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gps/tools/local/circt/include/llvm/Analysis/TargetTransformInfo.h
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//===- TargetTransformInfo.h ------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \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/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitmaskEnum.h"
#include "llvm/ADT/Uniformity.h"
#include "llvm/Analysis/IVDescriptors.h"
#include "llvm/Analysis/InterestingMemoryOperand.h"
#include "llvm/IR/FMF.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/AtomicOrdering.h"
#include "llvm/Support/BranchProbability.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/InstructionCost.h"
#include <functional>
#include <optional>
#include <utility>
namespace llvm {
namespace Intrinsic {
typedef unsigned ID;
}
class AllocaInst;
class AssumptionCache;
class BlockFrequencyInfo;
class DominatorTree;
class CondBrInst;
class Function;
class GlobalValue;
class InstCombiner;
class OptimizationRemarkEmitter;
class InterleavedAccessInfo;
class IntrinsicInst;
class LoadInst;
class Loop;
class LoopInfo;
class LoopVectorizationLegality;
class ProfileSummaryInfo;
class RecurrenceDescriptor;
class SCEV;
class ScalarEvolution;
class SmallBitVector;
class StoreInst;
class SwitchInst;
class TargetLibraryInfo;
class Type;
class VPIntrinsic;
struct KnownBits;
/// 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;
SmallVector<InterestingMemoryOperand, 1> InterestingOperands;
bool isUnordered() const {
return (Ordering == AtomicOrdering::NotAtomic ||
Ordering == AtomicOrdering::Unordered) &&
!IsVolatile;
}
};
/// Attributes of a target dependent hardware loop.
struct HardwareLoopInfo {
HardwareLoopInfo() = delete;
LLVM_ABI HardwareLoopInfo(Loop *L);
Loop *L = nullptr;
BasicBlock *ExitBlock = nullptr;
CondBrInst *ExitBranch = nullptr;
const SCEV *ExitCount = nullptr;
IntegerType *CountType = nullptr;
Value *LoopDecrement = nullptr; // Decrement the loop counter by this
// value in every iteration.
bool IsNestingLegal = false; // Can a hardware loop be a parent to
// another hardware loop?
bool CounterInReg = false; // Should loop counter be updated in
// the loop via a phi?
bool PerformEntryTest = false; // Generate the intrinsic which also performs
// icmp ne zero on the loop counter value and
// produces an i1 to guard the loop entry.
LLVM_ABI bool isHardwareLoopCandidate(ScalarEvolution &SE, LoopInfo &LI,
DominatorTree &DT,
bool ForceNestedLoop = false,
bool ForceHardwareLoopPHI = false);
LLVM_ABI bool canAnalyze(LoopInfo &LI);
};
/// Information for memory intrinsic cost model.
class MemIntrinsicCostAttributes {
/// Optional context instruction, if one exists, e.g. the
/// load/store to transform to the intrinsic.
const Instruction *I = nullptr;
/// Address in memory.
const Value *Ptr = nullptr;
/// Vector type of the data to be loaded or stored.
Type *DataTy = nullptr;
/// ID of the memory intrinsic.
Intrinsic::ID IID;
/// True when the memory access is predicated with a mask
/// that is not a compile-time constant.
bool VariableMask = true;
/// Address space of the pointer.
unsigned AddressSpace = 0;
/// Alignment of single element.
Align Alignment;
public:
MemIntrinsicCostAttributes(Intrinsic::ID Id, Type *DataTy, const Value *Ptr,
bool VariableMask, Align Alignment,
const Instruction *I = nullptr)
: I(I), Ptr(Ptr), DataTy(DataTy), IID(Id), VariableMask(VariableMask),
Alignment(Alignment) {}
MemIntrinsicCostAttributes(Intrinsic::ID Id, Type *DataTy, Align Alignment,
unsigned AddressSpace = 0)
: DataTy(DataTy), IID(Id), AddressSpace(AddressSpace),
Alignment(Alignment) {}
MemIntrinsicCostAttributes(Intrinsic::ID Id, Type *DataTy, bool VariableMask,
Align Alignment, const Instruction *I = nullptr)
: I(I), DataTy(DataTy), IID(Id), VariableMask(VariableMask),
Alignment(Alignment) {}
Intrinsic::ID getID() const { return IID; }
const Instruction *getInst() const { return I; }
const Value *getPointer() const { return Ptr; }
Type *getDataType() const { return DataTy; }
bool getVariableMask() const { return VariableMask; }
unsigned getAddressSpace() const { return AddressSpace; }
Align getAlignment() const { return Alignment; }
};
class IntrinsicCostAttributes {
const IntrinsicInst *II = nullptr;
Type *RetTy = nullptr;
Intrinsic::ID IID;
SmallVector<Type *, 4> ParamTys;
SmallVector<const Value *, 4> Arguments;
FastMathFlags FMF;
// If ScalarizationCost is UINT_MAX, the cost of scalarizing the
// arguments and the return value will be computed based on types.
InstructionCost ScalarizationCost = InstructionCost::getInvalid();
public:
LLVM_ABI IntrinsicCostAttributes(
Intrinsic::ID Id, const CallBase &CI,
InstructionCost ScalarCost = InstructionCost::getInvalid(),
bool TypeBasedOnly = false);
LLVM_ABI IntrinsicCostAttributes(
Intrinsic::ID Id, Type *RTy, ArrayRef<Type *> Tys,
FastMathFlags Flags = FastMathFlags(), const IntrinsicInst *I = nullptr,
InstructionCost ScalarCost = InstructionCost::getInvalid());
LLVM_ABI IntrinsicCostAttributes(Intrinsic::ID Id, Type *RTy,
ArrayRef<const Value *> Args);
LLVM_ABI IntrinsicCostAttributes(
Intrinsic::ID Id, Type *RTy, ArrayRef<const Value *> Args,
ArrayRef<Type *> Tys, FastMathFlags Flags = FastMathFlags(),
const IntrinsicInst *I = nullptr,
InstructionCost ScalarCost = InstructionCost::getInvalid());
Intrinsic::ID getID() const { return IID; }
const IntrinsicInst *getInst() const { return II; }
Type *getReturnType() const { return RetTy; }
FastMathFlags getFlags() const { return FMF; }
InstructionCost getScalarizationCost() const { return ScalarizationCost; }
const SmallVectorImpl<const Value *> &getArgs() const { return Arguments; }
const SmallVectorImpl<Type *> &getArgTypes() const { return ParamTys; }
bool isTypeBasedOnly() const {
return Arguments.empty();
}
bool skipScalarizationCost() const { return ScalarizationCost.isValid(); }
};
enum class TailFoldingStyle {
/// Don't use tail folding
None,
/// Use predicate only to mask operations on data in the loop.
/// When the VL is not known to be a power-of-2, this method requires a
/// runtime overflow check for the i + VL in the loop because it compares the
/// scalar induction variable against the tripcount rounded up by VL which may
/// overflow. When the VL is a power-of-2, both the increment and uprounded
/// tripcount will overflow to 0, which does not require a runtime check
/// since the loop is exited when the loop induction variable equals the
/// uprounded trip-count, which are both 0.
Data,
/// Same as Data, but avoids using the get.active.lane.mask intrinsic to
/// calculate the mask and instead implements this with a
/// splat/stepvector/cmp.
/// FIXME: Can this kind be removed now that SelectionDAGBuilder expands the
/// active.lane.mask intrinsic when it is not natively supported?
DataWithoutLaneMask,
/// Use predicate to control both data and control flow.
/// This method always requires a runtime overflow check for the i + VL
/// increment inside the loop, because it uses the result direclty in the
/// active.lane.mask to calculate the mask for the next iteration. If the
/// increment overflows, the mask is no longer correct.
DataAndControlFlow,
/// Use predicated EVL instructions for tail-folding.
/// Indicates that VP intrinsics should be used.
DataWithEVL,
};
struct TailFoldingInfo {
TargetLibraryInfo *TLI;
LoopVectorizationLegality *LVL;
InterleavedAccessInfo *IAI;
TailFoldingInfo(TargetLibraryInfo *TLI, LoopVectorizationLegality *LVL,
InterleavedAccessInfo *IAI)
: TLI(TLI), LVL(LVL), IAI(IAI) {}
};
class TargetTransformInfo;
typedef TargetTransformInfo TTI;
class TargetTransformInfoImplBase;
/// This pass provides access to the codegen interfaces that are needed
/// for IR-level transformations.
class TargetTransformInfo {
public:
enum PartialReductionExtendKind {
PR_None,
PR_SignExtend,
PR_ZeroExtend,
PR_FPExtend
};
/// Get the kind of extension that an instruction represents.
LLVM_ABI static PartialReductionExtendKind
getPartialReductionExtendKind(Instruction *I);
/// Get the kind of extension that a cast opcode represents.
LLVM_ABI static PartialReductionExtendKind
getPartialReductionExtendKind(Instruction::CastOps CastOpc);
/// Get the cast opcode for an extension kind.
LLVM_ABI static Instruction::CastOps
getOpcodeForPartialReductionExtendKind(PartialReductionExtendKind Kind);
/// 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
/// implementation that encodes appropriate costs for their target.
LLVM_ABI explicit TargetTransformInfo(
std::unique_ptr<const TargetTransformInfoImplBase> Impl);
/// 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.
LLVM_ABI explicit TargetTransformInfo(const DataLayout &DL);
// Provide move semantics.
LLVM_ABI TargetTransformInfo(TargetTransformInfo &&Arg);
LLVM_ABI TargetTransformInfo &operator=(TargetTransformInfo &&RHS);
// We need to define the destructor out-of-line to define our sub-classes
// out-of-line.
LLVM_ABI ~TargetTransformInfo();
/// 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
/// @{
/// 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.
/// e.g. TCK_SizeAndLatency should be comparable to target thresholds such as
/// those derived from MCSchedModel::LoopMicroOpBufferSize etc.
enum TargetCostKind {
TCK_RecipThroughput, ///< Reciprocal throughput.
TCK_Latency, ///< The latency of instruction.
TCK_CodeSize, ///< Instruction code size.
TCK_SizeAndLatency ///< The weighted sum of size and latency.
};
/// 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.
};
/// Estimate the cost of a GEP operation when lowered.
///
/// \p PointeeType is the source element type of the GEP.
/// \p Ptr is the base pointer operand.
/// \p Operands is the list of indices following the base pointer.
///
/// \p AccessType is a hint as to what type of memory might be accessed by
/// users of the GEP. getGEPCost will use it to determine if the GEP can be
/// folded into the addressing mode of a load/store. If AccessType is null,
/// then the resulting target type based off of PointeeType will be used as an
/// approximation.
LLVM_ABI InstructionCost
getGEPCost(Type *PointeeType, const Value *Ptr,
ArrayRef<const Value *> Operands, Type *AccessType = nullptr,
TargetCostKind CostKind = TCK_SizeAndLatency) const;
/// Describe known properties for a set of pointers.
struct PointersChainInfo {
/// All the GEPs in a set have same base address.
unsigned IsSameBaseAddress : 1;
/// These properties only valid if SameBaseAddress is set.
/// True if all pointers are separated by a unit stride.
unsigned IsUnitStride : 1;
/// True if distance between any two neigbouring pointers is a known value.
unsigned IsKnownStride : 1;
unsigned Reserved : 29;
bool isSameBase() const { return IsSameBaseAddress; }
bool isUnitStride() const { return IsSameBaseAddress && IsUnitStride; }
bool isKnownStride() const { return IsSameBaseAddress && IsKnownStride; }
static PointersChainInfo getUnitStride() {
return {/*IsSameBaseAddress=*/1, /*IsUnitStride=*/1,
/*IsKnownStride=*/1, 0};
}
static PointersChainInfo getKnownStride() {
return {/*IsSameBaseAddress=*/1, /*IsUnitStride=*/0,
/*IsKnownStride=*/1, 0};
}
static PointersChainInfo getUnknownStride() {
return {/*IsSameBaseAddress=*/1, /*IsUnitStride=*/0,
/*IsKnownStride=*/0, 0};
}
};
static_assert(sizeof(PointersChainInfo) == 4, "Was size increase justified?");
/// Estimate the cost of a chain of pointers (typically pointer operands of a
/// chain of loads or stores within same block) operations set when lowered.
/// \p AccessTy is the type of the loads/stores that will ultimately use the
/// \p Ptrs.
LLVM_ABI InstructionCost getPointersChainCost(
ArrayRef<const Value *> Ptrs, const Value *Base,
const PointersChainInfo &Info, Type *AccessTy,
TargetCostKind CostKind = TTI::TCK_RecipThroughput) 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.
LLVM_ABI unsigned getInliningThresholdMultiplier() const;
LLVM_ABI unsigned getInliningCostBenefitAnalysisSavingsMultiplier() const;
LLVM_ABI unsigned getInliningCostBenefitAnalysisProfitableMultiplier() const;
/// \returns The bonus of inlining the last call to a static function.
LLVM_ABI int getInliningLastCallToStaticBonus() const;
/// \returns A value to be added to the inlining threshold.
LLVM_ABI unsigned adjustInliningThreshold(const CallBase *CB) const;
/// \returns The cost of having an Alloca in the caller if not inlined, to be
/// added to the threshold
LLVM_ABI unsigned getCallerAllocaCost(const CallBase *CB,
const AllocaInst *AI) const;
/// \returns Vector bonus in percent.
///
/// Vector bonuses: We want to more aggressively inline vector-dense kernels
/// and apply this bonus based on the percentage of vector instructions. A
/// bonus is applied if the vector instructions exceed 50% and half that
/// amount is applied if it exceeds 10%. Note that these bonuses are some what
/// arbitrary and evolved over time by accident as much as because they are
/// principled bonuses.
/// FIXME: It would be nice to base the bonus values on something more
/// scientific. A target may has no bonus on vector instructions.
LLVM_ABI int getInlinerVectorBonusPercent() const;
/// \return the expected cost of a memcpy, which could e.g. depend on the
/// source/destination type and alignment and the number of bytes copied.
LLVM_ABI InstructionCost getMemcpyCost(const Instruction *I) const;
/// Returns the maximum memset / memcpy size in bytes that still makes it
/// profitable to inline the call.
LLVM_ABI uint64_t getMaxMemIntrinsicInlineSizeThreshold() 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.
LLVM_ABI unsigned
getEstimatedNumberOfCaseClusters(const SwitchInst &SI, unsigned &JTSize,
ProfileSummaryInfo *PSI,
BlockFrequencyInfo *BFI) const;
/// Estimate the cost of a given IR user when lowered.
///
/// This can estimate the cost of either a ConstantExpr or Instruction when
/// lowered.
///
/// \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.
LLVM_ABI InstructionCost getInstructionCost(const User *U,
ArrayRef<const Value *> Operands,
TargetCostKind CostKind) const;
/// This is a helper function which calls the three-argument
/// getInstructionCost with \p Operands which are the current operands U has.
InstructionCost getInstructionCost(const User *U,
TargetCostKind CostKind) const {
SmallVector<const Value *, 4> Operands(U->operand_values());
return getInstructionCost(U, Operands, CostKind);
}
/// If a branch or a select condition is skewed in one direction by more than
/// this factor, it is very likely to be predicted correctly.
LLVM_ABI BranchProbability getPredictableBranchThreshold() const;
/// Returns estimated penalty of a branch misprediction in latency. Indicates
/// how aggressive the target wants for eliminating unpredictable branches. A
/// zero return value means extra optimization applied to them should be
/// minimal.
LLVM_ABI InstructionCost getBranchMispredictPenalty() const;
/// 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.
///
/// If \p F is passed, provides a context function. If \p F is known to only
/// execute in a single threaded environment, the target may choose to skip
/// uniformity analysis and assume all values are uniform.
LLVM_ABI bool hasBranchDivergence(const Function *F = nullptr) const;
/// Get target-specific uniformity information for a value.
/// This allows targets to provide more fine-grained control over
/// uniformity analysis by specifying whether specific values
/// should always or never be considered uniform, or require custom
/// operand-based analysis.
/// \param V The value to query for uniformity information.
/// \return ValueUniformity.
LLVM_ABI ValueUniformity getValueUniformity(const Value *V) const;
/// Query the target whether the specified address space cast from FromAS to
/// ToAS is valid.
LLVM_ABI bool isValidAddrSpaceCast(unsigned FromAS, unsigned ToAS) const;
/// Return false if a \p AS0 address cannot possibly alias a \p AS1 address.
LLVM_ABI bool addrspacesMayAlias(unsigned AS0, unsigned AS1) 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.
LLVM_ABI unsigned getFlatAddressSpace() const;
/// Return any intrinsic address operand indexes which may be rewritten if
/// they use a flat address space pointer.
///
/// \returns true if the intrinsic was handled.
LLVM_ABI bool collectFlatAddressOperands(SmallVectorImpl<int> &OpIndexes,
Intrinsic::ID IID) const;
LLVM_ABI bool isNoopAddrSpaceCast(unsigned FromAS, unsigned ToAS) const;
// Given an address space cast of the given pointer value, calculate the known
// bits of the source pointer in the source addrspace and the destination
// pointer in the destination addrspace.
LLVM_ABI std::pair<KnownBits, KnownBits>
computeKnownBitsAddrSpaceCast(unsigned ToAS, const Value &PtrOp) const;
// Given an address space cast, calculate the known bits of the resulting ptr
// in the destination addrspace using the known bits of the source pointer in
// the source addrspace.
LLVM_ABI KnownBits computeKnownBitsAddrSpaceCast(
unsigned FromAS, unsigned ToAS, const KnownBits &FromPtrBits) const;
/// Returns a mask indicating which bits of a pointer remain unchanged when
/// casting between address spaces. The returned APInt has the same bit width
/// as the source address space pointer size.
///
/// Some targets allow certain bits of a pointer to change (e.g., the low
/// bits within a page) while still preserving the address space. This mask
/// identifies those bits that are guaranteed to be preserved. If the mask is
/// all zeros, no bits are preserved and address space inference cannot be
/// performed safely.
///
/// For example, given:
/// %gp = addrspacecast ptr addrspace(2) %sp to ptr
/// %a = ptrtoint ptr %gp to i64
/// %b = xor i64 7, %a
/// %gp2 = inttoptr i64 %b to ptr
/// store i16 0, ptr %gp2, align 2
/// if the target preserves the upper bits, `%gp2` can be safely replaced
/// with `inttoptr i64 %b to ptr addrspace(2)`.
LLVM_ABI APInt getAddrSpaceCastPreservedPtrMask(unsigned SrcAS,
unsigned DstAS) const;
/// Return true if globals in this address space can have initializers other
/// than `undef`.
LLVM_ABI bool
canHaveNonUndefGlobalInitializerInAddressSpace(unsigned AS) const;
LLVM_ABI unsigned getAssumedAddrSpace(const Value *V) const;
LLVM_ABI bool isSingleThreaded() const;
LLVM_ABI std::pair<const Value *, unsigned>
getPredicatedAddrSpace(const Value *V) const;
/// Rewrite intrinsic call \p II such that \p OldV will be replaced with \p
/// NewV, which has a different address space. This should happen for every
/// operand index that collectFlatAddressOperands returned for the intrinsic.
/// \returns nullptr if the intrinsic was not handled. Otherwise, returns the
/// new value (which may be the original \p II with modified operands).
LLVM_ABI Value *rewriteIntrinsicWithAddressSpace(IntrinsicInst *II,
Value *OldV,
Value *NewV) const;
/// 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.
LLVM_ABI 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
/// getInstructionCost 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;
/// 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 upper bound of trip count. Allowing the MaxUpperBound
/// to be overrided by a target gives more flexiblity on certain cases.
/// By default, MaxUpperBound uses UnrollMaxUpperBound which value is 8.
unsigned MaxUpperBound;
/// 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 unrolling of all the iterations of the runtime loop remainder.
bool UnrollRemainder;
/// Allow unroll and jam. Used to enable unroll and jam for the target.
bool UnrollAndJam;
/// Threshold for unroll and jam, for inner loop size. The 'Threshold'
/// value above is used during unroll and jam for the outer loop size.
/// This value is used in the same manner to limit the size of the inner
/// loop.
unsigned UnrollAndJamInnerLoopThreshold;
/// Don't allow loop unrolling to simulate more than this number of
/// iterations when checking full unroll profitability
unsigned MaxIterationsCountToAnalyze;
/// Disable runtime unrolling by default for vectorized loops.
bool UnrollVectorizedLoop = false;
/// Don't allow runtime unrolling if expanding the trip count takes more
/// than SCEVExpansionBudget.
unsigned SCEVExpansionBudget;
/// Allow runtime unrolling multi-exit loops. Should only be set if the
/// target determined that multi-exit unrolling is profitable for the loop.
/// Fall back to the generic logic to determine whether multi-exit unrolling
/// is profitable if set to false.
bool RuntimeUnrollMultiExit;
/// Allow unrolling to add parallel reduction phis.
bool AddAdditionalAccumulators;
};
/// Get target-customized preferences for the generic loop unrolling
/// transformation. The caller will initialize UP with the current
/// target-independent defaults.
LLVM_ABI void getUnrollingPreferences(Loop *L, ScalarEvolution &,
UnrollingPreferences &UP,
OptimizationRemarkEmitter *ORE) const;
/// Query the target whether it would be profitable to convert the given loop
/// into a hardware loop.
LLVM_ABI bool isHardwareLoopProfitable(Loop *L, ScalarEvolution &SE,
AssumptionCache &AC,
TargetLibraryInfo *LibInfo,
HardwareLoopInfo &HWLoopInfo) const;
// Query the target for which minimum vectorization factor epilogue
// vectorization should be considered.
LLVM_ABI unsigned getEpilogueVectorizationMinVF() const;
/// Query the target whether it would be preferred to create a tail-folded
/// vector loop, which can avoid the need to emit a scalar epilogue loop.
LLVM_ABI bool preferTailFoldingOverEpilogue(TailFoldingInfo *TFI) const;
/// Query the target what the preferred style of tail folding is.
LLVM_ABI TailFoldingStyle getPreferredTailFoldingStyle() const;
// Parameters that control the loop peeling transformation
struct PeelingPreferences {
/// 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
/// a peeling factor based on profile information and other factors.
unsigned PeelCount;
/// Allow peeling off loop iterations.
bool AllowPeeling;
/// Allow peeling off loop iterations for loop nests.
bool AllowLoopNestsPeeling;
/// Allow peeling basing on profile. Uses to enable peeling off all
/// iterations basing on provided profile.
/// If the value is true the peeling cost model can decide to peel only
/// some iterations and in this case it will set this to false.
bool PeelProfiledIterations;
/// Peel off the last PeelCount loop iterations.
bool PeelLast;
};
/// Get target-customized preferences for the generic loop peeling
/// transformation. The caller will initialize \p PP with the current
/// target-independent defaults with information from \p L and \p SE.
LLVM_ABI void getPeelingPreferences(Loop *L, ScalarEvolution &SE,
PeelingPreferences &PP) const;
/// Targets can implement their own combinations for target-specific
/// intrinsics. This function will be called from the InstCombine pass every
/// time a target-specific intrinsic is encountered.
///
/// \returns std::nullopt to not do anything target specific or a value that
/// will be returned from the InstCombiner. It is possible to return null and
/// stop further processing of the intrinsic by returning nullptr.
LLVM_ABI std::optional<Instruction *>
instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const;
/// Can be used to implement target-specific instruction combining.
/// \see instCombineIntrinsic
LLVM_ABI std::optional<Value *>
simplifyDemandedUseBitsIntrinsic(InstCombiner &IC, IntrinsicInst &II,
APInt DemandedMask, KnownBits &Known,
bool &KnownBitsComputed) const;
/// Can be used to implement target-specific instruction combining.
/// \see instCombineIntrinsic
LLVM_ABI std::optional<Value *> simplifyDemandedVectorEltsIntrinsic(
InstCombiner &IC, IntrinsicInst &II, APInt DemandedElts, APInt &UndefElts,
APInt &UndefElts2, APInt &UndefElts3,
std::function<void(Instruction *, unsigned, APInt, APInt &)>
SimplifyAndSetOp) const;
/// @}
/// \name Scalar Target Information
/// @{
/// 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 };
/// 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.
LLVM_ABI bool isLegalAddImmediate(int64_t Imm) const;
/// Return true if adding the specified scalable immediate is legal, that is
/// the target has add instructions which can add a register with the
/// immediate (multiplied by vscale) without having to materialize the
/// immediate into a register.
LLVM_ABI bool isLegalAddScalableImmediate(int64_t Imm) const;
/// 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.
LLVM_ABI bool isLegalICmpImmediate(int64_t Imm) const;
/// 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.
/// \param ScalableOffset represents a quantity of bytes multiplied by vscale,
/// an invariant value known only at runtime. Most targets should not accept
/// a scalable offset.
///
/// TODO: Handle pre/postinc as well.
LLVM_ABI bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset, bool HasBaseReg,
int64_t Scale, unsigned AddrSpace = 0,
Instruction *I = nullptr,
int64_t ScalableOffset = 0) const;
/// Return true if LSR cost of C1 is lower than C2.
LLVM_ABI bool isLSRCostLess(const TargetTransformInfo::LSRCost &C1,
const TargetTransformInfo::LSRCost &C2) const;
/// Return true if LSR major cost is number of registers. Targets which
/// implement their own isLSRCostLess and unset number of registers as major
/// cost should return false, otherwise return true.
LLVM_ABI bool isNumRegsMajorCostOfLSR() const;
/// Return true if LSR should drop a found solution if it's calculated to be
/// less profitable than the baseline.
LLVM_ABI bool shouldDropLSRSolutionIfLessProfitable() const;
/// \returns true if LSR should not optimize a chain that includes \p I.
LLVM_ABI bool isProfitableLSRChainElement(Instruction *I) 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.
LLVM_ABI bool canMacroFuseCmp() const;
/// Return true if the target can save a compare for loop count, for example
/// hardware loop saves a compare.
LLVM_ABI bool canSaveCmp(Loop *L, CondBrInst **BI, ScalarEvolution *SE,
LoopInfo *LI, DominatorTree *DT, AssumptionCache *AC,
TargetLibraryInfo *LibInfo) const;
/// Which addressing mode Loop Strength Reduction will try to generate.
enum AddressingModeKind {
AMK_None = 0x0, ///< Don't prefer any addressing mode
AMK_PreIndexed = 0x1, ///< Prefer pre-indexed addressing mode
AMK_PostIndexed = 0x2, ///< Prefer post-indexed addressing mode
AMK_All = 0x3, ///< Consider all addressing modes
LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/AMK_All)
};
/// Return the preferred addressing mode LSR should make efforts to generate.
LLVM_ABI AddressingModeKind
getPreferredAddressingMode(const Loop *L, ScalarEvolution *SE) const;
/// Some targets only support masked load/store with a constant mask.
enum MaskKind {
VariableOrConstantMask,
ConstantMask,
};
/// Return true if the target supports masked store.
LLVM_ABI bool
isLegalMaskedStore(Type *DataType, Align Alignment, unsigned AddressSpace,
MaskKind MaskKind = VariableOrConstantMask) const;
/// Return true if the target supports masked load.
LLVM_ABI bool
isLegalMaskedLoad(Type *DataType, Align Alignment, unsigned AddressSpace,
MaskKind MaskKind = VariableOrConstantMask) const;
/// Return true if the target supports nontemporal store.
LLVM_ABI bool isLegalNTStore(Type *DataType, Align Alignment) const;
/// Return true if the target supports nontemporal load.
LLVM_ABI bool isLegalNTLoad(Type *DataType, Align Alignment) const;
/// \Returns true if the target supports broadcasting a load to a vector of
/// type <NumElements x ElementTy>.
LLVM_ABI bool isLegalBroadcastLoad(Type *ElementTy,
ElementCount NumElements) const;
/// Return true if the target supports masked scatter.
LLVM_ABI bool isLegalMaskedScatter(Type *DataType, Align Alignment) const;
/// Return true if the target supports masked gather.
LLVM_ABI bool isLegalMaskedGather(Type *DataType, Align Alignment) const;
/// Return true if the target forces scalarizing of llvm.masked.gather
/// intrinsics.
LLVM_ABI bool forceScalarizeMaskedGather(VectorType *Type,
Align Alignment) const;
/// Return true if the target forces scalarizing of llvm.masked.scatter
/// intrinsics.
LLVM_ABI bool forceScalarizeMaskedScatter(VectorType *Type,
Align Alignment) const;
/// Return true if the target supports masked compress store.
LLVM_ABI bool isLegalMaskedCompressStore(Type *DataType,
Align Alignment) const;
/// Return true if the target supports masked expand load.
LLVM_ABI bool isLegalMaskedExpandLoad(Type *DataType, Align Alignment) const;
/// Return true if the target supports strided load.
LLVM_ABI bool isLegalStridedLoadStore(Type *DataType, Align Alignment) const;
/// Return true is the target supports interleaved access for the given vector
/// type \p VTy, interleave factor \p Factor, alignment \p Alignment and
/// address space \p AddrSpace.
LLVM_ABI bool isLegalInterleavedAccessType(VectorType *VTy, unsigned Factor,
Align Alignment,
unsigned AddrSpace) const;
// Return true if the target supports masked vector histograms.
LLVM_ABI bool isLegalMaskedVectorHistogram(Type *AddrType,
Type *DataType) const;
/// Return true if this is an alternating opcode pattern that can be lowered
/// to a single instruction on the target. In X86 this is for the addsub
/// instruction which corrsponds to a Shuffle + Fadd + FSub pattern in IR.
/// This function expectes two opcodes: \p Opcode1 and \p Opcode2 being
/// selected by \p OpcodeMask. The mask contains one bit per lane and is a `0`
/// when \p Opcode0 is selected and `1` when Opcode1 is selected.
/// \p VecTy is the vector type of the instruction to be generated.
LLVM_ABI bool isLegalAltInstr(VectorType *VecTy, unsigned Opcode0,
unsigned Opcode1,
const SmallBitVector &OpcodeMask) const;
/// Return true if we should be enabling ordered reductions for the target.
LLVM_ABI bool enableOrderedReductions() 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.
LLVM_ABI 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.
LLVM_ABI bool hasVolatileVariant(Instruction *I, unsigned AddrSpace) const;
/// Return true if target doesn't mind addresses in vectors.
LLVM_ABI bool prefersVectorizedAddressing() const;
/// 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.
LLVM_ABI InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
StackOffset BaseOffset,
bool HasBaseReg, int64_t Scale,
unsigned AddrSpace = 0) const;
/// 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.
LLVM_ABI bool LSRWithInstrQueries() const;
/// 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.
LLVM_ABI bool isTruncateFree(Type *Ty1, Type *Ty2) const;
/// Return true if it is profitable to hoist instruction in the
/// then/else to before if.
LLVM_ABI bool isProfitableToHoist(Instruction *I) const;
LLVM_ABI bool useAA() const;
/// Return true if this type is legal.
LLVM_ABI bool isTypeLegal(Type *Ty) const;
/// Returns the estimated number of registers required to represent \p Ty.
LLVM_ABI unsigned getRegUsageForType(Type *Ty) const;
/// Return true if switches should be turned into lookup tables for the
/// target.
LLVM_ABI bool shouldBuildLookupTables() const;
/// Return true if switches should be turned into lookup tables
/// containing this constant value for the target.
LLVM_ABI bool shouldBuildLookupTablesForConstant(Constant *C) const;
/// Return the minimum bit width to use for integer switch lookup table
/// elements on this target.
LLVM_ABI unsigned getMinimumLookupTableEntryBitWidth() const;
/// Return true if lookup tables should be turned into relative lookup tables.
LLVM_ABI bool shouldBuildRelLookupTables() const;
/// Return true if the input function which is cold at all call sites,
/// should use coldcc calling convention.
LLVM_ABI bool useColdCCForColdCall(Function &F) const;
/// Return true if the input function is internal, should use fastcc calling
/// convention.
LLVM_ABI bool useFastCCForInternalCall(Function &F) const;
/// Identifies if the vector form of the intrinsic has a scalar operand.
LLVM_ABI bool isTargetIntrinsicWithScalarOpAtArg(Intrinsic::ID ID,
unsigned ScalarOpdIdx) const;
/// Identifies if the vector form of the intrinsic is overloaded on the type
/// of the operand at index \p OpdIdx, or on the return type if \p OpdIdx is
/// -1.
LLVM_ABI bool isTargetIntrinsicWithOverloadTypeAtArg(Intrinsic::ID ID,
int OpdIdx) const;
/// Identifies if the vector form of the intrinsic that returns a struct is
/// overloaded at the struct element index \p RetIdx.
LLVM_ABI bool
isTargetIntrinsicWithStructReturnOverloadAtField(Intrinsic::ID ID,
int RetIdx) const;
/// Represents a hint about the context in which an insert/extract is used.
///
/// On some targets, inserts/extracts can cheaply be folded into loads/stores.
///
/// This enum allows the vectorizer to give getVectorInstrCost an idea of how
/// inserts/extracts are used
///
/// See \c getVectorInstrContextHint to compute a VectorInstrContext from an
/// insert/extract Instruction*.
enum class VectorInstrContext : uint8_t {
None, ///< The insert/extract is not used with a load/store.
Load, ///< The value being inserted comes from a load (InsertElement only).
Store, ///< The extracted value is stored (ExtractElement only).
};
/// Calculates a VectorInstrContext from \p I.
LLVM_ABI static VectorInstrContext
getVectorInstrContextHint(const Instruction *I);
/// Estimate the overhead of scalarizing an instruction. Insert and Extract
/// are set if the demanded result elements need to be inserted and/or
/// extracted from vectors. The involved values may be passed in VL if
/// Insert is true.
LLVM_ABI InstructionCost getScalarizationOverhead(
VectorType *Ty, const APInt &DemandedElts, bool Insert, bool Extract,
TTI::TargetCostKind CostKind, bool ForPoisonSrc = true,
ArrayRef<Value *> VL = {},
TTI::VectorInstrContext VIC = TTI::VectorInstrContext::None) const;
/// Estimate the overhead of scalarizing operands with the given types. The
/// (potentially vector) types to use for each of argument are passes via Tys.
LLVM_ABI InstructionCost getOperandsScalarizationOverhead(
ArrayRef<Type *> Tys, TTI::TargetCostKind CostKind,
TTI::VectorInstrContext VIC = TTI::VectorInstrContext::None) 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.
LLVM_ABI bool supportsEfficientVectorElementLoadStore() const;
/// If the target supports tail calls.
LLVM_ABI bool supportsTailCalls() const;
/// If target supports tail call on \p CB
LLVM_ABI bool supportsTailCallFor(const CallBase *CB) const;
/// Don't restrict interleaved unrolling to small loops.
LLVM_ABI bool enableAggressiveInterleaving(bool LoopHasReductions) const;
/// Returns options for expansion of memcmp. IsZeroCmp is
// true if this is the expansion of memcmp(p1, p2, s) == 0.
struct MemCmpExpansionOptions {
// Return true if memcmp expansion is enabled.
operator bool() const { return MaxNumLoads > 0; }
// Maximum number of load operations.
unsigned MaxNumLoads = 0;
// The list of available load sizes (in bytes), sorted in decreasing order.
SmallVector<unsigned, 8> LoadSizes;
// For memcmp expansion when the memcmp result is only compared equal or
// not-equal to 0, allow up to this number of load pairs per block. As an
// example, this may allow 'memcmp(a, b, 3) == 0' in a single block:
// a0 = load2bytes &a[0]
// b0 = load2bytes &b[0]
// a2 = load1byte &a[2]
// b2 = load1byte &b[2]
// r = cmp eq (a0 ^ b0 | a2 ^ b2), 0
unsigned NumLoadsPerBlock = 1;
// Set to true to allow overlapping loads. For example, 7-byte compares can
// be done with two 4-byte compares instead of 4+2+1-byte compares. This
// requires all loads in LoadSizes to be doable in an unaligned way.
bool AllowOverlappingLoads = false;
// Sometimes, the amount of data that needs to be compared is smaller than
// the standard register size, but it cannot be loaded with just one load
// instruction. For example, if the size of the memory comparison is 6
// bytes, we can handle it more efficiently by loading all 6 bytes in a
// single block and generating an 8-byte number, instead of generating two
// separate blocks with conditional jumps for 4 and 2 byte loads. This
// approach simplifies the process and produces the comparison result as
// normal. This array lists the allowed sizes of memcmp tails that can be
// merged into one block
SmallVector<unsigned, 4> AllowedTailExpansions;
};
LLVM_ABI MemCmpExpansionOptions enableMemCmpExpansion(bool OptSize,
bool IsZeroCmp) const;
/// Should the Select Optimization pass be enabled and ran.
LLVM_ABI bool enableSelectOptimize() const;
/// Should the Select Optimization pass treat the given instruction like a
/// select, potentially converting it to a conditional branch. This can
/// include select-like instructions like or(zext(c), x) that can be converted
/// to selects.
LLVM_ABI bool shouldTreatInstructionLikeSelect(const Instruction *I) const;
/// Enable matching of interleaved access groups.
LLVM_ABI bool enableInterleavedAccessVectorization() const;
/// Enable matching of interleaved access groups that contain predicated
/// accesses or gaps and therefore vectorized using masked
/// vector loads/stores.
LLVM_ABI bool enableMaskedInterleavedAccessVectorization() const;
/// 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.
LLVM_ABI bool isFPVectorizationPotentiallyUnsafe() const;
/// Determine if the target supports unaligned memory accesses.
LLVM_ABI bool allowsMisalignedMemoryAccesses(LLVMContext &Context,
unsigned BitWidth,
unsigned AddressSpace = 0,
Align Alignment = Align(1),
unsigned *Fast = nullptr) const;
/// Return hardware support for population count.
LLVM_ABI PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) const;
/// Return true if the hardware has a fast square-root instruction.
LLVM_ABI bool haveFastSqrt(Type *Ty) const;
/// Return true if the cost of the instruction is too high to speculatively
/// execute and should be kept behind a branch.
/// This normally just wraps around a getInstructionCost() call, but some
/// targets might report a low TCK_SizeAndLatency value that is incompatible
/// with the fixed TCC_Expensive value.
/// NOTE: This assumes the instruction passes isSafeToSpeculativelyExecute().
LLVM_ABI bool isExpensiveToSpeculativelyExecute(const Instruction *I) 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.
LLVM_ABI bool isFCmpOrdCheaperThanFCmpZero(Type *Ty) const;
/// Return the expected cost of supporting the floating point operation
/// of the specified type.
LLVM_ABI InstructionCost getFPOpCost(Type *Ty) const;
/// Return the expected cost of materializing for the given integer
/// immediate of the specified type.
LLVM_ABI InstructionCost getIntImmCost(const APInt &Imm, Type *Ty,
TargetCostKind CostKind) const;
/// 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.
LLVM_ABI InstructionCost getIntImmCostInst(unsigned Opc, unsigned Idx,
const APInt &Imm, Type *Ty,
TargetCostKind CostKind,
Instruction *Inst = nullptr) const;
LLVM_ABI InstructionCost getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
const APInt &Imm, Type *Ty,
TargetCostKind CostKind) const;
/// 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).
LLVM_ABI InstructionCost getIntImmCodeSizeCost(unsigned Opc, unsigned Idx,
const APInt &Imm,
Type *Ty) const;
/// It can be advantageous to detach complex constants from their uses to make
/// their generation cheaper. This hook allows targets to report when such
/// transformations might negatively effect the code generation of the
/// underlying operation. The motivating example is divides whereby hoisting
/// constants prevents the code generator's ability to transform them into
/// combinations of simpler operations.
LLVM_ABI bool preferToKeepConstantsAttached(const Instruction &Inst,
const Function &Fn) const;
/// @}
/// \name Vector Target Information
/// @{
/// 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_Select, ///< Selects elements from the corresponding lane of
///< either source operand. This is equivalent to a
///< vector select with a constant condition operand.
SK_Transpose, ///< Transpose two vectors.
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.
SK_Splice ///< Concatenates elements from the first input vector
///< with elements of the second input vector. Returning
///< a vector of the same type as the input vectors.
///< Index indicates start offset in first input vector.
};
/// 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.
};
/// Additional properties of an operand's values.
enum OperandValueProperties {
OP_None = 0,
OP_PowerOf2 = 1,
OP_NegatedPowerOf2 = 2,
};
// Describe the values an operand can take. We're in the process
// of migrating uses of OperandValueKind and OperandValueProperties
// to use this class, and then will change the internal representation.
struct OperandValueInfo {
OperandValueKind Kind = OK_AnyValue;
OperandValueProperties Properties = OP_None;
bool isConstant() const {
return Kind == OK_UniformConstantValue || Kind == OK_NonUniformConstantValue;
}
bool isUniform() const {
return Kind == OK_UniformConstantValue || Kind == OK_UniformValue;
}
bool isPowerOf2() const {
return Properties == OP_PowerOf2;
}
bool isNegatedPowerOf2() const {
return Properties == OP_NegatedPowerOf2;
}
OperandValueInfo getNoProps() const {
return {Kind, OP_None};
}
OperandValueInfo mergeWith(const OperandValueInfo OpInfoY) {
OperandValueKind MergeKind = OK_AnyValue;
if (isConstant() && OpInfoY.isConstant())
MergeKind = OK_NonUniformConstantValue;
OperandValueProperties MergeProp = OP_None;
if (Properties == OpInfoY.Properties)
MergeProp = Properties;
return {MergeKind, MergeProp};
}
};
/// \return the number of registers in the target-provided register class.
LLVM_ABI unsigned getNumberOfRegisters(unsigned ClassID) const;
/// \return true if the target supports load/store that enables fault
/// suppression of memory operands when the source condition is false.
LLVM_ABI bool hasConditionalLoadStoreForType(Type *Ty, bool IsStore) const;
/// \return the target-provided register class ID for the provided type,
/// accounting for type promotion and other type-legalization techniques that
/// the target might apply. However, it specifically does not account for the
/// scalarization or splitting of vector types. Should a vector type require
/// scalarization or splitting into multiple underlying vector registers, that
/// type should be mapped to a register class containing no registers.
/// Specifically, this is designed to provide a simple, high-level view of the
/// register allocation later performed by the backend. These register classes
/// don't necessarily map onto the register classes used by the backend.
/// FIXME: It's not currently possible to determine how many registers
/// are used by the provided type.
LLVM_ABI unsigned getRegisterClassForType(bool Vector,
Type *Ty = nullptr) const;
/// \return the target-provided register class name
LLVM_ABI const char *getRegisterClassName(unsigned ClassID) const;
/// \return the cost of spilling a register in the target-provided register
/// class to the stack.
LLVM_ABI InstructionCost
getRegisterClassSpillCost(unsigned ClassID, TargetCostKind CostKind) const;
/// \return the cost of reloading a register in the target-provided register
/// class from the stack.
LLVM_ABI InstructionCost
getRegisterClassReloadCost(unsigned ClassID, TargetCostKind CostKind) const;
enum RegisterKind { RGK_Scalar, RGK_FixedWidthVector, RGK_ScalableVector };
/// \return The width of the largest scalar or vector register type.
LLVM_ABI TypeSize getRegisterBitWidth(RegisterKind K) const;
/// \return The width of the smallest vector register type.
LLVM_ABI unsigned getMinVectorRegisterBitWidth() const;
/// \return The maximum value of vscale if the target specifies an
/// architectural maximum vector length, and std::nullopt otherwise.
LLVM_ABI std::optional<unsigned> getMaxVScale() const;
/// \return the value of vscale to tune the cost model for.
LLVM_ABI std::optional<unsigned> getVScaleForTuning() 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.
/// \p K Register Kind for vectorization.
LLVM_ABI bool
shouldMaximizeVectorBandwidth(TargetTransformInfo::RegisterKind K) const;
/// \return The minimum vectorization factor for types of given element
/// bit width, or 0 if there is no minimum VF. The returned value only
/// applies when shouldMaximizeVectorBandwidth returns true.
/// If IsScalable is true, the returned ElementCount must be a scalable VF.
LLVM_ABI ElementCount getMinimumVF(unsigned ElemWidth, bool IsScalable) const;
/// \return The maximum vectorization factor for types of given element
/// bit width and opcode, or 0 if there is no maximum VF.
/// Currently only used by the SLP vectorizer.
LLVM_ABI unsigned getMaximumVF(unsigned ElemWidth, unsigned Opcode) const;
/// \return The minimum vectorization factor for the store instruction. Given
/// the initial estimation of the minimum vector factor and store value type,
/// it tries to find possible lowest VF, which still might be profitable for
/// the vectorization.
/// \param VF Initial estimation of the minimum vector factor.
/// \param ScalarMemTy Scalar memory type of the store operation.
/// \param ScalarValTy Scalar type of the stored value.
/// \param Alignment Alignment of the store
/// \param AddrSpace Address space of the store
/// Currently only used by the SLP vectorizer.
LLVM_ABI unsigned getStoreMinimumVF(unsigned VF, Type *ScalarMemTy,
Type *ScalarValTy, Align Alignment,
unsigned AddrSpace) 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.
LLVM_ABI bool shouldConsiderAddressTypePromotion(
const Instruction &I, bool &AllowPromotionWithoutCommonHeader) const;
/// \return The size of a cache line in bytes.
LLVM_ABI 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_ABI std::optional<unsigned> getCacheSize(CacheLevel Level) const;
/// \return The associativity of the cache level, if available.
LLVM_ABI std::optional<unsigned>
getCacheAssociativity(CacheLevel Level) const;
/// \return The minimum architectural page size for the target.
LLVM_ABI std::optional<unsigned> getMinPageSize() const;
/// \return How much before a load we should place the prefetch
/// instruction. This is currently measured in number of
/// instructions.
LLVM_ABI unsigned getPrefetchDistance() const;
/// Some HW prefetchers can handle accesses up to a certain constant stride.
/// Sometimes prefetching is beneficial even below the HW prefetcher limit,
/// and the arguments provided are meant to serve as a basis for deciding this
/// for a particular loop.
///
/// \param NumMemAccesses Number of memory accesses in the loop.
/// \param NumStridedMemAccesses Number of the memory accesses that
/// ScalarEvolution could find a known stride
/// for.
/// \param NumPrefetches Number of software prefetches that will be
/// emitted as determined by the addresses
/// involved and the cache line size.
/// \param HasCall True if the loop contains a call.
///
/// \return 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.
LLVM_ABI unsigned getMinPrefetchStride(unsigned NumMemAccesses,
unsigned NumStridedMemAccesses,
unsigned NumPrefetches,
bool HasCall) 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.
LLVM_ABI unsigned getMaxPrefetchIterationsAhead() const;
/// \return True if prefetching should also be done for writes.
LLVM_ABI bool enableWritePrefetching() const;
/// \return if target want to issue a prefetch in address space \p AS.
LLVM_ABI bool shouldPrefetchAddressSpace(unsigned AS) const;
/// \return The cost of a partial reduction, which is a reduction from a
/// vector to another vector with fewer elements of larger size. They are
/// represented by the llvm.vector.partial.reduce.add and
/// llvm.vector.partial.reduce.fadd intrinsics, which take an accumulator of
/// type \p AccumType and a second vector operand to be accumulated, whose
/// element count is specified by \p VF. The type of reduction is specified by
/// \p Opcode. The second operand passed to the intrinsic could be the result
/// of an extend, such as sext or zext. In this case \p BinOp is nullopt,
/// \p InputTypeA represents the type being extended and \p OpAExtend the
/// operation, i.e. sign- or zero-extend.
/// For floating-point partial reductions, any fast math flags (FMF) should be
/// provided to govern which reductions are valid to perform (depending on
/// reassoc or contract, for example), whereas this must be nullopt for
/// integer partial reductions.
/// Also, \p InputTypeB should be nullptr and OpBExtend should be None.
/// Alternatively, the second operand could be the result of a binary
/// operation performed on two extends, i.e.
/// mul(zext i8 %a -> i32, zext i8 %b -> i32).
/// In this case \p BinOp may specify the opcode of the binary operation,
/// \p InputTypeA and \p InputTypeB the types being extended, and
/// \p OpAExtend, \p OpBExtend the form of extensions. An example of an
/// operation that uses a partial reduction is a dot product, which reduces
/// two vectors in binary mul operation to another of 4 times fewer and 4
/// times larger elements.
LLVM_ABI InstructionCost getPartialReductionCost(
unsigned Opcode, Type *InputTypeA, Type *InputTypeB, Type *AccumType,
ElementCount VF, PartialReductionExtendKind OpAExtend,
PartialReductionExtendKind OpBExtend, std::optional<unsigned> BinOp,
TTI::TargetCostKind CostKind, std::optional<FastMathFlags> FMF) 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.
LLVM_ABI unsigned getMaxInterleaveFactor(ElementCount VF) const;
/// Collect properties of V used in cost analysis, e.g. OP_PowerOf2.
LLVM_ABI static OperandValueInfo getOperandInfo(const Value *V);
/// Collect common data between two OperandValueInfo inputs
LLVM_ABI static OperandValueInfo commonOperandInfo(const Value *X,
const Value *Y);
/// 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.
/// \p CxtI is the optional original context instruction, if one exists, to
/// provide even more information.
/// \p TLibInfo is used to search for platform specific vector library
/// functions for instructions that might be converted to calls (e.g. frem).
LLVM_ABI InstructionCost getArithmeticInstrCost(
unsigned Opcode, Type *Ty,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput,
TTI::OperandValueInfo Opd1Info = {TTI::OK_AnyValue, TTI::OP_None},
TTI::OperandValueInfo Opd2Info = {TTI::OK_AnyValue, TTI::OP_None},
ArrayRef<const Value *> Args = {}, const Instruction *CxtI = nullptr,
const TargetLibraryInfo *TLibInfo = nullptr) const;
/// Returns the cost estimation for alternating opcode pattern that can be
/// lowered to a single instruction on the target. In X86 this is for the
/// addsub instruction which corrsponds to a Shuffle + Fadd + FSub pattern in
/// IR. This function expects two opcodes: \p Opcode1 and \p Opcode2 being
/// selected by \p OpcodeMask. The mask contains one bit per lane and is a `0`
/// when \p Opcode0 is selected and `1` when Opcode1 is selected.
/// \p VecTy is the vector type of the instruction to be generated.
LLVM_ABI InstructionCost getAltInstrCost(
VectorType *VecTy, unsigned Opcode0, unsigned Opcode1,
const SmallBitVector &OpcodeMask,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput) const;
/// \return The cost of a shuffle instruction of kind Kind with inputs of type
/// SrcTy, producing a vector of type DstTy. The exact mask may be passed as
/// Mask, or else the array will be empty. The Index and SubTp parameters
/// are used by the subvector insertions shuffle kinds to show the insert
/// point and the type of the subvector being inserted. The operands of the
/// shuffle can be passed through \p Args, which helps improve the cost
/// estimation in some cases, like in broadcast loads.
LLVM_ABI InstructionCost getShuffleCost(
ShuffleKind Kind, VectorType *DstTy, VectorType *SrcTy,
ArrayRef<int> Mask = {},
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput, int Index = 0,
VectorType *SubTp = nullptr, ArrayRef<const Value *> Args = {},
const Instruction *CxtI = nullptr) const;
/// Represents a hint about the context in which a cast is used.
///
/// For zext/sext, the context of the cast is the operand, which must be a
/// load of some kind. For trunc, the context is of the cast is the single
/// user of the instruction, which must be a store of some kind.
///
/// This enum allows the vectorizer to give getCastInstrCost an idea of the
/// type of cast it's dealing with, as not every cast is equal. For instance,
/// the zext of a load may be free, but the zext of an interleaving load can
//// be (very) expensive!
///
/// See \c getCastContextHint to compute a CastContextHint from a cast
/// Instruction*. Callers can use it if they don't need to override the
/// context and just want it to be calculated from the instruction.
///
/// FIXME: This handles the types of load/store that the vectorizer can
/// produce, which are the cases where the context instruction is most
/// likely to be incorrect. There are other situations where that can happen
/// too, which might be handled here but in the long run a more general
/// solution of costing multiple instructions at the same times may be better.
enum class CastContextHint : uint8_t {
None, ///< The cast is not used with a load/store of any kind.
Normal, ///< The cast is used with a normal load/store.
Masked, ///< The cast is used with a masked load/store.
GatherScatter, ///< The cast is used with a gather/scatter.
Interleave, ///< The cast is used with an interleaved load/store.
Reversed, ///< The cast is used with a reversed load/store.
};
/// Calculates a CastContextHint from \p I.
/// This should be used by callers of getCastInstrCost if they wish to
/// determine the context from some instruction.
/// \returns the CastContextHint for ZExt/SExt/Trunc, None if \p I is nullptr,
/// or if it's another type of cast.
LLVM_ABI static CastContextHint getCastContextHint(const Instruction *I);
/// \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.
LLVM_ABI InstructionCost getCastInstrCost(
unsigned Opcode, Type *Dst, Type *Src, TTI::CastContextHint CCH,
TTI::TargetCostKind CostKind = TTI::TCK_SizeAndLatency,
const Instruction *I = nullptr) const;
/// \return The expected cost of a sign- or zero-extended vector extract. Use
/// Index = -1 to indicate that there is no information about the index value.
LLVM_ABI InstructionCost
getExtractWithExtendCost(unsigned Opcode, Type *Dst, VectorType *VecTy,
unsigned Index, TTI::TargetCostKind CostKind) const;
/// \return The expected cost of control-flow related instructions such as
/// Phi, Ret, Br, Switch.
LLVM_ABI InstructionCost getCFInstrCost(
unsigned Opcode, TTI::TargetCostKind CostKind = TTI::TCK_SizeAndLatency,
const Instruction *I = nullptr) 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. The \p VecPred parameter can be used to indicate the select
/// is using a compare with the specified predicate as condition. When vector
/// types are passed, \p VecPred must be used for all lanes. For a
/// comparison, the two operands are the natural values. For a select, the
/// two operands are the *value* operands, not the condition operand.
LLVM_ABI InstructionCost getCmpSelInstrCost(
unsigned Opcode, Type *ValTy, Type *CondTy, CmpInst::Predicate VecPred,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput,
OperandValueInfo Op1Info = {OK_AnyValue, OP_None},
OperandValueInfo Op2Info = {OK_AnyValue, OP_None},
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.
/// This is used when the instruction is not available; a typical use
/// case is to provision the cost of vectorization/scalarization in
/// vectorizer passes.
LLVM_ABI InstructionCost getVectorInstrCost(
unsigned Opcode, Type *Val, TTI::TargetCostKind CostKind,
unsigned Index = -1, const Value *Op0 = nullptr,
const Value *Op1 = nullptr,
TTI::VectorInstrContext VIC = TTI::VectorInstrContext::None) const;
/// \return The expected cost of vector Insert and Extract.
/// Use -1 to indicate that there is no information on the index value.
/// This is used when the instruction is not available; a typical use
/// case is to provision the cost of vectorization/scalarization in
/// vectorizer passes.
/// \param ScalarUserAndIdx encodes the information about extracts from a
/// vector with 'Scalar' being the value being extracted,'User' being the user
/// of the extract(nullptr if user is not known before vectorization) and
/// 'Idx' being the extract lane.
LLVM_ABI InstructionCost getVectorInstrCost(
unsigned Opcode, Type *Val, TTI::TargetCostKind CostKind, unsigned Index,
Value *Scalar,
ArrayRef<std::tuple<Value *, User *, int>> ScalarUserAndIdx,
TTI::VectorInstrContext VIC = TTI::VectorInstrContext::None) const;
/// \return The expected cost of vector Insert and Extract.
/// This is used when instruction is available, and implementation
/// asserts 'I' is not nullptr.
///
/// A typical suitable use case is cost estimation when vector instruction
/// exists (e.g., from basic blocks during transformation).
LLVM_ABI InstructionCost getVectorInstrCost(
const Instruction &I, Type *Val, TTI::TargetCostKind CostKind,
unsigned Index = -1,
TTI::VectorInstrContext VIC = TTI::VectorInstrContext::None) const;
/// \return The expected cost of inserting or extracting a lane that is \p
/// Index elements from the end of a vector, i.e. the mathematical expression
/// for the lane is (VF - 1 - Index). This is required for scalable vectors
/// where the exact lane index is unknown at compile time.
LLVM_ABI InstructionCost getIndexedVectorInstrCostFromEnd(
unsigned Opcode, Type *Val, TTI::TargetCostKind CostKind,
unsigned Index) const;
/// \return The expected cost of aggregate inserts and extracts. This is
/// used when the instruction is not available; a typical use case is to
/// provision the cost of vectorization/scalarization in vectorizer passes.
LLVM_ABI InstructionCost getInsertExtractValueCost(
unsigned Opcode, TTI::TargetCostKind CostKind) const;
/// \return The cost of replication shuffle of \p VF elements typed \p EltTy
/// \p ReplicationFactor times.
///
/// For example, the mask for \p ReplicationFactor=3 and \p VF=4 is:
/// <0,0,0,1,1,1,2,2,2,3,3,3>
LLVM_ABI InstructionCost getReplicationShuffleCost(
Type *EltTy, int ReplicationFactor, int VF, const APInt &DemandedDstElts,
TTI::TargetCostKind CostKind) const;
/// \return The cost of Load and Store instructions. The operand info
/// \p OpdInfo should refer to the stored value for stores and the address
/// for loads.
LLVM_ABI InstructionCost getMemoryOpCost(
unsigned Opcode, Type *Src, Align Alignment, unsigned AddressSpace,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput,
OperandValueInfo OpdInfo = {OK_AnyValue, OP_None},
const Instruction *I = nullptr) 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.
/// \p UseMaskForCond indicates if the memory access is predicated.
/// \p UseMaskForGaps indicates if gaps should be masked.
LLVM_ABI InstructionCost getInterleavedMemoryOpCost(
unsigned Opcode, Type *VecTy, unsigned Factor, ArrayRef<unsigned> Indices,
Align Alignment, unsigned AddressSpace,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput,
bool UseMaskForCond = false, bool UseMaskForGaps = false) const;
/// A helper function to determine the type of reduction algorithm used
/// for a given \p Opcode and set of FastMathFlags \p FMF.
static bool requiresOrderedReduction(std::optional<FastMathFlags> FMF) {
return FMF && !(*FMF).allowReassoc();
}
/// Calculate the cost of vector reduction intrinsics.
///
/// 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 FastMathFlags
/// parameter \p FMF indicates what type of reduction we are performing:
/// 1. Tree-wise. This is the typical 'fast' reduction performed that
/// involves successively splitting a vector into half and doing the
/// operation on the pair of halves until you have a scalar value. For
/// example:
/// (v0, v1, v2, v3)
/// ((v0+v2), (v1+v3), undef, undef)
/// ((v0+v2+v1+v3), undef, undef, undef)
/// This is the default behaviour for integer operations, whereas for
/// floating point we only do this if \p FMF indicates that
/// reassociation is allowed.
/// 2. Ordered. For a vector with N elements this involves performing N
/// operations in lane order, starting with an initial scalar value, i.e.
/// result = InitVal + v0
/// result = result + v1
/// result = result + v2
/// result = result + v3
/// This is only the case for FP operations and when reassociation is not
/// allowed.
///
LLVM_ABI InstructionCost getArithmeticReductionCost(
unsigned Opcode, VectorType *Ty, std::optional<FastMathFlags> FMF,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput) const;
LLVM_ABI InstructionCost getMinMaxReductionCost(
Intrinsic::ID IID, VectorType *Ty, FastMathFlags FMF = FastMathFlags(),
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput) const;
/// Calculate the cost of an extended reduction pattern, similar to
/// getArithmeticReductionCost of an Add/Sub reduction with multiply and
/// optional extensions. This is the cost of as:
/// * ResTy vecreduce.add/sub(mul (A, B)) or,
/// * ResTy vecreduce.add/sub(mul(ext(Ty A), ext(Ty B)).
LLVM_ABI InstructionCost getMulAccReductionCost(
bool IsUnsigned, unsigned RedOpcode, Type *ResTy, VectorType *Ty,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput) const;
/// Calculate the cost of an extended reduction pattern, similar to
/// getArithmeticReductionCost of a reduction with an extension.
/// This is the cost of as:
/// ResTy vecreduce.opcode(ext(Ty A)).
LLVM_ABI InstructionCost getExtendedReductionCost(
unsigned Opcode, bool IsUnsigned, Type *ResTy, VectorType *Ty,
std::optional<FastMathFlags> FMF,
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput) 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.
LLVM_ABI InstructionCost getIntrinsicInstrCost(
const IntrinsicCostAttributes &ICA, TTI::TargetCostKind CostKind) const;
/// \returns The cost of memory intrinsic instructions.
/// Used when IntrinsicInst is not materialized.
LLVM_ABI InstructionCost
getMemIntrinsicInstrCost(const MemIntrinsicCostAttributes &MICA,
TTI::TargetCostKind CostKind) const;
/// \returns The cost of Call instructions.
LLVM_ABI InstructionCost getCallInstrCost(
Function *F, Type *RetTy, ArrayRef<Type *> Tys,
TTI::TargetCostKind CostKind = TTI::TCK_SizeAndLatency) const;
/// \returns The number of pieces into which the provided type must be
/// split during legalization. Zero is returned when the answer is unknown.
LLVM_ABI 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 with vector
/// pointer types and scalar pointer types. Such targets should override this
/// function. \p SE holds the pointer for the scalar evolution object which
/// was used in order to get the Ptr step value. \p Ptr holds the SCEV of the
/// access pointer.
LLVM_ABI InstructionCost
getAddressComputationCost(Type *PtrTy, ScalarEvolution *SE, const SCEV *Ptr,
TTI::TargetCostKind CostKind) 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.
LLVM_ABI InstructionCost
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.
LLVM_ABI bool getTgtMemIntrinsic(IntrinsicInst *Inst,
MemIntrinsicInfo &Info) const;
/// \returns The maximum element size, in bytes, for an element
/// unordered-atomic memory intrinsic.
LLVM_ABI unsigned getAtomicMemIntrinsicMaxElementSize() const;
/// \returns A value which is the result of the given memory intrinsic. If \p
/// CanCreate is true, 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.
LLVM_ABI Value *
getOrCreateResultFromMemIntrinsic(IntrinsicInst *Inst, Type *ExpectedType,
bool CanCreate = true) const;
/// \returns The type to use in a loop expansion of a memcpy call.
LLVM_ABI Type *getMemcpyLoopLoweringType(
LLVMContext &Context, Value *Length, unsigned SrcAddrSpace,
unsigned DestAddrSpace, Align SrcAlign, Align DestAlign,
std::optional<uint32_t> AtomicElementSize = std::nullopt) 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.
LLVM_ABI void getMemcpyLoopResidualLoweringType(
SmallVectorImpl<Type *> &OpsOut, LLVMContext &Context,
unsigned RemainingBytes, unsigned SrcAddrSpace, unsigned DestAddrSpace,
Align SrcAlign, Align DestAlign,
std::optional<uint32_t> AtomicCpySize = std::nullopt) const;
/// \returns True if the two functions have compatible attributes for inlining
/// purposes.
LLVM_ABI bool areInlineCompatible(const Function *Caller,
const Function *Callee) const;
/// Returns a penalty for invoking call \p Call in \p F.
/// For example, if a function F calls a function G, which in turn calls
/// function H, then getInlineCallPenalty(F, H()) would return the
/// penalty of calling H from F, e.g. after inlining G into F.
/// \p DefaultCallPenalty is passed to give a default penalty that
/// the target can amend or override.
LLVM_ABI unsigned getInlineCallPenalty(const Function *F,
const CallBase &Call,
unsigned DefaultCallPenalty) const;
/// \returns true if `Caller`'s `Attr` should be added to the new function
/// created by outlining part of `Caller`.
LLVM_ABI bool
shouldCopyAttributeWhenOutliningFrom(const Function *Caller,
const Attribute &Attr) const;
/// \returns True if the caller and callee agree on how \p Types will be
/// passed to or returned from the callee.
/// to the callee.
/// \param Types List of types to check.
LLVM_ABI bool areTypesABICompatible(const Function *Caller,
const Function *Callee,
ArrayRef<Type *> Types) const;
/// 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.
LLVM_ABI bool isIndexedLoadLegal(enum MemIndexedMode Mode, Type *Ty) const;
/// \returns True if the specified indexed store for the given type is legal.
LLVM_ABI 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.
LLVM_ABI unsigned getLoadStoreVecRegBitWidth(unsigned AddrSpace) const;
/// \returns True if the load instruction is legal to vectorize.
LLVM_ABI bool isLegalToVectorizeLoad(LoadInst *LI) const;
/// \returns True if the store instruction is legal to vectorize.
LLVM_ABI bool isLegalToVectorizeStore(StoreInst *SI) const;
/// \returns True if it is legal to vectorize the given load chain.
LLVM_ABI bool isLegalToVectorizeLoadChain(unsigned ChainSizeInBytes,
Align Alignment,
unsigned AddrSpace) const;
/// \returns True if it is legal to vectorize the given store chain.
LLVM_ABI bool isLegalToVectorizeStoreChain(unsigned ChainSizeInBytes,
Align Alignment,
unsigned AddrSpace) const;
/// \returns True if it is legal to vectorize the given reduction kind.
LLVM_ABI bool isLegalToVectorizeReduction(const RecurrenceDescriptor &RdxDesc,
ElementCount VF) const;
/// \returns True if the given type is supported for scalable vectors
LLVM_ABI bool isElementTypeLegalForScalableVector(Type *Ty) const;
/// \returns The new vector factor value if the target doesn't support \p
/// SizeInBytes loads or has a better vector factor.
LLVM_ABI 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.
LLVM_ABI unsigned getStoreVectorFactor(unsigned VF, unsigned StoreSize,
unsigned ChainSizeInBytes,
VectorType *VecTy) const;
/// \returns True if the target prefers fixed width vectorization if the
/// loop vectorizer's cost-model assigns an equal cost to the fixed and
/// scalable version of the vectorized loop.
/// \p IsEpilogue is true if the decision is for the epilogue loop.
LLVM_ABI bool preferFixedOverScalableIfEqualCost(bool IsEpilogue) const;
/// \returns True if target prefers SLP vectorizer with altermate opcode
/// vectorization, false - otherwise.
LLVM_ABI bool preferAlternateOpcodeVectorization() const;
/// \returns True if the SLP vectorizer should apply the instruction-count
/// check that rejects 2-element vector trees when the vector instruction
/// count exceeds the scalar instruction count, false if the target opts out
/// of this heuristic.
LLVM_ABI bool preferSLPInstCountCheck() const;
/// \returns True if the target prefers reductions of \p Kind to be performed
/// in the loop.
LLVM_ABI bool preferInLoopReduction(RecurKind Kind, Type *Ty) const;
/// \returns True if the target prefers reductions select kept in the loop
/// when tail folding. i.e.
/// loop:
/// p = phi (0, s)
/// a = add (p, x)
/// s = select (mask, a, p)
/// vecreduce.add(s)
///
/// As opposed to the normal scheme of p = phi (0, a) which allows the select
/// to be pulled out of the loop. If the select(.., add, ..) can be predicated
/// by the target, this can lead to cleaner code generation.
LLVM_ABI bool preferPredicatedReductionSelect() const;
/// Return true if the loop vectorizer should consider vectorizing an
/// otherwise scalar epilogue loop if the loop already has been vectorized
/// processing \p Iters scalar iterations per vector iteration.
LLVM_ABI bool preferEpilogueVectorization(ElementCount Iters) const;
/// \returns True if the loop vectorizer should discard any VFs where the
/// maximum register pressure exceeds getNumberOfRegisters.
LLVM_ABI bool shouldConsiderVectorizationRegPressure() const;
/// \returns True if the target wants to expand the given reduction intrinsic
/// into a shuffle sequence.
LLVM_ABI bool shouldExpandReduction(const IntrinsicInst *II) const;
enum struct ReductionShuffle { SplitHalf, Pairwise };
/// \returns The shuffle sequence pattern used to expand the given reduction
/// intrinsic.
LLVM_ABI ReductionShuffle
getPreferredExpandedReductionShuffle(const IntrinsicInst *II) const;
/// \returns the size cost of rematerializing a GlobalValue address relative
/// to a stack reload.
LLVM_ABI unsigned getGISelRematGlobalCost() const;
/// \returns the lower bound of a trip count to decide on vectorization
/// while tail-folding.
LLVM_ABI unsigned getMinTripCountTailFoldingThreshold() const;
/// \returns True if the target supports scalable vectors.
LLVM_ABI bool supportsScalableVectors() const;
/// \return true when scalable vectorization is preferred.
LLVM_ABI bool enableScalableVectorization() const;
/// \name Vector Predication Information
/// @{
/// Whether the target supports the %evl parameter of VP intrinsic efficiently
/// in hardware. (see LLVM Language Reference - "Vector Predication
/// Intrinsics"). Use of %evl is discouraged when that is not the case.
LLVM_ABI bool hasActiveVectorLength() const;
/// Return true if sinking I's operands to the same basic block as I is
/// profitable, e.g. because the operands can be folded into a target
/// instruction during instruction selection. After calling the function
/// \p Ops contains the Uses to sink ordered by dominance (dominating users
/// come first).
LLVM_ABI bool isProfitableToSinkOperands(Instruction *I,
SmallVectorImpl<Use *> &Ops) const;
/// Return true if it's significantly cheaper to shift a vector by a uniform
/// scalar than by an amount which will vary across each lane. On x86 before
/// AVX2 for example, there is a "psllw" instruction for the former case, but
/// no simple instruction for a general "a << b" operation on vectors.
/// This should also apply to lowering for vector funnel shifts (rotates).
LLVM_ABI bool isVectorShiftByScalarCheap(Type *Ty) const;
struct VPLegalization {
enum VPTransform {
// keep the predicating parameter
Legal = 0,
// where legal, discard the predicate parameter
Discard = 1,
// transform into something else that is also predicating
Convert = 2
};
// How to transform the EVL parameter.
// Legal: keep the EVL parameter as it is.
// Discard: Ignore the EVL parameter where it is safe to do so.
// Convert: Fold the EVL into the mask parameter.
VPTransform EVLParamStrategy;
// How to transform the operator.
// Legal: The target supports this operator.
// Convert: Convert this to a non-VP operation.
// The 'Discard' strategy is invalid.
VPTransform OpStrategy;
bool shouldDoNothing() const {
return (EVLParamStrategy == Legal) && (OpStrategy == Legal);
}
VPLegalization(VPTransform EVLParamStrategy, VPTransform OpStrategy)
: EVLParamStrategy(EVLParamStrategy), OpStrategy(OpStrategy) {}
};
/// \returns How the target needs this vector-predicated operation to be
/// transformed.
LLVM_ABI VPLegalization
getVPLegalizationStrategy(const VPIntrinsic &PI) const;
/// @}
/// \returns Whether a 32-bit branch instruction is available in Arm or Thumb
/// state.
///
/// Used by the LowerTypeTests pass, which constructs an IR inline assembler
/// node containing a jump table in a format suitable for the target, so it
/// needs to know what format of jump table it can legally use.
///
/// For non-Arm targets, this function isn't used. It defaults to returning
/// false, but it shouldn't matter what it returns anyway.
LLVM_ABI bool hasArmWideBranch(bool Thumb) const;
/// Returns a bitmask constructed from the target-features or fmv-features
/// metadata of a function corresponding to its Arch Extensions.
LLVM_ABI APInt getFeatureMask(const Function &F) const;
/// Returns a bitmask constructed from the target-features or fmv-features
/// metadata of a function corresponding to its FMV priority.
LLVM_ABI APInt getPriorityMask(const Function &F) const;
/// Returns true if this is an instance of a function with multiple versions.
LLVM_ABI bool isMultiversionedFunction(const Function &F) const;
/// \return The maximum number of function arguments the target supports.
LLVM_ABI unsigned getMaxNumArgs() const;
/// \return For an array of given Size, return alignment boundary to
/// pad to. Default is no padding.
LLVM_ABI unsigned getNumBytesToPadGlobalArray(unsigned Size,
Type *ArrayType) const;
/// @}
/// Collect kernel launch bounds for \p F into \p LB.
LLVM_ABI void collectKernelLaunchBounds(
const Function &F,
SmallVectorImpl<std::pair<StringRef, int64_t>> &LB) const;
/// Returns true if GEP should not be used to index into vectors for this
/// target.
LLVM_ABI bool allowVectorElementIndexingUsingGEP() const;
/// Determine if an instruction with Custom uniformity can be proven uniform
/// based on which operands are uniform.
///
/// \param I The instruction to check.
/// \param UniformArgs A bitvector indicating which operands are known to be
/// uniform (bit N corresponds to operand N).
/// \returns true if the instruction result can be proven uniform given the
/// uniform operands, false otherwise.
LLVM_ABI bool isUniform(const Instruction *I,
const SmallBitVector &UniformArgs) const;
private:
std::unique_ptr<const TargetTransformInfoImplBase> TTIImpl;
};
/// 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;
/// Default construct a target IR analysis.
///
/// This will use the module's datalayout to construct a baseline
/// conservative TTI result.
LLVM_ABI TargetIRAnalysis();
/// 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.
LLVM_ABI
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;
}
LLVM_ABI Result run(const Function &F, FunctionAnalysisManager &);
private:
friend AnalysisInfoMixin<TargetIRAnalysis>;
LLVM_ABI static AnalysisKey Key;
/// 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;
/// Helper function used as the callback in the default constructor.
static Result getDefaultTTI(const Function &F);
};
/// Wrapper pass for TargetTransformInfo.
///
/// This pass can be constructed from a TTI object which it stores internally
/// and is queried by passes.
class LLVM_ABI TargetTransformInfoWrapperPass : public ImmutablePass {
TargetIRAnalysis TIRA;
std::optional<TargetTransformInfo> TTI;
virtual void anchor();
public:
static char ID;
/// 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);
};
/// Create an analysis pass wrapper around a TTI object.
///
/// This analysis pass just holds the TTI instance and makes it available to
/// clients.
LLVM_ABI ImmutablePass *
createTargetTransformInfoWrapperPass(TargetIRAnalysis TIRA);
} // namespace llvm
#endif