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llvm-mirror/include/llvm/Target/TargetLowering.h
Duncan Sands e431120ddc In this unreachable code, return an initialized value. 
This stops gcc warning about possible uses of an uninitialized
value when compiling with assertions turned off.

llvm-svn: 74775
2009-07-03 16:00:23 +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.
//
//===----------------------------------------------------------------------===//
//
// 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/InlineAsm.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/DebugLoc.h"
#include "llvm/Target/TargetMachine.h"
#include <climits>
#include <map>
#include <vector>
namespace llvm {
class AllocaInst;
class CallInst;
class Function;
class FastISel;
class MachineBasicBlock;
class MachineFunction;
class MachineFrameInfo;
class MachineInstr;
class MachineModuleInfo;
class DwarfWriter;
class SDNode;
class SDValue;
class SelectionDAG;
class TargetData;
class TargetMachine;
class TargetRegisterClass;
class TargetSubtarget;
class Value;
// FIXME: should this be here?
namespace TLSModel {
enum Model {
GeneralDynamic,
LocalDynamic,
InitialExec,
LocalExec
};
}
TLSModel::Model getTLSModel(const GlobalValue *GV, Reloc::Model reloc);
//===----------------------------------------------------------------------===//
/// TargetLowering - 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:
/// LegalizeAction - 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.
};
enum OutOfRangeShiftAmount {
Undefined, // Oversized shift amounts are undefined (default).
Mask, // Shift amounts are auto masked (anded) to value size.
Extend // Oversized shift pulls in zeros or sign bits.
};
enum BooleanContent { // How the target represents true/false values.
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 SchedPreference {
SchedulingForLatency, // Scheduling for shortest total latency.
SchedulingForRegPressure // Scheduling for lowest register pressure.
};
explicit TargetLowering(TargetMachine &TM);
virtual ~TargetLowering();
TargetMachine &getTargetMachine() const { return TM; }
const TargetData *getTargetData() const { return TD; }
bool isBigEndian() const { return !IsLittleEndian; }
bool isLittleEndian() const { return IsLittleEndian; }
MVT getPointerTy() const { return PointerTy; }
MVT getShiftAmountTy() const { return ShiftAmountTy; }
OutOfRangeShiftAmount getShiftAmountFlavor() const {return ShiftAmtHandling; }
/// usesGlobalOffsetTable - Return true if this target uses a GOT for PIC
/// codegen.
bool usesGlobalOffsetTable() const { return UsesGlobalOffsetTable; }
/// isSelectExpensive - Return true if the select operation is expensive for
/// this target.
bool isSelectExpensive() const { return SelectIsExpensive; }
/// isIntDivCheap() - 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; }
/// isPow2DivCheap() - Return true if pow2 div is cheaper than a chain of
/// srl/add/sra.
bool isPow2DivCheap() const { return Pow2DivIsCheap; }
/// getSetCCResultType - Return the ValueType of the result of SETCC
/// operations. Also used to obtain the target's preferred type for
/// the condition operand of SELECT and BRCOND nodes. In the case of
/// BRCOND the argument passed is MVT::Other since there are no other
/// operands to get a type hint from.
virtual MVT getSetCCResultType(MVT VT) const;
/// getBooleanContents - 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.
BooleanContent getBooleanContents() const { return BooleanContents;}
/// getSchedulingPreference - Return target scheduling preference.
SchedPreference getSchedulingPreference() const {
return SchedPreferenceInfo;
}
/// getRegClassFor - Return the register class that should be used for the
/// specified value type. This may only be called on legal types.
TargetRegisterClass *getRegClassFor(MVT VT) const {
assert((unsigned)VT.getSimpleVT() < array_lengthof(RegClassForVT));
TargetRegisterClass *RC = RegClassForVT[VT.getSimpleVT()];
assert(RC && "This value type is not natively supported!");
return RC;
}
/// isTypeLegal - 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(MVT VT) const {
assert(!VT.isSimple() ||
(unsigned)VT.getSimpleVT() < array_lengthof(RegClassForVT));
return VT.isSimple() && RegClassForVT[VT.getSimpleVT()] != 0;
}
class ValueTypeActionImpl {
/// ValueTypeActions - This is a bitvector that contains two bits for each
/// value type, where the two bits correspond to the LegalizeAction enum.
/// This can be queried with "getTypeAction(VT)".
/// dimension by (MVT::MAX_ALLOWED_VALUETYPE/32) * 2
uint32_t ValueTypeActions[(MVT::MAX_ALLOWED_VALUETYPE/32)*2];
public:
ValueTypeActionImpl() {
ValueTypeActions[0] = ValueTypeActions[1] = 0;
ValueTypeActions[2] = ValueTypeActions[3] = 0;
}
ValueTypeActionImpl(const ValueTypeActionImpl &RHS) {
ValueTypeActions[0] = RHS.ValueTypeActions[0];
ValueTypeActions[1] = RHS.ValueTypeActions[1];
ValueTypeActions[2] = RHS.ValueTypeActions[2];
ValueTypeActions[3] = RHS.ValueTypeActions[3];
}
LegalizeAction getTypeAction(MVT VT) const {
if (VT.isExtended()) {
if (VT.isVector()) {
return VT.isPow2VectorType() ? Expand : Promote;
}
if (VT.isInteger())
// First promote to a power-of-two size, then expand if necessary.
return VT == VT.getRoundIntegerType() ? Expand : Promote;
assert(0 && "Unsupported extended type!");
return Legal;
}
unsigned I = VT.getSimpleVT();
assert(I<4*array_lengthof(ValueTypeActions)*sizeof(ValueTypeActions[0]));
return (LegalizeAction)((ValueTypeActions[I>>4] >> ((2*I) & 31)) & 3);
}
void setTypeAction(MVT VT, LegalizeAction Action) {
unsigned I = VT.getSimpleVT();
assert(I<4*array_lengthof(ValueTypeActions)*sizeof(ValueTypeActions[0]));
ValueTypeActions[I>>4] |= Action << ((I*2) & 31);
}
};
const ValueTypeActionImpl &getValueTypeActions() const {
return ValueTypeActions;
}
/// getTypeAction - 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.
LegalizeAction getTypeAction(MVT VT) const {
return ValueTypeActions.getTypeAction(VT);
}
/// getTypeToTransformTo - 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.
MVT getTypeToTransformTo(MVT VT) const {
if (VT.isSimple()) {
assert((unsigned)VT.getSimpleVT() < array_lengthof(TransformToType));
MVT NVT = TransformToType[VT.getSimpleVT()];
assert(getTypeAction(NVT) != Promote &&
"Promote may not follow Expand or Promote");
return NVT;
}
if (VT.isVector()) {
MVT NVT = VT.getPow2VectorType();
if (NVT == VT) {
// Vector length is a power of 2 - split to half the size.
unsigned NumElts = VT.getVectorNumElements();
MVT EltVT = VT.getVectorElementType();
return (NumElts == 1) ? EltVT : MVT::getVectorVT(EltVT, NumElts / 2);
}
// Promote to a power of two size, avoiding multi-step promotion.
return getTypeAction(NVT) == Promote ? getTypeToTransformTo(NVT) : NVT;
} else if (VT.isInteger()) {
MVT NVT = VT.getRoundIntegerType();
if (NVT == VT)
// Size is a power of two - expand to half the size.
return MVT::getIntegerVT(VT.getSizeInBits() / 2);
else
// Promote to a power of two size, avoiding multi-step promotion.
return getTypeAction(NVT) == Promote ? getTypeToTransformTo(NVT) : NVT;
}
assert(0 && "Unsupported extended type!");
return MVT(MVT::Other); // Not reached
}
/// getTypeToExpandTo - 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.
MVT getTypeToExpandTo(MVT VT) const {
assert(!VT.isVector());
while (true) {
switch (getTypeAction(VT)) {
case Legal:
return VT;
case Expand:
VT = getTypeToTransformTo(VT);
break;
default:
assert(false && "Type is not legal nor is it to be expanded!");
return VT;
}
}
return VT;
}
/// getVectorTypeBreakdown - Vector types are broken down into some number of
/// legal first class types. For example, MVT::v8f32 maps to 2 MVT::v4f32
/// with Altivec or SSE1, or 8 promoted MVT::f64 values with the X86 FP stack.
/// Similarly, MVT::v2i64 turns into 4 MVT::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(MVT VT,
MVT &IntermediateVT,
unsigned &NumIntermediates,
MVT &RegisterVT) const;
/// getTgtMemIntrinsic: 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.
typedef struct IntrinsicInfo {
unsigned opc; // target opcode
MVT memVT; // memory VT
const Value* ptrVal; // value representing memory location
int offset; // offset off of ptrVal
unsigned align; // alignment
bool vol; // is volatile?
bool readMem; // reads memory?
bool writeMem; // writes memory?
} IntrinisicInfo;
virtual bool getTgtMemIntrinsic(IntrinsicInfo& Info,
CallInst &I, unsigned Intrinsic) {
return false;
}
/// getWidenVectorType: given a vector type, returns the type to widen to
/// (e.g., v7i8 to v8i8). If the vector type is legal, it returns itself.
/// If there is no vector type that we want to widen to, returns MVT::Other
/// When and were to widen is target dependent based on the cost of
/// scalarizing vs using the wider vector type.
virtual MVT getWidenVectorType(MVT VT) const;
typedef std::vector<APFloat>::const_iterator legal_fpimm_iterator;
legal_fpimm_iterator legal_fpimm_begin() const {
return LegalFPImmediates.begin();
}
legal_fpimm_iterator legal_fpimm_end() const {
return LegalFPImmediates.end();
}
/// isShuffleMaskLegal - 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,
MVT VT) const {
return true;
}
/// isVectorClearMaskLegal - 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,
MVT VT) const {
return false;
}
/// getOperationAction - 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, MVT VT) const {
if (VT.isExtended()) return Expand;
assert(Op < array_lengthof(OpActions[0]) &&
(unsigned)VT.getSimpleVT() < sizeof(OpActions[0][0])*8 &&
"Table isn't big enough!");
unsigned I = (unsigned) VT.getSimpleVT();
unsigned J = I & 31;
I = I >> 5;
return (LegalizeAction)((OpActions[I][Op] >> (J*2) ) & 3);
}
/// isOperationLegalOrCustom - 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, MVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
(getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Custom);
}
/// isOperationLegal - Return true if the specified operation is legal on this
/// target.
bool isOperationLegal(unsigned Op, MVT VT) const {
return (VT == MVT::Other || isTypeLegal(VT)) &&
getOperationAction(Op, VT) == Legal;
}
/// getLoadExtAction - 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 LType, MVT VT) const {
assert(LType < array_lengthof(LoadExtActions) &&
(unsigned)VT.getSimpleVT() < sizeof(LoadExtActions[0])*4 &&
"Table isn't big enough!");
return (LegalizeAction)((LoadExtActions[LType] >> (2*VT.getSimpleVT())) & 3);
}
/// isLoadExtLegal - Return true if the specified load with extension is legal
/// on this target.
bool isLoadExtLegal(unsigned LType, MVT VT) const {
return VT.isSimple() &&
(getLoadExtAction(LType, VT) == Legal ||
getLoadExtAction(LType, VT) == Custom);
}
/// getTruncStoreAction - 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(MVT ValVT,
MVT MemVT) const {
assert((unsigned)ValVT.getSimpleVT() < array_lengthof(TruncStoreActions) &&
(unsigned)MemVT.getSimpleVT() < sizeof(TruncStoreActions[0])*4 &&
"Table isn't big enough!");
return (LegalizeAction)((TruncStoreActions[ValVT.getSimpleVT()] >>
(2*MemVT.getSimpleVT())) & 3);
}
/// isTruncStoreLegal - Return true if the specified store with truncation is
/// legal on this target.
bool isTruncStoreLegal(MVT ValVT, MVT MemVT) const {
return isTypeLegal(ValVT) && MemVT.isSimple() &&
(getTruncStoreAction(ValVT, MemVT) == Legal ||
getTruncStoreAction(ValVT, MemVT) == Custom);
}
/// getIndexedLoadAction - 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 < array_lengthof(IndexedModeActions[0][0]) &&
((unsigned)VT.getSimpleVT()) < MVT::LAST_VALUETYPE &&
"Table isn't big enough!");
return (LegalizeAction)((IndexedModeActions[(unsigned)VT.getSimpleVT()][0][IdxMode]));
}
/// isIndexedLoadLegal - Return true if the specified indexed load is legal
/// on this target.
bool isIndexedLoadLegal(unsigned IdxMode, MVT VT) const {
return VT.isSimple() &&
(getIndexedLoadAction(IdxMode, VT) == Legal ||
getIndexedLoadAction(IdxMode, VT) == Custom);
}
/// getIndexedStoreAction - 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 < array_lengthof(IndexedModeActions[0][1]) &&
(unsigned)VT.getSimpleVT() < MVT::LAST_VALUETYPE &&
"Table isn't big enough!");
return (LegalizeAction)((IndexedModeActions[(unsigned)VT.getSimpleVT()][1][IdxMode]));
}
/// isIndexedStoreLegal - Return true if the specified indexed load is legal
/// on this target.
bool isIndexedStoreLegal(unsigned IdxMode, MVT VT) const {
return VT.isSimple() &&
(getIndexedStoreAction(IdxMode, VT) == Legal ||
getIndexedStoreAction(IdxMode, VT) == Custom);
}
/// getConvertAction - Return how the conversion 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
getConvertAction(MVT FromVT, MVT ToVT) const {
assert((unsigned)FromVT.getSimpleVT() < array_lengthof(ConvertActions) &&
(unsigned)ToVT.getSimpleVT() < sizeof(ConvertActions[0])*4 &&
"Table isn't big enough!");
return (LegalizeAction)((ConvertActions[FromVT.getSimpleVT()] >>
(2*ToVT.getSimpleVT())) & 3);
}
/// isConvertLegal - Return true if the specified conversion is legal
/// on this target.
bool isConvertLegal(MVT FromVT, MVT ToVT) const {
return isTypeLegal(FromVT) && isTypeLegal(ToVT) &&
(getConvertAction(FromVT, ToVT) == Legal ||
getConvertAction(FromVT, ToVT) == Custom);
}
/// getCondCodeAction - 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.getSimpleVT() < sizeof(CondCodeActions[0])*4 &&
"Table isn't big enough!");
LegalizeAction Action = (LegalizeAction)
((CondCodeActions[CC] >> (2*VT.getSimpleVT())) & 3);
assert(Action != Promote && "Can't promote condition code!");
return Action;
}
/// isCondCodeLegal - 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;
}
/// getTypeToPromoteTo - 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.getSimpleVT()));
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.getSimpleVT()+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;
}
/// getValueType - Return the MVT 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 MVT
/// counterpart (e.g. structs), otherwise it will assert.
MVT getValueType(const Type *Ty, bool AllowUnknown = false) const {
MVT VT = MVT::getMVT(Ty, AllowUnknown);
return VT == MVT::iPTR ? PointerTy : VT;
}
/// getByValTypeAlignment - Return the desired alignment for ByVal aggregate
/// function arguments in the caller parameter area. This is the actual
/// alignment, not its logarithm.
virtual unsigned getByValTypeAlignment(const Type *Ty) const;
/// getRegisterType - Return the type of registers that this ValueType will
/// eventually require.
MVT getRegisterType(MVT VT) const {
if (VT.isSimple()) {
assert((unsigned)VT.getSimpleVT() < array_lengthof(RegisterTypeForVT));
return RegisterTypeForVT[VT.getSimpleVT()];
}
if (VT.isVector()) {
MVT VT1, RegisterVT;
unsigned NumIntermediates;
(void)getVectorTypeBreakdown(VT, VT1, NumIntermediates, RegisterVT);
return RegisterVT;
}
if (VT.isInteger()) {
return getRegisterType(getTypeToTransformTo(VT));
}
assert(0 && "Unsupported extended type!");
return MVT(MVT::Other); // Not reached
}
/// getNumRegisters - 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(MVT VT) const {
if (VT.isSimple()) {
assert((unsigned)VT.getSimpleVT() < array_lengthof(NumRegistersForVT));
return NumRegistersForVT[VT.getSimpleVT()];
}
if (VT.isVector()) {
MVT VT1, VT2;
unsigned NumIntermediates;
return getVectorTypeBreakdown(VT, VT1, NumIntermediates, VT2);
}
if (VT.isInteger()) {
unsigned BitWidth = VT.getSizeInBits();
unsigned RegWidth = getRegisterType(VT).getSizeInBits();
return (BitWidth + RegWidth - 1) / RegWidth;
}
assert(0 && "Unsupported extended type!");
return 0; // Not reached
}
/// ShouldShrinkFPConstant - 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(MVT VT) const { return true; }
/// hasTargetDAGCombine - 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));
}
/// 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.
/// @brief Get maximum # of store operations permitted for llvm.memset
unsigned getMaxStoresPerMemset() const { return maxStoresPerMemset; }
/// 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.
/// @brief Get maximum # of store operations permitted for llvm.memcpy
unsigned getMaxStoresPerMemcpy() const { return maxStoresPerMemcpy; }
/// 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.
/// @brief Get maximum # of store operations permitted for llvm.memmove
unsigned getMaxStoresPerMemmove() const { return maxStoresPerMemmove; }
/// This function returns true if the target allows unaligned memory accesses.
/// This is used, for example, in situations where an array copy/move/set is
/// converted to a sequence of store operations. It's use helps to ensure that
/// such replacements don't generate code that causes an alignment error
/// (trap) on the target machine.
/// @brief Determine if the target supports unaligned memory accesses.
bool allowsUnalignedMemoryAccesses() const {
return allowUnalignedMemoryAccesses;
}
/// This function returns true if the target would benefit from code placement
/// optimization.
/// @brief Determine if the target should perform code placement optimization.
bool shouldOptimizeCodePlacement() const {
return benefitFromCodePlacementOpt;
}
/// getOptimalMemOpType - Returns the target specific optimal type for load
/// and store operations as a result of memset, memcpy, and memmove lowering.
/// It returns MVT::iAny if SelectionDAG should be responsible for
/// determining it.
virtual MVT getOptimalMemOpType(uint64_t Size, unsigned Align,
bool isSrcConst, bool isSrcStr,
SelectionDAG &DAG) const {
return MVT::iAny;
}
/// usesUnderscoreSetJmp - Determine if we should use _setjmp or setjmp
/// to implement llvm.setjmp.
bool usesUnderscoreSetJmp() const {
return UseUnderscoreSetJmp;
}
/// usesUnderscoreLongJmp - Determine if we should use _longjmp or longjmp
/// to implement llvm.longjmp.
bool usesUnderscoreLongJmp() const {
return UseUnderscoreLongJmp;
}
/// getStackPointerRegisterToSaveRestore - If a physical register, this
/// specifies the register that llvm.savestack/llvm.restorestack should save
/// and restore.
unsigned getStackPointerRegisterToSaveRestore() const {
return StackPointerRegisterToSaveRestore;
}
/// getExceptionAddressRegister - If a physical register, this returns
/// the register that receives the exception address on entry to a landing
/// pad.
unsigned getExceptionAddressRegister() const {
return ExceptionPointerRegister;
}
/// getExceptionSelectorRegister - If a physical register, this returns
/// the register that receives the exception typeid on entry to a landing
/// pad.
unsigned getExceptionSelectorRegister() const {
return ExceptionSelectorRegister;
}
/// getJumpBufSize - returns the target's jmp_buf size in bytes (if never
/// set, the default is 200)
unsigned getJumpBufSize() const {
return JumpBufSize;
}
/// getJumpBufAlignment - returns the target's jmp_buf alignment in bytes
/// (if never set, the default is 0)
unsigned getJumpBufAlignment() const {
return JumpBufAlignment;
}
/// getIfCvtBlockLimit - returns the target specific if-conversion block size
/// limit. Any block whose size is greater should not be predicated.
unsigned getIfCvtBlockSizeLimit() const {
return IfCvtBlockSizeLimit;
}
/// getIfCvtDupBlockLimit - returns the target specific size limit for a
/// block to be considered for duplication. Any block whose size is greater
/// should not be duplicated to facilitate its predication.
unsigned getIfCvtDupBlockSizeLimit() const {
return IfCvtDupBlockSizeLimit;
}
/// getPrefLoopAlignment - return the preferred loop alignment.
///
unsigned getPrefLoopAlignment() const {
return PrefLoopAlignment;
}
/// getPreIndexedAddressParts - 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;
}
/// getPostIndexedAddressParts - 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;
}
/// getPICJumpTableRelocaBase - Returns relocation base for the given PIC
/// jumptable.
virtual SDValue getPICJumpTableRelocBase(SDValue Table,
SelectionDAG &DAG) const;
/// isOffsetFoldingLegal - 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;
/// getFunctionAlignment - Return the Log2 alignment of this function.
virtual unsigned getFunctionAlignment(const Function *) const = 0;
//===--------------------------------------------------------------------===//
// TargetLowering Optimization Methods
//
/// TargetLoweringOpt - 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;
SDValue Old;
SDValue New;
explicit TargetLoweringOpt(SelectionDAG &InDAG) : DAG(InDAG) {}
bool CombineTo(SDValue O, SDValue N) {
Old = O;
New = N;
return true;
}
/// ShrinkDemandedConstant - 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);
/// ShrinkDemandedOp - 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,
DebugLoc dl);
};
/// SimplifyDemandedBits - 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;
/// computeMaskedBitsForTargetNode - 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 computeMaskedBitsForTargetNode(const SDValue Op,
const APInt &Mask,
APInt &KnownZero,
APInt &KnownOne,
const SelectionDAG &DAG,
unsigned Depth = 0) const;
/// ComputeNumSignBitsForTargetNode - 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,
unsigned Depth = 0) const;
struct DAGCombinerInfo {
void *DC; // The DAG Combiner object.
bool BeforeLegalize;
bool CalledByLegalizer;
public:
SelectionDAG &DAG;
DAGCombinerInfo(SelectionDAG &dag, bool bl, bool cl, void *dc)
: DC(dc), BeforeLegalize(bl), CalledByLegalizer(cl), DAG(dag) {}
bool isBeforeLegalize() const { return BeforeLegalize; }
bool isCalledByLegalizer() const { return CalledByLegalizer; }
void AddToWorklist(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);
};
/// SimplifySetCC - 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(MVT VT, SDValue N0, SDValue N1,
ISD::CondCode Cond, bool foldBooleans,
DAGCombinerInfo &DCI, DebugLoc dl) const;
/// isGAPlusOffset - Returns true (and the GlobalValue and the offset) if the
/// node is a GlobalAddress + offset.
virtual bool
isGAPlusOffset(SDNode *N, GlobalValue* &GA, int64_t &Offset) const;
/// isConsecutiveLoad - Return true if LD is loading 'Bytes' bytes from a
/// location that is 'Dist' units away from the location that the 'Base' load
/// is loading from.
bool isConsecutiveLoad(LoadSDNode *LD, LoadSDNode *Base, unsigned Bytes,
int Dist, const MachineFrameInfo *MFI) const;
/// PerformDAGCombine - 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;
//===--------------------------------------------------------------------===//
// TargetLowering Configuration Methods - These methods should be invoked by
// the derived class constructor to configure this object for the target.
//
protected:
/// setUsesGlobalOffsetTable - Specify that this target does or doesn't use a
/// GOT for PC-relative code.
void setUsesGlobalOffsetTable(bool V) { UsesGlobalOffsetTable = V; }
/// setShiftAmountType - Describe the type that should be used for shift
/// amounts. This type defaults to the pointer type.
void setShiftAmountType(MVT VT) { ShiftAmountTy = VT; }
/// setBooleanContents - Specify how the target extends the result of a
/// boolean value from i1 to a wider type. See getBooleanContents.
void setBooleanContents(BooleanContent Ty) { BooleanContents = Ty; }
/// setSchedulingPreference - Specify the target scheduling preference.
void setSchedulingPreference(SchedPreference Pref) {
SchedPreferenceInfo = Pref;
}
/// setShiftAmountFlavor - Describe how the target handles out of range shift
/// amounts.
void setShiftAmountFlavor(OutOfRangeShiftAmount OORSA) {
ShiftAmtHandling = OORSA;
}
/// setUseUnderscoreSetJmp - Indicate whether this target prefers to
/// use _setjmp to implement llvm.setjmp or the non _ version.
/// Defaults to false.
void setUseUnderscoreSetJmp(bool Val) {
UseUnderscoreSetJmp = Val;
}
/// setUseUnderscoreLongJmp - Indicate whether this target prefers to
/// use _longjmp to implement llvm.longjmp or the non _ version.
/// Defaults to false.
void setUseUnderscoreLongJmp(bool Val) {
UseUnderscoreLongJmp = Val;
}
/// setStackPointerRegisterToSaveRestore - 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;
}
/// setExceptionPointerRegister - 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;
}
/// setExceptionSelectorRegister - 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;
}
/// SelectIsExpensive - Tells the code generator not to expand operations
/// into sequences that use the select operations if possible.
void setSelectIsExpensive() { SelectIsExpensive = true; }
/// setIntDivIsCheap - 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; }
/// setPow2DivIsCheap - Tells the code generator that it shouldn't generate
/// srl/add/sra for a signed divide by power of two, and let the target handle
/// it.
void setPow2DivIsCheap(bool isCheap = true) { Pow2DivIsCheap = isCheap; }
/// addRegisterClass - 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, TargetRegisterClass *RC) {
assert((unsigned)VT.getSimpleVT() < array_lengthof(RegClassForVT));
AvailableRegClasses.push_back(std::make_pair(VT, RC));
RegClassForVT[VT.getSimpleVT()] = RC;
}
/// computeRegisterProperties - Once all of the register classes are added,
/// this allows us to compute derived properties we expose.
void computeRegisterProperties();
/// setOperationAction - 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((unsigned)VT.getSimpleVT() < sizeof(OpActions[0][0])*8 &&
Op < array_lengthof(OpActions[0]) && "Table isn't big enough!");
unsigned I = (unsigned) VT.getSimpleVT();
unsigned J = I & 31;
I = I >> 5;
OpActions[I][Op] &= ~(uint64_t(3UL) << (J*2));
OpActions[I][Op] |= (uint64_t)Action << (J*2);
}
/// setLoadExtAction - Indicate that the specified load with extension does
/// not work with the with specified type and indicate what to do about it.
void setLoadExtAction(unsigned ExtType, MVT VT,
LegalizeAction Action) {
assert((unsigned)VT.getSimpleVT() < sizeof(LoadExtActions[0])*4 &&
ExtType < array_lengthof(LoadExtActions) &&
"Table isn't big enough!");
LoadExtActions[ExtType] &= ~(uint64_t(3UL) << VT.getSimpleVT()*2);
LoadExtActions[ExtType] |= (uint64_t)Action << VT.getSimpleVT()*2;
}
/// setTruncStoreAction - Indicate that the specified truncating store does
/// not work with the with specified type and indicate what to do about it.
void setTruncStoreAction(MVT ValVT, MVT MemVT,
LegalizeAction Action) {
assert((unsigned)ValVT.getSimpleVT() < array_lengthof(TruncStoreActions) &&
(unsigned)MemVT.getSimpleVT() < sizeof(TruncStoreActions[0])*4 &&
"Table isn't big enough!");
TruncStoreActions[ValVT.getSimpleVT()] &= ~(uint64_t(3UL) <<
MemVT.getSimpleVT()*2);
TruncStoreActions[ValVT.getSimpleVT()] |= (uint64_t)Action <<
MemVT.getSimpleVT()*2;
}
/// setIndexedLoadAction - Indicate that the specified indexed load does or
/// does not work with the with 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((unsigned)VT.getSimpleVT() < MVT::LAST_VALUETYPE &&
IdxMode < array_lengthof(IndexedModeActions[0][0]) &&
"Table isn't big enough!");
IndexedModeActions[(unsigned)VT.getSimpleVT()][0][IdxMode] = (uint8_t)Action;
}
/// setIndexedStoreAction - Indicate that the specified indexed store does or
/// does not work with the with 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((unsigned)VT.getSimpleVT() < MVT::LAST_VALUETYPE &&
IdxMode < array_lengthof(IndexedModeActions[0][1] ) &&
"Table isn't big enough!");
IndexedModeActions[(unsigned)VT.getSimpleVT()][1][IdxMode] = (uint8_t)Action;
}
/// setConvertAction - Indicate that the specified conversion does or does
/// not work with the with specified type and indicate what to do about it.
void setConvertAction(MVT FromVT, MVT ToVT,
LegalizeAction Action) {
assert((unsigned)FromVT.getSimpleVT() < array_lengthof(ConvertActions) &&
(unsigned)ToVT.getSimpleVT() < sizeof(ConvertActions[0])*4 &&
"Table isn't big enough!");
ConvertActions[FromVT.getSimpleVT()] &= ~(uint64_t(3UL) <<
ToVT.getSimpleVT()*2);
ConvertActions[FromVT.getSimpleVT()] |= (uint64_t)Action <<
ToVT.getSimpleVT()*2;
}
/// setCondCodeAction - 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((unsigned)VT.getSimpleVT() < sizeof(CondCodeActions[0])*4 &&
(unsigned)CC < array_lengthof(CondCodeActions) &&
"Table isn't big enough!");
CondCodeActions[(unsigned)CC] &= ~(uint64_t(3UL) << VT.getSimpleVT()*2);
CondCodeActions[(unsigned)CC] |= (uint64_t)Action << VT.getSimpleVT()*2;
}
/// AddPromotedToType - 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.getSimpleVT())] =
DestVT.getSimpleVT();
}
/// addLegalFPImmediate - Indicate that this target can instruction select
/// the specified FP immediate natively.
void addLegalFPImmediate(const APFloat& Imm) {
LegalFPImmediates.push_back(Imm);
}
/// setTargetDAGCombine - 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);
}
/// setJumpBufSize - Set the target's required jmp_buf buffer size (in
/// bytes); default is 200
void setJumpBufSize(unsigned Size) {
JumpBufSize = Size;
}
/// setJumpBufAlignment - Set the target's required jmp_buf buffer
/// alignment (in bytes); default is 0
void setJumpBufAlignment(unsigned Align) {
JumpBufAlignment = Align;
}
/// setIfCvtBlockSizeLimit - Set the target's if-conversion block size
/// limit (in number of instructions); default is 2.
void setIfCvtBlockSizeLimit(unsigned Limit) {
IfCvtBlockSizeLimit = Limit;
}
/// setIfCvtDupBlockSizeLimit - Set the target's block size limit (in number
/// of instructions) to be considered for code duplication during
/// if-conversion; default is 2.
void setIfCvtDupBlockSizeLimit(unsigned Limit) {
IfCvtDupBlockSizeLimit = Limit;
}
/// setPrefLoopAlignment - Set the target's preferred loop alignment. Default
/// alignment is zero, it means the target does not care about loop alignment.
void setPrefLoopAlignment(unsigned Align) {
PrefLoopAlignment = Align;
}
public:
virtual const TargetSubtarget *getSubtarget() {
assert(0 && "Not Implemented");
return NULL; // this is here to silence compiler errors
}
//===--------------------------------------------------------------------===//
// Lowering methods - These methods must be implemented by targets so that
// the SelectionDAGLowering code knows how to lower these.
//
/// LowerArguments - This hook must be implemented to indicate how we should
/// lower the arguments for the specified function, into the specified DAG.
virtual void
LowerArguments(Function &F, SelectionDAG &DAG,
SmallVectorImpl<SDValue>& ArgValues, DebugLoc dl);
/// LowerCallTo - This hook 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.
struct ArgListEntry {
SDValue Node;
const Type* Ty;
bool isSExt : 1;
bool isZExt : 1;
bool isInReg : 1;
bool isSRet : 1;
bool isNest : 1;
bool isByVal : 1;
uint16_t Alignment;
ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
isSRet(false), isNest(false), isByVal(false), Alignment(0) { }
};
typedef std::vector<ArgListEntry> ArgListTy;
virtual std::pair<SDValue, SDValue>
LowerCallTo(SDValue Chain, const Type *RetTy, bool RetSExt, bool RetZExt,
bool isVarArg, bool isInreg, unsigned NumFixedArgs,
unsigned CallingConv, bool isTailCall, SDValue Callee,
ArgListTy &Args, SelectionDAG &DAG, DebugLoc dl);
/// EmitTargetCodeForMemcpy - Emit target-specific code that performs a
/// memcpy. This can be used by targets to provide code sequences for cases
/// that don't fit the target's parameters for simple loads/stores and can be
/// more efficient than using a library call. This function can return a null
/// SDValue if the target declines to use custom code and a different
/// lowering strategy should be used.
///
/// If AlwaysInline is true, the size is constant and the target should not
/// emit any calls and is strongly encouraged to attempt to emit inline code
/// even if it is beyond the usual threshold because this intrinsic is being
/// expanded in a place where calls are not feasible (e.g. within the prologue
/// for another call). If the target chooses to decline an AlwaysInline
/// request here, legalize will resort to using simple loads and stores.
virtual SDValue
EmitTargetCodeForMemcpy(SelectionDAG &DAG, DebugLoc dl,
SDValue Chain,
SDValue Op1, SDValue Op2,
SDValue Op3, unsigned Align,
bool AlwaysInline,
const Value *DstSV, uint64_t DstOff,
const Value *SrcSV, uint64_t SrcOff) {
return SDValue();
}
/// EmitTargetCodeForMemmove - Emit target-specific code that performs a
/// memmove. This can be used by targets to provide code sequences for cases
/// that don't fit the target's parameters for simple loads/stores and can be
/// more efficient than using a library call. This function can return a null
/// SDValue if the target declines to use custom code and a different
/// lowering strategy should be used.
virtual SDValue
EmitTargetCodeForMemmove(SelectionDAG &DAG, DebugLoc dl,
SDValue Chain,
SDValue Op1, SDValue Op2,
SDValue Op3, unsigned Align,
const Value *DstSV, uint64_t DstOff,
const Value *SrcSV, uint64_t SrcOff) {
return SDValue();
}
/// EmitTargetCodeForMemset - Emit target-specific code that performs a
/// memset. This can be used by targets to provide code sequences for cases
/// that don't fit the target's parameters for simple stores and can be more
/// efficient than using a library call. This function can return a null
/// SDValue if the target declines to use custom code and a different
/// lowering strategy should be used.
virtual SDValue
EmitTargetCodeForMemset(SelectionDAG &DAG, DebugLoc dl,
SDValue Chain,
SDValue Op1, SDValue Op2,
SDValue Op3, unsigned Align,
const Value *DstSV, uint64_t DstOff) {
return SDValue();
}
/// LowerOperationWrapper - 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);
/// LowerOperation - 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);
/// ReplaceNodeResults - 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) {
assert(0 && "ReplaceNodeResults not implemented for this target!");
}
/// IsEligibleForTailCallOptimization - Check whether the call is eligible for
/// tail call optimization. Targets which want to do tail call optimization
/// should override this function.
virtual bool IsEligibleForTailCallOptimization(CallSDNode *Call,
SDValue Ret,
SelectionDAG &DAG) const {
return false;
}
/// CheckTailCallReturnConstraints - Check whether CALL node immediatly
/// preceeds the RET node and whether the return uses the result of the node
/// or is a void return. This function can be used by the target to determine
/// eligiblity of tail call optimization.
static bool CheckTailCallReturnConstraints(CallSDNode *TheCall, SDValue Ret);
/// GetPossiblePreceedingTailCall - Get preceeding TailCallNodeOpCode node if
/// it exists. Skip a possible ISD::TokenFactor.
static SDValue GetPossiblePreceedingTailCall(SDValue Chain,
unsigned TailCallNodeOpCode) {
if (Chain.getOpcode() == TailCallNodeOpCode) {
return Chain;
} else if (Chain.getOpcode() == ISD::TokenFactor) {
if (Chain.getNumOperands() &&
Chain.getOperand(0).getOpcode() == TailCallNodeOpCode)
return Chain.getOperand(0);
}
return Chain;
}
/// getTargetNodeName() - This method returns the name of a target specific
/// DAG node.
virtual const char *getTargetNodeName(unsigned Opcode) const;
/// createFastISel - This method returns a target specific FastISel object,
/// or null if the target does not support "fast" ISel.
virtual FastISel *
createFastISel(MachineFunction &,
MachineModuleInfo *, DwarfWriter *,
DenseMap<const Value *, unsigned> &,
DenseMap<const BasicBlock *, MachineBasicBlock *> &,
DenseMap<const AllocaInst *, int> &
#ifndef NDEBUG
, SmallSet<Instruction*, 8> &CatchInfoLost
#endif
) {
return 0;
}
//===--------------------------------------------------------------------===//
// Inline Asm Support hooks
//
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.
};
/// AsmOperandInfo - This contains information for each constraint that we are
/// lowering.
struct AsmOperandInfo : public InlineAsm::ConstraintInfo {
/// ConstraintCode - 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;
/// ConstraintType - Information about the constraint code, e.g. Register,
/// RegisterClass, Memory, Other, Unknown.
TargetLowering::ConstraintType ConstraintType;
/// CallOperandval - 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;
/// ConstraintVT - The ValueType for the operand value.
MVT ConstraintVT;
/// isMatchingInputConstraint - Return true of this is an input operand that
/// is a matching constraint like "4".
bool isMatchingInputConstraint() const;
/// getMatchedOperand - If this is an input matching constraint, this method
/// returns the output operand it matches.
unsigned getMatchedOperand() const;
AsmOperandInfo(const InlineAsm::ConstraintInfo &info)
: InlineAsm::ConstraintInfo(info),
ConstraintType(TargetLowering::C_Unknown),
CallOperandVal(0), ConstraintVT(MVT::Other) {
}
};
/// ComputeConstraintToUse - 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. If hasMemory is true it means one of the asm
/// constraint of the inline asm instruction being processed is 'm'.
virtual void ComputeConstraintToUse(AsmOperandInfo &OpInfo,
SDValue Op,
bool hasMemory,
SelectionDAG *DAG = 0) const;
/// getConstraintType - Given a constraint, return the type of constraint it
/// is for this target.
virtual ConstraintType getConstraintType(const std::string &Constraint) const;
/// getRegClassForInlineAsmConstraint - Given a constraint letter (e.g. "r"),
/// return a list of registers that can be used to satisfy the constraint.
/// This should only be used for C_RegisterClass constraints.
virtual std::vector<unsigned>
getRegClassForInlineAsmConstraint(const std::string &Constraint,
MVT VT) const;
/// getRegForInlineAsmConstraint - 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;
/// LowerXConstraint - 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(MVT ConstraintVT) const;
/// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
/// vector. If it is invalid, don't add anything to Ops. If hasMemory is true
/// it means one of the asm constraint of the inline asm instruction being
/// processed is 'm'.
virtual void LowerAsmOperandForConstraint(SDValue Op, char ConstraintLetter,
bool hasMemory,
std::vector<SDValue> &Ops,
SelectionDAG &DAG) const;
//===--------------------------------------------------------------------===//
// Scheduler hooks
//
// EmitInstrWithCustomInserter - This method should be implemented by targets
// that mark instructions with the 'usesCustomDAGSchedInserter' 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 the scheduler passes ownership of it to this method.
virtual MachineBasicBlock *EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *MBB) const;
//===--------------------------------------------------------------------===//
// Addressing mode description hooks (used by LSR etc).
//
/// AddrMode - 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(0), BaseOffs(0), HasBaseReg(false), Scale(0) {}
};
/// isLegalAddressingMode - 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, const Type *Ty) const;
/// isTruncateFree - 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(const Type *Ty1, const Type *Ty2) const {
return false;
}
virtual bool isTruncateFree(MVT VT1, MVT VT2) const {
return false;
}
/// isZExtFree - Return true if any actual instruction that defines a
/// value of type Ty1 implicit 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(const Type *Ty1, const Type *Ty2) const {
return false;
}
virtual bool isZExtFree(MVT VT1, MVT VT2) const {
return false;
}
/// isNarrowingProfitable - 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(MVT VT1, MVT VT2) const {
return false;
}
//===--------------------------------------------------------------------===//
// Div utility functions
//
SDValue BuildSDIV(SDNode *N, SelectionDAG &DAG,
std::vector<SDNode*>* Created) const;
SDValue BuildUDIV(SDNode *N, SelectionDAG &DAG,
std::vector<SDNode*>* Created) const;
//===--------------------------------------------------------------------===//
// Runtime Library hooks
//
/// setLibcallName - Rename the default libcall routine name for the specified
/// libcall.
void setLibcallName(RTLIB::Libcall Call, const char *Name) {
LibcallRoutineNames[Call] = Name;
}
/// getLibcallName - Get the libcall routine name for the specified libcall.
///
const char *getLibcallName(RTLIB::Libcall Call) const {
return LibcallRoutineNames[Call];
}
/// setCmpLibcallCC - 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;
}
/// getCmpLibcallCC - 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];
}
private:
TargetMachine &TM;
const TargetData *TD;
/// PointerTy - The type to use for pointers, usually i32 or i64.
///
MVT PointerTy;
/// IsLittleEndian - True if this is a little endian target.
///
bool IsLittleEndian;
/// UsesGlobalOffsetTable - True if this target uses a GOT for PIC codegen.
///
bool UsesGlobalOffsetTable;
/// SelectIsExpensive - Tells the code generator not to expand operations
/// into sequences that use the select operations if possible.
bool SelectIsExpensive;
/// IntDivIsCheap - 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;
/// Pow2DivIsCheap - Tells the code generator that it shouldn't generate
/// srl/add/sra for a signed divide by power of two, and let the target handle
/// it.
bool Pow2DivIsCheap;
/// UseUnderscoreSetJmp - This target prefers to use _setjmp to implement
/// llvm.setjmp. Defaults to false.
bool UseUnderscoreSetJmp;
/// UseUnderscoreLongJmp - This target prefers to use _longjmp to implement
/// llvm.longjmp. Defaults to false.
bool UseUnderscoreLongJmp;
/// ShiftAmountTy - The type to use for shift amounts, usually i8 or whatever
/// PointerTy is.
MVT ShiftAmountTy;
OutOfRangeShiftAmount ShiftAmtHandling;
/// BooleanContents - Information about the contents of the high-bits in
/// boolean values held in a type wider than i1. See getBooleanContents.
BooleanContent BooleanContents;
/// SchedPreferenceInfo - The target scheduling preference: shortest possible
/// total cycles or lowest register usage.
SchedPreference SchedPreferenceInfo;
/// JumpBufSize - The size, in bytes, of the target's jmp_buf buffers
unsigned JumpBufSize;
/// JumpBufAlignment - The alignment, in bytes, of the target's jmp_buf
/// buffers
unsigned JumpBufAlignment;
/// IfCvtBlockSizeLimit - The maximum allowed size for a block to be
/// if-converted.
unsigned IfCvtBlockSizeLimit;
/// IfCvtDupBlockSizeLimit - The maximum allowed size for a block to be
/// duplicated during if-conversion.
unsigned IfCvtDupBlockSizeLimit;
/// PrefLoopAlignment - The perferred loop alignment.
///
unsigned PrefLoopAlignment;
/// StackPointerRegisterToSaveRestore - If set to a physical register, this
/// specifies the register that llvm.savestack/llvm.restorestack should save
/// and restore.
unsigned StackPointerRegisterToSaveRestore;
/// ExceptionPointerRegister - If set to a physical register, this specifies
/// the register that receives the exception address on entry to a landing
/// pad.
unsigned ExceptionPointerRegister;
/// ExceptionSelectorRegister - If set to a physical register, this specifies
/// the register that receives the exception typeid on entry to a landing
/// pad.
unsigned ExceptionSelectorRegister;
/// RegClassForVT - This indicates the default register class to use for
/// each ValueType the target supports natively.
TargetRegisterClass *RegClassForVT[MVT::LAST_VALUETYPE];
unsigned char NumRegistersForVT[MVT::LAST_VALUETYPE];
MVT RegisterTypeForVT[MVT::LAST_VALUETYPE];
/// TransformToType - 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];
/// OpActions - 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.
/// This array is accessed using VT.getSimpleVT(), so it is subject to
/// the MVT::MAX_ALLOWED_VALUETYPE * 2 bits.
uint64_t OpActions[MVT::MAX_ALLOWED_VALUETYPE/(sizeof(uint64_t)*4)][ISD::BUILTIN_OP_END];
/// LoadExtActions - For each load of load extension type and each value type,
/// keep a LegalizeAction that indicates how instruction selection should deal
/// with the load.
uint64_t LoadExtActions[ISD::LAST_LOADEXT_TYPE];
/// TruncStoreActions - For each truncating store, keep a LegalizeAction that
/// indicates how instruction selection should deal with the store.
uint64_t TruncStoreActions[MVT::LAST_VALUETYPE];
/// IndexedModeActions - 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 now the value_type for the reference. The second
/// dimension is the load [0] vs. store[1]. The third dimension
/// represents the various modes for load store.
uint8_t IndexedModeActions[MVT::LAST_VALUETYPE][2][ISD::LAST_INDEXED_MODE];
/// ConvertActions - For each conversion from source type to destination type,
/// keep a LegalizeAction that indicates how instruction selection should
/// deal with the conversion.
/// Currently, this is used only for floating->floating conversions
/// (FP_EXTEND and FP_ROUND).
uint64_t ConvertActions[MVT::LAST_VALUETYPE];
/// CondCodeActions - For each condition code (ISD::CondCode) keep a
/// LegalizeAction that indicates how instruction selection should
/// deal with the condition code.
uint64_t CondCodeActions[ISD::SETCC_INVALID];
ValueTypeActionImpl ValueTypeActions;
std::vector<APFloat> LegalFPImmediates;
std::vector<std::pair<MVT, TargetRegisterClass*> > AvailableRegClasses;
/// TargetDAGCombineArray - 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];
/// PromoteToType - 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;
/// LibcallRoutineNames - Stores the name each libcall.
///
const char *LibcallRoutineNames[RTLIB::UNKNOWN_LIBCALL];
/// CmpLibcallCCs - 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];
protected:
/// 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.
/// @brief Specify maximum number of store instructions per memset call.
unsigned maxStoresPerMemset;
/// 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.
/// @brief Specify maximum bytes of store instructions per memcpy call.
unsigned maxStoresPerMemcpy;
/// 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.
/// @brief Specify maximum bytes of store instructions per memmove call.
unsigned maxStoresPerMemmove;
/// This field specifies whether the target machine permits unaligned memory
/// accesses. This is used, for example, to determine the size of store
/// operations when copying small arrays and other similar tasks.
/// @brief Indicate whether the target permits unaligned memory accesses.
bool allowUnalignedMemoryAccesses;
/// This field specifies whether the target can benefit from code placement
/// optimization.
bool benefitFromCodePlacementOpt;
};
} // end llvm namespace
#endif
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