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llvm-mirror/include/llvm/CodeGen/TargetLowering.h
Craig Topper ca39e09647 [TargetLowering][AMDGPU] Remove the SimplifyDemandedBits function that takes a User and OpIdx. Stop using it in AMDGPU target for simplifyI24. 
As we saw in D56057 when we tried to use this function on X86, it's unsafe. It allows the operand node to have multiple users, but doesn't prevent recursing past the first node when it does have multiple users. This can cause other simplifications earlier in the graph without regard to what bits are needed by the other users of the first node. Ideally all we should do to the first node if it has multiple uses is bypass it when its not needed by the user we started from. Doing any other transformation that SimplifyDemandedBits can do like turning ZEXT/SEXT into AEXT would result in an increase in instructions.

Fortunately, we already have a function that can do just that, GetDemandedBits. It will only make transformations that involve bypassing a node.

This patch changes AMDGPU's simplifyI24, to use a combination of GetDemandedBits to handle the multiple use simplifications. And then uses the regular SimplifyDemandedBits on each operand to handle simplifications allowed when the operand only has a single use. Unfortunately, GetDemandedBits simplifies constants more aggressively than SimplifyDemandedBits. This caused the -7 constant in the changed test to be simplified to remove the upper bits. I had to modify computeKnownBits to account for this by ignoring the upper 8 bits of the input.

Differential Revision: https://reviews.llvm.org/D56087

llvm-svn: 350560
2019-01-07 19:30:43 +00:00

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//===- llvm/CodeGen/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_CODEGEN_TARGETLOWERING_H
#define LLVM_CODEGEN_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/Analysis/LegacyDivergenceAnalysis.h"
#include "llvm/CodeGen/DAGCombine.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/TargetCallingConv.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/Support/MachineValueType.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.
MaskedIntrinsic, // Use a target-specific intrinsic for the LL/SC loop.
};
/// 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:
/// 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,
bool LegalTypes = true) 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 it is profitable to convert a select of FP constants into
/// a constant pool load whose address depends on the select condition. The
/// parameter may be used to differentiate a select with FP compare from
/// integer compare.
virtual bool reduceSelectOfFPConstantLoads(bool IsFPSetCC) 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(MVT 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 true; }
/// Returns if it's reasonable to merge stores to MemVT size.
virtual bool canMergeStoresTo(unsigned AS, EVT MemVT,
const SelectionDAG &DAG) const {
return true;
}
/// Return true if it is cheap to speculate a call to intrinsic cttz.
virtual bool isCheapToSpeculateCttz() const {
return false;
}
/// Return true if it is cheap to speculate a call to intrinsic ctlz.
virtual bool isCheapToSpeculateCtlz() const {
return false;
}
/// 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;
}
/// 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;
}
/// 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);
}
/// There are two ways to clear extreme bits (either low or high):
/// Mask: x & (-1 << y) (the instcombine canonical form)
/// Shifts: x >> y << y
/// Return true if the variant with 2 shifts is preferred.
/// Return false if there is no preference.
virtual bool preferShiftsToClearExtremeBits(SDValue X) const {
// By default, let's assume that no one prefers shifts.
return false;
}
/// Should we tranform the IR-optimal check for whether given truncation
/// down into KeptBits would be truncating or not:
/// (add %x, (1 << (KeptBits-1))) srccond (1 << KeptBits)
/// Into it's more traditional form:
/// ((%x << C) a>> C) dstcond %x
/// Return true if we should transform.
/// Return false if there is no preference.
virtual bool shouldTransformSignedTruncationCheck(EVT XVT,
unsigned KeptBits) const {
// By default, let's assume that no one prefers shifts.
return false;
}
/// 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 inserting a scalar into a variable element of an undef
/// vector is more efficiently handled by splatting the scalar instead.
virtual bool shouldSplatInsEltVarIndex(EVT) 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, CallingConv::ID CC, 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
// value representing memory location
PointerUnion<const Value *, const PseudoSourceValue *> ptrVal;
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
MachineMemOperand::Flags flags = MachineMemOperand::MONone;
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 &,
MachineFunction &,
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. 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(ArrayRef<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];
}
/// Custom method defined by each target to indicate if an operation which
/// may require a scale is supported natively by the target.
/// If not, the operation is illegal.
virtual bool isSupportedFixedPointOperation(unsigned Op, EVT VT,
unsigned Scale) const {
return false;
}
/// Some fixed point operations may be natively supported by the target but
/// only for specific scales. This method allows for checking
/// if the width is supported by the target for a given operation that may
/// depend on scale.
LegalizeAction getFixedPointOperationAction(unsigned Op, EVT VT,
unsigned Scale) const {
auto Action = getOperationAction(Op, VT);
if (Action != Legal)
return Action;
// This operation is supported in this type but may only work on specific
// scales.
bool Supported;
switch (Op) {
default:
llvm_unreachable("Unexpected fixed point operation.");
case ISD::SMULFIX:
Supported = isSupportedFixedPointOperation(Op, VT, Scale);
break;
}
return Supported ? Action : Expand;
}
LegalizeAction getStrictFPOperationAction(unsigned Op, EVT VT) const {
unsigned EqOpc;
switch (Op) {
default: llvm_unreachable("Unexpected FP pseudo-opcode");
case ISD::STRICT_FADD: EqOpc = ISD::FADD; break;
case ISD::STRICT_FSUB: EqOpc = ISD::FSUB; break;
case ISD::STRICT_FMUL: EqOpc = ISD::FMUL; break;
case ISD::STRICT_FDIV: EqOpc = ISD::FDIV; break;
case ISD::STRICT_FREM: EqOpc = ISD::FREM; break;
case ISD::STRICT_FSQRT: EqOpc = ISD::FSQRT; break;
case ISD::STRICT_FPOW: EqOpc = ISD::FPOW; break;
case ISD::STRICT_FPOWI: EqOpc = ISD::FPOWI; break;
case ISD::STRICT_FMA: EqOpc = ISD::FMA; break;
case ISD::STRICT_FSIN: EqOpc = ISD::FSIN; break;
case ISD::STRICT_FCOS: EqOpc = ISD::FCOS; break;
case ISD::STRICT_FEXP: EqOpc = ISD::FEXP; break;
case ISD::STRICT_FEXP2: EqOpc = ISD::FEXP2; break;
case ISD::STRICT_FLOG: EqOpc = ISD::FLOG; break;
case ISD::STRICT_FLOG10: EqOpc = ISD::FLOG10; break;
case ISD::STRICT_FLOG2: EqOpc = ISD::FLOG2; break;
case ISD::STRICT_FRINT: EqOpc = ISD::FRINT; break;
case ISD::STRICT_FNEARBYINT: EqOpc = ISD::FNEARBYINT; break;
case ISD::STRICT_FMAXNUM: EqOpc = ISD::FMAXNUM; break;
case ISD::STRICT_FMINNUM: EqOpc = ISD::FMINNUM; break;
case ISD::STRICT_FCEIL: EqOpc = ISD::FCEIL; break;
case ISD::STRICT_FFLOOR: EqOpc = ISD::FFLOOR; break;
case ISD::STRICT_FROUND: EqOpc = ISD::FROUND; break;
case ISD::STRICT_FTRUNC: EqOpc = ISD::FTRUNC; break;
}
auto Action = getOperationAction(EqOpc, VT);
// We don't currently handle Custom or Promote for strict FP pseudo-ops.
// For now, we just expand for those cases.
if (Action != Legal)
Action = Expand;
return Action;
}
/// 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.
virtual 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.getIndexSizeInBits(0u);
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 minimum size is
/// also combined within this function. Currently, the minimum size check is
/// performed in findJumpTable() in SelectionDAGBuiler and
/// getEstimatedNumberOfCaseClusters() in BasicTTIImpl.
virtual 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;
}
/// Return true if the specified condition code is legal or custom on this
/// target.
bool isCondCodeLegalOrCustom(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(LLVMContext &Context,
CallingConv::ID CC, 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,
CallingConv::ID CC,
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 a load to a smaller type.
/// Example: (i16 (trunc (i32 (load x))) -> i16 load x
virtual bool shouldReduceLoadWidth(SDNode *Load, ISD::LoadExtType ExtTy,
EVT NewVT) const {
// By default, assume that it is cheaper to extract a subvector from a wide
// vector load rather than creating multiple narrow vector loads.
if (NewVT.isVector() && !Load->hasOneUse())
return false;
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();
}
/// 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;
}
/// 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;
}
/// \brief Get maximum # of store operations to be glued together
///
/// This function returns the maximum number of store operations permitted
/// to glue together during lowering of llvm.memcpy. The value is set by
// the target at the performance threshold for such a replacement.
virtual unsigned getMaxGluedStoresPerMemcpy() const {
return MaxGluedStoresPerMemcpy;
}
/// 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;
}
/// For memcmp expansion when the memcmp result is only compared equal or
/// not-equal to 0, allow up to this number of load pairs per block. As an
/// example, this may allow 'memcmp(a, b, 3) == 0' in a single block:
/// a0 = load2bytes &a[0]
/// b0 = load2bytes &b[0]
/// a2 = load1byte &a[2]
/// b2 = load1byte &b[2]
/// r = cmp eq (a0 ^ b0 | a2 ^ b2), 0
virtual unsigned getMemcmpEqZeroLoadsPerBlock() const {
return 1;
}
/// 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;
}
/// 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.
virtual 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;
}
/// Should loops be aligned even when the function is marked OptSize (but not
/// MinSize).
virtual bool alignLoopsWithOptSize() const {
return false;
}
/// 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 this function returns true, stack protection checks should XOR the
/// frame pointer (or whichever pointer is used to address locals) into the
/// stack guard value before checking it. getIRStackGuard must return nullptr
/// if this returns true.
virtual bool useStackGuardXorFP() const { return false; }
/// 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 the target supports unaligned atomic operations.
bool supportsUnalignedAtomics() const { return SupportsUnalignedAtomics; }
/// 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");
}
/// Perform a masked atomicrmw using a target-specific intrinsic. This
/// represents the core LL/SC loop which will be lowered at a late stage by
/// the backend.
virtual Value *emitMaskedAtomicRMWIntrinsic(IRBuilder<> &Builder,
AtomicRMWInst *AI,
Value *AlignedAddr, Value *Incr,
Value *Mask, Value *ShiftAmt,
AtomicOrdering Ord) const {
llvm_unreachable("Masked atomicrmw expansion unimplemented on this target");
}
/// Perform a masked cmpxchg using a target-specific intrinsic. This
/// represents the core LL/SC loop which will be lowered at a late stage by
/// the backend.
virtual Value *emitMaskedAtomicCmpXchgIntrinsic(
IRBuilder<> &Builder, AtomicCmpXchgInst *CI, Value *AlignedAddr,
Value *CmpVal, Value *NewVal, Value *Mask, AtomicOrdering Ord) const {
llvm_unreachable("Masked cmpxchg expansion 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 how the given atomic cmpxchg should be expanded by the IR-level
/// AtomicExpand pass.
virtual AtomicExpansionKind
shouldExpandAtomicCmpXchgInIR(AtomicCmpXchgInst *AI) const {
return AtomicExpansionKind::None;
}
/// 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;
}
/// Return true if it is profitable to transform an integer
/// multiplication-by-constant into simpler operations like shifts and adds.
/// This may be true if the target does not directly support the
/// multiplication operation for the specified type or the sequence of simpler
/// ops is faster than the multiply.
virtual bool decomposeMulByConstant(EVT VT, SDValue C) const {
return false;
}
/// Return true if it is more correct/profitable to use strict FP_TO_INT
/// conversion operations - canonicalizing the FP source value instead of
/// converting all cases and then selecting based on value.
/// This may be true if the target throws exceptions for out of bounds
/// conversions or has fast FP CMOV.
virtual bool shouldUseStrictFP_TO_INT(EVT FpVT, EVT IntVT,
bool IsSigned) 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;
}
/// Sets whether unaligned atomic operations are supported.
void setSupportsUnalignedAtomics(bool UnalignedSupported) {
SupportsUnalignedAtomics = UnalignedSupported;
}
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;
/// 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 the specified immediate is legal for the value input of a
/// store instruction.
virtual bool isLegalStoreImmediate(int64_t Value) const {
// Default implementation assumes that at least 0 works since it is likely
// that a zero register exists or a zero immediate is allowed.
return Value == 0;
}
/// 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::FMINIMUM:
case ISD::FMAXIMUM:
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 sign-extension from FromTy to ToTy is cheaper than
/// zero-extension.
virtual bool isSExtCheaperThanZExt(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;
}
/// Return true if the target has a vector blend instruction.
virtual bool hasVectorBlend() const { return false; }
/// Get the maximum supported factor for interleaved memory accesses.
/// Default to be the minimum interleave factor: 2.
virtual unsigned getMaxSupportedInterleaveFactor() const { return 2; }
/// 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;
}
/// 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;
}
/// 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;
}
/// Try to convert an extract element of a vector binary operation into an
/// extract element followed by a scalar operation.
virtual bool shouldScalarizeBinop(SDValue VecOp) 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;
}
// Return true if CodeGenPrepare should consider splitting large offset of a
// GEP to make the GEP fit into the addressing mode and can be sunk into the
// same blocks of its users.
virtual bool shouldConsiderGEPOffsetSplit() 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;
/// This indicates if the target supports unaligned atomic operations.
bool SupportsUnalignedAtomics;
/// 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 + 1];
/// 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];
/// Set default libcall names and calling conventions.
void InitLibcalls(const Triple &TT);
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;
/// 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;
/// 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;
/// \brief Specify max number of store instructions to glue in inlined memcpy.
///
/// When memcpy is inlined based on MaxStoresPerMemcpy, specify maximum number
/// of store instructions to keep together. This helps in pairing and
// vectorization later on.
unsigned MaxGluedStoresPerMemcpy = 0;
/// 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;
/// 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;
/// Replace/modify the XRay custom event operands with target-dependent
/// details.
MachineBasicBlock *emitXRayCustomEvent(MachineInstr &MI,
MachineBasicBlock *MBB) const;
/// Replace/modify the XRay typed event operands with target-dependent
/// details.
MachineBasicBlock *emitXRayTypedEvent(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;
virtual bool isSDNodeSourceOfDivergence(const SDNode *N,
FunctionLoweringInfo *FLI,
LegacyDivergenceAnalysis *DA) const {
return false;
}
virtual bool isSDNodeAlwaysUniform(const SDNode * N) const {
return false;
}
/// 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;
/// Look at Op. At this point, we know that only the DemandedBits 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 Demanded masks.
/// \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 &DemandedBits,
const APInt &DemandedElts, KnownBits &Known,
TargetLoweringOpt &TLO, unsigned Depth = 0,
bool AssumeSingleUse = false) const;
/// Helper wrapper around SimplifyDemandedBits, demanding all elements.
/// Adds Op back to the worklist upon success.
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
KnownBits &Known, TargetLoweringOpt &TLO,
unsigned Depth = 0,
bool AssumeSingleUse = false) const;
/// Helper wrapper around SimplifyDemandedBits.
/// Adds Op back to the worklist upon success.
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedMask,
DAGCombinerInfo &DCI) const;
/// Look at Vector Op. At this point, we know that only the DemandedElts
/// elements 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, storing the original and new nodes in TLO.
/// Otherwise, analyze the expression and return a mask of KnownUndef and
/// KnownZero elements for the expression (used to simplify the caller).
/// The KnownUndef/Zero elements 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 SimplifyDemandedVectorElts(SDValue Op, const APInt &DemandedEltMask,
APInt &KnownUndef, APInt &KnownZero,
TargetLoweringOpt &TLO, unsigned Depth = 0,
bool AssumeSingleUse = false) const;
/// Helper wrapper around SimplifyDemandedVectorElts.
/// Adds Op back to the worklist upon success.
bool SimplifyDemandedVectorElts(SDValue Op, const APInt &DemandedElts,
APInt &KnownUndef, APInt &KnownZero,
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 Depth = 0) const;
/// Attempt to simplify any target nodes based on the demanded vector
/// elements, returning true on success. Otherwise, analyze the expression and
/// return a mask of KnownUndef and KnownZero elements for the expression
/// (used to simplify the caller). The KnownUndef/Zero elements may only be
/// accurate for those bits in the DemandedMask.
virtual bool SimplifyDemandedVectorEltsForTargetNode(
SDValue Op, const APInt &DemandedElts, APInt &KnownUndef,
APInt &KnownZero, TargetLoweringOpt &TLO, unsigned Depth = 0) const;
/// Attempt to simplify any target nodes based on the demanded bits/elts,
/// returning true on success. 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 Demanded masks.
virtual bool SimplifyDemandedBitsForTargetNode(SDValue Op,
const APInt &DemandedBits,
const APInt &DemandedElts,
KnownBits &Known,
TargetLoweringOpt &TLO,
unsigned Depth = 0) const;
/// If \p SNaN is false, \returns true if \p Op is known to never be any
/// NaN. If \p sNaN is true, returns if \p Op is known to never be a signaling
/// NaN.
virtual bool isKnownNeverNaNForTargetNode(SDValue Op,
const SelectionDAG &DAG,
bool SNaN = false,
unsigned Depth = 0) const;
struct DAGCombinerInfo {
void *DC; // The DAG Combiner object.
CombineLevel Level;
bool CalledByLegalizer;
public:
SelectionDAG &DAG;
DAGCombinerInfo(SelectionDAG &dag, CombineLevel level, bool cl, void *dc)
: DC(dc), Level(level), CalledByLegalizer(cl), DAG(dag) {}
bool isBeforeLegalize() const { return Level == BeforeLegalizeTypes; }
bool isBeforeLegalizeOps() const { return Level < AfterLegalizeVectorOps; }
bool isAfterLegalizeDAG() const {
return Level == AfterLegalizeDAG;
}
CombineLevel getDAGCombineLevel() { return Level; }
bool isCalledByLegalizer() const { return CalledByLegalizer; }
void AddToWorklist(SDNode *N);
SDValue CombineTo(SDNode *N, ArrayRef<SDValue> To, bool AddTo = true);
SDValue CombineTo(SDNode *N, SDValue Res, bool AddTo = true);
SDValue CombineTo(SDNode *N, SDValue Res0, SDValue Res1, bool AddTo = true);
void CommitTargetLoweringOpt(const TargetLoweringOpt &TLO);
};
/// Return if the N is a constant or constant vector equal to the true value
/// from getBooleanContents().
bool isConstTrueVal(const SDNode *N) const;
/// Return if the N is a constant or constant vector equal to the false value
/// from getBooleanContents().
bool isConstFalseVal(const SDNode *N) const;
/// Return if \p N is a True value when extended to \p VT.
bool isExtendedTrueVal(const ConstantSDNode *N, EVT VT, bool SExt) const;
/// Try to simplify a setcc built with the specified operands and cc. If it is
/// unable to simplify it, return a null SDValue.
SDValue SimplifySetCC(EVT VT, SDValue N0, SDValue N1, ISD::CondCode Cond,
bool foldBooleans, DAGCombinerInfo &DCI,
const SDLoc &dl) const;
// For targets which wrap address, unwrap for analysis.
virtual SDValue unwrapAddress(SDValue N) const { return N; }
/// Returns true (and the GlobalValue and the offset) if the node is a
/// GlobalAddress + offset.
virtual bool
isGAPlusOffset(SDNode *N, const GlobalValue* &GA, int64_t &Offset) const;
/// This method will be invoked for all target nodes and for any
/// target-independent nodes that the target has registered with invoke it
/// for.
///
/// The semantics are as follows:
/// Return Value:
/// SDValue.Val == 0 - No change was made
/// SDValue.Val == N - N was replaced, is dead, and is already handled.
/// otherwise - N should be replaced by the returned Operand.
///
/// In addition, methods provided by DAGCombinerInfo may be used to perform
/// more complex transformations.
///
virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
/// Return true if it is profitable to move this shift by a constant amount
/// though its operand, adjusting any immediate operands as necessary to
/// preserve semantics. This transformation may not be desirable if it
/// disrupts a particularly auspicious target-specific tree (e.g. bitfield
/// extraction in AArch64). By default, it returns true.
///
/// @param N the shift node
/// @param Level the current DAGCombine legalization level.
virtual bool isDesirableToCommuteWithShift(const SDNode *N,
CombineLevel Level) const {
return true;
}
/// Return true if it is profitable to fold a pair of shifts into a mask.
/// This is usually true on most targets. But some targets, like Thumb1,
/// have immediate shift instructions, but no immediate "and" instruction;
/// this makes the fold unprofitable.
virtual bool shouldFoldShiftPairToMask(const SDNode *N,
CombineLevel Level) const {
return true;
}
// Return true if it is profitable to combine a BUILD_VECTOR with a stride-pattern
// to a shuffle and a truncate.
// Example of such a combine:
// v4i32 build_vector((extract_elt V, 1),
// (extract_elt V, 3),
// (extract_elt V, 5),
// (extract_elt V, 7))
// -->
// v4i32 truncate (bitcast (shuffle<1,u,3,u,5,u,7,u> V, u) to v4i64)
virtual bool isDesirableToCombineBuildVectorToShuffleTruncate(
ArrayRef<int> ShuffleMask, EVT SrcVT, EVT TruncVT) const {
return false;
}
/// Return true if the target has native support for the specified value type
/// and it is 'desirable' to use the type for the given node type. e.g. On x86
/// i16 is legal, but undesirable since i16 instruction encodings are longer
/// and some i16 instructions are slow.
virtual bool isTypeDesirableForOp(unsigned /*Opc*/, EVT VT) const {
// By default, assume all legal types are desirable.
return isTypeLegal(VT);
}
/// Return true if it is profitable for dag combiner to transform a floating
/// point op of specified opcode to a equivalent op of an integer
/// type. e.g. f32 load -> i32 load can be profitable on ARM.
virtual bool isDesirableToTransformToIntegerOp(unsigned /*Opc*/,
EVT /*VT*/) const {
return false;
}
/// This method query the target whether it is beneficial for dag combiner to
/// promote the specified node. If true, it should return the desired
/// promotion type by reference.
virtual bool IsDesirableToPromoteOp(SDValue /*Op*/, EVT &/*PVT*/) const {
return false;
}
/// Return true if the target supports swifterror attribute. It optimizes
/// loads and stores to reading and writing a specific register.
virtual bool supportSwiftError() const {
return false;
}
/// Return true if the target supports that a subset of CSRs for the given
/// machine function is handled explicitly via copies.
virtual bool supportSplitCSR(MachineFunction *MF) const {
return false;
}
/// Perform necessary initialization to handle a subset of CSRs explicitly
/// via copies. This function is called at the beginning of instruction
/// selection.
virtual void initializeSplitCSR(MachineBasicBlock *Entry) const {
llvm_unreachable("Not Implemented");
}
/// Insert explicit copies in entry and exit blocks. We copy a subset of
/// CSRs to virtual registers in the entry block, and copy them back to
/// physical registers in the exit blocks. This function is called at the end
/// of instruction selection.
virtual void insertCopiesSplitCSR(
MachineBasicBlock *Entry,
const SmallVectorImpl<MachineBasicBlock *> &Exits) const {
llvm_unreachable("Not Implemented");
}
//===--------------------------------------------------------------------===//
// Lowering methods - These methods must be implemented by targets so that
// the SelectionDAGBuilder code knows how to lower these.
//
/// This hook must be implemented to lower the incoming (formal) arguments,
/// described by the Ins array, into the specified DAG. The implementation
/// should fill in the InVals array with legal-type argument values, and
/// return the resulting token chain value.
virtual SDValue LowerFormalArguments(
SDValue /*Chain*/, CallingConv::ID /*CallConv*/, bool /*isVarArg*/,
const SmallVectorImpl<ISD::InputArg> & /*Ins*/, const SDLoc & /*dl*/,
SelectionDAG & /*DAG*/, SmallVectorImpl<SDValue> & /*InVals*/) const {
llvm_unreachable("Not Implemented");
}
/// This structure contains all information that is necessary for lowering
/// calls. It is passed to TLI::LowerCallTo when the SelectionDAG builder
/// needs to lower a call, and targets will see this struct in their LowerCall
/// implementation.
struct CallLoweringInfo {
SDValue Chain;
Type *RetTy = nullptr;
bool RetSExt : 1;
bool RetZExt : 1;
bool IsVarArg : 1;
bool IsInReg : 1;
bool DoesNotReturn : 1;
bool IsReturnValueUsed : 1;
bool IsConvergent : 1;
bool IsPatchPoint : 1;
// IsTailCall should be modified by implementations of
// TargetLowering::LowerCall that perform tail call conversions.
bool IsTailCall = false;
// Is Call lowering done post SelectionDAG type legalization.
bool IsPostTypeLegalization = false;
unsigned NumFixedArgs = -1;
CallingConv::ID CallConv = CallingConv::C;
SDValue Callee;
ArgListTy Args;
SelectionDAG &DAG;
SDLoc DL;
ImmutableCallSite CS;
SmallVector<ISD::OutputArg, 32> Outs;
SmallVector<SDValue, 32> OutVals;
SmallVector<ISD::InputArg, 32> Ins;
SmallVector<SDValue, 4> InVals;
CallLoweringInfo(SelectionDAG &DAG)
: RetSExt(false), RetZExt(false), IsVarArg(false), IsInReg(false),
DoesNotReturn(false), IsReturnValueUsed(true), IsConvergent(false),
IsPatchPoint(false), DAG(DAG) {}
CallLoweringInfo &setDebugLoc(const SDLoc &dl) {
DL = dl;
return *this;
}
CallLoweringInfo &setChain(SDValue InChain) {
Chain = InChain;
return *this;
}
// setCallee with target/module-specific attributes
CallLoweringInfo &setLibCallee(CallingConv::ID CC, Type *ResultType,
SDValue Target, ArgListTy &&ArgsList) {
RetTy = ResultType;
Callee = Target;
CallConv = CC;
NumFixedArgs = ArgsList.size();
Args = std::move(ArgsList);
DAG.getTargetLoweringInfo().markLibCallAttributes(
&(DAG.getMachineFunction()), CC, Args);
return *this;
}
CallLoweringInfo &setCallee(CallingConv::ID CC, Type *ResultType,
SDValue Target, ArgListTy &&ArgsList) {
RetTy = ResultType;
Callee = Target;
CallConv = CC;
NumFixedArgs = ArgsList.size();
Args = std::move(ArgsList);
return *this;
}
CallLoweringInfo &setCallee(Type *ResultType, FunctionType *FTy,
SDValue Target, ArgListTy &&ArgsList,
ImmutableCallSite Call) {
RetTy = ResultType;
IsInReg = Call.hasRetAttr(Attribute::InReg);
DoesNotReturn =
Call.doesNotReturn() ||
(!Call.isInvoke() &&
isa<UnreachableInst>(Call.getInstruction()->getNextNode()));
IsVarArg = FTy->isVarArg();
IsReturnValueUsed = !Call.getInstruction()->use_empty();
RetSExt = Call.hasRetAttr(Attribute::SExt);
RetZExt = Call.hasRetAttr(Attribute::ZExt);
Callee = Target;
CallConv = Call.getCallingConv();
NumFixedArgs = FTy->getNumParams();
Args = std::move(ArgsList);
CS = Call;
return *this;
}
CallLoweringInfo &setInRegister(bool Value = true) {
IsInReg = Value;
return *this;
}
CallLoweringInfo &setNoReturn(bool Value = true) {
DoesNotReturn = Value;
return *this;
}
CallLoweringInfo &setVarArg(bool Value = true) {
IsVarArg = Value;
return *this;
}
CallLoweringInfo &setTailCall(bool Value = true) {
IsTailCall = Value;
return *this;
}
CallLoweringInfo &setDiscardResult(bool Value = true) {
IsReturnValueUsed = !Value;
return *this;
}
CallLoweringInfo &setConvergent(bool Value = true) {
IsConvergent = Value;
return *this;
}
CallLoweringInfo &setSExtResult(bool Value = true) {
RetSExt = Value;
return *this;
}
CallLoweringInfo &setZExtResult(bool Value = true) {
RetZExt = Value;
return *this;
}
CallLoweringInfo &setIsPatchPoint(bool Value = true) {
IsPatchPoint = Value;
return *this;
}
CallLoweringInfo &setIsPostTypeLegalization(bool Value=true) {
IsPostTypeLegalization = Value;
return *this;
}
ArgListTy &getArgs() {
return Args;
}
};
/// This function lowers an abstract call to a function into an actual call.
/// This returns a pair of operands. The first element is the return value
/// for the function (if RetTy is not VoidTy). The second element is the
/// outgoing token chain. It calls LowerCall to do the actual lowering.
std::pair<SDValue, SDValue> LowerCallTo(CallLoweringInfo &CLI) const;
/// This hook must be implemented to lower calls into the specified
/// DAG. The outgoing arguments to the call are described by the Outs array,
/// and the values to be returned by the call are described by the Ins
/// array. The implementation should fill in the InVals array with legal-type
/// return values from the call, and return the resulting token chain value.
virtual SDValue
LowerCall(CallLoweringInfo &/*CLI*/,
SmallVectorImpl<SDValue> &/*InVals*/) const {
llvm_unreachable("Not Implemented");
}
/// Target-specific cleanup for formal ByVal parameters.
virtual void HandleByVal(CCState *, unsigned &, unsigned) const {}
/// This hook should be implemented to check whether the return values
/// described by the Outs array can fit into the return registers. If false
/// is returned, an sret-demotion is performed.
virtual bool CanLowerReturn(CallingConv::ID /*CallConv*/,
MachineFunction &/*MF*/, bool /*isVarArg*/,
const SmallVectorImpl<ISD::OutputArg> &/*Outs*/,
LLVMContext &/*Context*/) const
{
// Return true by default to get preexisting behavior.
return true;
}
/// This hook must be implemented to lower outgoing return values, described
/// by the Outs array, into the specified DAG. The implementation should
/// return the resulting token chain value.
virtual SDValue LowerReturn(SDValue /*Chain*/, CallingConv::ID /*CallConv*/,
bool /*isVarArg*/,
const SmallVectorImpl<ISD::OutputArg> & /*Outs*/,
const SmallVectorImpl<SDValue> & /*OutVals*/,
const SDLoc & /*dl*/,
SelectionDAG & /*DAG*/) const {
llvm_unreachable("Not Implemented");
}
/// Return true if result of the specified node is used by a return node
/// only. It also compute and return the input chain for the tail call.
///
/// This is used to determine whether it is possible to codegen a libcall as
/// tail call at legalization time.
virtual bool isUsedByReturnOnly(SDNode *, SDValue &/*Chain*/) const {
return false;
}
/// Return true if the target may be able emit the call instruction as a tail
/// call. This is used by optimization passes to determine if it's profitable
/// to duplicate return instructions to enable tailcall optimization.
virtual bool mayBeEmittedAsTailCall(const CallInst *) const {
return false;
}
/// Return the builtin name for the __builtin___clear_cache intrinsic
/// Default is to invoke the clear cache library call
virtual const char * getClearCacheBuiltinName() const {
return "__clear_cache";
}
/// Return the register ID of the name passed in. Used by named register
/// global variables extension. There is no target-independent behaviour
/// so the default action is to bail.
virtual unsigned getRegisterByName(const char* RegName, EVT VT,
SelectionDAG &DAG) const {
report_fatal_error("Named registers not implemented for this target");
}
/// Return the type that should be used to zero or sign extend a
/// zeroext/signext integer return value. FIXME: Some C calling conventions
/// require the return type to be promoted, but this is not true all the time,
/// e.g. i1/i8/i16 on x86/x86_64. It is also not necessary for non-C calling
/// conventions. The frontend should handle this and include all of the
/// necessary information.
virtual EVT getTypeForExtReturn(LLVMContext &Context, EVT VT,
ISD::NodeType /*ExtendKind*/) const {
EVT MinVT = getRegisterType(Context, MVT::i32);
return VT.bitsLT(MinVT) ? MinVT : VT;
}
/// For some targets, an LLVM struct type must be broken down into multiple
/// simple types, but the calling convention specifies that the entire struct
/// must be passed in a block of consecutive registers.
virtual bool
functionArgumentNeedsConsecutiveRegisters(Type *Ty, CallingConv::ID CallConv,
bool isVarArg) const {
return false;
}
/// Returns a 0 terminated array of registers that can be safely used as
/// scratch registers.
virtual const MCPhysReg *getScratchRegisters(CallingConv::ID CC) const {
return nullptr;
}
/// This callback is used to prepare for a volatile or atomic load.
/// It takes a chain node as input and returns the chain for the load itself.
///
/// Having a callback like this is necessary for targets like SystemZ,
/// which allows a CPU to reuse the result of a previous load indefinitely,
/// even if a cache-coherent store is performed by another CPU. The default
/// implementation does nothing.
virtual SDValue prepareVolatileOrAtomicLoad(SDValue Chain, const SDLoc &DL,
SelectionDAG &DAG) const {
return Chain;
}
/// This callback is used to inspect load/store instructions and add
/// target-specific MachineMemOperand flags to them. The default
/// implementation does nothing.
virtual MachineMemOperand::Flags getMMOFlags(const Instruction &I) const {
return MachineMemOperand::MONone;
}
/// This callback is invoked by the type legalizer to legalize nodes with an
/// illegal operand type but legal result types. It replaces the
/// LowerOperation callback in the type Legalizer. The reason we can not do
/// away with LowerOperation entirely is that LegalizeDAG isn't yet ready to
/// use this callback.
///
/// TODO: Consider merging with ReplaceNodeResults.
///
/// The target places new result values for the node in Results (their number
/// and types must exactly match those of the original return values of
/// the node), or leaves Results empty, which indicates that the node is not
/// to be custom lowered after all.
/// The default implementation calls LowerOperation.
virtual void LowerOperationWrapper(SDNode *N,
SmallVectorImpl<SDValue> &Results,
SelectionDAG &DAG) const;
/// This callback is invoked for operations that are unsupported by the
/// target, which are registered to use 'custom' lowering, and whose defined
/// values are all legal. If the target has no operations that require custom
/// lowering, it need not implement this. The default implementation of this
/// aborts.
virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const;
/// This callback is invoked when a node result type is illegal for the
/// target, and the operation was registered to use 'custom' lowering for that
/// result type. The target places new result values for the node in Results
/// (their number and types must exactly match those of the original return
/// values of the node), or leaves Results empty, which indicates that the
/// node is not to be custom lowered after all.
///
/// If the target has no operations that require custom lowering, it need not
/// implement this. The default implementation aborts.
virtual void ReplaceNodeResults(SDNode * /*N*/,
SmallVectorImpl<SDValue> &/*Results*/,
SelectionDAG &/*DAG*/) const {
llvm_unreachable("ReplaceNodeResults not implemented for this target!");
}
/// This method returns the name of a target specific DAG node.
virtual const char *getTargetNodeName(unsigned Opcode) const;
/// This method returns a target specific FastISel object, or null if the
/// target does not support "fast" ISel.
virtual FastISel *createFastISel(FunctionLoweringInfo &,
const TargetLibraryInfo *) const {
return nullptr;
}
bool verifyReturnAddressArgumentIsConstant(SDValue Op,
SelectionDAG &DAG) const;
//===--------------------------------------------------------------------===//
// Inline Asm Support hooks
//
/// This hook allows the target to expand an inline asm call to be explicit
/// llvm code if it wants to. This is useful for turning simple inline asms
/// into LLVM intrinsics, which gives the compiler more information about the
/// behavior of the code.
virtual bool ExpandInlineAsm(CallInst *) const {
return false;
}
enum ConstraintType {
C_Register, // Constraint represents specific register(s).
C_RegisterClass, // Constraint represents any of register(s) in class.
C_Memory, // Memory constraint.
C_Other, // Something else.
C_Unknown // Unsupported constraint.
};
enum ConstraintWeight {
// Generic weights.
CW_Invalid = -1, // No match.
CW_Okay = 0, // Acceptable.
CW_Good = 1, // Good weight.
CW_Better = 2, // Better weight.
CW_Best = 3, // Best weight.
// Well-known weights.
CW_SpecificReg = CW_Okay, // Specific register operands.
CW_Register = CW_Good, // Register operands.
CW_Memory = CW_Better, // Memory operands.
CW_Constant = CW_Best, // Constant operand.
CW_Default = CW_Okay // Default or don't know type.
};
/// This contains information for each constraint that we are lowering.
struct AsmOperandInfo : public InlineAsm::ConstraintInfo {
/// This contains the actual string for the code, like "m". TargetLowering
/// picks the 'best' code from ConstraintInfo::Codes that most closely
/// matches the operand.
std::string ConstraintCode;
/// Information about the constraint code, e.g. Register, RegisterClass,
/// Memory, Other, Unknown.
TargetLowering::ConstraintType ConstraintType = TargetLowering::C_Unknown;
/// If this is the result output operand or a clobber, this is null,
/// otherwise it is the incoming operand to the CallInst. This gets
/// modified as the asm is processed.
Value *CallOperandVal = nullptr;
/// The ValueType for the operand value.
MVT ConstraintVT = MVT::Other;
/// Copy constructor for copying from a ConstraintInfo.
AsmOperandInfo(InlineAsm::ConstraintInfo Info)
: InlineAsm::ConstraintInfo(std::move(Info)) {}
/// Return true of this is an input operand that is a matching constraint
/// like "4".
bool isMatchingInputConstraint() const;
/// If this is an input matching constraint, this method returns the output
/// operand it matches.
unsigned getMatchedOperand() const;
};
using AsmOperandInfoVector = std::vector<AsmOperandInfo>;
/// Split up the constraint string from the inline assembly value into the
/// specific constraints and their prefixes, and also tie in the associated
/// operand values. If this returns an empty vector, and if the constraint
/// string itself isn't empty, there was an error parsing.
virtual AsmOperandInfoVector ParseConstraints(const DataLayout &DL,
const TargetRegisterInfo *TRI,
ImmutableCallSite CS) const;
/// Examine constraint type and operand type and determine a weight value.
/// The operand object must already have been set up with the operand type.
virtual ConstraintWeight getMultipleConstraintMatchWeight(
AsmOperandInfo &info, int maIndex) const;
/// Examine constraint string and operand type and determine a weight value.
/// The operand object must already have been set up with the operand type.
virtual ConstraintWeight getSingleConstraintMatchWeight(
AsmOperandInfo &info, const char *constraint) const;
/// Determines the constraint code and constraint type to use for the specific
/// AsmOperandInfo, setting OpInfo.ConstraintCode and OpInfo.ConstraintType.
/// If the actual operand being passed in is available, it can be passed in as
/// Op, otherwise an empty SDValue can be passed.
virtual void ComputeConstraintToUse(AsmOperandInfo &OpInfo,
SDValue Op,
SelectionDAG *DAG = nullptr) const;
/// Given a constraint, return the type of constraint it is for this target.
virtual ConstraintType getConstraintType(StringRef Constraint) const;
/// Given a physical register constraint (e.g. {edx}), return the register
/// number and the register class for the register.
///
/// Given a register class constraint, like 'r', if this corresponds directly
/// to an LLVM register class, return a register of 0 and the register class
/// pointer.
///
/// This should only be used for C_Register constraints. On error, this
/// returns a register number of 0 and a null register class pointer.
virtual std::pair<unsigned, const TargetRegisterClass *>
getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
StringRef Constraint, MVT VT) const;
virtual unsigned getInlineAsmMemConstraint(StringRef ConstraintCode) const {
if (ConstraintCode == "i")
return InlineAsm::Constraint_i;
else if (ConstraintCode == "m")
return InlineAsm::Constraint_m;
return InlineAsm::Constraint_Unknown;
}
/// Try to replace an X constraint, which matches anything, with another that
/// has more specific requirements based on the type of the corresponding
/// operand. This returns null if there is no replacement to make.
virtual const char *LowerXConstraint(EVT ConstraintVT) const;
/// Lower the specified operand into the Ops vector. If it is invalid, don't
/// add anything to Ops.
virtual void LowerAsmOperandForConstraint(SDValue Op, std::string &Constraint,
std::vector<SDValue> &Ops,
SelectionDAG &DAG) const;
//===--------------------------------------------------------------------===//
// Div utility functions
//
SDValue BuildSDIV(SDNode *N, SelectionDAG &DAG, bool IsAfterLegalization,
SmallVectorImpl<SDNode *> &Created) const;
SDValue BuildUDIV(SDNode *N, SelectionDAG &DAG, bool IsAfterLegalization,
SmallVectorImpl<SDNode *> &Created) const;
/// Targets may override this function to provide custom SDIV lowering for
/// power-of-2 denominators. If the target returns an empty SDValue, LLVM
/// assumes SDIV is expensive and replaces it with a series of other integer
/// operations.
virtual SDValue BuildSDIVPow2(SDNode *N, const APInt &Divisor,
SelectionDAG &DAG,
SmallVectorImpl<SDNode *> &Created) const;
/// Indicate whether this target prefers to combine FDIVs with the same
/// divisor. If the transform should never be done, return zero. If the
/// transform should be done, return the minimum number of divisor uses
/// that must exist.
virtual unsigned combineRepeatedFPDivisors() const {
return 0;
}
/// Hooks for building estimates in place of slower divisions and square
/// roots.
/// Return either a square root or its reciprocal estimate value for the input
/// operand.
/// \p Enabled is a ReciprocalEstimate enum with value either 'Unspecified' or
/// 'Enabled' as set by a potential default override attribute.
/// If \p RefinementSteps is 'Unspecified', the number of Newton-Raphson
/// refinement iterations required to generate a sufficient (though not
/// necessarily IEEE-754 compliant) estimate is returned in that parameter.
/// The boolean UseOneConstNR output is used to select a Newton-Raphson
/// algorithm implementation that uses either one or two constants.
/// The boolean Reciprocal is used to select whether the estimate is for the
/// square root of the input operand or the reciprocal of its square root.
/// A target may choose to implement its own refinement within this function.
/// If that's true, then return '0' as the number of RefinementSteps to avoid
/// any further refinement of the estimate.
/// An empty SDValue return means no estimate sequence can be created.
virtual SDValue getSqrtEstimate(SDValue Operand, SelectionDAG &DAG,
int Enabled, int &RefinementSteps,
bool &UseOneConstNR, bool Reciprocal) const {
return SDValue();
}
/// Return a reciprocal estimate value for the input operand.
/// \p Enabled is a ReciprocalEstimate enum with value either 'Unspecified' or
/// 'Enabled' as set by a potential default override attribute.
/// If \p RefinementSteps is 'Unspecified', the number of Newton-Raphson
/// refinement iterations required to generate a sufficient (though not
/// necessarily IEEE-754 compliant) estimate is returned in that parameter.
/// A target may choose to implement its own refinement within this function.
/// If that's true, then return '0' as the number of RefinementSteps to avoid
/// any further refinement of the estimate.
/// An empty SDValue return means no estimate sequence can be created.
virtual SDValue getRecipEstimate(SDValue Operand, SelectionDAG &DAG,
int Enabled, int &RefinementSteps) const {
return SDValue();
}
//===--------------------------------------------------------------------===//
// Legalization utility functions
//
/// Expand a MUL or [US]MUL_LOHI of n-bit values into two or four nodes,
/// respectively, each computing an n/2-bit part of the result.
/// \param Result A vector that will be filled with the parts of the result
/// in little-endian order.
/// \param LL Low bits of the LHS of the MUL. You can use this parameter
/// if you want to control how low bits are extracted from the LHS.
/// \param LH High bits of the LHS of the MUL. See LL for meaning.
/// \param RL Low bits of the RHS of the MUL. See LL for meaning
/// \param RH High bits of the RHS of the MUL. See LL for meaning.
/// \returns true if the node has been expanded, false if it has not
bool expandMUL_LOHI(unsigned Opcode, EVT VT, SDLoc dl, SDValue LHS,
SDValue RHS, SmallVectorImpl<SDValue> &Result, EVT HiLoVT,
SelectionDAG &DAG, MulExpansionKind Kind,
SDValue LL = SDValue(), SDValue LH = SDValue(),
SDValue RL = SDValue(), SDValue RH = SDValue()) const;
/// Expand a MUL into two nodes. One that computes the high bits of
/// the result and one that computes the low bits.
/// \param HiLoVT The value type to use for the Lo and Hi nodes.
/// \param LL Low bits of the LHS of the MUL. You can use this parameter
/// if you want to control how low bits are extracted from the LHS.
/// \param LH High bits of the LHS of the MUL. See LL for meaning.
/// \param RL Low bits of the RHS of the MUL. See LL for meaning
/// \param RH High bits of the RHS of the MUL. See LL for meaning.
/// \returns true if the node has been expanded. false if it has not
bool expandMUL(SDNode *N, SDValue &Lo, SDValue &Hi, EVT HiLoVT,
SelectionDAG &DAG, MulExpansionKind Kind,
SDValue LL = SDValue(), SDValue LH = SDValue(),
SDValue RL = SDValue(), SDValue RH = SDValue()) const;
/// Expand funnel shift.
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandFunnelShift(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand rotations.
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandROT(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand float(f32) to SINT(i64) conversion
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandFP_TO_SINT(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand float to UINT conversion
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandFP_TO_UINT(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand UINT(i64) to double(f64) conversion
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandUINT_TO_FP(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand fminnum/fmaxnum into fminnum_ieee/fmaxnum_ieee with quieted inputs.
SDValue expandFMINNUM_FMAXNUM(SDNode *N, SelectionDAG &DAG) const;
/// Expand CTPOP nodes. Expands vector/scalar CTPOP nodes,
/// vector nodes can only succeed if all operations are legal/custom.
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandCTPOP(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand CTLZ/CTLZ_ZERO_UNDEF nodes. Expands vector/scalar CTLZ nodes,
/// vector nodes can only succeed if all operations are legal/custom.
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandCTLZ(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Expand CTTZ/CTTZ_ZERO_UNDEF nodes. Expands vector/scalar CTTZ nodes,
/// vector nodes can only succeed if all operations are legal/custom.
/// \param N Node to expand
/// \param Result output after conversion
/// \returns True, if the expansion was successful, false otherwise
bool expandCTTZ(SDNode *N, SDValue &Result, SelectionDAG &DAG) const;
/// Turn load of vector type into a load of the individual elements.
/// \param LD load to expand
/// \returns MERGE_VALUEs of the scalar loads with their chains.
SDValue scalarizeVectorLoad(LoadSDNode *LD, SelectionDAG &DAG) const;
// Turn a store of a vector type into stores of the individual elements.
/// \param ST Store with a vector value type
/// \returns MERGE_VALUs of the individual store chains.
SDValue scalarizeVectorStore(StoreSDNode *ST, SelectionDAG &DAG) const;
/// Expands an unaligned load to 2 half-size loads for an integer, and
/// possibly more for vectors.
std::pair<SDValue, SDValue> expandUnalignedLoad(LoadSDNode *LD,
SelectionDAG &DAG) const;
/// Expands an unaligned store to 2 half-size stores for integer values, and
/// possibly more for vectors.
SDValue expandUnalignedStore(StoreSDNode *ST, SelectionDAG &DAG) const;
/// Increments memory address \p Addr according to the type of the value
/// \p DataVT that should be stored. If the data is stored in compressed
/// form, the memory address should be incremented according to the number of
/// the stored elements. This number is equal to the number of '1's bits
/// in the \p Mask.
/// \p DataVT is a vector type. \p Mask is a vector value.
/// \p DataVT and \p Mask have the same number of vector elements.
SDValue IncrementMemoryAddress(SDValue Addr, SDValue Mask, const SDLoc &DL,
EVT DataVT, SelectionDAG &DAG,
bool IsCompressedMemory) const;
/// Get a pointer to vector element \p Idx located in memory for a vector of
/// type \p VecVT starting at a base address of \p VecPtr. If \p Idx is out of
/// bounds the returned pointer is unspecified, but will be within the vector
/// bounds.
SDValue getVectorElementPointer(SelectionDAG &DAG, SDValue VecPtr, EVT VecVT,
SDValue Index) const;
/// Method for building the DAG expansion of ISD::[US][ADD|SUB]SAT. This
/// method accepts integers as its arguments.
SDValue getExpandedSaturationAdditionSubtraction(SDNode *Node,
SelectionDAG &DAG) const;
/// Method for building the DAG expansion of ISD::SMULFIX. This method accepts
/// integers as its arguments.
SDValue getExpandedFixedPointMultiplication(SDNode *Node,
SelectionDAG &DAG) const;
//===--------------------------------------------------------------------===//
// Instruction Emitting Hooks
//
/// This method should be implemented by targets that mark instructions with
/// the 'usesCustomInserter' flag. These instructions are special in various
/// ways, which require special support to insert. The specified MachineInstr
/// is created but not inserted into any basic blocks, and this method is
/// called to expand it into a sequence of instructions, potentially also
/// creating new basic blocks and control flow.
/// As long as the returned basic block is different (i.e., we created a new
/// one), the custom inserter is free to modify the rest of \p MBB.
virtual MachineBasicBlock *
EmitInstrWithCustomInserter(MachineInstr &MI, MachineBasicBlock *MBB) const;
/// This method should be implemented by targets that mark instructions with
/// the 'hasPostISelHook' flag. These instructions must be adjusted after
/// instruction selection by target hooks. e.g. To fill in optional defs for
/// ARM 's' setting instructions.
virtual void AdjustInstrPostInstrSelection(MachineInstr &MI,
SDNode *Node) const;
/// If this function returns true, SelectionDAGBuilder emits a
/// LOAD_STACK_GUARD node when it is lowering Intrinsic::stackprotector.
virtual bool useLoadStackGuardNode() const {
return false;
}
virtual SDValue emitStackGuardXorFP(SelectionDAG &DAG, SDValue Val,
const SDLoc &DL) const {
llvm_unreachable("not implemented for this target");
}
/// Lower TLS global address SDNode for target independent emulated TLS model.
virtual SDValue LowerToTLSEmulatedModel(const GlobalAddressSDNode *GA,
SelectionDAG &DAG) const;
/// Expands target specific indirect branch for the case of JumpTable
/// expanasion.
virtual SDValue expandIndirectJTBranch(const SDLoc& dl, SDValue Value, SDValue Addr,
SelectionDAG &DAG) const {
return DAG.getNode(ISD::BRIND, dl, MVT::Other, Value, Addr);
}
// seteq(x, 0) -> truncate(srl(ctlz(zext(x)), log2(#bits)))
// If we're comparing for equality to zero and isCtlzFast is true, expose the
// fact that this can be implemented as a ctlz/srl pair, so that the dag
// combiner can fold the new nodes.
SDValue lowerCmpEqZeroToCtlzSrl(SDValue Op, SelectionDAG &DAG) const;
private:
SDValue simplifySetCCWithAnd(EVT VT, SDValue N0, SDValue N1,
ISD::CondCode Cond, DAGCombinerInfo &DCI,
const SDLoc &DL) const;
SDValue optimizeSetCCOfSignedTruncationCheck(EVT SCCVT, SDValue N0,
SDValue N1, ISD::CondCode Cond,
DAGCombinerInfo &DCI,
const SDLoc &DL) const;
};
/// Given an LLVM IR type and return type attributes, compute the return value
/// EVTs and flags, and optionally also the offsets, if the return value is
/// being lowered to memory.
void GetReturnInfo(CallingConv::ID CC, Type *ReturnType, AttributeList attr,
SmallVectorImpl<ISD::OutputArg> &Outs,
const TargetLowering &TLI, const DataLayout &DL);
} // end namespace llvm
#endif // LLVM_CODEGEN_TARGETLOWERING_H
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