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//===- llvm/Target/TargetLowering.h - Target Lowering Info ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file describes how to lower LLVM code to machine code. This has two
/// main components:
///
/// 1. Which ValueTypes are natively supported by the target.
/// 2. Which operations are supported for supported ValueTypes.
/// 3. Cost thresholds for alternative implementations of certain operations.
///
/// In addition it has a few other components, like information about FP
/// immediates.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_TARGETLOWERING_H
#define LLVM_TARGET_TARGETLOWERING_H
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/DAGCombine.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineValueType.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Support/AtomicOrdering.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetCallingConv.h"
#include "llvm/Target/TargetMachine.h"
#include <algorithm>
#include <cassert>
#include <climits>
#include <cstdint>
#include <iterator>
#include <map>
#include <string>
#include <utility>
#include <vector>
namespace llvm {
class BranchProbability;
class CCState;
class CCValAssign;
class Constant;
class FastISel;
class FunctionLoweringInfo;
class GlobalValue;
class IntrinsicInst;
struct KnownBits;
class LLVMContext;
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MachineJumpTableInfo;
class MachineLoop;
class MachineRegisterInfo;
class MCContext;
class MCExpr;
class Module;
class TargetRegisterClass;
class TargetLibraryInfo;
class TargetRegisterInfo;
class Value;
namespace Sched {
enum Preference {
None, // No preference
Source, // Follow source order.
RegPressure, // Scheduling for lowest register pressure.
Hybrid, // Scheduling for both latency and register pressure.
ILP, // Scheduling for ILP in low register pressure mode.
VLIW // Scheduling for VLIW targets.
};
} // end namespace Sched
/// This base class for TargetLowering contains the SelectionDAG-independent
/// parts that can be used from the rest of CodeGen.
class TargetLoweringBase {
public:
/// This enum indicates whether operations are valid for a target, and if not,
/// what action should be used to make them valid.
enum LegalizeAction : uint8_t {
Legal, // The target natively supports this operation.
Promote, // This operation should be executed in a larger type.
Expand, // Try to expand this to other ops, otherwise use a libcall.
LibCall, // Don't try to expand this to other ops, always use a libcall.
Custom // Use the LowerOperation hook to implement custom lowering.
};
/// This enum indicates whether a types are legal for a target, and if not,
/// what action should be used to make them valid.
enum LegalizeTypeAction : uint8_t {
TypeLegal, // The target natively supports this type.
TypePromoteInteger, // Replace this integer with a larger one.
TypeExpandInteger, // Split this integer into two of half the size.
TypeSoftenFloat, // Convert this float to a same size integer type,
// if an operation is not supported in target HW.
TypeExpandFloat, // Split this float into two of half the size.
TypeScalarizeVector, // Replace this one-element vector with its element.
TypeSplitVector, // Split this vector into two of half the size.
TypeWidenVector, // This vector should be widened into a larger vector.
TypePromoteFloat // Replace this float with a larger one.
};
/// LegalizeKind holds the legalization kind that needs to happen to EVT
/// in order to type-legalize it.
using LegalizeKind = std::pair<LegalizeTypeAction, EVT>;
/// Enum that describes how the target represents true/false values.
enum BooleanContent {
UndefinedBooleanContent, // Only bit 0 counts, the rest can hold garbage.
ZeroOrOneBooleanContent, // All bits zero except for bit 0.
ZeroOrNegativeOneBooleanContent // All bits equal to bit 0.
};
/// Enum that describes what type of support for selects the target has.
enum SelectSupportKind {
ScalarValSelect, // The target supports scalar selects (ex: cmov).
ScalarCondVectorVal, // The target supports selects with a scalar condition
// and vector values (ex: cmov).
VectorMaskSelect // The target supports vector selects with a vector
// mask (ex: x86 blends).
};
/// Enum that specifies what an atomic load/AtomicRMWInst is expanded
/// to, if at all. Exists because different targets have different levels of
/// support for these atomic instructions, and also have different options
/// w.r.t. what they should expand to.
enum class AtomicExpansionKind {
None, // Don't expand the instruction.
LLSC, // Expand the instruction into loadlinked/storeconditional; used
// by ARM/AArch64.
LLOnly, // Expand the (load) instruction into just a load-linked, which has
// greater atomic guarantees than a normal load.
CmpXChg, // Expand the instruction into cmpxchg; used by at least X86.
};
/// Enum that specifies when a multiplication should be expanded.
enum class MulExpansionKind {
Always, // Always expand the instruction.
OnlyLegalOrCustom, // Only expand when the resulting instructions are legal
// or custom.
};
class ArgListEntry {
public:
Value *Val = nullptr;
SDValue Node = SDValue();
Type *Ty = nullptr;
bool IsSExt : 1;
bool IsZExt : 1;
bool IsInReg : 1;
bool IsSRet : 1;
bool IsNest : 1;
bool IsByVal : 1;
bool IsInAlloca : 1;
bool IsReturned : 1;
bool IsSwiftSelf : 1;
bool IsSwiftError : 1;
uint16_t Alignment = 0;
ArgListEntry()
: IsSExt(false), IsZExt(false), IsInReg(false), IsSRet(false),
IsNest(false), IsByVal(false), IsInAlloca(false), IsReturned(false),
IsSwiftSelf(false), IsSwiftError(false) {}
void setAttributes(ImmutableCallSite *CS, unsigned ArgIdx);
};
using ArgListTy = std::vector<ArgListEntry>;
virtual void markLibCallAttributes(MachineFunction *MF, unsigned CC,
ArgListTy &Args) const {};
static ISD::NodeType getExtendForContent(BooleanContent Content) {
switch (Content) {
case UndefinedBooleanContent:
// Extend by adding rubbish bits.
return ISD::ANY_EXTEND;
case ZeroOrOneBooleanContent:
// Extend by adding zero bits.
return ISD::ZERO_EXTEND;
case ZeroOrNegativeOneBooleanContent:
// Extend by copying the sign bit.
return ISD::SIGN_EXTEND;
}
llvm_unreachable("Invalid content kind");
}
/// NOTE: The TargetMachine owns TLOF.
explicit TargetLoweringBase(const TargetMachine &TM);
TargetLoweringBase(const TargetLoweringBase &) = delete;
TargetLoweringBase &operator=(const TargetLoweringBase &) = delete;
virtual ~TargetLoweringBase() = default;
protected:
/// \brief Initialize all of the actions to default values.
void initActions();
public:
const TargetMachine &getTargetMachine() const { return TM; }
virtual bool useSoftFloat() const { return false; }
/// Return the pointer type for the given address space, defaults to
/// the pointer type from the data layout.
/// FIXME: The default needs to be removed once all the code is updated.
MVT getPointerTy(const DataLayout &DL, uint32_t AS = 0) const {
return MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
}
/// Return the type for frame index, which is determined by
/// the alloca address space specified through the data layout.
MVT getFrameIndexTy(const DataLayout &DL) const {
return getPointerTy(DL, DL.getAllocaAddrSpace());
}
/// Return the type for operands of fence.
/// TODO: Let fence operands be of i32 type and remove this.
virtual MVT getFenceOperandTy(const DataLayout &DL) const {
return getPointerTy(DL);
}
/// EVT is not used in-tree, but is used by out-of-tree target.
/// A documentation for this function would be nice...
virtual MVT getScalarShiftAmountTy(const DataLayout &, EVT) const;
EVT getShiftAmountTy(EVT LHSTy, const DataLayout &DL) const;
/// Returns the type to be used for the index operand of:
/// ISD::INSERT_VECTOR_ELT, ISD::EXTRACT_VECTOR_ELT,
/// ISD::INSERT_SUBVECTOR, and ISD::EXTRACT_SUBVECTOR
virtual MVT getVectorIdxTy(const DataLayout &DL) const {
return getPointerTy(DL);
}
virtual bool isSelectSupported(SelectSupportKind /*kind*/) const {
return true;
}
/// Return true if multiple condition registers are available.
bool hasMultipleConditionRegisters() const {
return HasMultipleConditionRegisters;
}
/// Return true if the target has BitExtract instructions.
bool hasExtractBitsInsn() const { return HasExtractBitsInsn; }
/// Return the preferred vector type legalization action.
virtual TargetLoweringBase::LegalizeTypeAction
getPreferredVectorAction(EVT VT) const {
// The default action for one element vectors is to scalarize
if (VT.getVectorNumElements() == 1)
return TypeScalarizeVector;
// The default action for other vectors is to promote
return TypePromoteInteger;
}
// There are two general methods for expanding a BUILD_VECTOR node:
// 1. Use SCALAR_TO_VECTOR on the defined scalar values and then shuffle
// them together.
// 2. Build the vector on the stack and then load it.
// If this function returns true, then method (1) will be used, subject to
// the constraint that all of the necessary shuffles are legal (as determined
// by isShuffleMaskLegal). If this function returns false, then method (2) is
// always used. The vector type, and the number of defined values, are
// provided.
virtual bool
shouldExpandBuildVectorWithShuffles(EVT /* VT */,
unsigned DefinedValues) const {
return DefinedValues < 3;
}
/// Return true if integer divide is usually cheaper than a sequence of
/// several shifts, adds, and multiplies for this target.
/// The definition of "cheaper" may depend on whether we're optimizing
/// for speed or for size.
virtual bool isIntDivCheap(EVT VT, AttributeList Attr) const { return false; }
/// Return true if the target can handle a standalone remainder operation.
virtual bool hasStandaloneRem(EVT VT) const {
return true;
}
/// Return true if SQRT(X) shouldn't be replaced with X*RSQRT(X).
virtual bool isFsqrtCheap(SDValue X, SelectionDAG &DAG) const {
// Default behavior is to replace SQRT(X) with X*RSQRT(X).
return false;
}
/// Reciprocal estimate status values used by the functions below.
enum ReciprocalEstimate : int {
Unspecified = -1,
Disabled = 0,
Enabled = 1
};
/// Return a ReciprocalEstimate enum value for a square root of the given type
/// based on the function's attributes. If the operation is not overridden by
/// the function's attributes, "Unspecified" is returned and target defaults
/// are expected to be used for instruction selection.
int getRecipEstimateSqrtEnabled(EVT VT, MachineFunction &MF) const;
/// Return a ReciprocalEstimate enum value for a division of the given type
/// based on the function's attributes. If the operation is not overridden by
/// the function's attributes, "Unspecified" is returned and target defaults
/// are expected to be used for instruction selection.
int getRecipEstimateDivEnabled(EVT VT, MachineFunction &MF) const;
/// Return the refinement step count for a square root of the given type based
/// on the function's attributes. If the operation is not overridden by
/// the function's attributes, "Unspecified" is returned and target defaults
/// are expected to be used for instruction selection.
int getSqrtRefinementSteps(EVT VT, MachineFunction &MF) const;
/// Return the refinement step count for a division of the given type based
/// on the function's attributes. If the operation is not overridden by
/// the function's attributes, "Unspecified" is returned and target defaults
/// are expected to be used for instruction selection.
int getDivRefinementSteps(EVT VT, MachineFunction &MF) const;
/// Returns true if target has indicated at least one type should be bypassed.
bool isSlowDivBypassed() const { return !BypassSlowDivWidths.empty(); }
/// Returns map of slow types for division or remainder with corresponding
/// fast types
const DenseMap<unsigned int, unsigned int> &getBypassSlowDivWidths() const {
return BypassSlowDivWidths;
}
/// Return true if Flow Control is an expensive operation that should be
/// avoided.
bool isJumpExpensive() const { return JumpIsExpensive; }
/// Return true if selects are only cheaper than branches if the branch is
/// unlikely to be predicted right.
bool isPredictableSelectExpensive() const {
return PredictableSelectIsExpensive;
}
/// 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.
virtual BranchProbability getPredictableBranchThreshold() const;
/// Return true if the following transform is beneficial:
/// fold (conv (load x)) -> (load (conv*)x)
/// On architectures that don't natively support some vector loads
/// efficiently, casting the load to a smaller vector of larger types and
/// loading is more efficient, however, this can be undone by optimizations in
/// dag combiner.
virtual bool isLoadBitCastBeneficial(EVT LoadVT,
EVT BitcastVT) const {
// Don't do if we could do an indexed load on the original type, but not on
// the new one.
if (!LoadVT.isSimple() || !BitcastVT.isSimple())
return true;
MVT LoadMVT = LoadVT.getSimpleVT();
// Don't bother doing this if it's just going to be promoted again later, as
// doing so might interfere with other combines.
if (getOperationAction(ISD::LOAD, LoadMVT) == Promote &&
getTypeToPromoteTo(ISD::LOAD, LoadMVT) == BitcastVT.getSimpleVT())
return false;
return true;
}
/// Return true if the following transform is beneficial:
/// (store (y (conv x)), y*)) -> (store x, (x*))
virtual bool isStoreBitCastBeneficial(EVT StoreVT, EVT BitcastVT) const {
// Default to the same logic as loads.
return isLoadBitCastBeneficial(StoreVT, BitcastVT);
}
/// Return true if it is expected to be cheaper to do a store of a non-zero
/// vector constant with the given size and type for the address space than to
/// store the individual scalar element constants.
virtual bool storeOfVectorConstantIsCheap(EVT MemVT,
unsigned NumElem,
unsigned AddrSpace) const {
return false;
}
/// Allow store merging after legalization in addition to before legalization.
/// This may catch stores that do not exist earlier (eg, stores created from
/// intrinsics).
virtual bool mergeStoresAfterLegalization() const { return false; }
/// Returns if it's reasonable to merge stores to MemVT size.
virtual bool canMergeStoresTo(unsigned AS, EVT MemVT,
const SelectionDAG &DAG) const {
return true;
}
/// \brief Return true if it is cheap to speculate a call to intrinsic cttz.
virtual bool isCheapToSpeculateCttz() const {
return false;
}
/// \brief Return true if it is cheap to speculate a call to intrinsic ctlz.
virtual bool isCheapToSpeculateCtlz() const {
return false;
}
/// \brief Return true if ctlz instruction is fast.
virtual bool isCtlzFast() const {
return false;
}
/// Return true if it is safe to transform an integer-domain bitwise operation
/// into the equivalent floating-point operation. This should be set to true
/// if the target has IEEE-754-compliant fabs/fneg operations for the input
/// type.
virtual bool hasBitPreservingFPLogic(EVT VT) const {
return false;
}
/// \brief Return true if it is cheaper to split the store of a merged int val
/// from a pair of smaller values into multiple stores.
virtual bool isMultiStoresCheaperThanBitsMerge(EVT LTy, EVT HTy) const {
return false;
}
/// \brief Return if the target supports combining a
/// chain like:
/// \code
/// %andResult = and %val1, #mask
/// %icmpResult = icmp %andResult, 0
/// \endcode
/// into a single machine instruction of a form like:
/// \code
/// cc = test %register, #mask
/// \endcode
virtual bool isMaskAndCmp0FoldingBeneficial(const Instruction &AndI) const {
return false;
}
/// Use bitwise logic to make pairs of compares more efficient. For example:
/// and (seteq A, B), (seteq C, D) --> seteq (or (xor A, B), (xor C, D)), 0
/// This should be true when it takes more than one instruction to lower
/// setcc (cmp+set on x86 scalar), when bitwise ops are faster than logic on
/// condition bits (crand on PowerPC), and/or when reducing cmp+br is a win.
virtual bool convertSetCCLogicToBitwiseLogic(EVT VT) const {
return false;
}
/// Return the preferred operand type if the target has a quick way to compare
/// integer values of the given size. Assume that any legal integer type can
/// be compared efficiently. Targets may override this to allow illegal wide
/// types to return a vector type if there is support to compare that type.
virtual MVT hasFastEqualityCompare(unsigned NumBits) const {
MVT VT = MVT::getIntegerVT(NumBits);
return isTypeLegal(VT) ? VT : MVT::INVALID_SIMPLE_VALUE_TYPE;
}
/// Return true if the target should transform:
/// (X & Y) == Y ---> (~X & Y) == 0
/// (X & Y) != Y ---> (~X & Y) != 0
///
/// This may be profitable if the target has a bitwise and-not operation that
/// sets comparison flags. A target may want to limit the transformation based
/// on the type of Y or if Y is a constant.
///
/// Note that the transform will not occur if Y is known to be a power-of-2
/// because a mask and compare of a single bit can be handled by inverting the
/// predicate, for example:
/// (X & 8) == 8 ---> (X & 8) != 0
virtual bool hasAndNotCompare(SDValue Y) const {
return false;
}
/// Return true if the target has a bitwise and-not operation:
/// X = ~A & B
/// This can be used to simplify select or other instructions.
virtual bool hasAndNot(SDValue X) const {
// If the target has the more complex version of this operation, assume that
// it has this operation too.
return hasAndNotCompare(X);
}
/// \brief Return true if the target wants to use the optimization that
/// turns ext(promotableInst1(...(promotableInstN(load)))) into
/// promotedInst1(...(promotedInstN(ext(load)))).
bool enableExtLdPromotion() const { return EnableExtLdPromotion; }
/// Return true if the target can combine store(extractelement VectorTy,
/// Idx).
/// \p Cost[out] gives the cost of that transformation when this is true.
virtual bool canCombineStoreAndExtract(Type *VectorTy, Value *Idx,
unsigned &Cost) const {
return false;
}
/// Return true if target supports floating point exceptions.
bool hasFloatingPointExceptions() const {
return HasFloatingPointExceptions;
}
/// Return true if target always beneficiates from combining into FMA for a
/// given value type. This must typically return false on targets where FMA
/// takes more cycles to execute than FADD.
virtual bool enableAggressiveFMAFusion(EVT VT) const {
return false;
}
/// Return the ValueType of the result of SETCC operations.
virtual EVT getSetCCResultType(const DataLayout &DL, LLVMContext &Context,
EVT VT) const;
/// Return the ValueType for comparison libcalls. Comparions libcalls include
/// floating point comparion calls, and Ordered/Unordered check calls on
/// floating point numbers.
virtual
MVT::SimpleValueType getCmpLibcallReturnType() const;
/// For targets without i1 registers, this gives the nature of the high-bits
/// of boolean values held in types wider than i1.
///
/// "Boolean values" are special true/false values produced by nodes like
/// SETCC and consumed (as the condition) by nodes like SELECT and BRCOND.
/// Not to be confused with general values promoted from i1. Some cpus
/// distinguish between vectors of boolean and scalars; the isVec parameter
/// selects between the two kinds. For example on X86 a scalar boolean should
/// be zero extended from i1, while the elements of a vector of booleans
/// should be sign extended from i1.
///
/// Some cpus also treat floating point types the same way as they treat
/// vectors instead of the way they treat scalars.
BooleanContent getBooleanContents(bool isVec, bool isFloat) const {
if (isVec)
return BooleanVectorContents;
return isFloat ? BooleanFloatContents : BooleanContents;
}
BooleanContent getBooleanContents(EVT Type) const {
return getBooleanContents(Type.isVector(), Type.isFloatingPoint());
}
/// Return target scheduling preference.
Sched::Preference getSchedulingPreference() const {
return SchedPreferenceInfo;
}
/// Some scheduler, e.g. hybrid, can switch to different scheduling heuristics
/// for different nodes. This function returns the preference (or none) for
/// the given node.
virtual Sched::Preference getSchedulingPreference(SDNode *) const {
return Sched::None;
}
/// Return the register class that should be used for the specified value
/// type.
virtual const TargetRegisterClass *getRegClassFor(MVT VT) const {
const TargetRegisterClass *RC = RegClassForVT[VT.SimpleTy];
assert(RC && "This value type is not natively supported!");
return RC;
}
/// Return the 'representative' register class for the specified value
/// type.
///
/// The 'representative' register class is the largest legal super-reg
/// register class for the register class of the value type. For example, on
/// i386 the rep register class for i8, i16, and i32 are GR32; while the rep
/// register class is GR64 on x86_64.
virtual const TargetRegisterClass *getRepRegClassFor(MVT VT) const {
const TargetRegisterClass *RC = RepRegClassForVT[VT.SimpleTy];
return RC;
}
/// Return the cost of the 'representative' register class for the specified
/// value type.
virtual uint8_t getRepRegClassCostFor(MVT VT) const {
return RepRegClassCostForVT[VT.SimpleTy];
}
/// Return true if the target has native support for the specified value type.
/// This means that it has a register that directly holds it without
/// promotions or expansions.
bool isTypeLegal(EVT VT) const {
assert(!VT.isSimple() ||
(unsigned)VT.getSimpleVT().SimpleTy < array_lengthof(RegClassForVT));
return VT.isSimple() && RegClassForVT[VT.getSimpleVT().SimpleTy] != nullptr;
}
class ValueTypeActionImpl {
/// ValueTypeActions - For each value type, keep a LegalizeTypeAction enum
/// that indicates how instruction selection should deal with the type.
LegalizeTypeAction ValueTypeActions[MVT::LAST_VALUETYPE];
public:
ValueTypeActionImpl() {
std::fill(std::begin(ValueTypeActions), std::end(ValueTypeActions),
TypeLegal);
}
LegalizeTypeAction getTypeAction(MVT VT) const {
return ValueTypeActions[VT.SimpleTy];
}
void setTypeAction(MVT VT, LegalizeTypeAction Action) {
ValueTypeActions[VT.SimpleTy] = Action;
}
};
const ValueTypeActionImpl &getValueTypeActions() const {
return ValueTypeActions;
}
/// Return how we should legalize values of this type, either it is already
/// legal (return 'Legal') or we need to promote it to a larger type (return
/// 'Promote'), or we need to expand it into multiple registers of smaller
/// integer type (return 'Expand'). 'Custom' is not an option.
LegalizeTypeAction getTypeAction(LLVMContext &Context, EVT VT) const {
return getTypeConversion(Context, VT).first;
}
LegalizeTypeAction getTypeAction(MVT VT) const {
return ValueTypeActions.getTypeAction(VT);
}
/// For types supported by the target, this is an identity function. For
/// types that must be promoted to larger types, this returns the larger type
/// to promote to. For integer types that are larger than the largest integer
/// register, this contains one step in the expansion to get to the smaller
/// register. For illegal floating point types, this returns the integer type
/// to transform to.
EVT getTypeToTransformTo(LLVMContext &Context, EVT VT) const {
return getTypeConversion(Context, VT).second;
}
/// For types supported by the target, this is an identity function. For
/// types that must be expanded (i.e. integer types that are larger than the
/// largest integer register or illegal floating point types), this returns
/// the largest legal type it will be expanded to.
EVT getTypeToExpandTo(LLVMContext &Context, EVT VT) const {
assert(!VT.isVector());
while (true) {
switch (getTypeAction(Context, VT)) {
case TypeLegal:
return VT;
case TypeExpandInteger:
VT = getTypeToTransformTo(Context, VT);
break;
default:
llvm_unreachable("Type is not legal nor is it to be expanded!");
}
}
}
/// Vector types are broken down into some number of legal first class types.
/// For example, EVT::v8f32 maps to 2 EVT::v4f32 with Altivec or SSE1, or 8
/// promoted EVT::f64 values with the X86 FP stack. Similarly, EVT::v2i64
/// turns into 4 EVT::i32 values with both PPC and X86.
///
/// This method returns the number of registers needed, and the VT for each
/// register. It also returns the VT and quantity of the intermediate values
/// before they are promoted/expanded.
unsigned getVectorTypeBreakdown(LLVMContext &Context, EVT VT,
EVT &IntermediateVT,
unsigned &NumIntermediates,
MVT &RegisterVT) const;
/// Certain targets such as MIPS require that some types such as vectors are
/// always broken down into scalars in some contexts. This occurs even if the
/// vector type is legal.
virtual unsigned getVectorTypeBreakdownForCallingConv(
LLVMContext &Context, EVT VT, EVT &IntermediateVT,
unsigned &NumIntermediates, MVT &RegisterVT) const {
return getVectorTypeBreakdown(Context, VT, IntermediateVT, NumIntermediates,
RegisterVT);
}
struct IntrinsicInfo {
unsigned opc = 0; // target opcode
EVT memVT; // memory VT
const Value* ptrVal = nullptr; // value representing memory location
int offset = 0; // offset off of ptrVal
unsigned size = 0; // the size of the memory location
// (taken from memVT if zero)
unsigned align = 1; // alignment
bool vol = false; // is volatile?
bool readMem = false; // reads memory?
bool writeMem = false; // writes memory?
IntrinsicInfo() = default;
};
/// Given an intrinsic, checks if on the target the intrinsic will need to map
/// to a MemIntrinsicNode (touches memory). If this is the case, it returns
/// true and store the intrinsic information into the IntrinsicInfo that was
/// passed to the function.
virtual bool getTgtMemIntrinsic(IntrinsicInfo &, const CallInst &,
unsigned /*Intrinsic*/) const {
return false;
}
/// Returns true if the target can instruction select the specified FP
/// immediate natively. If false, the legalizer will materialize the FP
/// immediate as a load from a constant pool.
virtual bool isFPImmLegal(const APFloat &/*Imm*/, EVT /*VT*/) const {
return false;
}
/// Targets can use this to indicate that they only support *some*
/// VECTOR_SHUFFLE operations, those with specific masks. By default, if a
/// target supports the VECTOR_SHUFFLE node, all mask values are assumed to be
/// legal.
virtual bool isShuffleMaskLegal(ArrayRef<int> /*Mask*/, EVT /*VT*/) const {
return true;
}
/// Returns true if the operation can trap for the value type.
///
/// VT must be a legal type. By default, we optimistically assume most
/// operations don't trap except for integer divide and remainder.
virtual bool canOpTrap(unsigned Op, EVT VT) const;
/// Similar to isShuffleMaskLegal. This is used by Targets can use this to
/// indicate if there is a suitable VECTOR_SHUFFLE that can be used to replace
/// a VAND with a constant pool entry.
virtual bool isVectorClearMaskLegal(const SmallVectorImpl<int> &/*Mask*/,
EVT /*VT*/) const {
return false;
}
/// Return how this operation should be treated: either it is legal, needs to
/// be promoted to a larger size, needs to be expanded to some other code
/// sequence, or the target has a custom expander for it.
LegalizeAction getOperationAction(unsigned Op, EVT VT) const {
if (VT.isExtended()) return Expand;
// If a target-specific SDNode requires legalization, require the target
// to provide custom legalization for it.
if (Op >= array_lengthof(OpActions[0])) return Custom;
return OpActions[(unsigned)VT.getSimpleVT().SimpleTy][Op];
}
/// Return true if the specified operation is legal on this target or can be
/// made legal with custom lowering. This is used to help guide high-level
/// lowering decisions.
bool isOperationLegalOrCustom(unsigned Op, EVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
(getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Custom);
}
/// Return true if the specified operation is legal on this target or can be
/// made legal using promotion. This is used to help guide high-level lowering
/// decisions.
bool isOperationLegalOrPromote(unsigned Op, EVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
(getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Promote);
}
/// Return true if the specified operation is legal on this target or can be
/// made legal with custom lowering or using promotion. This is used to help
/// guide high-level lowering decisions.
bool isOperationLegalOrCustomOrPromote(unsigned Op, EVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
(getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Custom ||
getOperationAction(Op, VT) == Promote);
}
/// Return true if the operation uses custom lowering, regardless of whether
/// the type is legal or not.
bool isOperationCustom(unsigned Op, EVT VT) const {
return getOperationAction(Op, VT) == Custom;
}
/// Return true if lowering to a jump table is allowed.
bool areJTsAllowed(const Function *Fn) const {
if (Fn->getFnAttribute("no-jump-tables").getValueAsString() == "true")
return false;
return isOperationLegalOrCustom(ISD::BR_JT, MVT::Other) ||
isOperationLegalOrCustom(ISD::BRIND, MVT::Other);
}
/// Check whether the range [Low,High] fits in a machine word.
bool rangeFitsInWord(const APInt &Low, const APInt &High,
const DataLayout &DL) const {
// FIXME: Using the pointer type doesn't seem ideal.
uint64_t BW = DL.getPointerSizeInBits();
uint64_t Range = (High - Low).getLimitedValue(UINT64_MAX - 1) + 1;
return Range <= BW;
}
/// Return true if lowering to a jump table is suitable for a set of case
/// clusters which may contain \p NumCases cases, \p Range range of values.
/// FIXME: This function check the maximum table size and density, but the
/// minimum size is not checked. It would be nice if the the minimum size is
/// also combined within this function. Currently, the minimum size check is
/// performed in findJumpTable() in SelectionDAGBuiler and
/// getEstimatedNumberOfCaseClusters() in BasicTTIImpl.
bool isSuitableForJumpTable(const SwitchInst *SI, uint64_t NumCases,
uint64_t Range) const {
const bool OptForSize = SI->getParent()->getParent()->optForSize();
const unsigned MinDensity = getMinimumJumpTableDensity(OptForSize);
const unsigned MaxJumpTableSize =
OptForSize || getMaximumJumpTableSize() == 0
? UINT_MAX
: getMaximumJumpTableSize();
// Check whether a range of clusters is dense enough for a jump table.
if (Range <= MaxJumpTableSize &&
(NumCases * 100 >= Range * MinDensity)) {
return true;
}
return false;
}
/// Return true if lowering to a bit test is suitable for a set of case
/// clusters which contains \p NumDests unique destinations, \p Low and
/// \p High as its lowest and highest case values, and expects \p NumCmps
/// case value comparisons. Check if the number of destinations, comparison
/// metric, and range are all suitable.
bool isSuitableForBitTests(unsigned NumDests, unsigned NumCmps,
const APInt &Low, const APInt &High,
const DataLayout &DL) const {
// FIXME: I don't think NumCmps is the correct metric: a single case and a
// range of cases both require only one branch to lower. Just looking at the
// number of clusters and destinations should be enough to decide whether to
// build bit tests.
// To lower a range with bit tests, the range must fit the bitwidth of a
// machine word.
if (!rangeFitsInWord(Low, High, DL))
return false;
// Decide whether it's profitable to lower this range with bit tests. Each
// destination requires a bit test and branch, and there is an overall range
// check branch. For a small number of clusters, separate comparisons might
// be cheaper, and for many destinations, splitting the range might be
// better.
return (NumDests == 1 && NumCmps >= 3) || (NumDests == 2 && NumCmps >= 5) ||
(NumDests == 3 && NumCmps >= 6);
}
/// Return true if the specified operation is illegal on this target or
/// unlikely to be made legal with custom lowering. This is used to help guide
/// high-level lowering decisions.
bool isOperationExpand(unsigned Op, EVT VT) const {
return (!isTypeLegal(VT) || getOperationAction(Op, VT) == Expand);
}
/// Return true if the specified operation is legal on this target.
bool isOperationLegal(unsigned Op, EVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
getOperationAction(Op, VT) == Legal;
}
/// Return how this load with extension should be treated: either it is legal,
/// needs to be promoted to a larger size, needs to be expanded to some other
/// code sequence, or the target has a custom expander for it.
LegalizeAction getLoadExtAction(unsigned ExtType, EVT ValVT,
EVT MemVT) const {
if (ValVT.isExtended() || MemVT.isExtended()) return Expand;
unsigned ValI = (unsigned) ValVT.getSimpleVT().SimpleTy;
unsigned MemI = (unsigned) MemVT.getSimpleVT().SimpleTy;
assert(ExtType < ISD::LAST_LOADEXT_TYPE && ValI < MVT::LAST_VALUETYPE &&
MemI < MVT::LAST_VALUETYPE && "Table isn't big enough!");
unsigned Shift = 4 * ExtType;
return (LegalizeAction)((LoadExtActions[ValI][MemI] >> Shift) & 0xf);
}
/// Return true if the specified load with extension is legal on this target.
bool isLoadExtLegal(unsigned ExtType, EVT ValVT, EVT MemVT) const {
return getLoadExtAction(ExtType, ValVT, MemVT) == Legal;
}
/// Return true if the specified load with extension is legal or custom
/// on this target.
bool isLoadExtLegalOrCustom(unsigned ExtType, EVT ValVT, EVT MemVT) const {
return getLoadExtAction(ExtType, ValVT, MemVT) == Legal ||
getLoadExtAction(ExtType, ValVT, MemVT) == Custom;
}
/// Return how this store with truncation should be treated: either it is
/// legal, needs to be promoted to a larger size, needs to be expanded to some
/// other code sequence, or the target has a custom expander for it.
LegalizeAction getTruncStoreAction(EVT ValVT, EVT MemVT) const {
if (ValVT.isExtended() || MemVT.isExtended()) return Expand;
unsigned ValI = (unsigned) ValVT.getSimpleVT().SimpleTy;
unsigned MemI = (unsigned) MemVT.getSimpleVT().SimpleTy;
assert(ValI < MVT::LAST_VALUETYPE && MemI < MVT::LAST_VALUETYPE &&
"Table isn't big enough!");
return TruncStoreActions[ValI][MemI];
}
/// Return true if the specified store with truncation is legal on this
/// target.
bool isTruncStoreLegal(EVT ValVT, EVT MemVT) const {
return isTypeLegal(ValVT) && getTruncStoreAction(ValVT, MemVT) == Legal;
}
/// Return true if the specified store with truncation has solution on this
/// target.
bool isTruncStoreLegalOrCustom(EVT ValVT, EVT MemVT) const {
return isTypeLegal(ValVT) &&
(getTruncStoreAction(ValVT, MemVT) == Legal ||
getTruncStoreAction(ValVT, MemVT) == Custom);
}
/// Return how the indexed load should be treated: either it is legal, needs
/// to be promoted to a larger size, needs to be expanded to some other code
/// sequence, or the target has a custom expander for it.
LegalizeAction
getIndexedLoadAction(unsigned IdxMode, MVT VT) const {
assert(IdxMode < ISD::LAST_INDEXED_MODE && VT.isValid() &&
"Table isn't big enough!");
unsigned Ty = (unsigned)VT.SimpleTy;
return (LegalizeAction)((IndexedModeActions[Ty][IdxMode] & 0xf0) >> 4);
}
/// Return true if the specified indexed load is legal on this target.
bool isIndexedLoadLegal(unsigned IdxMode, EVT VT) const {
return VT.isSimple() &&
(getIndexedLoadAction(IdxMode, VT.getSimpleVT()) == Legal ||
getIndexedLoadAction(IdxMode, VT.getSimpleVT()) == Custom);
}
/// Return how the indexed store should be treated: either it is legal, needs
/// to be promoted to a larger size, needs to be expanded to some other code
/// sequence, or the target has a custom expander for it.
LegalizeAction
getIndexedStoreAction(unsigned IdxMode, MVT VT) const {
assert(IdxMode < ISD::LAST_INDEXED_MODE && VT.isValid() &&
"Table isn't big enough!");
unsigned Ty = (unsigned)VT.SimpleTy;
return (LegalizeAction)(IndexedModeActions[Ty][IdxMode] & 0x0f);
}
/// Return true if the specified indexed load is legal on this target.
bool isIndexedStoreLegal(unsigned IdxMode, EVT VT) const {
return VT.isSimple() &&
(getIndexedStoreAction(IdxMode, VT.getSimpleVT()) == Legal ||
getIndexedStoreAction(IdxMode, VT.getSimpleVT()) == Custom);
}
/// Return how the condition code should be treated: either it is legal, needs
/// to be expanded to some other code sequence, or the target has a custom
/// expander for it.
LegalizeAction
getCondCodeAction(ISD::CondCode CC, MVT VT) const {
assert((unsigned)CC < array_lengthof(CondCodeActions) &&
((unsigned)VT.SimpleTy >> 3) < array_lengthof(CondCodeActions[0]) &&
"Table isn't big enough!");
// See setCondCodeAction for how this is encoded.
uint32_t Shift = 4 * (VT.SimpleTy & 0x7);
uint32_t Value = CondCodeActions[CC][VT.SimpleTy >> 3];
LegalizeAction Action = (LegalizeAction) ((Value >> Shift) & 0xF);
assert(Action != Promote && "Can't promote condition code!");
return Action;
}
/// Return true if the specified condition code is legal on this target.
bool isCondCodeLegal(ISD::CondCode CC, MVT VT) const {
return
getCondCodeAction(CC, VT) == Legal ||
getCondCodeAction(CC, VT) == Custom;
}
/// If the action for this operation is to promote, this method returns the
/// ValueType to promote to.
MVT getTypeToPromoteTo(unsigned Op, MVT VT) const {
assert(getOperationAction(Op, VT) == Promote &&
"This operation isn't promoted!");
// See if this has an explicit type specified.
std::map<std::pair<unsigned, MVT::SimpleValueType>,
MVT::SimpleValueType>::const_iterator PTTI =
PromoteToType.find(std::make_pair(Op, VT.SimpleTy));
if (PTTI != PromoteToType.end()) return PTTI->second;
assert((VT.isInteger() || VT.isFloatingPoint()) &&
"Cannot autopromote this type, add it with AddPromotedToType.");
MVT NVT = VT;
do {
NVT = (MVT::SimpleValueType)(NVT.SimpleTy+1);
assert(NVT.isInteger() == VT.isInteger() && NVT != MVT::isVoid &&
"Didn't find type to promote to!");
} while (!isTypeLegal(NVT) ||
getOperationAction(Op, NVT) == Promote);
return NVT;
}
/// Return the EVT corresponding to this LLVM type. This is fixed by the LLVM
/// operations except for the pointer size. If AllowUnknown is true, this
/// will return MVT::Other for types with no EVT counterpart (e.g. structs),
/// otherwise it will assert.
EVT getValueType(const DataLayout &DL, Type *Ty,
bool AllowUnknown = false) const {
// Lower scalar pointers to native pointer types.
if (PointerType *PTy = dyn_cast<PointerType>(Ty))
return getPointerTy(DL, PTy->getAddressSpace());
if (Ty->isVectorTy()) {
VectorType *VTy = cast<VectorType>(Ty);
Type *Elm = VTy->getElementType();
// Lower vectors of pointers to native pointer types.
if (PointerType *PT = dyn_cast<PointerType>(Elm)) {
EVT PointerTy(getPointerTy(DL, PT->getAddressSpace()));
Elm = PointerTy.getTypeForEVT(Ty->getContext());
}
return EVT::getVectorVT(Ty->getContext(), EVT::getEVT(Elm, false),
VTy->getNumElements());
}
return EVT::getEVT(Ty, AllowUnknown);
}
/// Return the MVT corresponding to this LLVM type. See getValueType.
MVT getSimpleValueType(const DataLayout &DL, Type *Ty,
bool AllowUnknown = false) const {
return getValueType(DL, Ty, AllowUnknown).getSimpleVT();
}
/// Return the desired alignment for ByVal or InAlloca aggregate function
/// arguments in the caller parameter area. This is the actual alignment, not
/// its logarithm.
virtual unsigned getByValTypeAlignment(Type *Ty, const DataLayout &DL) const;
/// Return the type of registers that this ValueType will eventually require.
MVT getRegisterType(MVT VT) const {
assert((unsigned)VT.SimpleTy < array_lengthof(RegisterTypeForVT));
return RegisterTypeForVT[VT.SimpleTy];
}
/// Return the type of registers that this ValueType will eventually require.
MVT getRegisterType(LLVMContext &Context, EVT VT) const {
if (VT.isSimple()) {
assert((unsigned)VT.getSimpleVT().SimpleTy <
array_lengthof(RegisterTypeForVT));
return RegisterTypeForVT[VT.getSimpleVT().SimpleTy];
}
if (VT.isVector()) {
EVT VT1;
MVT RegisterVT;
unsigned NumIntermediates;
(void)getVectorTypeBreakdown(Context, VT, VT1,
NumIntermediates, RegisterVT);
return RegisterVT;
}
if (VT.isInteger()) {
return getRegisterType(Context, getTypeToTransformTo(Context, VT));
}
llvm_unreachable("Unsupported extended type!");
}
/// Return the number of registers that this ValueType will eventually
/// require.
///
/// This is one for any types promoted to live in larger registers, but may be
/// more than one for types (like i64) that are split into pieces. For types
/// like i140, which are first promoted then expanded, it is the number of
/// registers needed to hold all the bits of the original type. For an i140
/// on a 32 bit machine this means 5 registers.
unsigned getNumRegisters(LLVMContext &Context, EVT VT) const {
if (VT.isSimple()) {
assert((unsigned)VT.getSimpleVT().SimpleTy <
array_lengthof(NumRegistersForVT));
return NumRegistersForVT[VT.getSimpleVT().SimpleTy];
}
if (VT.isVector()) {
EVT VT1;
MVT VT2;
unsigned NumIntermediates;
return getVectorTypeBreakdown(Context, VT, VT1, NumIntermediates, VT2);
}
if (VT.isInteger()) {
unsigned BitWidth = VT.getSizeInBits();
unsigned RegWidth = getRegisterType(Context, VT).getSizeInBits();
return (BitWidth + RegWidth - 1) / RegWidth;
}
llvm_unreachable("Unsupported extended type!");
}
/// Certain combinations of ABIs, Targets and features require that types
/// are legal for some operations and not for other operations.
/// For MIPS all vector types must be passed through the integer register set.
virtual MVT getRegisterTypeForCallingConv(MVT VT) const {
return getRegisterType(VT);
}
virtual MVT getRegisterTypeForCallingConv(LLVMContext &Context,
EVT VT) const {
return getRegisterType(Context, VT);
}
/// Certain targets require unusual breakdowns of certain types. For MIPS,
/// this occurs when a vector type is used, as vector are passed through the
/// integer register set.
virtual unsigned getNumRegistersForCallingConv(LLVMContext &Context,
EVT VT) const {
return getNumRegisters(Context, VT);
}
/// Certain targets have context senstive alignment requirements, where one
/// type has the alignment requirement of another type.
virtual unsigned getABIAlignmentForCallingConv(Type *ArgTy,
DataLayout DL) const {
return DL.getABITypeAlignment(ArgTy);
}
/// If true, then instruction selection should seek to shrink the FP constant
/// of the specified type to a smaller type in order to save space and / or
/// reduce runtime.
virtual bool ShouldShrinkFPConstant(EVT) const { return true; }
// Return true if it is profitable to reduce the given load node to a smaller
// type.
//
// e.g. (i16 (trunc (i32 (load x))) -> i16 load x should be performed
virtual bool shouldReduceLoadWidth(SDNode *Load,
ISD::LoadExtType ExtTy,
EVT NewVT) const {
return true;
}
/// When splitting a value of the specified type into parts, does the Lo
/// or Hi part come first? This usually follows the endianness, except
/// for ppcf128, where the Hi part always comes first.
bool hasBigEndianPartOrdering(EVT VT, const DataLayout &DL) const {
return DL.isBigEndian() || VT == MVT::ppcf128;
}
/// If true, the target has custom DAG combine transformations that it can
/// perform for the specified node.
bool hasTargetDAGCombine(ISD::NodeType NT) const {
assert(unsigned(NT >> 3) < array_lengthof(TargetDAGCombineArray));
return TargetDAGCombineArray[NT >> 3] & (1 << (NT&7));
}
unsigned getGatherAllAliasesMaxDepth() const {
return GatherAllAliasesMaxDepth;
}
/// Returns the size of the platform's va_list object.
virtual unsigned getVaListSizeInBits(const DataLayout &DL) const {
return getPointerTy(DL).getSizeInBits();
}
/// \brief Get maximum # of store operations permitted for llvm.memset
///
/// This function returns the maximum number of store operations permitted
/// to replace a call to llvm.memset. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxStoresPerMemset(bool OptSize) const {
return OptSize ? MaxStoresPerMemsetOptSize : MaxStoresPerMemset;
}
/// \brief Get maximum # of store operations permitted for llvm.memcpy
///
/// This function returns the maximum number of store operations permitted
/// to replace a call to llvm.memcpy. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxStoresPerMemcpy(bool OptSize) const {
return OptSize ? MaxStoresPerMemcpyOptSize : MaxStoresPerMemcpy;
}
/// Get maximum # of load operations permitted for memcmp
///
/// This function returns the maximum number of load operations permitted
/// to replace a call to memcmp. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxExpandSizeMemcmp(bool OptSize) const {
return OptSize ? MaxLoadsPerMemcmpOptSize : MaxLoadsPerMemcmp;
}
/// \brief Get maximum # of store operations permitted for llvm.memmove
///
/// This function returns the maximum number of store operations permitted
/// to replace a call to llvm.memmove. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxStoresPerMemmove(bool OptSize) const {
return OptSize ? MaxStoresPerMemmoveOptSize : MaxStoresPerMemmove;
}
/// \brief Determine if the target supports unaligned memory accesses.
///
/// This function returns true if the target allows unaligned memory accesses
/// of the specified type in the given address space. If true, it also returns
/// whether the unaligned memory access is "fast" in the last argument by
/// reference. This is used, for example, in situations where an array
/// copy/move/set is converted to a sequence of store operations. Its use
/// helps to ensure that such replacements don't generate code that causes an
/// alignment error (trap) on the target machine.
virtual bool allowsMisalignedMemoryAccesses(EVT,
unsigned AddrSpace = 0,
unsigned Align = 1,
bool * /*Fast*/ = nullptr) const {
return false;
}
/// Return true if the target supports a memory access of this type for the
/// given address space and alignment. If the access is allowed, the optional
/// final parameter returns if the access is also fast (as defined by the
/// target).
bool allowsMemoryAccess(LLVMContext &Context, const DataLayout &DL, EVT VT,
unsigned AddrSpace = 0, unsigned Alignment = 1,
bool *Fast = nullptr) const;
/// Returns the target specific optimal type for load and store operations as
/// a result of memset, memcpy, and memmove lowering.
///
/// If DstAlign is zero that means it's safe to destination alignment can
/// satisfy any constraint. Similarly if SrcAlign is zero it means there isn't
/// a need to check it against alignment requirement, probably because the
/// source does not need to be loaded. If 'IsMemset' is true, that means it's
/// expanding a memset. If 'ZeroMemset' is true, that means it's a memset of
/// zero. 'MemcpyStrSrc' indicates whether the memcpy source is constant so it
/// does not need to be loaded. It returns EVT::Other if the type should be
/// determined using generic target-independent logic.
virtual EVT getOptimalMemOpType(uint64_t /*Size*/,
unsigned /*DstAlign*/, unsigned /*SrcAlign*/,
bool /*IsMemset*/,
bool /*ZeroMemset*/,
bool /*MemcpyStrSrc*/,
MachineFunction &/*MF*/) const {
return MVT::Other;
}
/// Returns true if it's safe to use load / store of the specified type to
/// expand memcpy / memset inline.
///
/// This is mostly true for all types except for some special cases. For
/// example, on X86 targets without SSE2 f64 load / store are done with fldl /
/// fstpl which also does type conversion. Note the specified type doesn't
/// have to be legal as the hook is used before type legalization.
virtual bool isSafeMemOpType(MVT /*VT*/) const { return true; }
/// Determine if we should use _setjmp or setjmp to implement llvm.setjmp.
bool usesUnderscoreSetJmp() const {
return UseUnderscoreSetJmp;
}
/// Determine if we should use _longjmp or longjmp to implement llvm.longjmp.
bool usesUnderscoreLongJmp() const {
return UseUnderscoreLongJmp;
}
/// Return lower limit for number of blocks in a jump table.
unsigned getMinimumJumpTableEntries() const;
/// Return lower limit of the density in a jump table.
unsigned getMinimumJumpTableDensity(bool OptForSize) const;
/// Return upper limit for number of entries in a jump table.
/// Zero if no limit.
unsigned getMaximumJumpTableSize() const;
virtual bool isJumpTableRelative() const {
return TM.isPositionIndependent();
}
/// If a physical register, this specifies the register that
/// llvm.savestack/llvm.restorestack should save and restore.
unsigned getStackPointerRegisterToSaveRestore() const {
return StackPointerRegisterToSaveRestore;
}
/// If a physical register, this returns the register that receives the
/// exception address on entry to an EH pad.
virtual unsigned
getExceptionPointerRegister(const Constant *PersonalityFn) const {
// 0 is guaranteed to be the NoRegister value on all targets
return 0;
}
/// If a physical register, this returns the register that receives the
/// exception typeid on entry to a landing pad.
virtual unsigned
getExceptionSelectorRegister(const Constant *PersonalityFn) const {
// 0 is guaranteed to be the NoRegister value on all targets
return 0;
}
virtual bool needsFixedCatchObjects() const {
report_fatal_error("Funclet EH is not implemented for this target");
}
/// Returns the target's jmp_buf size in bytes (if never set, the default is
/// 200)
unsigned getJumpBufSize() const {
return JumpBufSize;
}
/// Returns the target's jmp_buf alignment in bytes (if never set, the default
/// is 0)
unsigned getJumpBufAlignment() const {
return JumpBufAlignment;
}
/// Return the minimum stack alignment of an argument.
unsigned getMinStackArgumentAlignment() const {
return MinStackArgumentAlignment;
}
/// Return the minimum function alignment.
unsigned getMinFunctionAlignment() const {
return MinFunctionAlignment;
}
/// Return the preferred function alignment.
unsigned getPrefFunctionAlignment() const {
return PrefFunctionAlignment;
}
/// Return the preferred loop alignment.
virtual unsigned getPrefLoopAlignment(MachineLoop *ML = nullptr) const {
return PrefLoopAlignment;
}
/// If the target has a standard location for the stack protector guard,
/// returns the address of that location. Otherwise, returns nullptr.
/// DEPRECATED: please override useLoadStackGuardNode and customize
/// LOAD_STACK_GUARD, or customize @llvm.stackguard().
virtual Value *getIRStackGuard(IRBuilder<> &IRB) const;
/// Inserts necessary declarations for SSP (stack protection) purpose.
/// Should be used only when getIRStackGuard returns nullptr.
virtual void insertSSPDeclarations(Module &M) const;
/// Return the variable that's previously inserted by insertSSPDeclarations,
/// if any, otherwise return nullptr. Should be used only when
/// getIRStackGuard returns nullptr.
virtual Value *getSDagStackGuard(const Module &M) const;
/// If the target has a standard stack protection check function that
/// performs validation and error handling, returns the function. Otherwise,
/// returns nullptr. Must be previously inserted by insertSSPDeclarations.
/// Should be used only when getIRStackGuard returns nullptr.
virtual Value *getSSPStackGuardCheck(const Module &M) const;
protected:
Value *getDefaultSafeStackPointerLocation(IRBuilder<> &IRB,
bool UseTLS) const;
public:
/// Returns the target-specific address of the unsafe stack pointer.
virtual Value *getSafeStackPointerLocation(IRBuilder<> &IRB) const;
/// Returns the name of the symbol used to emit stack probes or the empty
/// string if not applicable.
virtual StringRef getStackProbeSymbolName(MachineFunction &MF) const {
return "";
}
/// Returns true if a cast between SrcAS and DestAS is a noop.
virtual bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const {
return false;
}
/// Returns true if a cast from SrcAS to DestAS is "cheap", such that e.g. we
/// are happy to sink it into basic blocks.
virtual bool isCheapAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const {
return isNoopAddrSpaceCast(SrcAS, DestAS);
}
/// Return true if the pointer arguments to CI should be aligned by aligning
/// the object whose address is being passed. If so then MinSize is set to the
/// minimum size the object must be to be aligned and PrefAlign is set to the
/// preferred alignment.
virtual bool shouldAlignPointerArgs(CallInst * /*CI*/, unsigned & /*MinSize*/,
unsigned & /*PrefAlign*/) const {
return false;
}
//===--------------------------------------------------------------------===//
/// \name Helpers for TargetTransformInfo implementations
/// @{
/// Get the ISD node that corresponds to the Instruction class opcode.
int InstructionOpcodeToISD(unsigned Opcode) const;
/// Estimate the cost of type-legalization and the legalized type.
std::pair<int, MVT> getTypeLegalizationCost(const DataLayout &DL,
Type *Ty) const;
/// @}
//===--------------------------------------------------------------------===//
/// \name Helpers for atomic expansion.
/// @{
/// Returns the maximum atomic operation size (in bits) supported by
/// the backend. Atomic operations greater than this size (as well
/// as ones that are not naturally aligned), will be expanded by
/// AtomicExpandPass into an __atomic_* library call.
unsigned getMaxAtomicSizeInBitsSupported() const {
return MaxAtomicSizeInBitsSupported;
}
/// Returns the size of the smallest cmpxchg or ll/sc instruction
/// the backend supports. Any smaller operations are widened in
/// AtomicExpandPass.
///
/// Note that *unlike* operations above the maximum size, atomic ops
/// are still natively supported below the minimum; they just
/// require a more complex expansion.
unsigned getMinCmpXchgSizeInBits() const { return MinCmpXchgSizeInBits; }
/// Whether AtomicExpandPass should automatically insert fences and reduce
/// ordering for this atomic. This should be true for most architectures with
/// weak memory ordering. Defaults to false.
virtual bool shouldInsertFencesForAtomic(const Instruction *I) const {
return false;
}
/// Perform a load-linked operation on Addr, returning a "Value *" with the
/// corresponding pointee type. This may entail some non-trivial operations to
/// truncate or reconstruct types that will be illegal in the backend. See
/// ARMISelLowering for an example implementation.
virtual Value *emitLoadLinked(IRBuilder<> &Builder, Value *Addr,
AtomicOrdering Ord) const {
llvm_unreachable("Load linked unimplemented on this target");
}
/// Perform a store-conditional operation to Addr. Return the status of the
/// store. This should be 0 if the store succeeded, non-zero otherwise.
virtual Value *emitStoreConditional(IRBuilder<> &Builder, Value *Val,
Value *Addr, AtomicOrdering Ord) const {
llvm_unreachable("Store conditional unimplemented on this target");
}
/// Inserts in the IR a target-specific intrinsic specifying a fence.
/// It is called by AtomicExpandPass before expanding an
/// AtomicRMW/AtomicCmpXchg/AtomicStore/AtomicLoad
/// if shouldInsertFencesForAtomic returns true.
///
/// Inst is the original atomic instruction, prior to other expansions that
/// may be performed.
///
/// This function should either return a nullptr, or a pointer to an IR-level
/// Instruction*. Even complex fence sequences can be represented by a
/// single Instruction* through an intrinsic to be lowered later.
/// Backends should override this method to produce target-specific intrinsic
/// for their fences.
/// FIXME: Please note that the default implementation here in terms of
/// IR-level fences exists for historical/compatibility reasons and is
/// *unsound* ! Fences cannot, in general, be used to restore sequential
/// consistency. For example, consider the following example:
/// atomic<int> x = y = 0;
/// int r1, r2, r3, r4;
/// Thread 0:
/// x.store(1);
/// Thread 1:
/// y.store(1);
/// Thread 2:
/// r1 = x.load();
/// r2 = y.load();
/// Thread 3:
/// r3 = y.load();
/// r4 = x.load();
/// r1 = r3 = 1 and r2 = r4 = 0 is impossible as long as the accesses are all
/// seq_cst. But if they are lowered to monotonic accesses, no amount of
/// IR-level fences can prevent it.
/// @{
virtual Instruction *emitLeadingFence(IRBuilder<> &Builder, Instruction *Inst,
AtomicOrdering Ord) const {
if (isReleaseOrStronger(Ord) && Inst->hasAtomicStore())
return Builder.CreateFence(Ord);
else
return nullptr;
}
virtual Instruction *emitTrailingFence(IRBuilder<> &Builder,
Instruction *Inst,
AtomicOrdering Ord) const {
if (isAcquireOrStronger(Ord))
return Builder.CreateFence(Ord);
else
return nullptr;
}
/// @}
// Emits code that executes when the comparison result in the ll/sc
// expansion of a cmpxchg instruction is such that the store-conditional will
// not execute. This makes it possible to balance out the load-linked with
// a dedicated instruction, if desired.
// E.g., on ARM, if ldrex isn't followed by strex, the exclusive monitor would
// be unnecessarily held, except if clrex, inserted by this hook, is executed.
virtual void emitAtomicCmpXchgNoStoreLLBalance(IRBuilder<> &Builder) const {}
/// Returns true if the given (atomic) store should be expanded by the
/// IR-level AtomicExpand pass into an "atomic xchg" which ignores its input.
virtual bool shouldExpandAtomicStoreInIR(StoreInst *SI) const {
return false;
}
/// Returns true if arguments should be sign-extended in lib calls.
virtual bool shouldSignExtendTypeInLibCall(EVT Type, bool IsSigned) const {
return IsSigned;
}
/// Returns how the given (atomic) load should be expanded by the
/// IR-level AtomicExpand pass.
virtual AtomicExpansionKind shouldExpandAtomicLoadInIR(LoadInst *LI) const {
return AtomicExpansionKind::None;
}
/// Returns true if the given atomic cmpxchg should be expanded by the
/// IR-level AtomicExpand pass into a load-linked/store-conditional sequence
/// (through emitLoadLinked() and emitStoreConditional()).
virtual bool shouldExpandAtomicCmpXchgInIR(AtomicCmpXchgInst *AI) const {
return false;
}
/// Returns how the IR-level AtomicExpand pass should expand the given
/// AtomicRMW, if at all. Default is to never expand.
virtual AtomicExpansionKind shouldExpandAtomicRMWInIR(AtomicRMWInst *) const {
return AtomicExpansionKind::None;
}
/// On some platforms, an AtomicRMW that never actually modifies the value
/// (such as fetch_add of 0) can be turned into a fence followed by an
/// atomic load. This may sound useless, but it makes it possible for the
/// processor to keep the cacheline shared, dramatically improving
/// performance. And such idempotent RMWs are useful for implementing some
/// kinds of locks, see for example (justification + benchmarks):
/// http://www.hpl.hp.com/techreports/2012/HPL-2012-68.pdf
/// This method tries doing that transformation, returning the atomic load if
/// it succeeds, and nullptr otherwise.
/// If shouldExpandAtomicLoadInIR returns true on that load, it will undergo
/// another round of expansion.
virtual LoadInst *
lowerIdempotentRMWIntoFencedLoad(AtomicRMWInst *RMWI) const {
return nullptr;
}
/// Returns how the platform's atomic operations are extended (ZERO_EXTEND,
/// SIGN_EXTEND, or ANY_EXTEND).
virtual ISD::NodeType getExtendForAtomicOps() const {
return ISD::ZERO_EXTEND;
}
/// @}
/// Returns true if we should normalize
/// select(N0&N1, X, Y) => select(N0, select(N1, X, Y), Y) and
/// select(N0|N1, X, Y) => select(N0, select(N1, X, Y, Y)) if it is likely
/// that it saves us from materializing N0 and N1 in an integer register.
/// Targets that are able to perform and/or on flags should return false here.
virtual bool shouldNormalizeToSelectSequence(LLVMContext &Context,
EVT VT) const {
// If a target has multiple condition registers, then it likely has logical
// operations on those registers.
if (hasMultipleConditionRegisters())
return false;
// Only do the transform if the value won't be split into multiple
// registers.
LegalizeTypeAction Action = getTypeAction(Context, VT);
return Action != TypeExpandInteger && Action != TypeExpandFloat &&
Action != TypeSplitVector;
}
/// Return true if a select of constants (select Cond, C1, C2) should be
/// transformed into simple math ops with the condition value. For example:
/// select Cond, C1, C1-1 --> add (zext Cond), C1-1
virtual bool convertSelectOfConstantsToMath(EVT VT) const {
return false;
}
//===--------------------------------------------------------------------===//
// TargetLowering Configuration Methods - These methods should be invoked by
// the derived class constructor to configure this object for the target.
//
protected:
/// Specify how the target extends the result of integer and floating point
/// boolean values from i1 to a wider type. See getBooleanContents.
void setBooleanContents(BooleanContent Ty) {
BooleanContents = Ty;
BooleanFloatContents = Ty;
}
/// Specify how the target extends the result of integer and floating point
/// boolean values from i1 to a wider type. See getBooleanContents.
void setBooleanContents(BooleanContent IntTy, BooleanContent FloatTy) {
BooleanContents = IntTy;
BooleanFloatContents = FloatTy;
}
/// Specify how the target extends the result of a vector boolean value from a
/// vector of i1 to a wider type. See getBooleanContents.
void setBooleanVectorContents(BooleanContent Ty) {
BooleanVectorContents = Ty;
}
/// Specify the target scheduling preference.
void setSchedulingPreference(Sched::Preference Pref) {
SchedPreferenceInfo = Pref;
}
/// Indicate whether this target prefers to use _setjmp to implement
/// llvm.setjmp or the version without _. Defaults to false.
void setUseUnderscoreSetJmp(bool Val) {
UseUnderscoreSetJmp = Val;
}
/// Indicate whether this target prefers to use _longjmp to implement
/// llvm.longjmp or the version without _. Defaults to false.
void setUseUnderscoreLongJmp(bool Val) {
UseUnderscoreLongJmp = Val;
}
/// Indicate the minimum number of blocks to generate jump tables.
void setMinimumJumpTableEntries(unsigned Val);
/// Indicate the maximum number of entries in jump tables.
/// Set to zero to generate unlimited jump tables.
void setMaximumJumpTableSize(unsigned);
/// If set to a physical register, this specifies the register that
/// llvm.savestack/llvm.restorestack should save and restore.
void setStackPointerRegisterToSaveRestore(unsigned R) {
StackPointerRegisterToSaveRestore = R;
}
/// Tells the code generator that the target has multiple (allocatable)
/// condition registers that can be used to store the results of comparisons
/// for use by selects and conditional branches. With multiple condition
/// registers, the code generator will not aggressively sink comparisons into
/// the blocks of their users.
void setHasMultipleConditionRegisters(bool hasManyRegs = true) {
HasMultipleConditionRegisters = hasManyRegs;
}
/// Tells the code generator that the target has BitExtract instructions.
/// The code generator will aggressively sink "shift"s into the blocks of
/// their users if the users will generate "and" instructions which can be
/// combined with "shift" to BitExtract instructions.
void setHasExtractBitsInsn(bool hasExtractInsn = true) {
HasExtractBitsInsn = hasExtractInsn;
}
/// Tells the code generator not to expand logic operations on comparison
/// predicates into separate sequences that increase the amount of flow
/// control.
void setJumpIsExpensive(bool isExpensive = true);
/// Tells the code generator that this target supports floating point
/// exceptions and cares about preserving floating point exception behavior.
void setHasFloatingPointExceptions(bool FPExceptions = true) {
HasFloatingPointExceptions = FPExceptions;
}
/// Tells the code generator which bitwidths to bypass.
void addBypassSlowDiv(unsigned int SlowBitWidth, unsigned int FastBitWidth) {
BypassSlowDivWidths[SlowBitWidth] = FastBitWidth;
}
/// Add the specified register class as an available regclass for the
/// specified value type. This indicates the selector can handle values of
/// that class natively.
void addRegisterClass(MVT VT, const TargetRegisterClass *RC) {
assert((unsigned)VT.SimpleTy < array_lengthof(RegClassForVT));
RegClassForVT[VT.SimpleTy] = RC;
}
/// Return the largest legal super-reg register class of the register class
/// for the specified type and its associated "cost".
virtual std::pair<const TargetRegisterClass *, uint8_t>
findRepresentativeClass(const TargetRegisterInfo *TRI, MVT VT) const;
/// Once all of the register classes are added, this allows us to compute
/// derived properties we expose.
void computeRegisterProperties(const TargetRegisterInfo *TRI);
/// Indicate that the specified operation does not work with the specified
/// type and indicate what to do about it. Note that VT may refer to either
/// the type of a result or that of an operand of Op.
void setOperationAction(unsigned Op, MVT VT,
LegalizeAction Action) {
assert(Op < array_lengthof(OpActions[0]) && "Table isn't big enough!");
OpActions[(unsigned)VT.SimpleTy][Op] = Action;
}
/// Indicate that the specified load with extension does not work with the
/// specified type and indicate what to do about it.
void setLoadExtAction(unsigned ExtType, MVT ValVT, MVT MemVT,
LegalizeAction Action) {
assert(ExtType < ISD::LAST_LOADEXT_TYPE && ValVT.isValid() &&
MemVT.isValid() && "Table isn't big enough!");
assert((unsigned)Action < 0x10 && "too many bits for bitfield array");
unsigned Shift = 4 * ExtType;
LoadExtActions[ValVT.SimpleTy][MemVT.SimpleTy] &= ~((uint16_t)0xF << Shift);
LoadExtActions[ValVT.SimpleTy][MemVT.SimpleTy] |= (uint16_t)Action << Shift;
}
/// Indicate that the specified truncating store does not work with the
/// specified type and indicate what to do about it.
void setTruncStoreAction(MVT ValVT, MVT MemVT,
LegalizeAction Action) {
assert(ValVT.isValid() && MemVT.isValid() && "Table isn't big enough!");
TruncStoreActions[(unsigned)ValVT.SimpleTy][MemVT.SimpleTy] = Action;
}
/// Indicate that the specified indexed load does or does not work with the
/// specified type and indicate what to do abort it.
///
/// NOTE: All indexed mode loads are initialized to Expand in
/// TargetLowering.cpp
void setIndexedLoadAction(unsigned IdxMode, MVT VT,
LegalizeAction Action) {
assert(VT.isValid() && IdxMode < ISD::LAST_INDEXED_MODE &&
(unsigned)Action < 0xf && "Table isn't big enough!");
// Load action are kept in the upper half.
IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0xf0;
IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] |= ((uint8_t)Action) <<4;
}
/// Indicate that the specified indexed store does or does not work with the
/// specified type and indicate what to do about it.
///
/// NOTE: All indexed mode stores are initialized to Expand in
/// TargetLowering.cpp
void setIndexedStoreAction(unsigned IdxMode, MVT VT,
LegalizeAction Action) {
assert(VT.isValid() && IdxMode < ISD::LAST_INDEXED_MODE &&
(unsigned)Action < 0xf && "Table isn't big enough!");
// Store action are kept in the lower half.
IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] &= ~0x0f;
IndexedModeActions[(unsigned)VT.SimpleTy][IdxMode] |= ((uint8_t)Action);
}
/// Indicate that the specified condition code is or isn't supported on the
/// target and indicate what to do about it.
void setCondCodeAction(ISD::CondCode CC, MVT VT,
LegalizeAction Action) {
assert(VT.isValid() && (unsigned)CC < array_lengthof(CondCodeActions) &&
"Table isn't big enough!");
assert((unsigned)Action < 0x10 && "too many bits for bitfield array");
/// The lower 3 bits of the SimpleTy index into Nth 4bit set from the 32-bit
/// value and the upper 29 bits index into the second dimension of the array
/// to select what 32-bit value to use.
uint32_t Shift = 4 * (VT.SimpleTy & 0x7);
CondCodeActions[CC][VT.SimpleTy >> 3] &= ~((uint32_t)0xF << Shift);
CondCodeActions[CC][VT.SimpleTy >> 3] |= (uint32_t)Action << Shift;
}
/// If Opc/OrigVT is specified as being promoted, the promotion code defaults
/// to trying a larger integer/fp until it can find one that works. If that
/// default is insufficient, this method can be used by the target to override
/// the default.
void AddPromotedToType(unsigned Opc, MVT OrigVT, MVT DestVT) {
PromoteToType[std::make_pair(Opc, OrigVT.SimpleTy)] = DestVT.SimpleTy;
}
/// Convenience method to set an operation to Promote and specify the type
/// in a single call.
void setOperationPromotedToType(unsigned Opc, MVT OrigVT, MVT DestVT) {
setOperationAction(Opc, OrigVT, Promote);
AddPromotedToType(Opc, OrigVT, DestVT);
}
/// Targets should invoke this method for each target independent node that
/// they want to provide a custom DAG combiner for by implementing the
/// PerformDAGCombine virtual method.
void setTargetDAGCombine(ISD::NodeType NT) {
assert(unsigned(NT >> 3) < array_lengthof(TargetDAGCombineArray));
TargetDAGCombineArray[NT >> 3] |= 1 << (NT&7);
}
/// Set the target's required jmp_buf buffer size (in bytes); default is 200
void setJumpBufSize(unsigned Size) {
JumpBufSize = Size;
}
/// Set the target's required jmp_buf buffer alignment (in bytes); default is
/// 0
void setJumpBufAlignment(unsigned Align) {
JumpBufAlignment = Align;
}
/// Set the target's minimum function alignment (in log2(bytes))
void setMinFunctionAlignment(unsigned Align) {
MinFunctionAlignment = Align;
}
/// Set the target's preferred function alignment. This should be set if
/// there is a performance benefit to higher-than-minimum alignment (in
/// log2(bytes))
void setPrefFunctionAlignment(unsigned Align) {
PrefFunctionAlignment = Align;
}
/// Set the target's preferred loop alignment. Default alignment is zero, it
/// means the target does not care about loop alignment. The alignment is
/// specified in log2(bytes). The target may also override
/// getPrefLoopAlignment to provide per-loop values.
void setPrefLoopAlignment(unsigned Align) {
PrefLoopAlignment = Align;
}
/// Set the minimum stack alignment of an argument (in log2(bytes)).
void setMinStackArgumentAlignment(unsigned Align) {
MinStackArgumentAlignment = Align;
}
/// Set the maximum atomic operation size supported by the
/// backend. Atomic operations greater than this size (as well as
/// ones that are not naturally aligned), will be expanded by
/// AtomicExpandPass into an __atomic_* library call.
void setMaxAtomicSizeInBitsSupported(unsigned SizeInBits) {
MaxAtomicSizeInBitsSupported = SizeInBits;
}
// Sets the minimum cmpxchg or ll/sc size supported by the backend.
void setMinCmpXchgSizeInBits(unsigned SizeInBits) {
MinCmpXchgSizeInBits = SizeInBits;
}
public:
//===--------------------------------------------------------------------===//
// Addressing mode description hooks (used by LSR etc).
//
/// CodeGenPrepare sinks address calculations into the same BB as Load/Store
/// instructions reading the address. This allows as much computation as
/// possible to be done in the address mode for that operand. This hook lets
/// targets also pass back when this should be done on intrinsics which
/// load/store.
virtual bool getAddrModeArguments(IntrinsicInst * /*I*/,
SmallVectorImpl<Value*> &/*Ops*/,
Type *&/*AccessTy*/) const {
return false;
}
/// This represents an addressing mode of:
/// BaseGV + BaseOffs + BaseReg + Scale*ScaleReg
/// If BaseGV is null, there is no BaseGV.
/// If BaseOffs is zero, there is no base offset.
/// If HasBaseReg is false, there is no base register.
/// If Scale is zero, there is no ScaleReg. Scale of 1 indicates a reg with
/// no scale.
struct AddrMode {
GlobalValue *BaseGV = nullptr;
int64_t BaseOffs = 0;
bool HasBaseReg = false;
int64_t Scale = 0;
AddrMode() = default;
};
/// 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. TODO: Handle
/// pre/postinc as well.
///
/// If the address space cannot be determined, it will be -1.
///
/// TODO: Remove default argument
virtual bool isLegalAddressingMode(const DataLayout &DL, const AddrMode &AM,
Type *Ty, unsigned AddrSpace,
Instruction *I = nullptr) const;
/// \brief Return the cost of the scaling factor used in the addressing mode
/// represented by AM for this target, for a load/store of the specified type.
///
/// If the AM is supported, the return value must be >= 0.
/// If the AM is not supported, it returns a negative value.
/// TODO: Handle pre/postinc as well.
/// TODO: Remove default argument
virtual int getScalingFactorCost(const DataLayout &DL, const AddrMode &AM,
Type *Ty, unsigned AS = 0) const {
// Default: assume that any scaling factor used in a legal AM is free.
if (isLegalAddressingMode(DL, AM, Ty, AS))
return 0;
return -1;
}
/// 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.
virtual bool isLegalICmpImmediate(int64_t) const {
return true;
}
/// 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.
virtual bool isLegalAddImmediate(int64_t) const {
return true;
}
/// 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, for
/// example, there is a "psllw" instruction for the former case, but no simple
/// instruction for a general "a << b" operation on vectors.
virtual bool isVectorShiftByScalarCheap(Type *Ty) const {
return false;
}
/// Returns true if the opcode is a commutative binary operation.
virtual bool isCommutativeBinOp(unsigned Opcode) const {
// FIXME: This should get its info from the td file.
switch (Opcode) {
case ISD::ADD:
case ISD::SMIN:
case ISD::SMAX:
case ISD::UMIN:
case ISD::UMAX:
case ISD::MUL:
case ISD::MULHU:
case ISD::MULHS:
case ISD::SMUL_LOHI:
case ISD::UMUL_LOHI:
case ISD::FADD:
case ISD::FMUL:
case ISD::AND:
case ISD::OR:
case ISD::XOR:
case ISD::SADDO:
case ISD::UADDO:
case ISD::ADDC:
case ISD::ADDE:
case ISD::FMINNUM:
case ISD::FMAXNUM:
case ISD::FMINNAN:
case ISD::FMAXNAN:
return true;
default: return false;
}
}
/// Return true if it's free to truncate a value of type FromTy to type
/// ToTy. e.g. On x86 it's free to truncate a i32 value in register EAX to i16
/// by referencing its sub-register AX.
/// Targets must return false when FromTy <= ToTy.
virtual bool isTruncateFree(Type *FromTy, Type *ToTy) const {
return false;
}
/// Return true if a truncation from FromTy to ToTy is permitted when deciding
/// whether a call is in tail position. Typically this means that both results
/// would be assigned to the same register or stack slot, but it could mean
/// the target performs adequate checks of its own before proceeding with the
/// tail call. Targets must return false when FromTy <= ToTy.
virtual bool allowTruncateForTailCall(Type *FromTy, Type *ToTy) const {
return false;
}
virtual bool isTruncateFree(EVT FromVT, EVT ToVT) const {
return false;
}
virtual bool isProfitableToHoist(Instruction *I) const { return true; }
/// Return true if the extension represented by \p I is free.
/// Unlikely the is[Z|FP]ExtFree family which is based on types,
/// this method can use the context provided by \p I to decide
/// whether or not \p I is free.
/// This method extends the behavior of the is[Z|FP]ExtFree family.
/// In other words, if is[Z|FP]Free returns true, then this method
/// returns true as well. The converse is not true.
/// The target can perform the adequate checks by overriding isExtFreeImpl.
/// \pre \p I must be a sign, zero, or fp extension.
bool isExtFree(const Instruction *I) const {
switch (I->getOpcode()) {
case Instruction::FPExt:
if (isFPExtFree(EVT::getEVT(I->getType()),
EVT::getEVT(I->getOperand(0)->getType())))
return true;
break;
case Instruction::ZExt:
if (isZExtFree(I->getOperand(0)->getType(), I->getType()))
return true;
break;
case Instruction::SExt:
break;
default:
llvm_unreachable("Instruction is not an extension");
}
return isExtFreeImpl(I);
}
/// Return true if \p Load and \p Ext can form an ExtLoad.
/// For example, in AArch64
/// %L = load i8, i8* %ptr
/// %E = zext i8 %L to i32
/// can be lowered into one load instruction
/// ldrb w0, [x0]
bool isExtLoad(const LoadInst *Load, const Instruction *Ext,
const DataLayout &DL) const {
EVT VT = getValueType(DL, Ext->getType());
EVT LoadVT = getValueType(DL, Load->getType());
// If the load has other users and the truncate is not free, the ext
// probably isn't free.
if (!Load->hasOneUse() && (isTypeLegal(LoadVT) || !isTypeLegal(VT)) &&
!isTruncateFree(Ext->getType(), Load->getType()))
return false;
// Check whether the target supports casts folded into loads.
unsigned LType;
if (isa<ZExtInst>(Ext))
LType = ISD::ZEXTLOAD;
else {
assert(isa<SExtInst>(Ext) && "Unexpected ext type!");
LType = ISD::SEXTLOAD;
}
return isLoadExtLegal(LType, VT, LoadVT);
}
/// Return true if any actual instruction that defines a value of type FromTy
/// implicitly zero-extends the value to ToTy in the result register.
///
/// The function should return true when it is likely that the truncate can
/// be freely folded with an instruction defining a value of FromTy. If
/// the defining instruction is unknown (because you're looking at a
/// function argument, PHI, etc.) then the target may require an
/// explicit truncate, which is not necessarily free, but this function
/// does not deal with those cases.
/// Targets must return false when FromTy >= ToTy.
virtual bool isZExtFree(Type *FromTy, Type *ToTy) const {
return false;
}
virtual bool isZExtFree(EVT FromTy, EVT ToTy) const {
return false;
}
/// Return true if the target supplies and combines to a paired load
/// two loaded values of type LoadedType next to each other in memory.
/// RequiredAlignment gives the minimal alignment constraints that must be met
/// to be able to select this paired load.
///
/// This information is *not* used to generate actual paired loads, but it is
/// used to generate a sequence of loads that is easier to combine into a
/// paired load.
/// For instance, something like this:
/// a = load i64* addr
/// b = trunc i64 a to i32
/// c = lshr i64 a, 32
/// d = trunc i64 c to i32
/// will be optimized into:
/// b = load i32* addr1
/// d = load i32* addr2
/// Where addr1 = addr2 +/- sizeof(i32).
///
/// In other words, unless the target performs a post-isel load combining,
/// this information should not be provided because it will generate more
/// loads.
virtual bool hasPairedLoad(EVT /*LoadedType*/,
unsigned & /*RequiredAlignment*/) const {
return false;
}
/// \brief Get the maximum supported factor for interleaved memory accesses.
/// Default to be the minimum interleave factor: 2.
virtual unsigned getMaxSupportedInterleaveFactor() const { return 2; }
/// \brief Lower an interleaved load to target specific intrinsics. Return
/// true on success.
///
/// \p LI is the vector load instruction.
/// \p Shuffles is the shufflevector list to DE-interleave the loaded vector.
/// \p Indices is the corresponding indices for each shufflevector.
/// \p Factor is the interleave factor.
virtual bool lowerInterleavedLoad(LoadInst *LI,
ArrayRef<ShuffleVectorInst *> Shuffles,
ArrayRef<unsigned> Indices,
unsigned Factor) const {
return false;
}
/// \brief Lower an interleaved store to target specific intrinsics. Return
/// true on success.
///
/// \p SI is the vector store instruction.
/// \p SVI is the shufflevector to RE-interleave the stored vector.
/// \p Factor is the interleave factor.
virtual bool lowerInterleavedStore(StoreInst *SI, ShuffleVectorInst *SVI,
unsigned Factor) const {
return false;
}
/// Return true if zero-extending the specific node Val to type VT2 is free
/// (either because it's implicitly zero-extended such as ARM ldrb / ldrh or
/// because it's folded such as X86 zero-extending loads).
virtual bool isZExtFree(SDValue Val, EVT VT2) const {
return isZExtFree(Val.getValueType(), VT2);
}
/// Return true if an fpext operation is free (for instance, because
/// single-precision floating-point numbers are implicitly extended to
/// double-precision).
virtual bool isFPExtFree(EVT DestVT, EVT SrcVT) const {
assert(SrcVT.isFloatingPoint() && DestVT.isFloatingPoint() &&
"invalid fpext types");
return false;
}
/// Return true if an fpext operation input to an \p Opcode operation is free
/// (for instance, because half-precision floating-point numbers are
/// implicitly extended to float-precision) for an FMA instruction.
virtual bool isFPExtFoldable(unsigned Opcode, EVT DestVT, EVT SrcVT) const {
assert(DestVT.isFloatingPoint() && SrcVT.isFloatingPoint() &&
"invalid fpext types");
return isFPExtFree(DestVT, SrcVT);
}
/// Return true if folding a vector load into ExtVal (a sign, zero, or any
/// extend node) is profitable.
virtual bool isVectorLoadExtDesirable(SDValue ExtVal) const { return false; }
/// Return true if an fneg operation is free to the point where it is never
/// worthwhile to replace it with a bitwise operation.
virtual bool isFNegFree(EVT VT) const {
assert(VT.isFloatingPoint());
return false;
}
/// Return true if an fabs operation is free to the point where it is never
/// worthwhile to replace it with a bitwise operation.
virtual bool isFAbsFree(EVT VT) const {
assert(VT.isFloatingPoint());
return false;
}
/// Return true if an FMA operation is faster than a pair of fmul and fadd
/// instructions. fmuladd intrinsics will be expanded to FMAs when this method
/// returns true, otherwise fmuladd is expanded to fmul + fadd.
///
/// NOTE: This may be called before legalization on types for which FMAs are
/// not legal, but should return true if those types will eventually legalize
/// to types that support FMAs. After legalization, it will only be called on
/// types that support FMAs (via Legal or Custom actions)
virtual bool isFMAFasterThanFMulAndFAdd(EVT) const {
return false;
}
/// Return true if it's profitable to narrow operations of type VT1 to
/// VT2. e.g. on x86, it's profitable to narrow from i32 to i8 but not from
/// i32 to i16.
virtual bool isNarrowingProfitable(EVT /*VT1*/, EVT /*VT2*/) const {
return false;
}
/// \brief Return true if it is beneficial to convert a load of a constant to
/// just the constant itself.
/// On some targets it might be more efficient to use a combination of
/// arithmetic instructions to materialize the constant instead of loading it
/// from a constant pool.
virtual bool shouldConvertConstantLoadToIntImm(const APInt &Imm,
Type *Ty) const {
return false;
}
/// Return true if EXTRACT_SUBVECTOR is cheap for extracting this result type
/// from this source type with this index. This is needed because
/// EXTRACT_SUBVECTOR usually has custom lowering that depends on the index of
/// the first element, and only the target knows which lowering is cheap.
virtual bool isExtractSubvectorCheap(EVT ResVT, EVT SrcVT,
unsigned Index) const {
return false;
}
// Return true if it is profitable to use a scalar input to a BUILD_VECTOR
// even if the vector itself has multiple uses.
virtual bool aggressivelyPreferBuildVectorSources(EVT VecVT) const {
return false;
}
//===--------------------------------------------------------------------===//
// Runtime Library hooks
//
/// Rename the default libcall routine name for the specified libcall.
void setLibcallName(RTLIB::Libcall Call, const char *Name) {
LibcallRoutineNames[Call] = Name;
}
/// Get the libcall routine name for the specified libcall.
const char *getLibcallName(RTLIB::Libcall Call) const {
return LibcallRoutineNames[Call];
}
/// Override the default CondCode to be used to test the result of the
/// comparison libcall against zero.
void setCmpLibcallCC(RTLIB::Libcall Call, ISD::CondCode CC) {
CmpLibcallCCs[Call] = CC;
}
/// Get the CondCode that's to be used to test the result of the comparison
/// libcall against zero.
ISD::CondCode getCmpLibcallCC(RTLIB::Libcall Call) const {
return CmpLibcallCCs[Call];
}
/// Set the CallingConv that should be used for the specified libcall.
void setLibcallCallingConv(RTLIB::Libcall Call, CallingConv::ID CC) {
LibcallCallingConvs[Call] = CC;
}
/// Get the CallingConv that should be used for the specified libcall.
CallingConv::ID getLibcallCallingConv(RTLIB::Libcall Call) const {
return LibcallCallingConvs[Call];
}
/// Execute target specific actions to finalize target lowering.
/// This is used to set extra flags in MachineFrameInformation and freezing
/// the set of reserved registers.
/// The default implementation just freezes the set of reserved registers.
virtual void finalizeLowering(MachineFunction &MF) const;
private:
const TargetMachine &TM;
/// Tells the code generator that the target has multiple (allocatable)
/// condition registers that can be used to store the results of comparisons
/// for use by selects and conditional branches. With multiple condition
/// registers, the code generator will not aggressively sink comparisons into
/// the blocks of their users.
bool HasMultipleConditionRegisters;
/// Tells the code generator that the target has BitExtract instructions.
/// The code generator will aggressively sink "shift"s into the blocks of
/// their users if the users will generate "and" instructions which can be
/// combined with "shift" to BitExtract instructions.
bool HasExtractBitsInsn;
/// Tells the code generator to bypass slow divide or remainder
/// instructions. For example, BypassSlowDivWidths[32,8] tells the code
/// generator to bypass 32-bit integer div/rem with an 8-bit unsigned integer
/// div/rem when the operands are positive and less than 256.
DenseMap <unsigned int, unsigned int> BypassSlowDivWidths;
/// Tells the code generator that it shouldn't generate extra flow control
/// instructions and should attempt to combine flow control instructions via
/// predication.
bool JumpIsExpensive;
/// Whether the target supports or cares about preserving floating point
/// exception behavior.
bool HasFloatingPointExceptions;
/// This target prefers to use _setjmp to implement llvm.setjmp.
///
/// Defaults to false.
bool UseUnderscoreSetJmp;
/// This target prefers to use _longjmp to implement llvm.longjmp.
///
/// Defaults to false.
bool UseUnderscoreLongJmp;
/// Information about the contents of the high-bits in boolean values held in
/// a type wider than i1. See getBooleanContents.
BooleanContent BooleanContents;
/// Information about the contents of the high-bits in boolean values held in
/// a type wider than i1. See getBooleanContents.
BooleanContent BooleanFloatContents;
/// Information about the contents of the high-bits in boolean vector values
/// when the element type is wider than i1. See getBooleanContents.
BooleanContent BooleanVectorContents;
/// The target scheduling preference: shortest possible total cycles or lowest
/// register usage.
Sched::Preference SchedPreferenceInfo;
/// The size, in bytes, of the target's jmp_buf buffers
unsigned JumpBufSize;
/// The alignment, in bytes, of the target's jmp_buf buffers
unsigned JumpBufAlignment;
/// The minimum alignment that any argument on the stack needs to have.
unsigned MinStackArgumentAlignment;
/// The minimum function alignment (used when optimizing for size, and to
/// prevent explicitly provided alignment from leading to incorrect code).
unsigned MinFunctionAlignment;
/// The preferred function alignment (used when alignment unspecified and
/// optimizing for speed).
unsigned PrefFunctionAlignment;
/// The preferred loop alignment.
unsigned PrefLoopAlignment;
/// Size in bits of the maximum atomics size the backend supports.
/// Accesses larger than this will be expanded by AtomicExpandPass.
unsigned MaxAtomicSizeInBitsSupported;
/// Size in bits of the minimum cmpxchg or ll/sc operation the
/// backend supports.
unsigned MinCmpXchgSizeInBits;
/// If set to a physical register, this specifies the register that
/// llvm.savestack/llvm.restorestack should save and restore.
unsigned StackPointerRegisterToSaveRestore;
/// This indicates the default register class to use for each ValueType the
/// target supports natively.
const TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
unsigned char NumRegistersForVT[MVT::LAST_VALUETYPE];
MVT RegisterTypeForVT[MVT::LAST_VALUETYPE];
/// This indicates the "representative" register class to use for each
/// ValueType the target supports natively. This information is used by the
/// scheduler to track register pressure. By default, the representative
/// register class is the largest legal super-reg register class of the
/// register class of the specified type. e.g. On x86, i8, i16, and i32's
/// representative class would be GR32.
const TargetRegisterClass *RepRegClassForVT[MVT::LAST_VALUETYPE];
/// This indicates the "cost" of the "representative" register class for each
/// ValueType. The cost is used by the scheduler to approximate register
/// pressure.
uint8_t RepRegClassCostForVT[MVT::LAST_VALUETYPE];
/// For any value types we are promoting or expanding, this contains the value
/// type that we are changing to. For Expanded types, this contains one step
/// of the expand (e.g. i64 -> i32), even if there are multiple steps required
/// (e.g. i64 -> i16). For types natively supported by the system, this holds
/// the same type (e.g. i32 -> i32).
MVT TransformToType[MVT::LAST_VALUETYPE];
/// For each operation and each value type, keep a LegalizeAction that
/// indicates how instruction selection should deal with the operation. Most
/// operations are Legal (aka, supported natively by the target), but
/// operations that are not should be described. Note that operations on
/// non-legal value types are not described here.
LegalizeAction OpActions[MVT::LAST_VALUETYPE][ISD::BUILTIN_OP_END];
/// For each load extension type and each value type, keep a LegalizeAction
/// that indicates how instruction selection should deal with a load of a
/// specific value type and extension type. Uses 4-bits to store the action
/// for each of the 4 load ext types.
uint16_t LoadExtActions[MVT::LAST_VALUETYPE][MVT::LAST_VALUETYPE];
/// For each value type pair keep a LegalizeAction that indicates whether a
/// truncating store of a specific value type and truncating type is legal.
LegalizeAction TruncStoreActions[MVT::LAST_VALUETYPE][MVT::LAST_VALUETYPE];
/// For each indexed mode and each value type, keep a pair of LegalizeAction
/// that indicates how instruction selection should deal with the load /
/// store.
///
/// The first dimension is the value_type for the reference. The second
/// dimension represents the various modes for load store.
uint8_t IndexedModeActions[MVT::LAST_VALUETYPE][ISD::LAST_INDEXED_MODE];
/// For each condition code (ISD::CondCode) keep a LegalizeAction that
/// indicates how instruction selection should deal with the condition code.
///
/// Because each CC action takes up 4 bits, we need to have the array size be
/// large enough to fit all of the value types. This can be done by rounding
/// up the MVT::LAST_VALUETYPE value to the next multiple of 8.
uint32_t CondCodeActions[ISD::SETCC_INVALID][(MVT::LAST_VALUETYPE + 7) / 8];
protected:
ValueTypeActionImpl ValueTypeActions;
private:
LegalizeKind getTypeConversion(LLVMContext &Context, EVT VT) const;
/// Targets can specify ISD nodes that they would like PerformDAGCombine
/// callbacks for by calling setTargetDAGCombine(), which sets a bit in this
/// array.
unsigned char
TargetDAGCombineArray[(ISD::BUILTIN_OP_END+CHAR_BIT-1)/CHAR_BIT];
/// For operations that must be promoted to a specific type, this holds the
/// destination type. This map should be sparse, so don't hold it as an
/// array.
///
/// Targets add entries to this map with AddPromotedToType(..), clients access
/// this with getTypeToPromoteTo(..).
std::map<std::pair<unsigned, MVT::SimpleValueType>, MVT::SimpleValueType>
PromoteToType;
/// Stores the name each libcall.
const char *LibcallRoutineNames[RTLIB::UNKNOWN_LIBCALL];
/// The ISD::CondCode that should be used to test the result of each of the
/// comparison libcall against zero.
ISD::CondCode CmpLibcallCCs[RTLIB::UNKNOWN_LIBCALL];
/// Stores the CallingConv that should be used for each libcall.
CallingConv::ID LibcallCallingConvs[RTLIB::UNKNOWN_LIBCALL];
protected:
/// Return true if the extension represented by \p I is free.
/// \pre \p I is a sign, zero, or fp extension and
/// is[Z|FP]ExtFree of the related types is not true.
virtual bool isExtFreeImpl(const Instruction *I) const { return false; }
/// Depth that GatherAllAliases should should continue looking for chain
/// dependencies when trying to find a more preferable chain. As an
/// approximation, this should be more than the number of consecutive stores
/// expected to be merged.
unsigned GatherAllAliasesMaxDepth;
/// \brief Specify maximum number of store instructions per memset call.
///
/// When lowering \@llvm.memset this field specifies the maximum number of
/// store operations that may be substituted for the call to memset. Targets
/// must set this value based on the cost threshold for that target. Targets
/// should assume that the memset will be done using as many of the largest
/// store operations first, followed by smaller ones, if necessary, per
/// alignment restrictions. For example, storing 9 bytes on a 32-bit machine
/// with 16-bit alignment would result in four 2-byte stores and one 1-byte
/// store. This only applies to setting a constant array of a constant size.
unsigned MaxStoresPerMemset;
/// Maximum number of stores operations that may be substituted for the call
/// to memset, used for functions with OptSize attribute.
unsigned MaxStoresPerMemsetOptSize;
/// \brief Specify maximum bytes of store instructions per memcpy call.
///
/// When lowering \@llvm.memcpy this field specifies the maximum number of
/// store operations that may be substituted for a call to memcpy. Targets
/// must set this value based on the cost threshold for that target. Targets
/// should assume that the memcpy will be done using as many of the largest
/// store operations first, followed by smaller ones, if necessary, per
/// alignment restrictions. For example, storing 7 bytes on a 32-bit machine
/// with 32-bit alignment would result in one 4-byte store, a one 2-byte store
/// and one 1-byte store. This only applies to copying a constant array of
/// constant size.
unsigned MaxStoresPerMemcpy;
/// Maximum number of store operations that may be substituted for a call to
/// memcpy, used for functions with OptSize attribute.
unsigned MaxStoresPerMemcpyOptSize;
unsigned MaxLoadsPerMemcmp;
unsigned MaxLoadsPerMemcmpOptSize;
/// \brief Specify maximum bytes of store instructions per memmove call.
///
/// When lowering \@llvm.memmove this field specifies the maximum number of
/// store instructions that may be substituted for a call to memmove. Targets
/// must set this value based on the cost threshold for that target. Targets
/// should assume that the memmove will be done using as many of the largest
/// store operations first, followed by smaller ones, if necessary, per
/// alignment restrictions. For example, moving 9 bytes on a 32-bit machine
/// with 8-bit alignment would result in nine 1-byte stores. This only
/// applies to copying a constant array of constant size.
unsigned MaxStoresPerMemmove;
/// Maximum number of store instructions that may be substituted for a call to
/// memmove, used for functions with OptSize attribute.
unsigned MaxStoresPerMemmoveOptSize;
/// Tells the code generator that select is more expensive than a branch if
/// the branch is usually predicted right.
bool PredictableSelectIsExpensive;
/// \see enableExtLdPromotion.
bool EnableExtLdPromotion;
/// Return true if the value types that can be represented by the specified
/// register class are all legal.
bool isLegalRC(const TargetRegisterInfo &TRI,
const TargetRegisterClass &RC) const;
/// Replace/modify any TargetFrameIndex operands with a targte-dependent
/// sequence of memory operands that is recognized by PrologEpilogInserter.
MachineBasicBlock *emitPatchPoint(MachineInstr &MI,
MachineBasicBlock *MBB) const;
};
/// This class defines information used to lower LLVM code to legal SelectionDAG
/// operators that the target instruction selector can accept natively.
///
/// This class also defines callbacks that targets must implement to lower
/// target-specific constructs to SelectionDAG operators.
class TargetLowering : public TargetLoweringBase {
public:
struct DAGCombinerInfo;
TargetLowering(const TargetLowering &) = delete;
TargetLowering &operator=(const TargetLowering &) = delete;
/// NOTE: The TargetMachine owns TLOF.
explicit TargetLowering(const TargetMachine &TM);
bool isPositionIndependent() const;
/// Returns true by value, base pointer and offset pointer and addressing mode
/// by reference if the node's address can be legally represented as
/// pre-indexed load / store address.
virtual bool getPreIndexedAddressParts(SDNode * /*N*/, SDValue &/*Base*/,
SDValue &/*Offset*/,
ISD::MemIndexedMode &/*AM*/,
SelectionDAG &/*DAG*/) const {
return false;
}
/// Returns true by value, base pointer and offset pointer and addressing mode
/// by reference if this node can be combined with a load / store to form a
/// post-indexed load / store.
virtual bool getPostIndexedAddressParts(SDNode * /*N*/, SDNode * /*Op*/,
SDValue &/*Base*/,
SDValue &/*Offset*/,
ISD::MemIndexedMode &/*AM*/,
SelectionDAG &/*DAG*/) const {
return false;
}
/// Return the entry encoding for a jump table in the current function. The
/// returned value is a member of the MachineJumpTableInfo::JTEntryKind enum.
virtual unsigned getJumpTableEncoding() const;
virtual const MCExpr *
LowerCustomJumpTableEntry(const MachineJumpTableInfo * /*MJTI*/,
const MachineBasicBlock * /*MBB*/, unsigned /*uid*/,
MCContext &/*Ctx*/) const {
llvm_unreachable("Need to implement this hook if target has custom JTIs");
}
/// Returns relocation base for the given PIC jumptable.
virtual SDValue getPICJumpTableRelocBase(SDValue Table,
SelectionDAG &DAG) const;
/// This returns the relocation base for the given PIC jumptable, the same as
/// getPICJumpTableRelocBase, but as an MCExpr.
virtual const MCExpr *
getPICJumpTableRelocBaseExpr(const MachineFunction *MF,
unsigned JTI, MCContext &Ctx) const;
/// Return true if folding a constant offset with the given GlobalAddress is
/// legal. It is frequently not legal in PIC relocation models.
virtual bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const;
bool isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
SDValue &Chain) const;
void softenSetCCOperands(SelectionDAG &DAG, EVT VT, SDValue &NewLHS,
SDValue &NewRHS, ISD::CondCode &CCCode,
const SDLoc &DL) const;
/// Returns a pair of (return value, chain).
/// It is an error to pass RTLIB::UNKNOWN_LIBCALL as \p LC.
std::pair<SDValue, SDValue> makeLibCall(SelectionDAG &DAG, RTLIB::Libcall LC,
EVT RetVT, ArrayRef<SDValue> Ops,
bool isSigned, const SDLoc &dl,
bool doesNotReturn = false,
bool isReturnValueUsed = true) const;
/// Check whether parameters to a call that are passed in callee saved
/// registers are the same as from the calling function. This needs to be
/// checked for tail call eligibility.
bool parametersInCSRMatch(const MachineRegisterInfo &MRI,
const uint32_t *CallerPreservedMask,
const SmallVectorImpl<CCValAssign> &ArgLocs,
const SmallVectorImpl<SDValue> &OutVals) const;
//===--------------------------------------------------------------------===//
// TargetLowering Optimization Methods
//
/// A convenience struct that encapsulates a DAG, and two SDValues for
/// returning information from TargetLowering to its clients that want to
/// combine.
struct TargetLoweringOpt {
SelectionDAG &DAG;
bool LegalTys;
bool LegalOps;
SDValue Old;
SDValue New;
explicit TargetLoweringOpt(SelectionDAG &InDAG,
bool LT, bool LO) :
DAG(InDAG), LegalTys(LT), LegalOps(LO) {}
bool LegalTypes() const { return LegalTys; }
bool LegalOperations() const { return LegalOps; }
bool CombineTo(SDValue O, SDValue N) {
Old = O;
New = N;
return true;
}
};
/// Check to see if the specified operand of the specified instruction is a
/// constant integer. If so, check to see if there are any bits set in the
/// constant that are not demanded. If so, shrink the constant and return
/// true.
bool ShrinkDemandedConstant(SDValue Op, const APInt &Demanded,
TargetLoweringOpt &TLO) const;
// Target hook to do target-specific const optimization, which is called by
// ShrinkDemandedConstant. This function should return true if the target
// doesn't want ShrinkDemandedConstant to further optimize the constant.
virtual bool targetShrinkDemandedConstant(SDValue Op, const APInt &Demanded,
TargetLoweringOpt &TLO) const {
return false;
}
/// Convert x+y to (VT)((SmallVT)x+(SmallVT)y) if the casts are free. This
/// uses isZExtFree and ZERO_EXTEND for the widening cast, but it could be
/// generalized for targets with other types of implicit widening casts.
bool ShrinkDemandedOp(SDValue Op, unsigned BitWidth, const APInt &Demanded,
TargetLoweringOpt &TLO) const;
/// Helper for SimplifyDemandedBits that can simplify an operation with
/// multiple uses. This function simplifies operand \p OpIdx of \p User and
/// then updates \p User with the simplified version. No other uses of
/// \p OpIdx are updated. If \p User is the only user of \p OpIdx, this
/// function behaves exactly like function SimplifyDemandedBits declared
/// below except that it also updates the DAG by calling
/// DCI.CommitTargetLoweringOpt.
bool SimplifyDemandedBits(SDNode *User, unsigned OpIdx, const APInt &Demanded,
DAGCombinerInfo &DCI, TargetLoweringOpt &TLO) const;
/// Look at Op. At this point, we know that only the DemandedMask bits of the
/// result of Op are ever used downstream. If we can use this information to
/// simplify Op, create a new simplified DAG node and return true, returning
/// the original and new nodes in Old and New. Otherwise, analyze the
/// expression and return a mask of KnownOne and KnownZero bits for the
/// expression (used to simplify the caller). The KnownZero/One bits may only
/// be accurate for those bits in the DemandedMask.
/// \p AssumeSingleUse When this parameter is true, this function will
/// attempt to simplify \p Op even if there are multiple uses.
/// Callers are responsible for correctly updating the DAG based on the
/// results of this function, because simply replacing replacing TLO.Old
/// with TLO.New will be incorrect when this parameter is true and TLO.Old
/// has multiple uses.
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedMask,
KnownBits &Known,
TargetLoweringOpt &TLO,
unsigned Depth = 0,
bool AssumeSingleUse = false) const;
/// Helper wrapper around SimplifyDemandedBits
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedMask,
DAGCombinerInfo &DCI) const;
/// Determine which of the bits specified in Mask are known to be either zero
/// or one and return them in the KnownZero/KnownOne bitsets. The DemandedElts
/// argument allows us to only collect the known bits that are shared by the
/// requested vector elements.
virtual void computeKnownBitsForTargetNode(const SDValue Op,
KnownBits &Known,
const APInt &DemandedElts,
const SelectionDAG &DAG,
unsigned Depth = 0) const;
/// Determine which of the bits of FrameIndex \p FIOp are known to be 0.
/// Default implementation computes low bits based on alignment
/// information. This should preserve known bits passed into it.
virtual void computeKnownBitsForFrameIndex(const SDValue FIOp,
KnownBits &Known,
const APInt &DemandedElts,
const SelectionDAG &DAG,
unsigned Depth = 0) const;
/// This method can be implemented by targets that want to expose additional
/// information about sign bits to the DAG Combiner. The DemandedElts
/// argument allows us to only collect the minimum sign bits that are shared
/// by the requested vector elements.
virtual unsigned ComputeNumSignBitsForTargetNode(SDValue Op,
const APInt &DemandedElts,
const SelectionDAG &DAG,
unsigned