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llvm-6502/include/llvm/Target/TargetLowering.h
Ahmed Bougacha ec35069525 [CodeGen] Add hook/combine to form vector extloads, enabled on X86. 
The combine that forms extloads used to be disabled on vector types,
because "None of the supported targets knows how to perform load and
sign extend on vectors in one instruction."

That's not entirely true, since at least SSE4.1 X86 knows how to do
those sextloads/zextloads (with PMOVS/ZX).
But there are several aspects to getting this right.
First, vector extloads are controlled by a profitability callback.
For instance, on ARM, several instructions have folded extload forms,
so it's not always beneficial to create an extload node (and trying to
match extloads is a whole 'nother can of worms).

The interesting optimization enables folding of s/zextloads to illegal
(splittable) vector types, expanding them into smaller legal extloads.

It's not ideal (it introduces some legalization-like behavior in the
combine) but it's better than the obvious alternative: form illegal
extloads, and later try to split them up.  If you do that, you might
generate extloads that can't be split up, but have a valid ext+load
expansion.  At vector-op legalization time, it's too late to generate
this kind of code, so you end up forced to scalarize. It's better to
just avoid creating egregiously illegal nodes.

This optimization is enabled unconditionally on X86.

Note that the splitting combine is happy with "custom" extloads. As
is, this bypasses the actual custom lowering, and just unrolls the
extload. But from what I've seen, this is still much better than the
current custom lowering, which does some kind of unrolling at the end
anyway (see for instance load_sext_4i8_to_4i64 on SSE2, and the added
FIXME).

Also note that the existing combine that forms extloads is now also
enabled on legal vectors.  This doesn't have a big effect on X86
(because sext+load is usually combined to sext_inreg+aextload).
On ARM it fires on some rare occasions; that's for a separate commit.

Differential Revision: http://reviews.llvm.org/D6904


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228325 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 18:31:02 +00:00

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//===-- llvm/Target/TargetLowering.h - Target Lowering Info -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file describes how to lower LLVM code to machine code. This has two
/// main components:
///
/// 1. Which ValueTypes are natively supported by the target.
/// 2. Which operations are supported for supported ValueTypes.
/// 3. Cost thresholds for alternative implementations of certain operations.
///
/// In addition it has a few other components, like information about FP
/// immediates.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_TARGETLOWERING_H
#define LLVM_TARGET_TARGETLOWERING_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/CodeGen/DAGCombine.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Instructions.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Target/TargetCallingConv.h"
#include "llvm/Target/TargetMachine.h"
#include <climits>
#include <map>
#include <vector>
namespace llvm {
class CallInst;
class CCState;
class FastISel;
class FunctionLoweringInfo;
class ImmutableCallSite;
class IntrinsicInst;
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MachineJumpTableInfo;
class MachineLoop;
class Mangler;
class MCContext;
class MCExpr;
class MCSymbol;
template<typename T> class SmallVectorImpl;
class DataLayout;
class TargetRegisterClass;
class TargetLibraryInfo;
class TargetLoweringObjectFile;
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.
};
}
/// This base class for TargetLowering contains the SelectionDAG-independent
/// parts that can be used from the rest of CodeGen.
class TargetLoweringBase {
TargetLoweringBase(const TargetLoweringBase&) LLVM_DELETED_FUNCTION;
void operator=(const TargetLoweringBase&) LLVM_DELETED_FUNCTION;
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 {
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.
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 {
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.
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.
};
/// LegalizeKind holds the legalization kind that needs to happen to EVT
/// in order to type-legalize it.
typedef std::pair<LegalizeTypeAction, EVT> LegalizeKind;
/// 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).
};
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);
virtual ~TargetLoweringBase() {}
protected:
/// \brief Initialize all of the actions to default values.
void initActions();
public:
const TargetMachine &getTargetMachine() const { return TM; }
const DataLayout *getDataLayout() const { return DL; }
bool isBigEndian() const { return !IsLittleEndian; }
bool isLittleEndian() const { return IsLittleEndian; }
/// 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.
virtual MVT getPointerTy(uint32_t /*AS*/ = 0) const;
unsigned getPointerSizeInBits(uint32_t AS = 0) const;
unsigned getPointerTypeSizeInBits(Type *Ty) const;
virtual MVT getScalarShiftAmountTy(EVT LHSTy) const;
EVT getShiftAmountTy(EVT LHSTy) 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 {
return getPointerTy();
}
/// Return true if the select operation is expensive for this target.
bool isSelectExpensive() const { return SelectIsExpensive; }
virtual bool isSelectSupported(SelectSupportKind /*kind*/) const {
return true;
}
/// Return true if multiple condition registers are available.
bool hasMultipleConditionRegisters() const {
return HasMultipleConditionRegisters;
}
/// Return true if the target has BitExtract instructions.
bool hasExtractBitsInsn() const { return HasExtractBitsInsn; }
/// Return the preferred vector type legalization action.
virtual TargetLoweringBase::LegalizeTypeAction
getPreferredVectorAction(EVT VT) const {
// The default action for one element vectors is to scalarize
if (VT.getVectorNumElements() == 1)
return TypeScalarizeVector;
// The default action for other vectors is to promote
return TypePromoteInteger;
}
// There are two general methods for expanding a BUILD_VECTOR node:
// 1. Use SCALAR_TO_VECTOR on the defined scalar values and then shuffle
// them together.
// 2. Build the vector on the stack and then load it.
// If this function returns true, then method (1) will be used, subject to
// the constraint that all of the necessary shuffles are legal (as determined
// by isShuffleMaskLegal). If this function returns false, then method (2) is
// always used. The vector type, and the number of defined values, are
// provided.
virtual bool
shouldExpandBuildVectorWithShuffles(EVT /* VT */,
unsigned DefinedValues) const {
return DefinedValues < 3;
}
/// Return true if integer divide is usually cheaper than a sequence of
/// several shifts, adds, and multiplies for this target.
bool isIntDivCheap() const { return IntDivIsCheap; }
/// Return true if sqrt(x) is as cheap or cheaper than 1 / rsqrt(x)
bool isFsqrtCheap() const {
return FsqrtIsCheap;
}
/// 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 pow2 sdiv is cheaper than a chain of sra/srl/add/sra.
bool isPow2SDivCheap() const { return Pow2SDivIsCheap; }
/// 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;
}
/// isLoadBitCastBeneficial() - 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 /* Load */, EVT /* Bitcast */) const {
return true;
}
/// \brief Return true if it is cheap to speculate a call to intrinsic cttz.
virtual bool isCheapToSpeculateCttz() const {
return false;
}
/// \brief Return true if it is cheap to speculate a call to intrinsic ctlz.
virtual bool isCheapToSpeculateCtlz() const {
return false;
}
/// \brief Return if the target supports combining a
/// chain like:
/// \code
/// %andResult = and %val1, #imm-with-one-bit-set;
/// %icmpResult = icmp %andResult, 0
/// br i1 %icmpResult, label %dest1, label %dest2
/// \endcode
/// into a single machine instruction of a form like:
/// \code
/// brOnBitSet %register, #bitNumber, dest
/// \endcode
bool isMaskAndBranchFoldingLegal() const {
return MaskAndBranchFoldingIsLegal;
}
/// \brief Return true if the target wants to use the optimization that
/// turns ext(promotableInst1(...(promotableInstN(load)))) into
/// promotedInst1(...(promotedInstN(ext(load)))).
bool enableExtLdPromotion() const { return EnableExtLdPromotion; }
/// Return true if the target can combine store(extractelement VectorTy,
/// Idx).
/// \p Cost[out] gives the cost of that transformation when this is true.
virtual bool canCombineStoreAndExtract(Type *VectorTy, Value *Idx,
unsigned &Cost) const {
return false;
}
/// Return true if target supports floating point exceptions.
bool hasFloatingPointExceptions() const {
return HasFloatingPointExceptions;
}
/// Return true if target always beneficiates from combining into FMA for a
/// given value type. This must typically return false on targets where FMA
/// takes more cycles to execute than FADD.
virtual bool enableAggressiveFMAFusion(EVT VT) const {
return false;
}
/// Return the ValueType of the result of SETCC operations.
virtual EVT getSetCCResultType(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.
uint8_t ValueTypeActions[MVT::LAST_VALUETYPE];
public:
ValueTypeActionImpl() {
std::fill(std::begin(ValueTypeActions), std::end(ValueTypeActions), 0);
}
LegalizeTypeAction getTypeAction(MVT VT) const {
return (LegalizeTypeAction)ValueTypeActions[VT.SimpleTy];
}
void setTypeAction(MVT VT, LegalizeTypeAction Action) {
unsigned I = VT.SimpleTy;
ValueTypeActions[I] = 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;
struct IntrinsicInfo {
unsigned opc; // target opcode
EVT memVT; // memory VT
const Value* ptrVal; // value representing memory location
int offset; // offset off of ptrVal
unsigned size; // the size of the memory location
// (taken from memVT if zero)
unsigned align; // alignment
bool vol; // is volatile?
bool readMem; // reads memory?
bool writeMem; // writes memory?
IntrinsicInfo() : opc(0), ptrVal(nullptr), offset(0), size(0), align(1),
vol(false), readMem(false), writeMem(false) {}
};
/// Given an intrinsic, checks if on the target the intrinsic will need to map
/// to a MemIntrinsicNode (touches memory). If this is the case, it returns
/// true and store the intrinsic information into the IntrinsicInfo that was
/// passed to the function.
virtual bool getTgtMemIntrinsic(IntrinsicInfo &, const CallInst &,
unsigned /*Intrinsic*/) const {
return false;
}
/// Returns true if the target can instruction select the specified FP
/// immediate natively. If false, the legalizer will materialize the FP
/// immediate as a load from a constant pool.
virtual bool isFPImmLegal(const APFloat &/*Imm*/, EVT /*VT*/) const {
return false;
}
/// Targets can use this to indicate that they only support *some*
/// VECTOR_SHUFFLE operations, those with specific masks. By default, if a
/// target supports the VECTOR_SHUFFLE node, all mask values are assumed to be
/// legal.
virtual bool isShuffleMaskLegal(const SmallVectorImpl<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 divide and remainder.
virtual bool canOpTrap(unsigned Op, EVT VT) const;
/// Similar to isShuffleMaskLegal. This is used by Targets can use this to
/// indicate if there is a suitable VECTOR_SHUFFLE that can be used to replace
/// a VAND with a constant pool entry.
virtual bool isVectorClearMaskLegal(const SmallVectorImpl<int> &/*Mask*/,
EVT /*VT*/) const {
return false;
}
/// Return how this operation should be treated: either it is legal, needs to
/// be promoted to a larger size, needs to be expanded to some other code
/// sequence, or the target has a custom expander for it.
LegalizeAction getOperationAction(unsigned Op, EVT VT) const {
if (VT.isExtended()) return Expand;
// If a target-specific SDNode requires legalization, require the target
// to provide custom legalization for it.
if (Op > array_lengthof(OpActions[0])) return Custom;
unsigned I = (unsigned) VT.getSimpleVT().SimpleTy;
return (LegalizeAction)OpActions[I][Op];
}
/// Return true if the specified operation is legal on this target or can be
/// made legal with custom lowering. This is used to help guide high-level
/// lowering decisions.
bool isOperationLegalOrCustom(unsigned Op, EVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
(getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Custom);
}
/// Return true if the specified operation is legal on this target or can be
/// made legal using promotion. This is used to help guide high-level lowering
/// decisions.
bool isOperationLegalOrPromote(unsigned Op, EVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
(getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Promote);
}
/// Return true if the specified operation is 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!");
return (LegalizeAction)LoadExtActions[ValI][MemI][ExtType];
}
/// Return true if the specified load with extension is legal on this target.
bool isLoadExtLegal(unsigned ExtType, EVT ValVT, EVT MemVT) const {
return ValVT.isSimple() && MemVT.isSimple() &&
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 ValVT.isSimple() && MemVT.isSimple() &&
(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 (LegalizeAction)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) && MemVT.isSimple() &&
getTruncStoreAction(ValVT.getSimpleVT(), MemVT.getSimpleVT()) == Legal;
}
/// 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 >> 4) < array_lengthof(CondCodeActions[0]) &&
"Table isn't big enough!");
// See setCondCodeAction for how this is encoded.
uint32_t Shift = 2 * (VT.SimpleTy & 0xF);
uint32_t Value = CondCodeActions[CC][VT.SimpleTy >> 4];
LegalizeAction Action = (LegalizeAction) ((Value >> Shift) & 0x3);
assert(Action != Promote && "Can't promote condition code!");
return Action;
}
/// Return true if the specified condition code is legal on this target.
bool isCondCodeLegal(ISD::CondCode CC, MVT VT) const {
return
getCondCodeAction(CC, VT) == Legal ||
getCondCodeAction(CC, VT) == Custom;
}
/// If the action for this operation is to promote, this method returns the
/// ValueType to promote to.
MVT getTypeToPromoteTo(unsigned Op, MVT VT) const {
assert(getOperationAction(Op, VT) == Promote &&
"This operation isn't promoted!");
// See if this has an explicit type specified.
std::map<std::pair<unsigned, MVT::SimpleValueType>,
MVT::SimpleValueType>::const_iterator PTTI =
PromoteToType.find(std::make_pair(Op, VT.SimpleTy));
if (PTTI != PromoteToType.end()) return PTTI->second;
assert((VT.isInteger() || VT.isFloatingPoint()) &&
"Cannot autopromote this type, add it with AddPromotedToType.");
MVT NVT = VT;
do {
NVT = (MVT::SimpleValueType)(NVT.SimpleTy+1);
assert(NVT.isInteger() == VT.isInteger() && NVT != MVT::isVoid &&
"Didn't find type to promote to!");
} while (!isTypeLegal(NVT) ||
getOperationAction(Op, NVT) == Promote);
return NVT;
}
/// Return the EVT corresponding to this LLVM type. This is fixed by the LLVM
/// operations except for the pointer size. If AllowUnknown is true, this
/// will return MVT::Other for types with no EVT counterpart (e.g. structs),
/// otherwise it will assert.
EVT getValueType(Type *Ty, bool AllowUnknown = false) const {
// Lower scalar pointers to native pointer types.
if (PointerType *PTy = dyn_cast<PointerType>(Ty))
return getPointerTy(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(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(Type *Ty, bool AllowUnknown = false) const {
return getValueType(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;
/// 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!");
}
/// If true, then instruction selection should seek to shrink the FP constant
/// of the specified type to a smaller type in order to save space and / or
/// reduce runtime.
virtual bool ShouldShrinkFPConstant(EVT) const { return true; }
// Return true if it is profitable to reduce the given load node to a smaller
// type.
//
// e.g. (i16 (trunc (i32 (load x))) -> i16 load x should be performed
virtual bool shouldReduceLoadWidth(SDNode *Load,
ISD::LoadExtType ExtTy,
EVT NewVT) const {
return true;
}
/// When splitting a value of the specified type into parts, does the Lo
/// or Hi part come first? This usually follows the endianness, except
/// for ppcf128, where the Hi part always comes first.
bool hasBigEndianPartOrdering(EVT VT) const {
return 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));
}
/// \brief Get maximum # of store operations permitted for llvm.memset
///
/// This function returns the maximum number of store operations permitted
/// to replace a call to llvm.memset. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxStoresPerMemset(bool OptSize) const {
return OptSize ? MaxStoresPerMemsetOptSize : MaxStoresPerMemset;
}
/// \brief Get maximum # of store operations permitted for llvm.memcpy
///
/// This function returns the maximum number of store operations permitted
/// to replace a call to llvm.memcpy. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxStoresPerMemcpy(bool OptSize) const {
return OptSize ? MaxStoresPerMemcpyOptSize : MaxStoresPerMemcpy;
}
/// \brief Get maximum # of store operations permitted for llvm.memmove
///
/// This function returns the maximum number of store operations permitted
/// to replace a call to llvm.memmove. The value is set by the target at the
/// performance threshold for such a replacement. If OptSize is true,
/// return the limit for functions that have OptSize attribute.
unsigned getMaxStoresPerMemmove(bool OptSize) const {
return OptSize ? MaxStoresPerMemmoveOptSize : MaxStoresPerMemmove;
}
/// \brief Determine if the target supports unaligned memory accesses.
///
/// This function returns true if the target allows unaligned memory accesses
/// of the specified type in the given address space. If true, it also returns
/// whether the unaligned memory access is "fast" in the last argument by
/// reference. This is used, for example, in situations where an array
/// copy/move/set is converted to a sequence of store operations. Its use
/// helps to ensure that such replacements don't generate code that causes an
/// alignment error (trap) on the target machine.
virtual bool allowsMisalignedMemoryAccesses(EVT,
unsigned AddrSpace = 0,
unsigned Align = 1,
bool * /*Fast*/ = nullptr) const {
return false;
}
/// 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 integer threshold on number of blocks to use jump tables rather
/// than if sequence.
int getMinimumJumpTableEntries() const {
return MinimumJumpTableEntries;
}
/// 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 a landing pad.
unsigned getExceptionPointerRegister() const {
return ExceptionPointerRegister;
}
/// If a physical register, this returns the register that receives the
/// exception typeid on entry to a landing pad.
unsigned getExceptionSelectorRegister() const {
return ExceptionSelectorRegister;
}
/// 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;
}
/// Return whether the DAG builder should automatically insert fences and
/// reduce ordering for atomics.
bool getInsertFencesForAtomic() const {
return InsertFencesForAtomic;
}
/// Return true if the target stores stack protector cookies at a fixed offset
/// in some non-standard address space, and populates the address space and
/// offset as appropriate.
virtual bool getStackCookieLocation(unsigned &/*AddressSpace*/,
unsigned &/*Offset*/) const {
return false;
}
/// Returns the maximal possible offset which can be used for loads / stores
/// from the global.
virtual unsigned getMaximalGlobalOffset() const {
return 0;
}
/// Returns true if a cast between SrcAS and DestAS is a noop.
virtual bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) 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<unsigned, MVT> getTypeLegalizationCost(Type *Ty) const;
/// @}
//===--------------------------------------------------------------------===//
/// \name Helpers for atomic expansion.
/// @{
/// True if AtomicExpandPass should use emitLoadLinked/emitStoreConditional
/// and expand AtomicCmpXchgInst.
virtual bool hasLoadLinkedStoreConditional() const { return false; }
/// Perform a load-linked operation on Addr, returning a "Value *" with the
/// corresponding pointee type. This may entail some non-trivial operations to
/// truncate or reconstruct types that will be illegal in the backend. See
/// ARMISelLowering for an example implementation.
virtual Value *emitLoadLinked(IRBuilder<> &Builder, Value *Addr,
AtomicOrdering Ord) const {
llvm_unreachable("Load linked unimplemented on this target");
}
/// Perform a store-conditional operation to Addr. Return the status of the
/// store. This should be 0 if the store succeeded, non-zero otherwise.
virtual Value *emitStoreConditional(IRBuilder<> &Builder, Value *Val,
Value *Addr, AtomicOrdering Ord) const {
llvm_unreachable("Store conditional unimplemented on this target");
}
/// Inserts in the IR a target-specific intrinsic specifying a fence.
/// It is called by AtomicExpandPass before expanding an
/// AtomicRMW/AtomicCmpXchg/AtomicStore/AtomicLoad.
/// RMW and CmpXchg set both IsStore and IsLoad to true.
/// 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 with !getInsertFencesForAtomic() should keep a no-op here.
/// 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, AtomicOrdering Ord,
bool IsStore, bool IsLoad) const {
if (!getInsertFencesForAtomic())
return nullptr;
if (isAtLeastRelease(Ord) && IsStore)
return Builder.CreateFence(Ord);
else
return nullptr;
}
virtual Instruction* emitTrailingFence(IRBuilder<> &Builder, AtomicOrdering Ord,
bool IsStore, bool IsLoad) const {
if (!getInsertFencesForAtomic())
return nullptr;
if (isAtLeastAcquire(Ord))
return Builder.CreateFence(Ord);
else
return nullptr;
}
/// @}
/// 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 the given (atomic) load should be expanded by the
/// IR-level AtomicExpand pass into a load-linked instruction
/// (through emitLoadLinked()).
virtual bool shouldExpandAtomicLoadInIR(LoadInst *LI) const { return false; }
/// Returns true if the given AtomicRMW should be expanded by the
/// IR-level AtomicExpand pass into a loop using LoadLinked/StoreConditional.
virtual bool shouldExpandAtomicRMWInIR(AtomicRMWInst *RMWI) const {
return false;
}
/// 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;
}
//===--------------------------------------------------------------------===//
// 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 number of blocks to generate jump tables rather than if
/// sequence.
void setMinimumJumpTableEntries(int Val) {
MinimumJumpTableEntries = Val;
}
/// 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;
}
/// If set to a physical register, this sets the register that receives the
/// exception address on entry to a landing pad.
void setExceptionPointerRegister(unsigned R) {
ExceptionPointerRegister = R;
}
/// If set to a physical register, this sets the register that receives the
/// exception typeid on entry to a landing pad.
void setExceptionSelectorRegister(unsigned R) {
ExceptionSelectorRegister = R;
}
/// Tells the code generator not to expand operations into sequences that use
/// the select operations if possible.
void setSelectIsExpensive(bool isExpensive = true) {
SelectIsExpensive = isExpensive;
}
/// 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 sequence of operations into a
/// separate sequences that increases the amount of flow control.
void setJumpIsExpensive(bool isExpensive = true) {
JumpIsExpensive = isExpensive;
}
/// Tells the code generator that integer divide is expensive, and if
/// possible, should be replaced by an alternate sequence of instructions not
/// containing an integer divide.
void setIntDivIsCheap(bool isCheap = true) { IntDivIsCheap = isCheap; }
/// Tells the code generator that fsqrt is cheap, and should not be replaced
/// with an alternative sequence of instructions.
void setFsqrtIsCheap(bool isCheap = true) { FsqrtIsCheap = isCheap; }
/// 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;
}
/// Tells the code generator that it shouldn't generate sra/srl/add/sra for a
/// signed divide by power of two; let the target handle it.
void setPow2SDivIsCheap(bool isCheap = true) { Pow2SDivIsCheap = isCheap; }
/// 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));
AvailableRegClasses.push_back(std::make_pair(VT, RC));
RegClassForVT[VT.SimpleTy] = RC;
}
/// Remove all register classes.
void clearRegisterClasses() {
memset(RegClassForVT, 0,MVT::LAST_VALUETYPE * sizeof(TargetRegisterClass*));
AvailableRegClasses.clear();
}
/// \brief Remove all operation actions.
void clearOperationActions() {
}
/// 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(MVT VT) const;
/// Once all of the register classes are added, this allows us to compute
/// derived properties we expose.
void computeRegisterProperties();
/// Indicate that the specified operation does not work with the specified
/// type and indicate what to do about it.
void setOperationAction(unsigned Op, MVT VT,
LegalizeAction Action) {
assert(Op < array_lengthof(OpActions[0]) && "Table isn't big enough!");
OpActions[(unsigned)VT.SimpleTy][Op] = (uint8_t)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!");
LoadExtActions[ValVT.SimpleTy][MemVT.SimpleTy][ExtType] = (uint8_t)Action;
}
/// 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[ValVT.SimpleTy][MemVT.SimpleTy] = (uint8_t)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!");
/// The lower 5 bits of the SimpleTy index into Nth 2bit set from the 32-bit
/// value and the upper 27 bits index into the second dimension of the array
/// to select what 32-bit value to use.
uint32_t Shift = 2 * (VT.SimpleTy & 0xF);
CondCodeActions[CC][VT.SimpleTy >> 4] &= ~((uint32_t)0x3 << Shift);
CondCodeActions[CC][VT.SimpleTy >> 4] |= (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;
}
/// 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 if the DAG builder should automatically insert fences and reduce the
/// order of atomic memory operations to Monotonic.
void setInsertFencesForAtomic(bool fence) {
InsertFencesForAtomic = fence;
}
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;
int64_t BaseOffs;
bool HasBaseReg;
int64_t Scale;
AddrMode() : BaseGV(nullptr), BaseOffs(0), HasBaseReg(false), Scale(0) {}
};
/// 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.
virtual bool isLegalAddressingMode(const AddrMode &AM, Type *Ty) const;
/// \brief Return the cost of the scaling factor used in the addressing mode
/// represented by AM for this target, for a load/store of the specified type.
///
/// If the AM is supported, the return value must be >= 0.
/// If the AM is not supported, it returns a negative value.
/// TODO: Handle pre/postinc as well.
virtual int getScalingFactorCost(const AddrMode &AM, Type *Ty) const {
// Default: assume that any scaling factor used in a legal AM is free.
if (isLegalAddressingMode(AM, Ty)) return 0;
return -1;
}
/// Return true if the specified immediate is legal icmp immediate, that is
/// the target has icmp instructions which can compare a register against the
/// immediate without having to materialize the immediate into a register.
virtual bool isLegalICmpImmediate(int64_t) const {
return true;
}
/// Return true if the specified immediate is legal add immediate, that is the
/// target has add instructions which can add a register with the immediate
/// without having to materialize the immediate into a register.
virtual bool isLegalAddImmediate(int64_t) const {
return true;
}
/// Return true if it's significantly cheaper to shift a vector by a uniform
/// scalar than by an amount which will vary across each lane. On x86, for
/// example, there is a "psllw" instruction for the former case, but no simple
/// instruction for a general "a << b" operation on vectors.
virtual bool isVectorShiftByScalarCheap(Type *Ty) const {
return false;
}
/// Return true if it's free to truncate a value of type Ty1 to type
/// Ty2. e.g. On x86 it's free to truncate a i32 value in register EAX to i16
/// by referencing its sub-register AX.
virtual bool isTruncateFree(Type * /*Ty1*/, Type * /*Ty2*/) const {
return false;
}
/// Return true if a truncation from Ty1 to Ty2 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.
virtual bool allowTruncateForTailCall(Type * /*Ty1*/, Type * /*Ty2*/) const {
return false;
}
virtual bool isTruncateFree(EVT /*VT1*/, EVT /*VT2*/) const {
return false;
}
/// Return true if any actual instruction that defines a value of type Ty1
/// implicitly zero-extends the value to Ty2 in the result register.
///
/// This does not necessarily include registers defined in unknown ways, such
/// as incoming arguments, or copies from unknown virtual registers. Also, if
/// isTruncateFree(Ty2, Ty1) is true, this does not necessarily apply to
/// truncate instructions. e.g. on x86-64, all instructions that define 32-bit
/// values implicit zero-extend the result out to 64 bits.
virtual bool isZExtFree(Type * /*Ty1*/, Type * /*Ty2*/) const {
return false;
}
virtual bool isZExtFree(EVT /*VT1*/, EVT /*VT2*/) 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(Type * /*LoadedType*/,
unsigned & /*RequiredAligment*/) const {
return false;
}
virtual bool hasPairedLoad(EVT /*LoadedType*/,
unsigned & /*RequiredAligment*/) 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 VT) const {
assert(VT.isFloatingPoint());
return false;
}
/// Return true if folding a vector load into ExtVal (a sign, zero, or any
/// extend node) is profitable.
virtual bool isVectorLoadExtDesirable(SDValue ExtVal) const { return false; }
/// Return true if an fneg operation is free to the point where it is never
/// worthwhile to replace it with a bitwise operation.
virtual bool isFNegFree(EVT VT) const {
assert(VT.isFloatingPoint());
return false;
}
/// Return true if an fabs operation is free to the point where it is never
/// worthwhile to replace it with a bitwise operation.
virtual bool isFAbsFree(EVT VT) const {
assert(VT.isFloatingPoint());
return false;
}
/// Return true if an FMA operation is faster than a pair of fmul and fadd
/// instructions. fmuladd intrinsics will be expanded to FMAs when this method
/// returns true, otherwise fmuladd is expanded to fmul + fadd.
///
/// NOTE: This may be called before legalization on types for which FMAs are
/// not legal, but should return true if those types will eventually legalize
/// to types that support FMAs. After legalization, it will only be called on
/// types that support FMAs (via Legal or Custom actions)
virtual bool isFMAFasterThanFMulAndFAdd(EVT) const {
return false;
}
/// Return true if it's profitable to narrow operations of type VT1 to
/// VT2. e.g. on x86, it's profitable to narrow from i32 to i8 but not from
/// i32 to i16.
virtual bool isNarrowingProfitable(EVT /*VT1*/, EVT /*VT2*/) const {
return false;
}
/// \brief Return true if it is beneficial to convert a load of a constant to
/// just the constant itself.
/// On some targets it might be more efficient to use a combination of
/// arithmetic instructions to materialize the constant instead of loading it
/// from a constant pool.
virtual bool shouldConvertConstantLoadToIntImm(const APInt &Imm,
Type *Ty) const {
return false;
}
/// Return true if EXTRACT_SUBVECTOR is cheap for this result 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, unsigned Index) 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];
}
private:
const TargetMachine &TM;
const DataLayout *DL;
/// True if this is a little endian target.
bool IsLittleEndian;
/// Tells the code generator not to expand operations into sequences that use
/// the select operations if possible.
bool SelectIsExpensive;
/// 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 not to expand integer divides by constants into a
/// sequence of muls, adds, and shifts. This is a hack until a real cost
/// model is in place. If we ever optimize for size, this will be set to true
/// unconditionally.
bool IntDivIsCheap;
// Don't expand fsqrt with an approximation based on the inverse sqrt.
bool FsqrtIsCheap;
/// 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 sra/srl/add/sra for a
/// signed divide by power of two; let the target handle it.
bool Pow2SDivIsCheap;
/// 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;
/// Number of blocks threshold to use jump tables.
int MinimumJumpTableEntries;
/// 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;
/// Whether the DAG builder should automatically insert fences and reduce
/// ordering for atomics. (This will be set for for most architectures with
/// weak memory ordering.)
bool InsertFencesForAtomic;
/// If set to a physical register, this specifies the register that
/// llvm.savestack/llvm.restorestack should save and restore.
unsigned StackPointerRegisterToSaveRestore;
/// If set to a physical register, this specifies the register that receives
/// the exception address on entry to a landing pad.
unsigned ExceptionPointerRegister;
/// If set to a physical register, this specifies the register that receives
/// the exception typeid on entry to a landing pad.
unsigned ExceptionSelectorRegister;
/// 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.
uint8_t 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.
uint8_t LoadExtActions[MVT::LAST_VALUETYPE][MVT::LAST_VALUETYPE]
[ISD::LAST_LOADEXT_TYPE];
/// For each value type pair keep a LegalizeAction that indicates whether a
/// truncating store of a specific value type and truncating type is legal.
uint8_t 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 2 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 16.
uint32_t CondCodeActions[ISD::SETCC_INVALID][(MVT::LAST_VALUETYPE + 15) / 16];
ValueTypeActionImpl ValueTypeActions;
public:
LegalizeKind
getTypeConversion(LLVMContext &Context, EVT VT) const {
// If this is a simple type, use the ComputeRegisterProp mechanism.
if (VT.isSimple()) {
MVT SVT = VT.getSimpleVT();
assert((unsigned)SVT.SimpleTy < array_lengthof(TransformToType));
MVT NVT = TransformToType[SVT.SimpleTy];
LegalizeTypeAction LA = ValueTypeActions.getTypeAction(SVT);
assert(
(LA == TypeLegal || LA == TypeSoftenFloat ||
ValueTypeActions.getTypeAction(NVT) != TypePromoteInteger)
&& "Promote may not follow Expand or Promote");
if (LA == TypeSplitVector)
return LegalizeKind(LA, EVT::getVectorVT(Context,
SVT.getVectorElementType(),
SVT.getVectorNumElements()/2));
if (LA == TypeScalarizeVector)
return LegalizeKind(LA, SVT.getVectorElementType());
return LegalizeKind(LA, NVT);
}
// Handle Extended Scalar Types.
if (!VT.isVector()) {
assert(VT.isInteger() && "Float types must be simple");
unsigned BitSize = VT.getSizeInBits();
// First promote to a power-of-two size, then expand if necessary.
if (BitSize < 8 || !isPowerOf2_32(BitSize)) {
EVT NVT = VT.getRoundIntegerType(Context);
assert(NVT != VT && "Unable to round integer VT");
LegalizeKind NextStep = getTypeConversion(Context, NVT);
// Avoid multi-step promotion.
if (NextStep.first == TypePromoteInteger) return NextStep;
// Return rounded integer type.
return LegalizeKind(TypePromoteInteger, NVT);
}
return LegalizeKind(TypeExpandInteger,
EVT::getIntegerVT(Context, VT.getSizeInBits()/2));
}
// Handle vector types.
unsigned NumElts = VT.getVectorNumElements();
EVT EltVT = VT.getVectorElementType();
// Vectors with only one element are always scalarized.
if (NumElts == 1)
return LegalizeKind(TypeScalarizeVector, EltVT);
// Try to widen vector elements until the element type is a power of two and
// promote it to a legal type later on, for example:
// <3 x i8> -> <4 x i8> -> <4 x i32>
if (EltVT.isInteger()) {
// Vectors with a number of elements that is not a power of two are always
// widened, for example <3 x i8> -> <4 x i8>.
if (!VT.isPow2VectorType()) {
NumElts = (unsigned)NextPowerOf2(NumElts);
EVT NVT = EVT::getVectorVT(Context, EltVT, NumElts);
return LegalizeKind(TypeWidenVector, NVT);
}
// Examine the element type.
LegalizeKind LK = getTypeConversion(Context, EltVT);
// If type is to be expanded, split the vector.
// <4 x i140> -> <2 x i140>
if (LK.first == TypeExpandInteger)
return LegalizeKind(TypeSplitVector,
EVT::getVectorVT(Context, EltVT, NumElts / 2));
// Promote the integer element types until a legal vector type is found
// or until the element integer type is too big. If a legal type was not
// found, fallback to the usual mechanism of widening/splitting the
// vector.
EVT OldEltVT = EltVT;
while (1) {
// Increase the bitwidth of the element to the next pow-of-two
// (which is greater than 8 bits).
EltVT = EVT::getIntegerVT(Context, 1 + EltVT.getSizeInBits()
).getRoundIntegerType(Context);
// Stop trying when getting a non-simple element type.
// Note that vector elements may be greater than legal vector element
// types. Example: X86 XMM registers hold 64bit element on 32bit
// systems.
if (!EltVT.isSimple()) break;
// Build a new vector type and check if it is legal.
MVT NVT = MVT::getVectorVT(EltVT.getSimpleVT(), NumElts);
// Found a legal promoted vector type.
if (NVT != MVT() && ValueTypeActions.getTypeAction(NVT) == TypeLegal)
return LegalizeKind(TypePromoteInteger,
EVT::getVectorVT(Context, EltVT, NumElts));
}
// Reset the type to the unexpanded type if we did not find a legal vector
// type with a promoted vector element type.
EltVT = OldEltVT;
}
// Try to widen the vector until a legal type is found.
// If there is no wider legal type, split the vector.
while (1) {
// Round up to the next power of 2.
NumElts = (unsigned)NextPowerOf2(NumElts);
// If there is no simple vector type with this many elements then there
// cannot be a larger legal vector type. Note that this assumes that
// there are no skipped intermediate vector types in the simple types.
if (!EltVT.isSimple()) break;
MVT LargerVector = MVT::getVectorVT(EltVT.getSimpleVT(), NumElts);
if (LargerVector == MVT()) break;
// If this type is legal then widen the vector.
if (ValueTypeActions.getTypeAction(LargerVector) == TypeLegal)
return LegalizeKind(TypeWidenVector, LargerVector);
}
// Widen odd vectors to next power of two.
if (!VT.isPow2VectorType()) {
EVT NVT = VT.getPow2VectorType(Context);
return LegalizeKind(TypeWidenVector, NVT);
}
// Vectors with illegal element types are expanded.
EVT NVT = EVT::getVectorVT(Context, EltVT, VT.getVectorNumElements() / 2);
return LegalizeKind(TypeSplitVector, NVT);
}
private:
std::vector<std::pair<MVT, const TargetRegisterClass*> > AvailableRegClasses;
/// Targets can specify ISD nodes that they would like PerformDAGCombine
/// callbacks for by calling setTargetDAGCombine(), which sets a bit in this
/// array.
unsigned char
TargetDAGCombineArray[(ISD::BUILTIN_OP_END+CHAR_BIT-1)/CHAR_BIT];
/// For operations that must be promoted to a specific type, this holds the
/// destination type. This map should be sparse, so don't hold it as an
/// array.
///
/// Targets add entries to this map with AddPromotedToType(..), clients access
/// this with getTypeToPromoteTo(..).
std::map<std::pair<unsigned, MVT::SimpleValueType>, MVT::SimpleValueType>
PromoteToType;
/// Stores the name each libcall.
const char *LibcallRoutineNames[RTLIB::UNKNOWN_LIBCALL];
/// The ISD::CondCode that should be used to test the result of each of the
/// comparison libcall against zero.
ISD::CondCode CmpLibcallCCs[RTLIB::UNKNOWN_LIBCALL];
/// Stores the CallingConv that should be used for each libcall.
CallingConv::ID LibcallCallingConvs[RTLIB::UNKNOWN_LIBCALL];
protected:
/// \brief Specify maximum number of store instructions per memset call.
///
/// When lowering \@llvm.memset this field specifies the maximum number of
/// store operations that may be substituted for the call to memset. Targets
/// must set this value based on the cost threshold for that target. Targets
/// should assume that the memset will be done using as many of the largest
/// store operations first, followed by smaller ones, if necessary, per
/// alignment restrictions. For example, storing 9 bytes on a 32-bit machine
/// with 16-bit alignment would result in four 2-byte stores and one 1-byte
/// store. This only applies to setting a constant array of a constant size.
unsigned MaxStoresPerMemset;
/// Maximum number of stores operations that may be substituted for the call
/// to memset, used for functions with OptSize attribute.
unsigned MaxStoresPerMemsetOptSize;
/// \brief Specify maximum bytes of store instructions per memcpy call.
///
/// When lowering \@llvm.memcpy this field specifies the maximum number of
/// store operations that may be substituted for a call to memcpy. Targets
/// must set this value based on the cost threshold for that target. Targets
/// should assume that the memcpy will be done using as many of the largest
/// store operations first, followed by smaller ones, if necessary, per
/// alignment restrictions. For example, storing 7 bytes on a 32-bit machine
/// with 32-bit alignment would result in one 4-byte store, a one 2-byte store
/// and one 1-byte store. This only applies to copying a constant array of
/// constant size.
unsigned MaxStoresPerMemcpy;
/// Maximum number of store operations that may be substituted for a call to
/// memcpy, used for functions with OptSize attribute.
unsigned MaxStoresPerMemcpyOptSize;
/// \brief Specify maximum bytes of store instructions per memmove call.
///
/// When lowering \@llvm.memmove this field specifies the maximum number of
/// store instructions that may be substituted for a call to memmove. Targets
/// must set this value based on the cost threshold for that target. Targets
/// should assume that the memmove will be done using as many of the largest
/// store operations first, followed by smaller ones, if necessary, per
/// alignment restrictions. For example, moving 9 bytes on a 32-bit machine
/// with 8-bit alignment would result in nine 1-byte stores. This only
/// applies to copying a constant array of constant size.
unsigned MaxStoresPerMemmove;
/// Maximum number of store instructions that may be substituted for a call to
/// memmove, used for functions with OpSize attribute.
unsigned MaxStoresPerMemmoveOptSize;
/// Tells the code generator that select is more expensive than a branch if
/// the branch is usually predicted right.
bool PredictableSelectIsExpensive;
/// MaskAndBranchFoldingIsLegal - Indicates if the target supports folding
/// a mask of a single bit, a compare, and a branch into a single instruction.
bool MaskAndBranchFoldingIsLegal;
/// \see enableExtLdPromotion.
bool EnableExtLdPromotion;
protected:
/// Return true if the value types that can be represented by the specified
/// register class are all legal.
bool isLegalRC(const TargetRegisterClass *RC) const;
/// Replace/modify any TargetFrameIndex operands with a targte-dependent
/// sequence of memory operands that is recognized by PrologEpilogInserter.
MachineBasicBlock *emitPatchPoint(MachineInstr *MI, MachineBasicBlock *MBB) const;
};
/// This class defines information used to lower LLVM code to legal SelectionDAG
/// operators that the target instruction selector can accept natively.
///
/// This class also defines callbacks that targets must implement to lower
/// target-specific constructs to SelectionDAG operators.
class TargetLowering : public TargetLoweringBase {
TargetLowering(const TargetLowering&) LLVM_DELETED_FUNCTION;
void operator=(const TargetLowering&) LLVM_DELETED_FUNCTION;
public:
/// NOTE: The TargetMachine owns TLOF.
explicit TargetLowering(const TargetMachine &TM);
/// 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, SDLoc DL) const;
/// Returns a pair of (return value, chain).
std::pair<SDValue, SDValue> makeLibCall(SelectionDAG &DAG, RTLIB::Libcall LC,
EVT RetVT, const SDValue *Ops,
unsigned NumOps, bool isSigned,
SDLoc dl, bool doesNotReturn = false,
bool isReturnValueUsed = true) 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);
/// 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,
SDLoc dl);
};
/// Look at Op. At this point, we know that only the DemandedMask bits of the
/// result of Op are ever used downstream. If we can use this information to
/// simplify Op, create a new simplified DAG node and return true, returning
/// the original and new nodes in Old and New. Otherwise, analyze the
/// expression and return a mask of KnownOne and KnownZero bits for the
/// expression (used to simplify the caller). The KnownZero/One bits may only
/// be accurate for those bits in the DemandedMask.
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedMask,
APInt &KnownZero, APInt &KnownOne,
TargetLoweringOpt &TLO, unsigned Depth = 0) 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.
virtual void computeKnownBitsForTargetNode(const SDValue Op,
APInt &KnownZero,
APInt &KnownOne,
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.
virtual unsigned ComputeNumSignBitsForTargetNode(SDValue Op,
const SelectionDAG &DAG,
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 isAfterLegalizeVectorOps() const {
return Level == AfterLegalizeDAG;
}
CombineLevel getDAGCombineLevel() { return Level; }
bool isCalledByLegalizer() const { return CalledByLegalizer; }
void AddToWorklist(SDNode *N);
void RemoveFromWorklist(SDNode *N);
SDValue CombineTo(SDNode *N, const std::vector<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;
/// 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, SDLoc dl) const;
/// 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 a following shift through this
// node, 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.
virtual bool isDesirableToCommuteWithShift(const SDNode *N /*Op*/) const {
return true;
}
/// 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;
}
//===--------------------------------------------------------------------===//
// 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*/,
SDLoc /*dl*/, SelectionDAG &/*DAG*/,
SmallVectorImpl<SDValue> &/*InVals*/) const {
llvm_unreachable("Not Implemented");
}
struct ArgListEntry {
SDValue Node;
Type* Ty;
bool isSExt : 1;
bool isZExt : 1;
bool isInReg : 1;
bool isSRet : 1;
bool isNest : 1;
bool isByVal : 1;
bool isInAlloca : 1;
bool isReturned : 1;
uint16_t Alignment;
ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
isSRet(false), isNest(false), isByVal(false), isInAlloca(false),
isReturned(false), Alignment(0) { }
void setAttributes(ImmutableCallSite *CS, unsigned AttrIdx);
};
typedef std::vector<ArgListEntry> ArgListTy;
/// 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;
bool RetSExt : 1;
bool RetZExt : 1;
bool IsVarArg : 1;
bool IsInReg : 1;
bool DoesNotReturn : 1;
bool IsReturnValueUsed : 1;
// IsTailCall should be modified by implementations of
// TargetLowering::LowerCall that perform tail call conversions.
bool IsTailCall;
unsigned NumFixedArgs;
CallingConv::ID CallConv;
SDValue Callee;
ArgListTy Args;
SelectionDAG &DAG;
SDLoc DL;
ImmutableCallSite *CS;
bool IsPatchPoint;
SmallVector<ISD::OutputArg, 32> Outs;
SmallVector<SDValue, 32> OutVals;
SmallVector<ISD::InputArg, 32> Ins;
CallLoweringInfo(SelectionDAG &DAG)
: RetTy(nullptr), RetSExt(false), RetZExt(false), IsVarArg(false),
IsInReg(false), DoesNotReturn(false), IsReturnValueUsed(true),
IsTailCall(false), NumFixedArgs(-1), CallConv(CallingConv::C),
DAG(DAG), CS(nullptr), IsPatchPoint(false) {}
CallLoweringInfo &setDebugLoc(SDLoc dl) {
DL = dl;
return *this;
}
CallLoweringInfo &setChain(SDValue InChain) {
Chain = InChain;
return *this;
}
CallLoweringInfo &setCallee(CallingConv::ID CC, Type *ResultType,
SDValue Target, ArgListTy &&ArgsList,
unsigned FixedArgs = -1) {
RetTy = ResultType;
Callee = Target;
CallConv = CC;
NumFixedArgs =
(FixedArgs == static_cast<unsigned>(-1) ? Args.size() : FixedArgs);
Args = std::move(ArgsList);
return *this;
}
CallLoweringInfo &setCallee(Type *ResultType, FunctionType *FTy,
SDValue Target, ArgListTy &&ArgsList,
ImmutableCallSite &Call) {
RetTy = ResultType;
IsInReg = Call.paramHasAttr(0, Attribute::InReg);
DoesNotReturn = Call.doesNotReturn();
IsVarArg = FTy->isVarArg();
IsReturnValueUsed = !Call.getInstruction()->use_empty();
RetSExt = Call.paramHasAttr(0, Attribute::SExt);
RetZExt = Call.paramHasAttr(0, 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 &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;
}
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 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*/,
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(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) 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 argument or return value. FIXME: Most C calling
/// convention requires the return type to be promoted, but this is not true
/// all the time, e.g. i1 on 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 getTypeForExtArgOrReturn(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, SDLoc DL,
SelectionDAG &DAG) const {
return Chain;
}
/// 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;
/// 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;
/// The ValueType for the operand value.
MVT ConstraintVT;
/// 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;
/// Copy constructor for copying from a ConstraintInfo.
AsmOperandInfo(InlineAsm::ConstraintInfo Info)
: InlineAsm::ConstraintInfo(std::move(Info)),
ConstraintType(TargetLowering::C_Unknown), CallOperandVal(nullptr),
ConstraintVT(MVT::Other) {}
};
typedef std::vector<AsmOperandInfo> AsmOperandInfoVector;
/// 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(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(const std::string &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 std::string &Constraint,
MVT VT) const;
/// 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 BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl,
SelectionDAG &DAG) const;
SDValue BuildSDIV(SDNode *N, const APInt &Divisor, SelectionDAG &DAG,
bool IsAfterLegalization,
std::vector<SDNode *> *Created) const;
SDValue BuildUDIV(SDNode *N, const APInt &Divisor, SelectionDAG &DAG,
bool IsAfterLegalization,
std::vector<SDNode *> *Created) const;
virtual SDValue BuildSDIVPow2(SDNode *N, const APInt &Divisor,
SelectionDAG &DAG,
std::vector<SDNode *> *Created) const {
return SDValue();
}
/// Indicate whether this target prefers to combine the given number of FDIVs
/// with the same divisor.
virtual bool combineRepeatedFPDivisors(unsigned NumUsers) const {
return false;
}
/// Hooks for building estimates in place of slower divisions and square
/// roots.
/// Return a reciprocal square root estimate value for the input operand.
/// The RefinementSteps output is the number of Newton-Raphson refinement
/// iterations required to generate a sufficient (though not necessarily
/// IEEE-754 compliant) estimate for the value type.
/// The boolean UseOneConstNR output is used to select a Newton-Raphson
/// algorithm implementation that uses one constant or two constants.
/// 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 getRsqrtEstimate(SDValue Operand,
DAGCombinerInfo &DCI,
unsigned &RefinementSteps,
bool &UseOneConstNR) const {
return SDValue();
}
/// Return a reciprocal estimate value for the input operand.
/// The RefinementSteps output is the number of Newton-Raphson refinement
/// iterations required to generate a sufficient (though not necessarily
/// IEEE-754 compliant) estimate for the value type.
/// 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,
DAGCombinerInfo &DCI,
unsigned &RefinementSteps) const {
return SDValue();
}
//===--------------------------------------------------------------------===//
// Legalization utility functions
//
/// 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, SDValue LL = SDValue(),
SDValue LH = SDValue(), SDValue RL = SDValue(),
SDValue RH = SDValue()) 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;
//===--------------------------------------------------------------------===//
// 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.
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;
}
};
/// 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(Type* ReturnType, AttributeSet attr,
SmallVectorImpl<ISD::OutputArg> &Outs,
const TargetLowering &TLI);
} // end llvm namespace
#endif
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