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cc41586b9d
llvm-6502/include/llvm/Target/TargetLowering.h
Evan Cheng cc41586b9d Much improved pic jumptable codegen: 
Then:
        call    "L1$pb"
"L1$pb":
        popl    %eax
		...
LBB1_1: # entry
        imull   $4, %ecx, %ecx
        leal    LJTI1_0-"L1$pb"(%eax), %edx
        addl    LJTI1_0-"L1$pb"(%ecx,%eax), %edx
        jmpl    *%edx

        .align  2
        .set L1_0_set_3,LBB1_3-LJTI1_0
        .set L1_0_set_2,LBB1_2-LJTI1_0
        .set L1_0_set_5,LBB1_5-LJTI1_0
        .set L1_0_set_4,LBB1_4-LJTI1_0
LJTI1_0:
        .long    L1_0_set_3
        .long    L1_0_set_2

Now:
        call    "L1$pb"
"L1$pb":
        popl    %eax
		...
LBB1_1: # entry
        addl    LJTI1_0-"L1$pb"(%eax,%ecx,4), %eax
        jmpl    *%eax

		.align  2
		.set L1_0_set_3,LBB1_3-"L1$pb"
		.set L1_0_set_2,LBB1_2-"L1$pb"
		.set L1_0_set_5,LBB1_5-"L1$pb"
		.set L1_0_set_4,LBB1_4-"L1$pb"
LJTI1_0:
        .long    L1_0_set_3
        .long    L1_0_set_2


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43924 91177308-0d34-0410-b5e6-96231b3b80d8
2007-11-09 01:32:10 +00:00

1269 lines
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//===-- llvm/Target/TargetLowering.h - Target Lowering Info -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/STLExtras.h"
#include <map>
#include <vector>
namespace llvm {
class Value;
class Function;
class TargetMachine;
class TargetData;
class TargetRegisterClass;
class SDNode;
class SDOperand;
class SelectionDAG;
class MachineBasicBlock;
class MachineInstr;
class VectorType;
class TargetSubtarget;
//===----------------------------------------------------------------------===//
/// 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 SetCCResultValue {
UndefinedSetCCResult, // SetCC returns a garbage/unknown extend.
ZeroOrOneSetCCResult, // SetCC returns a zero extended result.
ZeroOrNegativeOneSetCCResult // SetCC returns a sign extended result.
};
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 isLittleEndian() const { return IsLittleEndian; }
MVT::ValueType getPointerTy() const { return PointerTy; }
MVT::ValueType 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; }
/// getSetCCResultTy - Return the ValueType of the result of setcc operations.
///
MVT::ValueType getSetCCResultTy() const { return SetCCResultTy; }
/// getSetCCResultContents - For targets without boolean registers, this flag
/// returns information about the contents of the high-bits in the setcc
/// result register.
SetCCResultValue getSetCCResultContents() const { return SetCCResultContents;}
/// 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::ValueType VT) const {
assert(!MVT::isExtendedVT(VT));
TargetRegisterClass *RC = RegClassForVT[VT];
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::ValueType VT) const {
return !MVT::isExtendedVT(VT) && RegClassForVT[VT] != 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)".
uint32_t ValueTypeActions[2];
public:
ValueTypeActionImpl() {
ValueTypeActions[0] = ValueTypeActions[1] = 0;
}
ValueTypeActionImpl(const ValueTypeActionImpl &RHS) {
ValueTypeActions[0] = RHS.ValueTypeActions[0];
ValueTypeActions[1] = RHS.ValueTypeActions[1];
}
LegalizeAction getTypeAction(MVT::ValueType VT) const {
if (MVT::isExtendedVT(VT)) {
if (MVT::isVector(VT)) return Expand;
if (MVT::isInteger(VT))
// First promote to a power-of-two size, then expand if necessary.
return VT == MVT::RoundIntegerType(VT) ? Expand : Promote;
assert(0 && "Unsupported extended type!");
}
return (LegalizeAction)((ValueTypeActions[VT>>4] >> ((2*VT) & 31)) & 3);
}
void setTypeAction(MVT::ValueType VT, LegalizeAction Action) {
assert(!MVT::isExtendedVT(VT));
assert(unsigned(VT >> 4) < array_lengthof(ValueTypeActions));
ValueTypeActions[VT>>4] |= Action << ((VT*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::ValueType 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::ValueType getTypeToTransformTo(MVT::ValueType VT) const {
if (!MVT::isExtendedVT(VT)) {
MVT::ValueType NVT = TransformToType[VT];
assert(getTypeAction(NVT) != Promote &&
"Promote may not follow Expand or Promote");
return NVT;
}
if (MVT::isVector(VT))
return MVT::getVectorType(MVT::getVectorElementType(VT),
MVT::getVectorNumElements(VT) / 2);
if (MVT::isInteger(VT)) {
MVT::ValueType NVT = MVT::RoundIntegerType(VT);
if (NVT == VT)
// Size is a power of two - expand to half the size.
return MVT::getIntegerType(MVT::getSizeInBits(VT) / 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!");
}
/// 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::ValueType getTypeToExpandTo(MVT::ValueType VT) const {
assert(!MVT::isVector(VT));
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::ValueType VT,
MVT::ValueType &IntermediateVT,
unsigned &NumIntermediates,
MVT::ValueType &RegisterVT) 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(SDOperand Mask, MVT::ValueType 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(std::vector<SDOperand> &BVOps,
MVT::ValueType EVT,
SelectionDAG &DAG) 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::ValueType VT) const {
if (MVT::isExtendedVT(VT)) return Expand;
return (LegalizeAction)((OpActions[Op] >> (2*VT)) & 3);
}
/// isOperationLegal - Return true if the specified operation is legal on this
/// target.
bool isOperationLegal(unsigned Op, MVT::ValueType VT) const {
return getOperationAction(Op, VT) == Legal ||
getOperationAction(Op, VT) == Custom;
}
/// getLoadXAction - 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 getLoadXAction(unsigned LType, MVT::ValueType VT) const {
if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
return (LegalizeAction)((LoadXActions[LType] >> (2*VT)) & 3);
}
/// isLoadXLegal - Return true if the specified load with extension is legal
/// on this target.
bool isLoadXLegal(unsigned LType, MVT::ValueType VT) const {
return getLoadXAction(LType, VT) == Legal ||
getLoadXAction(LType, VT) == Custom;
}
/// getStoreXAction - 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 getStoreXAction(MVT::ValueType VT) const {
if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
return (LegalizeAction)((StoreXActions >> (2*VT)) & 3);
}
/// isStoreXLegal - Return true if the specified store with truncation is
/// legal on this target.
bool isStoreXLegal(MVT::ValueType VT) const {
return getStoreXAction(VT) == Legal || getStoreXAction(VT) == 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::ValueType VT) const {
if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
return (LegalizeAction)((IndexedModeActions[0][IdxMode] >> (2*VT)) & 3);
}
/// isIndexedLoadLegal - Return true if the specified indexed load is legal
/// on this target.
bool isIndexedLoadLegal(unsigned IdxMode, MVT::ValueType VT) const {
return 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::ValueType VT) const {
if (MVT::isExtendedVT(VT)) return getTypeAction(VT);
return (LegalizeAction)((IndexedModeActions[1][IdxMode] >> (2*VT)) & 3);
}
/// isIndexedStoreLegal - Return true if the specified indexed load is legal
/// on this target.
bool isIndexedStoreLegal(unsigned IdxMode, MVT::ValueType VT) const {
return 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::ValueType FromVT, MVT::ValueType ToVT) const {
assert(FromVT < MVT::LAST_VALUETYPE && ToVT < 32 &&
"Table isn't big enough!");
return (LegalizeAction)((ConvertActions[FromVT] >> (2*ToVT)) & 3);
}
/// isConvertLegal - Return true if the specified conversion is legal
/// on this target.
bool isConvertLegal(MVT::ValueType FromVT, MVT::ValueType ToVT) const {
return getConvertAction(FromVT, ToVT) == Legal ||
getConvertAction(FromVT, ToVT) == Custom;
}
/// getTypeToPromoteTo - If the action for this operation is to promote, this
/// method returns the ValueType to promote to.
MVT::ValueType getTypeToPromoteTo(unsigned Op, MVT::ValueType 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::ValueType>,
MVT::ValueType>::const_iterator PTTI =
PromoteToType.find(std::make_pair(Op, VT));
if (PTTI != PromoteToType.end()) return PTTI->second;
assert((MVT::isInteger(VT) || MVT::isFloatingPoint(VT)) &&
"Cannot autopromote this type, add it with AddPromotedToType.");
MVT::ValueType NVT = VT;
do {
NVT = (MVT::ValueType)(NVT+1);
assert(MVT::isInteger(NVT) == MVT::isInteger(VT) && NVT != MVT::isVoid &&
"Didn't find type to promote to!");
} while (!isTypeLegal(NVT) ||
getOperationAction(Op, NVT) == Promote);
return NVT;
}
/// getValueType - Return the MVT::ValueType 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::ValueType getValueType(const Type *Ty, bool AllowUnknown = false) const {
MVT::ValueType VT = MVT::getValueType(Ty, AllowUnknown);
return VT == MVT::iPTR ? PointerTy : VT;
}
/// getRegisterType - Return the type of registers that this ValueType will
/// eventually require.
MVT::ValueType getRegisterType(MVT::ValueType VT) const {
if (!MVT::isExtendedVT(VT))
return RegisterTypeForVT[VT];
if (MVT::isVector(VT)) {
MVT::ValueType VT1, RegisterVT;
unsigned NumIntermediates;
(void)getVectorTypeBreakdown(VT, VT1, NumIntermediates, RegisterVT);
return RegisterVT;
}
assert(0 && "Unsupported extended type!");
}
/// 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.
unsigned getNumRegisters(MVT::ValueType VT) const {
if (!MVT::isExtendedVT(VT))
return NumRegistersForVT[VT];
if (MVT::isVector(VT)) {
MVT::ValueType VT1, VT2;
unsigned NumIntermediates;
return getVectorTypeBreakdown(VT, VT1, NumIntermediates, VT2);
}
assert(0 && "Unsupported extended type!");
}
/// hasTargetDAGCombine - If true, the target has custom DAG combine
/// transformations that it can perform for the specified node.
bool hasTargetDAGCombine(ISD::NodeType NT) const {
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;
}
/// 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.
virtual 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.
virtual unsigned getIfCvtDupBlockSizeLimit() const {
return IfCvtDupBlockSizeLimit;
}
/// 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, SDOperand &Base,
SDOperand &Offset,
ISD::MemIndexedMode &AM,
SelectionDAG &DAG) {
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,
SDOperand &Base, SDOperand &Offset,
ISD::MemIndexedMode &AM,
SelectionDAG &DAG) {
return false;
}
/// getPICJumpTableRelocaBase - Returns relocation base for the given PIC
/// jumptable.
virtual SDOperand getPICJumpTableRelocBase(SDOperand Table,
SelectionDAG &DAG) const;
//===--------------------------------------------------------------------===//
// TargetLowering Optimization Methods
//
/// TargetLoweringOpt - A convenience struct that encapsulates a DAG, and two
/// SDOperands for returning information from TargetLowering to its clients
/// that want to combine
struct TargetLoweringOpt {
SelectionDAG &DAG;
SDOperand Old;
SDOperand New;
explicit TargetLoweringOpt(SelectionDAG &InDAG) : DAG(InDAG) {}
bool CombineTo(SDOperand O, SDOperand 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(SDOperand Op, uint64_t Demanded);
};
/// 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(SDOperand Op, uint64_t DemandedMask,
uint64_t &KnownZero, uint64_t &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 SDOperand Op,
uint64_t Mask,
uint64_t &KnownZero,
uint64_t &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(SDOperand 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);
SDOperand CombineTo(SDNode *N, const std::vector<SDOperand> &To);
SDOperand CombineTo(SDNode *N, SDOperand Res);
SDOperand CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1);
};
/// SimplifySetCC - Try to simplify a setcc built with the specified operands
/// and cc. If it is unable to simplify it, return a null SDOperand.
SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1,
ISD::CondCode Cond, bool foldBooleans,
DAGCombinerInfo &DCI) 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:
/// SDOperand.Val == 0 - No change was made
/// SDOperand.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 SDOperand 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::ValueType VT) { ShiftAmountTy = VT; }
/// setSetCCResultType - Describe the type that shoudl be used as the result
/// of a setcc operation. This defaults to the pointer type.
void setSetCCResultType(MVT::ValueType VT) { SetCCResultTy = VT; }
/// setSetCCResultContents - Specify how the target extends the result of a
/// setcc operation in a register.
void setSetCCResultContents(SetCCResultValue Ty) { SetCCResultContents = 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::ValueType VT, TargetRegisterClass *RC) {
assert(!MVT::isExtendedVT(VT));
AvailableRegClasses.push_back(std::make_pair(VT, RC));
RegClassForVT[VT] = 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::ValueType VT,
LegalizeAction Action) {
assert(VT < 32 && Op < array_lengthof(OpActions) &&
"Table isn't big enough!");
OpActions[Op] &= ~(uint64_t(3UL) << VT*2);
OpActions[Op] |= (uint64_t)Action << VT*2;
}
/// setLoadXAction - Indicate that the specified load with extension does not
/// work with the with specified type and indicate what to do about it.
void setLoadXAction(unsigned ExtType, MVT::ValueType VT,
LegalizeAction Action) {
assert(VT < 32 && ExtType < array_lengthof(LoadXActions) &&
"Table isn't big enough!");
LoadXActions[ExtType] &= ~(uint64_t(3UL) << VT*2);
LoadXActions[ExtType] |= (uint64_t)Action << VT*2;
}
/// setStoreXAction - Indicate that the specified store with truncation does
/// not work with the with specified type and indicate what to do about it.
void setStoreXAction(MVT::ValueType VT, LegalizeAction Action) {
assert(VT < 32 && "Table isn't big enough!");
StoreXActions &= ~(uint64_t(3UL) << VT*2);
StoreXActions |= (uint64_t)Action << VT*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::ValueType VT,
LegalizeAction Action) {
assert(VT < 32 && IdxMode <
array_lengthof(IndexedModeActions[0]) &&
"Table isn't big enough!");
IndexedModeActions[0][IdxMode] &= ~(uint64_t(3UL) << VT*2);
IndexedModeActions[0][IdxMode] |= (uint64_t)Action << VT*2;
}
/// 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::ValueType VT,
LegalizeAction Action) {
assert(VT < 32 && IdxMode <
array_lengthof(IndexedModeActions[1]) &&
"Table isn't big enough!");
IndexedModeActions[1][IdxMode] &= ~(uint64_t(3UL) << VT*2);
IndexedModeActions[1][IdxMode] |= (uint64_t)Action << VT*2;
}
/// 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::ValueType FromVT, MVT::ValueType ToVT,
LegalizeAction Action) {
assert(FromVT < MVT::LAST_VALUETYPE && ToVT < 32 &&
"Table isn't big enough!");
ConvertActions[FromVT] &= ~(uint64_t(3UL) << ToVT*2);
ConvertActions[FromVT] |= (uint64_t)Action << ToVT*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::ValueType OrigVT,
MVT::ValueType DestVT) {
PromoteToType[std::make_pair(Opc, OrigVT)] = DestVT;
}
/// 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) {
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;
}
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 std::vector<SDOperand>
LowerArguments(Function &F, SelectionDAG &DAG);
/// 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 {
SDOperand Node;
const Type* Ty;
bool isSExt;
bool isZExt;
bool isInReg;
bool isSRet;
bool isNest;
bool isByVal;
ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
isSRet(false), isNest(false), isByVal(false) { }
};
typedef std::vector<ArgListEntry> ArgListTy;
virtual std::pair<SDOperand, SDOperand>
LowerCallTo(SDOperand Chain, const Type *RetTy, bool RetTyIsSigned,
bool isVarArg, unsigned CallingConv, bool isTailCall,
SDOperand Callee, ArgListTy &Args, SelectionDAG &DAG);
virtual SDOperand LowerMEMCPY(SDOperand Op, SelectionDAG &DAG);
virtual SDOperand LowerMEMCPYCall(SDOperand Chain, SDOperand Dest,
SDOperand Source, SDOperand Count,
SelectionDAG &DAG);
virtual SDOperand LowerMEMCPYInline(SDOperand Chain, SDOperand Dest,
SDOperand Source, unsigned Size,
unsigned Align, SelectionDAG &DAG) {
assert(0 && "Not Implemented");
return SDOperand(); // this is here to silence compiler errors
}
/// 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 SDOperand LowerOperation(SDOperand Op, SelectionDAG &DAG);
/// ExpandOperationResult - This callback is invoked for operations that are
/// unsupported by the target, which are registered to use 'custom' lowering,
/// and whose result type needs to be expanded.
///
/// If the target has no operations that require custom lowering, it need not
/// implement this. The default implementation of this aborts.
virtual std::pair<SDOperand,SDOperand>
ExpandOperationResult(SDNode *N, SelectionDAG &DAG);
/// 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(SDOperand Call,
SDOperand Ret,
SelectionDAG &DAG) const {
return false;
}
/// CustomPromoteOperation - This callback is invoked for operations that are
/// unsupported by the target, are registered to use 'custom' lowering, and
/// whose type needs to be promoted.
virtual SDOperand CustomPromoteOperation(SDOperand Op, SelectionDAG &DAG);
/// getTargetNodeName() - This method returns the name of a target specific
/// DAG node.
virtual const char *getTargetNodeName(unsigned Opcode) const;
//===--------------------------------------------------------------------===//
// Inline Asm Support hooks
//
enum ConstraintType {
C_Register, // Constraint represents a single register.
C_RegisterClass, // Constraint represents one or more registers.
C_Memory, // Memory constraint.
C_Other, // Something else.
C_Unknown // Unsupported constraint.
};
/// 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::ValueType 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::ValueType VT) const;
/// LowerAsmOperandForConstraint - Lower the specified operand into the Ops
/// vector. If it is invalid, don't add anything to Ops.
virtual void LowerAsmOperandForConstraint(SDOperand Op, char ConstraintLetter,
std::vector<SDOperand> &Ops,
SelectionDAG &DAG);
//===--------------------------------------------------------------------===//
// Scheduler hooks
//
// InsertAtEndOfBasicBlock - 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 *InsertAtEndOfBasicBlock(MachineInstr *MI,
MachineBasicBlock *MBB);
//===--------------------------------------------------------------------===//
// 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.
/// 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::ValueType VT1, MVT::ValueType VT2) const {
return false;
}
//===--------------------------------------------------------------------===//
// Div utility functions
//
SDOperand BuildSDIV(SDNode *N, SelectionDAG &DAG,
std::vector<SDNode*>* Created) const;
SDOperand 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;
/// IsLittleEndian - True if this is a little endian target.
///
bool IsLittleEndian;
/// PointerTy - The type to use for pointers, usually i32 or i64.
///
MVT::ValueType PointerTy;
/// UsesGlobalOffsetTable - True if this target uses a GOT for PIC codegen.
///
bool UsesGlobalOffsetTable;
/// ShiftAmountTy - The type to use for shift amounts, usually i8 or whatever
/// PointerTy is.
MVT::ValueType ShiftAmountTy;
OutOfRangeShiftAmount ShiftAmtHandling;
/// 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;
/// SetCCResultTy - The type that SetCC operations use. This defaults to the
/// PointerTy.
MVT::ValueType SetCCResultTy;
/// SetCCResultContents - Information about the contents of the high-bits in
/// the result of a setcc comparison operation.
SetCCResultValue SetCCResultContents;
/// SchedPreferenceInfo - The target scheduling preference: shortest possible
/// total cycles or lowest register usage.
SchedPreference SchedPreferenceInfo;
/// 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;
/// 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;
/// 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::ValueType 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::ValueType 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.
uint64_t OpActions[156];
/// LoadXActions - 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 LoadXActions[ISD::LAST_LOADX_TYPE];
/// StoreXActions - For each store with truncation of each value type, keep a
/// LegalizeAction that indicates how instruction selection should deal with
/// the store.
uint64_t StoreXActions;
/// 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.
uint64_t IndexedModeActions[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];
ValueTypeActionImpl ValueTypeActions;
std::vector<APFloat> LegalFPImmediates;
std::vector<std::pair<MVT::ValueType,
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[156/(sizeof(unsigned char)*8)];
/// 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::ValueType>, MVT::ValueType> 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;
};
} // end llvm namespace
#endif
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