgs = -1) const;

  /// \brief Estimate the cost of calling a specific function when lowered.
  ///
  /// This overload allows specifying a set of candidate argument values.
  int getCallCost(const Function *F, ArrayRef<const Value *> Arguments) const;

  /// \returns A value by which our inlining threshold should be multiplied.
  /// This is primarily used to bump up the inlining threshold wholesale on
  /// targets where calls are unusually expensive.
  ///
  /// TODO: This is a rather blunt instrument.  Perhaps altering the costs of
  /// individual classes of instructions would be better.
  unsigned getInliningThresholdMultiplier() const;

  /// \brief Estimate the cost of an intrinsic when lowered.
  ///
  /// Mirrors the \c getCallCost method but uses an intrinsic identifier.
  int getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
                       ArrayRef<Type *> ParamTys) const;

  /// \brief Estimate the cost of an intrinsic when lowered.
  ///
  /// Mirrors the \c getCallCost method but uses an intrinsic identifier.
  int getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
                       ArrayRef<const Value *> Arguments) const;

  /// \return The estimated number of case clusters when lowering \p 'SI'.
  /// \p JTSize Set a jump table size only when \p SI is suitable for a jump
  /// table.
  unsigned getEstimatedNumberOfCaseClusters(const SwitchInst &SI,
                                            unsigned &JTSize) const;

  /// \brief Estimate the cost of a given IR user when lowered.
  ///
  /// This can estimate the cost of either a ConstantExpr or Instruction when
  /// lowered. It has two primary advantages over the \c getOperationCost and
  /// \c getGEPCost above, and one significant disadvantage: it can only be
  /// used when the IR construct has already been formed.
  ///
  /// The advantages are that it can inspect the SSA use graph to reason more
  /// accurately about the cost. For example, all-constant-GEPs can often be
  /// folded into a load or other instruction, but if they are used in some
  /// other context they may not be folded. This routine can distinguish such
  /// cases.
  ///
  /// \p Operands is a list of operands which can be a result of transformations
  /// of the current operands. The number of the operands on the list must equal
  /// to the number of the current operands the IR user has. Their order on the
  /// list must be the same as the order of the current operands the IR user
  /// has.
  ///
  /// The returned cost is defined in terms of \c TargetCostConstants, see its
  /// comments for a detailed explanation of the cost values.
  int getUserCost(const User *U, ArrayRef<const Value *> Operands) const;

  /// \brief This is a helper function which calls the two-argument getUserCost
  /// with \p Operands which are the current operands U has.
  int getUserCost(const User *U) const {
    SmallVector<const Value *, 4> Operands(U->value_op_begin(),
                                           U->value_op_end());
    return getUserCost(U, Operands);
  }

  /// \brief Return true if branch divergence exists.
  ///
  /// Branch divergence has a significantly negative impact on GPU performance
  /// when threads in the same wavefront take different paths due to conditional
  /// branches.
  bool hasBranchDivergence() const;

  /// \brief Returns whether V is a source of divergence.
  ///
  /// This function provides the target-dependent information for
  /// the target-independent DivergenceAnalysis. DivergenceAnalysis first
  /// builds the dependency graph, and then runs the reachability algorithm
  /// starting with the sources of divergence.
  bool isSourceOfDivergence(const Value *V) const;

  // \brief Returns true for the target specific
  // set of operations which produce uniform result
  // even taking non-unform arguments
  bool isAlwaysUniform(const Value *V) const;

  /// Returns the address space ID for a target's 'flat' address space. Note
  /// this is not necessarily the same as addrspace(0), which LLVM sometimes
  /// refers to as the generic address space. The flat address space is a
  /// generic address space that can be used access multiple segments of memory
  /// with different address spaces. Access of a memory location through a
  /// pointer with this address space is expected to be legal but slower
  /// compared to the same memory location accessed through a pointer with a
  /// different address space.
  //
  /// This is for targets with different pointer representations which can
  /// be converted with the addrspacecast instruction. If a pointer is converted
  /// to this address space, optimizations should attempt to replace the access
  /// with the source address space.
  ///
  /// \returns ~0u if the target does not have such a flat address space to
  /// optimize away.
  unsigned getFlatAddressSpace() const;

  /// \brief Test whether calls to a function lower to actual program function
  /// calls.
  ///
  /// The idea is to test whether the program is likely to require a 'call'
  /// instruction or equivalent in order to call the given function.
  ///
  /// FIXME: It's not clear that this is a good or useful query API. Client's
  /// should probably move to simpler cost metrics using the above.
  /// Alternatively, we could split the cost interface into distinct code-size
  /// and execution-speed costs. This would allow modelling the core of this
  /// query more accurately as a call is a single small instruction, but
  /// incurs significant execution cost.
  bool isLoweredToCall(const Function *F) const;

  struct LSRCost {
    /// TODO: Some of these could be merged. Also, a lexical ordering
    /// isn't always optimal.
    unsigned Insns;
    unsigned NumRegs;
    unsigned AddRecCost;
    unsigned NumIVMuls;
    unsigned NumBaseAdds;
    unsigned ImmCost;
    unsigned SetupCost;
    unsigned ScaleCost;
  };

  /// Parameters that control the generic loop unrolling transformation.
  struct UnrollingPreferences {
    /// The cost threshold for the unrolled loop. Should be relative to the
    /// getUserCost values returned by this API, and the expectation is that
    /// the unrolled loop's instructions when run through that interface should
    /// not exceed this cost. However, this is only an estimate. Also, specific
    /// loops may be unrolled even with a cost above this threshold if deemed
    /// profitable. Set this to UINT_MAX to disable the loop body cost
    /// restriction.
    unsigned Threshold;
    /// If complete unrolling will reduce the cost of the loop, we will boost
    /// the Threshold by a certain percent to allow more aggressive complete
    /// unrolling. This value provides the maximum boost percentage that we
    /// can apply to Threshold (The value should be no less than 100).
    /// BoostedThreshold = Threshold * min(RolledCost / UnrolledCost,
    ///                                    MaxPercentThresholdBoost / 100)
    /// E.g. if complete unrolling reduces the loop execution time by 50%
    /// then we boost the threshold by the factor of 2x. If unrolling is not
    /// expected to reduce the running time, then we do not increase the
    /// threshold.
    unsigned MaxPercentThresholdBoost;
    /// The cost threshold for the unrolled loop when optimizing for size (set
    /// to UINT_MAX to disable).
    unsigned OptSizeThreshold;
    /// The cost threshold for the unrolled loop, like Threshold, but used
    /// for partial/runtime unrolling (set to UINT_MAX to disable).
    unsigned PartialThreshold;
    /// The cost threshold for the unrolled loop when optimizing for size, like
    /// OptSizeThreshold, but used for partial/runtime unrolling (set to
    /// UINT_MAX to disable).
    unsigned PartialOptSizeThreshold;
    /// A forced unrolling factor (the number of concatenated bodies of the
    /// original loop in the unrolled loop body). When set to 0, the unrolling
    /// transformation will select an unrolling factor based on the current cost
    /// threshold and other factors.
    unsigned Count;
    /// A forced peeling factor (the number of bodied of the original loop
    /// that should be peeled off before the loop body). When set to 0, the
    /// unrolling transformation will select a peeling factor based on profile
    /// information and other factors.
    unsigned PeelCount;
    /// Default unroll count for loops with run-time trip count.
    unsigned DefaultUnrollRuntimeCount;
    // Set the maximum unrolling factor. The unrolling factor may be selected
    // using the appropriate cost threshold, but may not exceed this number
    // (set to UINT_MAX to disable). This does not apply in cases where the
    // loop is being fully unrolled.
    unsigned MaxCount;
    /// Set the maximum unrolling factor for full unrolling. Like MaxCount, but
    /// applies even if full unrolling is selected. This allows a target to fall
    /// back to Partial unrolling if full unrolling is above FullUnrollMaxCount.
    unsigned FullUnrollMaxCount;
    // Represents number of instructions optimized when "back edge"
    // becomes "fall through" in unrolled loop.
    // For now we count a conditional branch on a backedge and a comparison
    // feeding it.
    unsigned BEInsns;
    /// Allow partial unrolling (unrolling of loops to expand the size of the
    /// loop body, not only to eliminate small constant-trip-count loops).
    bool Partial;
    /// Allow runtime unrolling (unrolling of loops to expand the size of the
    /// loop body even when the number of loop iterations is not known at
    /// compile time).
    bool Runtime;
    /// Allow generation of a loop remainder (extra iterations after unroll).
    bool AllowRemainder;
    /// Allow emitting expensive instructions (such as divisions) when computing
    /// the trip count of a loop for runtime unrolling.
    bool AllowExpensiveTripCount;
    /// Apply loop unroll on any kind of loop
    /// (mainly to loops that fail runtime unrolling).
    bool Force;
    /// Allow using trip count upper bound to unroll loops.
    bool UpperBound;
    /// Allow peeling off loop iterations for loops with low dynamic tripcount.
    bool AllowPeeling;
    /// Allow unrolling of all the iterations of the runtime loop remainder.
    bool UnrollRemainder;
  };

  /// \brief Get target-customized preferences for the generic loop unrolling
  /// transformation. The caller will initialize UP with the current
  /// target-independent defaults.
  void getUnrollingPreferences(Loop *L, ScalarEvolution &,
                               UnrollingPreferences &UP) const;

  /// @}

  /// \name Scalar Target Information
  /// @{

  /// \brief Flags indicating the kind of support for population count.
  ///
  /// Compared to the SW implementation, HW support is supposed to
  /// significantly boost the performance when the population is dense, and it
  /// may or may not degrade performance if the population is sparse. A HW
  /// support is considered as "Fast" if it can outperform, or is on a par
  /// with, SW implementation when the population is sparse; otherwise, it is
  /// considered as "Slow".
  enum PopcntSupportKind { PSK_Software, PSK_SlowHardware, PSK_FastHardware };

  /// \brief Return true if the specified immediate is legal add immediate, that
  /// is the target has add instructions which can add a register with the
  /// immediate without having to materialize the immediate into a register.
  bool isLegalAddImmediate(int64_t Imm) const;

  /// \brief Return true if the specified immediate is legal icmp immediate,
  /// that is the target has icmp instructions which can compare a register
  /// against the immediate without having to materialize the immediate into a
  /// register.
  bool isLegalICmpImmediate(int64_t Imm) const;

  /// \brief Return true if the addressing mode represented by AM is legal for
  /// this target, for a load/store of the specified type.
  /// The type may be VoidTy, in which case only return true if the addressing
  /// mode is legal for a load/store of any legal type.
  /// If target returns true in LSRWithInstrQueries(), I may be valid.
  /// TODO: Handle pre/postinc as well.
  bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
                             bool HasBaseReg, int64_t Scale,
                             unsigned AddrSpace = 0,
                             Instruction *I = nullptr) const;

  /// \brief Return true if LSR cost of C1 is lower than C1.
  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
                     TargetTransformInfo::LSRCost &C2) const;

  /// Return true if the target can fuse a compare and branch.
  /// Loop-strength-reduction (LSR) uses that knowledge to adjust its cost
  /// calculation for the instructions in a loop.
  bool canMacroFuseCmp() const;

  /// \return True is LSR should make efforts to create/preserve post-inc
  /// addressing mode expressions.
  bool shouldFavorPostInc() const;

  /// \brief Return true if the target supports masked load/store
  /// AVX2 and AVX-512 targets allow masks for consecutive load and store
  bool isLegalMaskedStore(Type *DataType) const;
  bool isLegalMaskedLoad(Type *DataType) const;

  /// \brief Return true if the target supports masked gather/scatter
  /// AVX-512 fully supports gather and scatter for vectors with 32 and 64
  /// bits scalar type.
  bool isLegalMaskedScatter(Type *DataType) const;
  bool isLegalMaskedGather(Type *DataType) const;

  /// Return true if the target has a unified operation to calculate division
  /// and remainder. If so, the additional implicit multiplication and
  /// subtraction required to calculate a remainder from division are free. This
  /// can enable more aggressive transformations for division and remainder than
  /// would typically be allowed using throughput or size cost models.
  bool hasDivRemOp(Type *DataType, bool IsSigned) const;

  /// Return true if the given instruction (assumed to be a memory access
  /// instruction) has a volatile variant. If that's the case then we can avoid
  /// addrspacecast to generic AS for volatile loads/stores. Default
  /// implementation returns false, which prevents address space inference for
  /// volatile loads/stores.
  bool hasVolatileVariant(Instruction *I, unsigned AddrSpace) const;

  /// Return true if target doesn't mind addresses in vectors.
  bool prefersVectorizedAddressing() const;

  /// \brief Return the cost of the scaling factor used in the addressing
  /// mode represented by AM for this target, for a load/store
  /// of the specified type.
  /// If the AM is supported, the return value must be >= 0.
  /// If the AM is not supported, it returns a negative value.
  /// TODO: Handle pre/postinc as well.
  int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
                           bool HasBaseReg, int64_t Scale,
                           unsigned AddrSpace = 0) const;

  /// \brief Return true if the loop strength reduce pass should make
  /// Instruction* based TTI queries to isLegalAddressingMode(). This is
  /// needed on SystemZ, where e.g. a memcpy can only have a 12 bit unsigned
  /// immediate offset and no index register.
  bool LSRWithInstrQueries() const;

  /// \brief Return true if it's free to truncate a value of type Ty1 to type
  /// Ty2. e.g. On x86 it's free to truncate a i32 value in register EAX to i16
  /// by referencing its sub-register AX.
  bool isTruncateFree(Type *Ty1, Type *Ty2) const;

  /// \brief Return true if it is profitable to hoist instruction in the
  /// then/else to before if.
  bool isProfitableToHoist(Instruction *I) const;

  bool useAA() const;

  /// \brief Return true if this type is legal.
  bool isTypeLegal(Type *Ty) const;

  /// \brief Returns the target's jmp_buf alignment in bytes.
  unsigned getJumpBufAlignment() const;

  /// \brief Returns the target's jmp_buf size in bytes.
  unsigned getJumpBufSize() const;

  /// \brief Return true if switches should be turned into lookup tables for the
  /// target.
  bool shouldBuildLookupTables() const;

  /// \brief Return true if switches should be turned into lookup tables
  /// containing this constant value for the target.
  bool shouldBuildLookupTablesForConstant(Constant *C) const;

  /// \brief Return true if the input function which is cold at all call sites,
  ///  should use coldcc calling convention.
  bool useColdCCForColdCall(Function &F) const;

  unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) const;

  unsigned getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
                                            unsigned VF) const;

  /// If target has efficient vector element load/store instructions, it can
  /// return true here so that insertion/extraction costs are not added to
  /// the scalarization cost of a load/store.
  bool supportsEfficientVectorElementLoadStore() const;

  /// \brief Don't restrict interleaved unrolling to small loops.
  bool enableAggressiveInterleaving(bool LoopHasReductions) const;

  /// \brief If not nullptr, enable inline expansion of memcmp. IsZeroCmp is
  /// true if this is the expansion of memcmp(p1, p2, s) == 0.
  struct MemCmpExpansionOptions {
    // The list of available load sizes (in bytes), sorted in decreasing order.
    SmallVector<unsigned, 8> LoadSizes;
  };
  const MemCmpExpansionOptions *enableMemCmpExpansion(bool IsZeroCmp) const;

  /// \brief Enable matching of interleaved access groups.
  bool enableInterleavedAccessVectorization() const;

  /// \brief Indicate that it is potentially unsafe to automatically vectorize
  /// floating-point operations because the semantics of vector and scalar
  /// floating-point semantics may differ. For example, ARM NEON v7 SIMD math
  /// does not support IEEE-754 denormal numbers, while depending on the
  /// platform, scalar floating-point math does.
  /// This applies to floating-point math operations and calls, not memory
  /// operations, shuffles, or casts.
  bool isFPVectorizationPotentiallyUnsafe() const;

  /// \brief Determine if the target supports unaligned memory accesses.
  bool allowsMisalignedMemoryAccesses(LLVMContext &Context,
                                      unsigned BitWidth, unsigned AddressSpace = 0,
                                      unsigned Alignment = 1,
                                      bool *Fast = nullptr) const;

  /// \brief Return hardware support for population count.
  PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) const;

  /// \brief Return true if the hardware has a fast square-root instruction.
  bool haveFastSqrt(Type *Ty) const;

  /// Return true if it is faster to check if a floating-point value is NaN
  /// (or not-NaN) versus a comparison against a constant FP zero value.
  /// Targets should override this if materializing a 0.0 for comparison is
  /// generally as cheap as checking for ordered/unordered.
  bool isFCmpOrdCheaperThanFCmpZero(Type *Ty) const;

  /// \brief Return the expected cost of supporting the floating point operation
  /// of the specified type.
  int getFPOpCost(Type *Ty) const;

  /// \brief Return the expected cost of materializing for the given integer
  /// immediate of the specified type.
  int getIntImmCost(const APInt &Imm, Type *Ty) const;

  /// \brief Return the expected cost of materialization for the given integer
  /// immediate of the specified type for a given instruction. The cost can be
  /// zero if the immediate can be folded into the specified instruction.
  int getIntImmCost(unsigned Opc, unsigned Idx, const APInt &Imm,
                    Type *Ty) const;
  int getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
                    Type *Ty) const;

  /// \brief Return the expected cost for the given integer when optimising
  /// for size. This is different than the other integer immediate cost
  /// functions in that it is subtarget agnostic. This is useful when you e.g.
  /// target one ISA such as Aarch32 but smaller encodings could be possible
  /// with another such as Thumb. This return value is used as a penalty when
  /// the total costs for a constant is calculated (the bigger the cost, the
  /// more beneficial constant hoisting is).
  int getIntImmCodeSizeCost(unsigned Opc, unsigned Idx, const APInt &Imm,
                            Type *Ty) const;
  /// @}

  /// \name Vector Target Information
  /// @{

  /// \brief The various kinds of shuffle patterns for vector queries.
  enum ShuffleKind {
    SK_Broadcast,       ///< Broadcast element 0 to all other elements.
    SK_Reverse,         ///< Reverse the order of the vector.
    SK_Alternate,       ///< Choose alternate elements from vector.
    SK_InsertSubvector, ///< InsertSubvector. Index indicates start offset.
    SK_ExtractSubvector,///< ExtractSubvector Index indicates start offset.
    SK_PermuteTwoSrc,   ///< Merge elements from two source vectors into one
                        ///< with any shuffle mask.
    SK_PermuteSingleSrc ///< Shuffle elements of single source vector with any
                        ///< shuffle mask.
  };

  /// \brief Additional information about an operand's possible values.
  enum OperandValueKind {
    OK_AnyValue,               // Operand can have any value.
    OK_UniformValue,           // Operand is uniform (splat of a value).
    OK_UniformConstantValue,   // Operand is uniform constant.
    OK_NonUniformConstantValue // Operand is a non uniform constant value.
  };

  /// \brief Additional properties of an operand's values.
  enum OperandValueProperties { OP_None = 0, OP_PowerOf2 = 1 };

  /// \return The number of scalar or vector registers that the target has.
  /// If 'Vectors' is true, it returns the number of vector registers. If it is
  /// set to false, it returns the number of scalar registers.
  unsigned getNumberOfRegisters(bool Vector) const;

  /// \return The width of the largest scalar or vector register type.
  unsigned getRegisterBitWidth(bool Vector) const;

  /// \return The width of the smallest vector register type.
  unsigned getMinVectorRegisterBitWidth() const;

  /// \return True if the vectorization factor should be chosen to
  /// make the vector of the smallest element type match the size of a
  /// vector register. For wider element types, this could result in
  /// creating vectors that span multiple vector registers.
  /// If false, the vectorization factor will be chosen based on the
  /// size of the widest element type.
  bool shouldMaximizeVectorBandwidth(bool OptSize) const;

  /// \return True if it should be considered for address type promotion.
  /// \p AllowPromotionWithoutCommonHeader Set true if promoting \p I is
  /// profitable without finding other extensions fed by the same input.
  bool shouldConsiderAddressTypePromotion(
      const Instruction &I, bool &AllowPromotionWithoutCommonHeader) const;

  /// \return The size of a cache line in bytes.
  unsigned getCacheLineSize() const;

  /// The possible cache levels
  enum class CacheLevel {
    L1D,   // The L1 data cache
    L2D,   // The L2 data cache

    // We currently do not model L3 caches, as their sizes differ widely between
    // microarchitectures. Also, we currently do not have a use for L3 cache
    // size modeling yet.
  };

  /// \return The size of the cache level in bytes, if available.
  llvm::Optional<unsigned> getCacheSize(CacheLevel Level) const;

  /// \return The associativity of the cache level, if available.
  llvm::Optional<unsigned> getCacheAssociativity(CacheLevel Level) const;

  /// \return How much before a load we should place the prefetch instruction.
  /// This is currently measured in number of instructions.
  unsigned getPrefetchDistance() const;

  /// \return Some HW prefetchers can handle accesses up to a certain constant
  /// stride.  This is the minimum stride in bytes where it makes sense to start
  /// adding SW prefetches.  The default is 1, i.e. prefetch with any stride.
  unsigned getMinPrefetchStride() const;

  /// \return The maximum number of iterations to prefetch ahead.  If the
  /// required number of iterations is more than this number, no prefetching is
  /// performed.
  unsigned getMaxPrefetchIterationsAhead() const;

  /// \return The maximum interleave factor that any transform should try to
  /// perform for this target. This number depends on the level of parallelism
  /// and the number of execution units in the CPU.
  unsigned getMaxInterleaveFactor(unsigned VF) const;

  /// This is an approximation of reciprocal throughput of a math/logic op.
  /// A higher cost indicates less expected throughput.
  /// From Agner Fog's guides, reciprocal throughput is "the average number of
  /// clock cycles per instruction when the instructions are not part of a
  /// limiting dependency chain."
  /// Therefore, costs should be scaled to account for multiple execution units
  /// on the target that can process this type of instruction. For example, if
  /// there are 5 scalar integer units and 2 vector integer units that can
  /// calculate an 'add' in a single cycle, this model should indicate that the
  /// cost of the vector add instruction is 2.5 times the cost of the scalar
  /// add instruction.
  /// \p Args is an optional argument which holds the instruction operands
  /// values so the TTI can analyze those values searching for special
  /// cases or optimizations based on those values.
  int getArithmeticInstrCost(
      unsigned Opcode, Type *Ty, OperandValueKind Opd1Info = OK_AnyValue,
      OperandValueKind Opd2Info = OK_AnyValue,
      OperandValueProperties Opd1PropInfo = OP_None,
      OperandValueProperties Opd2PropInfo = OP_None,
      ArrayRef<const Value *> Args = ArrayRef<const Value *>()) const;

  /// \return The cost of a shuffle instruction of kind Kind and of type Tp.
  /// The index and subtype parameters are used by the subvector insertion and
  /// extraction shuffle kinds.
  int getShuffleCost(ShuffleKind Kind, Type *Tp, int Index = 0,
                     Type *SubTp = nullptr) const;

  /// \return The expected cost of cast instructions, such as bitcast, trunc,
  /// zext, etc. If there is an existing instruction that holds Opcode, it
  /// may be passed in the 'I' parameter.
  int getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
                       const Instruction *I = nullptr) const;

  /// \return The expected cost of a sign- or zero-extended vector extract. Use
  /// -1 to indicate that there is no information about the index value.
  int getExtractWithExtendCost(unsigned Opcode, Type *Dst, VectorType *VecTy,
                               unsigned Index = -1) const;

  /// \return The expected cost of control-flow related instructions such as
  /// Phi, Ret, Br.
  int getCFInstrCost(unsigned Opcode) const;

  /// \returns The expected cost of compare and select instructions. If there
  /// is an existing instruction that holds Opcode, it may be passed in the
  /// 'I' parameter.
  int getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
                 Type *CondTy = nullptr, const Instruction *I = nullptr) const;

  /// \return The expected cost of vector Insert and Extract.
  /// Use -1 to indicate that there is no information on the index value.
  int getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index = -1) const;

  /// \return The cost of Load and Store instructions.
  int getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
                      unsigned AddressSpace, const Instruction *I = nullptr) const;

  /// \return The cost of masked Load and Store instructions.
  int getMaskedMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
                            unsigned AddressSpace) const;

  /// \return The cost of Gather or Scatter operation
  /// \p Opcode - is a type of memory access Load or Store
  /// \p DataTy - a vector type of the data to be loaded or stored
  /// \p Ptr - pointer [or vector of pointers] - address[es] in memory
  /// \p VariableMask - true when the memory access is predicated with a mask
  ///                   that is not a compile-time constant
  /// \p Alignment - alignment of single element
  int getGatherScatterOpCost(unsigned Opcode, Type *DataTy, Value *Ptr,
                             bool VariableMask, unsigned Alignment) const;

  /// \return The cost of the interleaved memory operation.
  /// \p Opcode is the memory operation code
  /// \p VecTy is the vector type of the interleaved access.
  /// \p Factor is the interleave factor
  /// \p Indices is the indices for interleaved load members (as interleaved
  ///    load allows gaps)
  /// \p Alignment is the alignment of the memory operation
  /// \p AddressSpace is address space of the pointer.
  int getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy, unsigned Factor,
                                 ArrayRef<unsigned> Indices, unsigned Alignment,
                                 unsigned AddressSpace) const;

  /// \brief Calculate the cost of performing a vector reduction.
  ///
  /// This is the cost of reducing the vector value of type \p Ty to a scalar
  /// value using the operation denoted by \p Opcode. The form of the reduction
  /// can either be a pairwise reduction or a reduction that splits the vector
  /// at every reduction level.
  ///
  /// Pairwise:
  ///  (v0, v1, v2, v3)
  ///  ((v0+v1), (v2+v3), undef, undef)
  /// Split:
  ///  (v0, v1, v2, v3)
  ///  ((v0+v2), (v1+v3), undef, undef)
  int getArithmeticReductionCost(unsigned Opcode, Type *Ty,
                                 bool IsPairwiseForm) const;
  int getMinMaxReductionCost(Type *Ty, Type *CondTy, bool IsPairwiseForm,
                             bool IsUnsigned) const;

  /// \returns The cost of Intrinsic instructions. Analyses the real arguments.
  /// Three cases are handled: 1. scalar instruction 2. vector instruction
  /// 3. scalar instruction which is to be vectorized with VF.
  int getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
                            ArrayRef<Value *> Args, FastMathFlags FMF,
                            unsigned VF = 1) const;

  /// \returns The cost of Intrinsic instructions. Types analysis only.
  /// If ScalarizationCostPassed is UINT_MAX, the cost of scalarizing the
  /// arguments and the return value will be computed based on types.
  int getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
                            ArrayRef<Type *> Tys, FastMathFlags FMF,
                            unsigned ScalarizationCostPassed = UINT_MAX) const;

  /// \returns The cost of Call instructions.
  int getCallInstrCost(Function *F, Type *RetTy, ArrayRef<Type *> Tys) const;

  /// \returns The number of pieces into which the provided type must be
  /// split during legalization. Zero is returned when the answer is unknown.
  unsigned getNumberOfParts(Type *Tp) const;

  /// \returns The cost of the address computation. For most targets this can be
  /// merged into the instruction indexing mode. Some targets might want to
  /// distinguish between address computation for memory operations on vector
  /// types and scalar types. Such targets should override this function.
  /// The 'SE' parameter holds pointer for the scalar evolution object which
  /// is used in order to get the Ptr step value in case of constant stride.
  /// The 'Ptr' parameter holds SCEV of the access pointer.
  int getAddressComputationCost(Type *Ty, ScalarEvolution *SE = nullptr,
                                const SCEV *Ptr = nullptr) const;

  /// \returns The cost, if any, of keeping values of the given types alive
  /// over a callsite.
  ///
  /// Some types may require the use of register classes that do not have
  /// any callee-saved registers, so would require a spill and fill.
  unsigned getCostOfKeepingLiveOverCall(ArrayRef<Type *> Tys) const;

  /// \returns True if the intrinsic is a supported memory intrinsic.  Info
  /// will contain additional information - whether the intrinsic may write
  /// or read to memory, volatility and the pointer.  Info is undefined
  /// if false is returned.
  bool getTgtMemIntrinsic(IntrinsicInst *Inst, MemIntrinsicInfo &Info) const;

  /// \returns The maximum element size, in bytes, for an element
  /// unordered-atomic memory intrinsic.
  unsigned getAtomicMemIntrinsicMaxElementSize() const;

  /// \returns A value which is the result of the given memory intrinsic.  New
  /// instructions may be created to extract the result from the given intrinsic
  /// memory operation.  Returns nullptr if the target cannot create a result
  /// from the given intrinsic.
  Value *getOrCreateResultFromMemIntrinsic(IntrinsicInst *Inst,
                                           Type *ExpectedType) const;

  /// \returns The type to use in a loop expansion of a memcpy call.
  Type *getMemcpyLoopLoweringType(LLVMContext &Context, Value *Length,
                                  unsigned SrcAlign, unsigned DestAlign) const;

  /// \param[out] OpsOut The operand types to copy RemainingBytes of memory.
  /// \param RemainingBytes The number of bytes to copy.
  ///
  /// Calculates the operand types to use when copying \p RemainingBytes of
  /// memory, where source and destination alignments are \p SrcAlign and
  /// \p DestAlign respectively.
  void getMemcpyLoopResidualLoweringType(SmallVectorImpl<Type *> &OpsOut,
                                         LLVMContext &Context,
                                         unsigned RemainingBytes,
                                         unsigned SrcAlign,
                                         unsigned DestAlign) const;

  /// \returns True if the two functions have compatible attributes for inlining
  /// purposes.
  bool areInlineCompatible(const Function *Caller,
                           const Function *Callee) const;

  /// \brief The type of load/store indexing.
  enum MemIndexedMode {
    MIM_Unindexed,  ///< No indexing.
    MIM_PreInc,     ///< Pre-incrementing.
    MIM_PreDec,     ///< Pre-decrementing.
    MIM_PostInc,    ///< Post-incrementing.
    MIM_PostDec     ///< Post-decrementing.
  };

  /// \returns True if the specified indexed load for the given type is legal.
  bool isIndexedLoadLegal(enum MemIndexedMode Mode, Type *Ty) const;

  /// \returns True if the specified indexed store for the given type is legal.
  bool isIndexedStoreLegal(enum MemIndexedMode Mode, Type *Ty) const;

  /// \returns The bitwidth of the largest vector type that should be used to
  /// load/store in the given address space.
  unsigned getLoadStoreVecRegBitWidth(unsigned AddrSpace) const;

  /// \returns True if the load instruction is legal to vectorize.
  bool isLegalToVectorizeLoad(LoadInst *LI) const;

  /// \returns True if the store instruction is legal to vectorize.
  bool isLegalToVectorizeStore(StoreInst *SI) const;

  /// \returns True if it is legal to vectorize the given load chain.
  bool isLegalToVectorizeLoadChain(unsigned ChainSizeInBytes,
                                   unsigned Alignment,
                                   unsigned AddrSpace) const;

  /// \returns True if it is legal to vectorize the given store chain.
  bool isLegalToVectorizeStoreChain(unsigned ChainSizeInBytes,
                                    unsigned Alignment,
                                    unsigned AddrSpace) const;

  /// \returns The new vector factor value if the target doesn't support \p
  /// SizeInBytes loads or has a better vector factor.
  unsigned getLoadVectorFactor(unsigned VF, unsigned LoadSize,
                               unsigned ChainSizeInBytes,
                               VectorType *VecTy) const;

  /// \returns The new vector factor value if the target doesn't support \p
  /// SizeInBytes stores or has a better vector factor.
  unsigned getStoreVectorFactor(unsigned VF, unsigned StoreSize,
                                unsigned ChainSizeInBytes,
                                VectorType *VecTy) const;

  /// Flags describing the kind of vector reduction.
  struct ReductionFlags {
    ReductionFlags() : IsMaxOp(false), IsSigned(false), NoNaN(false) {}
    bool IsMaxOp;  ///< If the op a min/max kind, true if it's a max operation.
    bool IsSigned; ///< Whether the operation is a signed int reduction.
    bool NoNaN;    ///< If op is an fp min/max, whether NaNs may be present.
  };

  /// \returns True if the target wants to handle the given reduction idiom in
  /// the intrinsics form instead of the shuffle form.
  bool useReductionIntrinsic(unsigned Opcode, Type *Ty,
                             ReductionFlags Flags) const;

  /// \returns True if the target wants to expand the given reduction intrinsic
  /// into a shuffle sequence.
  bool shouldExpandReduction(const IntrinsicInst *II) const;
  /// @}

private:
  /// \brief Estimate the latency of specified instruction.
  /// Returns 1 as the default value.
  int getInstructionLatency(const Instruction *I) const;

  /// \brief Returns the expected throughput cost of the instruction.
  /// Returns -1 if the cost is unknown.
  int getInstructionThroughput(const Instruction *I) const;

  /// \brief The abstract base class used to type erase specific TTI
  /// implementations.
  class Concept;

  /// \brief The template model for the base class which wraps a concrete
  /// implementation in a type erased interface.
  template <typename T> class Model;

  std::unique_ptr<Concept> TTIImpl;
};

class TargetTransformInfo::Concept {
public:
  virtual ~Concept() = 0;
  virtual const DataLayout &getDataLayout() const = 0;
  virtual int getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) = 0;
  virtual int getGEPCost(Type *PointeeType, const Value *Ptr,
                         ArrayRef<const Value *> Operands) = 0;
  virtual int getExtCost(const Instruction *I, const Value *Src) = 0;
  virtual int getCallCost(FunctionType *FTy, int NumArgs) = 0;
  virtual int getCallCost(const Function *F, int NumArgs) = 0;
  virtual int getCallCost(const Function *F,
                          ArrayRef<const Value *> Arguments) = 0;
  virtual unsigned getInliningThresholdMultiplier() = 0;
  virtual int getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
                               ArrayRef<Type *> ParamTys) = 0;
  virtual int getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
                               ArrayRef<const Value *> Arguments) = 0;
  virtual unsigned getEstimatedNumberOfCaseClusters(const SwitchInst &SI,
                                                    unsigned &JTSize) = 0;
  virtual int
  getUserCost(const User *U, ArrayRef<const Value *> Operands) = 0;
  virtual bool hasBranchDivergence() = 0;
  virtual bool isSourceOfDivergence(const Value *V) = 0;
  virtual bool isAlwaysUniform(const Value *V) = 0;
  virtual unsigned getFlatAddressSpace() = 0;
  virtual bool isLoweredToCall(const Function *F) = 0;
  virtual void getUnrollingPreferences(Loop *L, ScalarEvolution &,
                                       UnrollingPreferences &UP) = 0;
  virtual bool isLegalAddImmediate(int64_t Imm) = 0;
  virtual bool isLegalICmpImmediate(int64_t Imm) = 0;
  virtual bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
                                     int64_t BaseOffset, bool HasBaseReg,
                                     int64_t Scale,
                                     unsigned AddrSpace,
                                     Instruction *I) = 0;
  virtual bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
                             TargetTransformInfo::LSRCost &C2) = 0;
  virtual bool canMacroFuseCmp() = 0;
  virtual bool shouldFavorPostInc() const = 0;
  virtual bool isLegalMaskedStore(Type *DataType) = 0;
  virtual bool isLegalMaskedLoad(Type *DataType) = 0;
  virtual bool isLegalMaskedScatter(Type *DataType) = 0;
  virtual bool isLegalMaskedGather(Type *DataType) = 0;
  virtual bool hasDivRemOp(Type *DataType, bool IsSigned) = 0;
  virtual bool hasVolatileVariant(Instruction *I, unsigned AddrSpace) = 0;
  virtual bool prefersVectorizedAddressing() = 0;
  virtual int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
                                   int64_t BaseOffset, bool HasBaseReg,
                                   int64_t Scale, unsigned AddrSpace) = 0;
  virtual bool LSRWithInstrQueries() = 0;
  virtual bool isTruncateFree(Type *Ty1, Type *Ty2) = 0;
  virtual bool isProfitableToHoist(Instruction *I) = 0;
  virtual bool useAA() = 0;
  virtual bool isTypeLegal(Type *Ty) = 0;
  virtual unsigned getJumpBufAlignment() = 0;
  virtual unsigned getJumpBufSize() = 0;
  virtual bool shouldBuildLookupTables() = 0;
  virtual bool shouldBuildLookupTablesForConstant(Constant *C) = 0;
  virtual bool useColdCCForColdCall(Function &F) = 0;
  virtual unsigned
  getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) = 0;
  virtual unsigned getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
                                                    unsigned VF) = 0;
  virtual bool supportsEfficientVectorElementLoadStore() = 0;
  virtual bool enableAggressiveInterleaving(bool LoopHasReductions) = 0;
  virtual const MemCmpExpansionOptions *enableMemCmpExpansion(
      bool IsZeroCmp) const = 0;
  virtual bool enableInterleavedAccessVectorization() = 0;
  virtual bool isFPVectorizationPotentiallyUnsafe() = 0;
  virtual bool allowsMisalignedMemoryAccesses(LLVMContext &Context,
                                              unsigned BitWidth,
                                              unsigned AddressSpace,
                                              unsigned Alignment,
                                              bool *Fast) = 0;
  virtual PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) = 0;
  virtual bool haveFastSqrt(Type *Ty) = 0;
  virtual bool isFCmpOrdCheaperThanFCmpZero(Type *Ty) = 0;
  virtual int getFPOpCost(Type *Ty) = 0;
  virtual int getIntImmCodeSizeCost(unsigned Opc, unsigned Idx, const APInt &Imm,
                                    Type *Ty) = 0;
  virtual int getIntImmCost(const APInt &Imm, Type *Ty) = 0;
  virtual int getIntImmCost(unsigned Opc, unsigned Idx, const APInt &Imm,
                            Type *Ty) = 0;
  virtual int getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
                            Type *Ty) = 0;
  virtual unsigned getNumberOfRegisters(bool Vector) = 0;
  virtual unsigned getRegisterBitWidth(bool Vector) const = 0;
  virtual unsigned getMinVectorRegisterBitWidth() = 0;
  virtual bool shouldMaximizeVectorBandwidth(bool OptSize) const = 0;
  virtual bool shouldConsiderAddressTypePromotion(
      const Instruction &I, bool &AllowPromotionWithoutCommonHeader) = 0;
  virtual unsigned getCacheLineSize() = 0;
  virtual llvm::Optional<unsigned> getCacheSize(CacheLevel Level) = 0;
  virtual llvm::Optional<unsigned> getCacheAssociativity(CacheLevel Level) = 0;
  virtual unsigned getPrefetchDistance() = 0;
  virtual unsigned getMinPrefetchStride() = 0;
  virtual unsigned getMaxPrefetchIterationsAhead() = 0;
  virtual unsigned getMaxInterleaveFactor(unsigned VF) = 0;
  virtual unsigned
  getArithmeticInstrCost(unsigned Opcode, Type *Ty, OperandValueKind Opd1Info,
                         OperandValueKind Opd2Info,
                         OperandValueProperties Opd1PropInfo,
                         OperandValueProperties Opd2PropInfo,
                         ArrayRef<const Value *> Args) = 0;
  virtual int getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
                             Type *SubTp) = 0;
  virtual int getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
                               const Instruction *I) = 0;
  virtual int getExtractWithExtendCost(unsigned Opcode, Type *Dst,
                                       VectorType *VecTy, unsigned Index) = 0;
  virtual int getCFInstrCost(unsigned Opcode) = 0;
  virtual int getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
                                Type *CondTy, const Instruction *I) = 0;
  virtual int getVectorInstrCost(unsigned Opcode, Type *Val,
                                 unsigned Index) = 0;
  virtual int getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
                              unsigned AddressSpace, const Instruction *I) = 0;
  virtual int getMaskedMemoryOpCost(unsigned Opcode, Type *Src,
                                    unsigned Alignment,
                                    unsigned AddressSpace) = 0;
  virtual int getGatherScatterOpCost(unsigned Opcode, Type *DataTy,
                                     Value *Ptr, bool VariableMask,
                                     unsigned Alignment) = 0;
  virtual int getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy,
                                         unsigned Factor,
                                         ArrayRef<unsigned> Indices,
                                         unsigned Alignment,
                                         unsigned AddressSpace) = 0;
  virtual int getArithmeticReductionCost(unsigned Opcode, Type *Ty,
                                         bool IsPairwiseForm) = 0;
  virtual int getMinMaxReductionCost(Type *Ty, Type *CondTy,
                                     bool IsPairwiseForm, bool IsUnsigned) = 0;
  virtual int getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
                      ArrayRef<Type *> Tys, FastMathFlags FMF,
                      unsigned ScalarizationCostPassed) = 0;
  virtual int getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
         ArrayRef<Value *> Args, FastMathFlags FMF, unsigned VF) = 0;
  virtual int getCallInstrCost(Function *F, Type *RetTy,
                               ArrayRef<Type *> Tys) = 0;
  virtual unsigned getNumberOfParts(Type *Tp) = 0;
  virtual int getAddressComputationCost(Type *Ty, ScalarEvolution *SE,
                                        const SCEV *Ptr) = 0;
  virtual unsigned getCostOfKeepingLiveOverCall(ArrayRef<Type *> Tys) = 0;
  virtual bool getTgtMemIntrinsic(IntrinsicInst *Inst,
                                  MemIntrinsicInfo &Info) = 0;
  virtual unsigned getAtomicMemIntrinsicMaxElementSize() const = 0;
  virtual Value *getOrCreateResultFromMemIntrinsic(IntrinsicInst *Inst,
                                                   Type *ExpectedType) = 0;
  virtual Type *getMemcpyLoopLoweringType(LLVMContext &Context, Value *Length,
                                          unsigned SrcAlign,
                                          unsigned DestAlign) const = 0;
  virtual void getMemcpyLoopResidualLoweringType(
      SmallVectorImpl<Type *> &OpsOut, LLVMContext &Context,
      unsigned RemainingBytes, unsigned SrcAlign, unsigned DestAlign) const = 0;
  virtual bool areInlineCompatible(const Function *Caller,
                                   const Function *Callee) const = 0;
  virtual bool isIndexedLoadLegal(MemIndexedMode Mode, Type *Ty) const = 0;
  virtual bool isIndexedStoreLegal(MemIndexedMode Mode,Type *Ty) const = 0;
  virtual unsigned getLoadStoreVecRegBitWidth(unsigned AddrSpace) const = 0;
  virtual bool isLegalToVectorizeLoad(LoadInst *LI) const = 0;
  virtual bool isLegalToVectorizeStore(StoreInst *SI) const = 0;
  virtual bool isLegalToVectorizeLoadChain(unsigned ChainSizeInBytes,
                                           unsigned Alignment,
                                           unsigned AddrSpace) const = 0;
  virtual bool isLegalToVectorizeStoreChain(unsigned ChainSizeInBytes,
                                            unsigned Alignment,
                                            unsigned AddrSpace) const = 0;
  virtual unsigned getLoadVectorFactor(unsigned VF, unsigned LoadSize,
                                       unsigned ChainSizeInBytes,
                                       VectorType *VecTy) const = 0;
  virtual unsigned getStoreVectorFactor(unsigned VF, unsigned StoreSize,
                                        unsigned ChainSizeInBytes,
                                        VectorType *VecTy) const = 0;
  virtual bool useReductionIntrinsic(unsigned Opcode, Type *Ty,
                                     ReductionFlags) const = 0;
  virtual bool shouldExpandReduction(const IntrinsicInst *II) const = 0;
  virtual int getInstructionLatency(const Instruction *I) = 0;
};

template <typename T>
class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
  T Impl;

public:
  Model(T Impl) : Impl(std::move(Impl)) {}
  ~Model() override {}

  const DataLayout &getDataLayout() const override {
    return Impl.getDataLayout();
  }

  int getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) override {
    return Impl.getOperationCost(Opcode, Ty, OpTy);
  }
  int getGEPCost(Type *PointeeType, const Value *Ptr,
                 ArrayRef<const Value *> Operands) override {
    return Impl.getGEPCost(PointeeType, Ptr, Operands);
  }
  int getExtCost(const Instruction *I, const Value *Src) override {
    return Impl.getExtCost(I, Src);
  }
  int getCallCost(FunctionType *FTy, int NumArgs) override {
    return Impl.getCallCost(FTy, NumArgs);
  }
  int getCallCost(const Function *F, int NumArgs) override {
    return Impl.getCallCost(F, NumArgs);
  }
  int getCallCost(const Function *F,
                  ArrayRef<const Value *> Arguments) override {
    return Impl.getCallCost(F, Arguments);
  }
  unsigned getInliningThresholdMultiplier() override {
    return Impl.getInliningThresholdMultiplier();
  }
  int getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
                       ArrayRef<Type *> ParamTys) override {
    return Impl.getIntrinsicCost(IID, RetTy, ParamTys);
  }
  int getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
                       ArrayRef<const Value *> Arguments) override {
    return Impl.getIntrinsicCost(IID, RetTy, Arguments);
  }
  int getUserCost(const User *U, ArrayRef<const Value *> Operands) override {
    return Impl.getUserCost(U, Operands);
  }
  bool hasBranchDivergence() override { return Impl.hasBranchDivergence(); }
  bool isSourceOfDivergence(const Value *V) override {
    return Impl.isSourceOfDivergence(V);
  }

  bool isAlwaysUniform(const Value *V) override {
    return Impl.isAlwaysUniform(V);
  }

  unsigned getFlatAddressSpace() override {
    return Impl.getFlatAddressSpace();
  }

  bool isLoweredToCall(const Function *F) override {
    return Impl.isLoweredToCall(F);
  }
  void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                               UnrollingPreferences &UP) override {
    return Impl.getUnrollingPreferences(L, SE, UP);
  }
  bool isLegalAddImmediate(int64_t Imm) override {
    return Impl.isLegalAddImmediate(Imm);
  }
  bool isLegalICmpImmediate(int64_t Imm) override {
    return Impl.isLegalICmpImmediate(Imm);
  }
  bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
                             bool HasBaseReg, int64_t Scale,
                             unsigned AddrSpace,
                             Instruction *I) override {
    return Impl.isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg,
                                      Scale, AddrSpace, I);
  }
  bool isLSRCostLess(TargetTransformInfo::LSRCost &C1,
                     TargetTransformInfo::LSRCost &C2) override {
    return Impl.isLSRCostLess(C1, C2);
  }
  bool canMacroFuseCmp() override {
    return Impl.canMacroFuseCmp();
  }
  bool shouldFavorPostInc() const override {
    return Impl.shouldFavorPostInc();
  }
  bool isLegalMaskedStore(Type *DataType) override {
    return Impl.isLegalMaskedStore(DataType);
  }
  bool isLegalMaskedLoad(Type *DataType) override {
    return Impl.isLegalMaskedLoad(DataType);
  }
  bool isLegalMaskedScatter(Type *DataType) override {
    return Impl.isLegalMaskedScatter(DataType);
  }
  bool isLegalMaskedGather(Type *DataType) override {
    return Impl.isLegalMaskedGather(DataType);
  }
  bool hasDivRemOp(Type *DataType, bool IsSigned) override {
    return Impl.hasDivRemOp(DataType, IsSigned);
  }
  bool hasVolatileVariant(Instruction *I, unsigned AddrSpace) override {
    return Impl.hasVolatileVariant(I, AddrSpace);
  }
  bool prefersVectorizedAddressing() override {
    return Impl.prefersVectorizedAddressing();
  }
  int getScalingFactorCost(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
                           bool HasBaseReg, int64_t Scale,
                           unsigned AddrSpace) override {
    return Impl.getScalingFactorCost(Ty, BaseGV, BaseOffset, HasBaseReg,
                                     Scale, AddrSpace);
  }
  bool LSRWithInstrQueries() override {
    return Impl.LSRWithInstrQueries();
  }
  bool isTruncateFree(Type *Ty1, Type *Ty2) override {
    return Impl.isTruncateFree(Ty1, Ty2);
  }
  bool isProfitableToHoist(Instruction *I) override {
    return Impl.isProfitableToHoist(I);
  }
  bool useAA() override { return Impl.useAA(); }
  bool isTypeLegal(Type *Ty) override { return Impl.isTypeLegal(Ty); }
  unsigned getJumpBufAlignment() override { return Impl.getJumpBufAlignment(); }
  unsigned getJumpBufSize() override { return Impl.getJumpBufSize(); }
  bool shouldBuildLookupTables() override {
    return Impl.shouldBuildLookupTables();
  }
  bool shouldBuildLookupTablesForConstant(Constant *C) override {
    return Impl.shouldBuildLookupTablesForConstant(C);
  }
  bool useColdCCForColdCall(Function &F) override {
    return Impl.useColdCCForColdCall(F);
  }

  unsigned getScalarizationOverhead(Type *Ty, bool Insert,
                                    bool Extract) override {
    return Impl.getScalarizationOverhead(Ty, Insert, Extract);
  }
  unsigned getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
                                            unsigned VF) override {
    return Impl.getOperandsScalarizationOverhead(Args, VF);
  }

  bool supportsEfficientVectorElementLoadStore() override {
    return Impl.supportsEfficientVectorElementLoadStore();
  }

  bool enableAggressiveInterleaving(bool LoopHasReductions) override {
    return Impl.enableAggressiveInterleaving(LoopHasReductions);
  }
  const MemCmpExpansionOptions *enableMemCmpExpansion(
      bool IsZeroCmp) const override {
    return Impl.enableMemCmpExpansion(IsZeroCmp);
  }
  bool enableInterleavedAccessVectorization() override {
    return Impl.enableInterleavedAccessVectorization();
  }
  bool isFPVectorizationPotentiallyUnsafe() override {
    return Impl.isFPVectorizationPotentiallyUnsafe();
  }
  bool allowsMisalignedMemoryAccesses(LLVMContext &Context,
                                      unsigned BitWidth, unsigned AddressSpace,
                                      unsigned Alignment, bool *Fast) override {
    return Impl.allowsMisalignedMemoryAccesses(Context, BitWidth, AddressSpace,
                                               Alignment, Fast);
  }
  PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) override {
    return Impl.getPopcntSupport(IntTyWidthInBit);
  }
  bool haveFastSqrt(Type *Ty) override { return Impl.haveFastSqrt(Ty); }

  bool isFCmpOrdCheaperThanFCmpZero(Type *Ty) override {
    return Impl.isFCmpOrdCheaperThanFCmpZero(Ty);
  }

  int getFPOpCost(Type *Ty) override { return Impl.getFPOpCost(Ty); }

  int getIntImmCodeSizeCost(unsigned Opc, unsigned Idx, const APInt &Imm,
                            Type *Ty) override {
    return Impl.getIntImmCodeSizeCost(Opc, Idx, Imm, Ty);
  }
  int getIntImmCost(const APInt &Imm, Type *Ty) override {
    return Impl.getIntImmCost(Imm, Ty);
  }
  int getIntImmCost(unsigned Opc, unsigned Idx, const APInt &Imm,
                    Type *Ty) override {
    return Impl.getIntImmCost(Opc, Idx, Imm, Ty);
  }
  int getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
                    Type *Ty) override {
    return Impl.getIntImmCost(IID, Idx, Imm, Ty);
  }
  unsigned getNumberOfRegisters(bool Vector) override {
    return Impl.getNumberOfRegisters(Vector);
  }
  unsigned getRegisterBitWidth(bool Vector) const override {
    return Impl.getRegisterBitWidth(Vector);
  }
  unsigned getMinVectorRegisterBitWidth() override {
    return Impl.getMinVectorRegisterBitWidth();
  }
  bool shouldMaximizeVectorBandwidth(bool OptSize) const override {
    return Impl.shouldMaximizeVectorBandwidth(OptSize);
  }
  bool shouldConsiderAddressTypePromotion(
      const Instruction &I, bool &AllowPromotionWithoutCommonHeader) override {
    return Impl.shouldConsiderAddressTypePromotion(
        I, AllowPromotionWithoutCommonHeader);
  }
  unsigned getCacheLineSize() override {
    return Impl.getCacheLineSize();
  }
  llvm::Optional<unsigned> getCacheSize(CacheLevel Level) override {
    return Impl.getCacheSize(Level);
  }
  llvm::Optional<unsigned> getCacheAssociativity(CacheLevel Level) override {
    return Impl.getCacheAssociativity(Level);
  }
  unsigned getPrefetchDistance() override { return Impl.getPrefetchDistance(); }
  unsigned getMinPrefetchStride() override {
    return Impl.getMinPrefetchStride();
  }
  unsigned getMaxPrefetchIterationsAhead() override {
    return Impl.getMaxPrefetchIterationsAhead();
  }
  unsigned getMaxInterleaveFactor(unsigned VF) override {
    return Impl.getMaxInterleaveFactor(VF);
  }
  unsigned getEstimatedNumberOfCaseClusters(const SwitchInst &SI,
                                            unsigned &JTSize) override {
    return Impl.getEstimatedNumberOfCaseClusters(SI, JTSize);
  }
  unsigned
  getArithmeticInstrCost(unsigned Opcode, Type *Ty, OperandValueKind Opd1Info,
                         OperandValueKind Opd2Info,
                         OperandValueProperties Opd1PropInfo,
                         OperandValueProperties Opd2PropInfo,
                         ArrayRef<const Value *> Args) override {
    return Impl.getArithmeticInstrCost(Opcode, Ty, Opd1Info, Opd2Info,
                                       Opd1PropInfo, Opd2PropInfo, Args);
  }
  int getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
                     Type *SubTp) override {
    return Impl.getShuffleCost(Kind, Tp, Index, SubTp);
  }
  int getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
                       const Instruction *I) override {
    return Impl.getCastInstrCost(Opcode, Dst, Src, I);
  }
  int getExtractWithExtendCost(unsigned Opcode, Type *Dst, VectorType *VecTy,
                               unsigned Index) override {
    return Impl.getExtractWithExtendCost(Opcode, Dst, VecTy, Index);
  }
  int getCFInstrCost(unsigned Opcode) override {
    return Impl.getCFInstrCost(Opcode);
  }
  int getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
                         const Instruction *I) override {
    return Impl.getCmpSelInstrCost(Opcode, ValTy, CondTy, I);
  }
  int getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index) override {
    return Impl.getVectorInstrCost(Opcode, Val, Index);
  }
  int getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
                      unsigned AddressSpace, const Instruction *I) override {
    return Impl.getMemoryOpCost(Opcode, Src, Alignment, AddressSpace, I);
  }
  int getMaskedMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
                            unsigned AddressSpace) override {
    return Impl.getMaskedMemoryOpCost(Opcode, Src, Alignment, AddressSpace);
  }
  int getGatherScatterOpCost(unsigned Opcode, Type *DataTy,
                             Value *Ptr, bool VariableMask,
                             unsigned Alignment) override {
    return Impl.getGatherScatterOpCost(Opcode, DataTy, Ptr, VariableMask,
                                       Alignment);
  }
  int getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy, unsigned Factor,
                                 ArrayRef<unsigned> Indices, unsigned Alignment,
                                 unsigned AddressSpace) override {
    return Impl.getInterleavedMemoryOpCost(Opcode, VecTy, Factor, Indices,
                                           Alignment, AddressSpace);
  }
  int getArithmeticReductionCost(unsigned Opcode, Type *Ty,
                                 bool IsPairwiseForm) override {
    return Impl.getArithmeticReductionCost(Opcode, Ty, IsPairwiseForm);
  }
  int getMinMaxReductionCost(Type *Ty, Type *CondTy,
                             bool IsPairwiseForm, bool IsUnsigned) override {
    return Impl.getMinMaxReductionCost(Ty, CondTy, IsPairwiseForm, IsUnsigned);
   }
  int getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy, ArrayRef<Type *> Tys,
               FastMathFlags FMF, unsigned ScalarizationCostPassed) override {
    return Impl.getIntrinsicInstrCost(ID, RetTy, Tys, FMF,
                                      ScalarizationCostPassed);
  }
  int getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
       ArrayRef<Value *> Args, FastMathFlags FMF, unsigned VF) override {
    return Impl.getIntrinsicInstrCost(ID, RetTy, Args, FMF, VF);
  }
  int getCallInstrCost(Function *F, Type *RetTy,
                       ArrayRef<Type *> Tys) override {
    return Impl.getCallInstrCost(F, RetTy, Tys);
  }
  unsigned getNumberOfParts(Type *Tp) override {
    return Impl.getNumberOfParts(Tp);
  }
  int getAddressComputationCost(Type *Ty, ScalarEvolution *SE,
                                const SCEV *Ptr) override {
    return Impl.getAddressComputationCost(Ty, SE, Ptr);
  }
  unsigned getCostOfKeepingLiveOverCall(ArrayRef<Type *> Tys) override {
    return Impl.getCostOfKeepingLiveOverCall(Tys);
  }
  bool getTgtMemIntrinsic(IntrinsicInst *Inst,
                          MemIntrinsicInfo &Info) override {
    return Impl.getTgtMemIntrinsic(Inst, Info);
  }
  unsigned getAtomicMemIntrinsicMaxElementSize() const override {
    return Impl.getAtomicMemIntrinsicMaxElementSize();
  }
  Value *getOrCreateResultFromMemIntrinsic(IntrinsicInst *Inst,
                                           Type *ExpectedType) override {
    return Impl.getOrCreateResultFromMemIntrinsic(Inst, ExpectedType);
  }
  Type *getMemcpyLoopLoweringType(LLVMContext &Context, Value *Length,
                                  unsigned SrcAlign,
                                  unsigned DestAlign) const override {
    return Impl.getMemcpyLoopLoweringType(Context, Length, SrcAlign, DestAlign);
  }
  void getMemcpyLoopResidualLoweringType(SmallVectorImpl<Type *> &OpsOut,
                                         LLVMContext &Context,
                                         unsigned RemainingBytes,
                                         unsigned SrcAlign,
                                         unsigned DestAlign) const override {
    Impl.getMemcpyLoopResidualLoweringType(OpsOut, Context, RemainingBytes,
                                           SrcAlign, DestAlign);
  }
  bool areInlineCompatible(const Function *Caller,
                           const Function *Callee) const override {
    return Impl.areInlineCompatible(Caller, Callee);
  }
  bool isIndexedLoadLegal(MemIndexedMode Mode, Type *Ty) const override {
    return Impl.isIndexedLoadLegal(Mode, Ty, getDataLayout());
  }
  bool isIndexedStoreLegal(MemIndexedMode Mode, Type *Ty) const override {
    return Impl.isIndexedStoreLegal(Mode, Ty, getDataLayout());
  }
  unsigned getLoadStoreVecRegBitWidth(unsigned AddrSpace) const override {
    return Impl.getLoadStoreVecRegBitWidth(AddrSpace);
  }
  bool isLegalToVectorizeLoad(LoadInst *LI) const override {
    return Impl.isLegalToVectorizeLoad(LI);
  }
  bool isLegalToVectorizeStore(StoreInst *SI) const override {
    return Impl.isLegalToVectorizeStore(SI);
  }
  bool isLegalToVectorizeLoadChain(unsigned ChainSizeInBytes,
                                   unsigned Alignment,
                                   unsigned AddrSpace) const override {
    return Impl.isLegalToVectorizeLoadChain(ChainSizeInBytes, Alignment,
                                            AddrSpace);
  }
  bool isLegalToVectorizeStoreChain(unsigned ChainSizeInBytes,
                                    unsigned Alignment,
                                    unsigned AddrSpace) const override {
    return Impl.isLegalToVectorizeStoreChain(ChainSizeInBytes, Alignment,
                                             AddrSpace);
  }
  unsigned getLoadVectorFactor(unsigned VF, unsigned LoadSize,
                               unsigned ChainSizeInBytes,
                               VectorType *VecTy) const override {
    return Impl.getLoadVectorFactor(VF, LoadSize, ChainSizeInBytes, VecTy);
  }
  unsigned getStoreVectorFactor(unsigned VF, unsigned StoreSize,
                                unsigned ChainSizeInBytes,
                                VectorType *VecTy) const override {
    return Impl.getStoreVectorFactor(VF, StoreSize, ChainSizeInBytes, VecTy);
  }
  bool useReductionIntrinsic(unsigned Opcode, Type *Ty,
                             ReductionFlags Flags) const override {
    return Impl.useReductionIntrinsic(Opcode, Ty, Flags);
  }
  bool shouldExpandReduction(const IntrinsicInst *II) const override {
    return Impl.shouldExpandReduction(II);
  }
  int getInstructionLatency(const Instruction *I) override {
    return Impl.getInstructionLatency(I);
  }
};

template <typename T>
TargetTransformInfo::TargetTransformInfo(T Impl)
    : TTIImpl(new Model<T>(Impl)) {}

/// \brief Analysis pass providing the \c TargetTransformInfo.
///
/// The core idea of the TargetIRAnalysis is to expose an interface through
/// which LLVM targets can analyze and provide information about the middle
/// end's target-independent IR. This supports use cases such as target-aware
/// cost modeling of IR constructs.
///
/// This is a function analysis because much of the cost modeling for targets
/// is done in a subtarget specific way and LLVM supports compiling different
/// functions targeting different subtargets in order to support runtime
/// dispatch according to the observed subtarget.
class TargetIRAnalysis : public AnalysisInfoMixin<TargetIRAnalysis> {
public:
  typedef TargetTransformInfo Result;

  /// \brief Default construct a target IR analysis.
  ///
  /// This will use the module's datalayout to construct a baseline
  /// conservative TTI result.
  TargetIRAnalysis();

  /// \brief Construct an IR analysis pass around a target-provide callback.
  ///
  /// The callback will be called with a particular function for which the TTI
  /// is needed and must return a TTI object for that function.
  TargetIRAnalysis(std::function<Result(const Function &)> TTICallback);

  // Value semantics. We spell out the constructors for MSVC.
  TargetIRAnalysis(const TargetIRAnalysis &Arg)
      : TTICallback(Arg.TTICallback) {}
  TargetIRAnalysis(TargetIRAnalysis &&Arg)
      : TTICallback(std::move(Arg.TTICallback)) {}
  TargetIRAnalysis &operator=(const TargetIRAnalysis &RHS) {
    TTICallback = RHS.TTICallback;
    return *this;
  }
  TargetIRAnalysis &operator=(TargetIRAnalysis &&RHS) {
    TTICallback = std::move(RHS.TTICallback);
    return *this;
  }

  Result run(const Function &F, FunctionAnalysisManager &);

private:
  friend AnalysisInfoMixin<TargetIRAnalysis>;
  static AnalysisKey Key;

  /// \brief The callback used to produce a result.
  ///
  /// We use a completely opaque callback so that targets can provide whatever
  /// mechanism they desire for constructing the TTI for a given function.
  ///
  /// FIXME: Should we really use std::function? It's relatively inefficient.
  /// It might be possible to arrange for even stateful callbacks to outlive
  /// the analysis and thus use a function_ref which would be lighter weight.
  /// This may also be less error prone as the callback is likely to reference
  /// the external TargetMachine, and that reference needs to never dangle.
  std::function<Result(const Function &)> TTICallback;

  /// \brief Helper function used as the callback in the default constructor.
  static Result getDefaultTTI(const Function &F);
};

/// \brief Wrapper pass for TargetTransformInfo.
///
/// This pass can be constructed from a TTI object which it stores internally
/// and is queried by passes.
class TargetTransformInfoWrapperPass : public ImmutablePass {
  TargetIRAnalysis TIRA;
  Optional<TargetTransformInfo> TTI;

  virtual void anchor();

public:
  static char ID;

  /// \brief We must provide a default constructor for the pass but it should
  /// never be used.
  ///
  /// Use the constructor below or call one of the creation routines.
  TargetTransformInfoWrapperPass();

  explicit TargetTransformInfoWrapperPass(TargetIRAnalysis TIRA);

  TargetTransformInfo &getTTI(const Function &F);
};

/// \brief Create an analysis pass wrapper around a TTI object.
///
/// This analysis pass just holds the TTI instance and makes it available to
/// clients.
ImmutablePass *createTargetTransformInfoWrapperPass(TargetIRAnalysis TIRA);

} // End llvm namespace

#endif