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llvm-6502/lib/CodeGen/SelectionDAG/TargetLowering.cpp
Dan Gohman 2d74a318de Tidy up ValueType names in comments. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37688 91177308-0d34-0410-b5e6-96231b3b80d8
2007-06-21 14:48:26 +00:00

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//===-- TargetLowering.cpp - Implement the TargetLowering class -----------===//
//
// 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 implements the TargetLowering class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/DerivedTypes.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
/// InitLibcallNames - Set default libcall names.
///
static void InitLibcallNames(const char **Names) {
Names[RTLIB::SHL_I32] = "__ashlsi3";
Names[RTLIB::SHL_I64] = "__ashldi3";
Names[RTLIB::SRL_I32] = "__lshrsi3";
Names[RTLIB::SRL_I64] = "__lshrdi3";
Names[RTLIB::SRA_I32] = "__ashrsi3";
Names[RTLIB::SRA_I64] = "__ashrdi3";
Names[RTLIB::MUL_I32] = "__mulsi3";
Names[RTLIB::MUL_I64] = "__muldi3";
Names[RTLIB::SDIV_I32] = "__divsi3";
Names[RTLIB::SDIV_I64] = "__divdi3";
Names[RTLIB::UDIV_I32] = "__udivsi3";
Names[RTLIB::UDIV_I64] = "__udivdi3";
Names[RTLIB::SREM_I32] = "__modsi3";
Names[RTLIB::SREM_I64] = "__moddi3";
Names[RTLIB::UREM_I32] = "__umodsi3";
Names[RTLIB::UREM_I64] = "__umoddi3";
Names[RTLIB::NEG_I32] = "__negsi2";
Names[RTLIB::NEG_I64] = "__negdi2";
Names[RTLIB::ADD_F32] = "__addsf3";
Names[RTLIB::ADD_F64] = "__adddf3";
Names[RTLIB::SUB_F32] = "__subsf3";
Names[RTLIB::SUB_F64] = "__subdf3";
Names[RTLIB::MUL_F32] = "__mulsf3";
Names[RTLIB::MUL_F64] = "__muldf3";
Names[RTLIB::DIV_F32] = "__divsf3";
Names[RTLIB::DIV_F64] = "__divdf3";
Names[RTLIB::REM_F32] = "fmodf";
Names[RTLIB::REM_F64] = "fmod";
Names[RTLIB::NEG_F32] = "__negsf2";
Names[RTLIB::NEG_F64] = "__negdf2";
Names[RTLIB::POWI_F32] = "__powisf2";
Names[RTLIB::POWI_F64] = "__powidf2";
Names[RTLIB::SQRT_F32] = "sqrtf";
Names[RTLIB::SQRT_F64] = "sqrt";
Names[RTLIB::SIN_F32] = "sinf";
Names[RTLIB::SIN_F64] = "sin";
Names[RTLIB::COS_F32] = "cosf";
Names[RTLIB::COS_F64] = "cos";
Names[RTLIB::FPEXT_F32_F64] = "__extendsfdf2";
Names[RTLIB::FPROUND_F64_F32] = "__truncdfsf2";
Names[RTLIB::FPTOSINT_F32_I32] = "__fixsfsi";
Names[RTLIB::FPTOSINT_F32_I64] = "__fixsfdi";
Names[RTLIB::FPTOSINT_F64_I32] = "__fixdfsi";
Names[RTLIB::FPTOSINT_F64_I64] = "__fixdfdi";
Names[RTLIB::FPTOUINT_F32_I32] = "__fixunssfsi";
Names[RTLIB::FPTOUINT_F32_I64] = "__fixunssfdi";
Names[RTLIB::FPTOUINT_F64_I32] = "__fixunsdfsi";
Names[RTLIB::FPTOUINT_F64_I64] = "__fixunsdfdi";
Names[RTLIB::SINTTOFP_I32_F32] = "__floatsisf";
Names[RTLIB::SINTTOFP_I32_F64] = "__floatsidf";
Names[RTLIB::SINTTOFP_I64_F32] = "__floatdisf";
Names[RTLIB::SINTTOFP_I64_F64] = "__floatdidf";
Names[RTLIB::UINTTOFP_I32_F32] = "__floatunsisf";
Names[RTLIB::UINTTOFP_I32_F64] = "__floatunsidf";
Names[RTLIB::UINTTOFP_I64_F32] = "__floatundisf";
Names[RTLIB::UINTTOFP_I64_F64] = "__floatundidf";
Names[RTLIB::OEQ_F32] = "__eqsf2";
Names[RTLIB::OEQ_F64] = "__eqdf2";
Names[RTLIB::UNE_F32] = "__nesf2";
Names[RTLIB::UNE_F64] = "__nedf2";
Names[RTLIB::OGE_F32] = "__gesf2";
Names[RTLIB::OGE_F64] = "__gedf2";
Names[RTLIB::OLT_F32] = "__ltsf2";
Names[RTLIB::OLT_F64] = "__ltdf2";
Names[RTLIB::OLE_F32] = "__lesf2";
Names[RTLIB::OLE_F64] = "__ledf2";
Names[RTLIB::OGT_F32] = "__gtsf2";
Names[RTLIB::OGT_F64] = "__gtdf2";
Names[RTLIB::UO_F32] = "__unordsf2";
Names[RTLIB::UO_F64] = "__unorddf2";
Names[RTLIB::O_F32] = "__unordsf2";
Names[RTLIB::O_F64] = "__unorddf2";
}
/// InitCmpLibcallCCs - Set default comparison libcall CC.
///
static void InitCmpLibcallCCs(ISD::CondCode *CCs) {
memset(CCs, ISD::SETCC_INVALID, sizeof(ISD::CondCode)*RTLIB::UNKNOWN_LIBCALL);
CCs[RTLIB::OEQ_F32] = ISD::SETEQ;
CCs[RTLIB::OEQ_F64] = ISD::SETEQ;
CCs[RTLIB::UNE_F32] = ISD::SETNE;
CCs[RTLIB::UNE_F64] = ISD::SETNE;
CCs[RTLIB::OGE_F32] = ISD::SETGE;
CCs[RTLIB::OGE_F64] = ISD::SETGE;
CCs[RTLIB::OLT_F32] = ISD::SETLT;
CCs[RTLIB::OLT_F64] = ISD::SETLT;
CCs[RTLIB::OLE_F32] = ISD::SETLE;
CCs[RTLIB::OLE_F64] = ISD::SETLE;
CCs[RTLIB::OGT_F32] = ISD::SETGT;
CCs[RTLIB::OGT_F64] = ISD::SETGT;
CCs[RTLIB::UO_F32] = ISD::SETNE;
CCs[RTLIB::UO_F64] = ISD::SETNE;
CCs[RTLIB::O_F32] = ISD::SETEQ;
CCs[RTLIB::O_F64] = ISD::SETEQ;
}
TargetLowering::TargetLowering(TargetMachine &tm)
: TM(tm), TD(TM.getTargetData()) {
assert(ISD::BUILTIN_OP_END <= 156 &&
"Fixed size array in TargetLowering is not large enough!");
// All operations default to being supported.
memset(OpActions, 0, sizeof(OpActions));
memset(LoadXActions, 0, sizeof(LoadXActions));
memset(&StoreXActions, 0, sizeof(StoreXActions));
// Initialize all indexed load / store to expand.
for (unsigned VT = 0; VT != (unsigned)MVT::LAST_VALUETYPE; ++VT) {
for (unsigned IM = (unsigned)ISD::PRE_INC;
IM != (unsigned)ISD::LAST_INDEXED_MODE; ++IM) {
setIndexedLoadAction(IM, (MVT::ValueType)VT, Expand);
setIndexedStoreAction(IM, (MVT::ValueType)VT, Expand);
}
}
IsLittleEndian = TD->isLittleEndian();
UsesGlobalOffsetTable = false;
ShiftAmountTy = SetCCResultTy = PointerTy = getValueType(TD->getIntPtrType());
ShiftAmtHandling = Undefined;
memset(RegClassForVT, 0,MVT::LAST_VALUETYPE*sizeof(TargetRegisterClass*));
memset(TargetDAGCombineArray, 0,
sizeof(TargetDAGCombineArray)/sizeof(TargetDAGCombineArray[0]));
maxStoresPerMemset = maxStoresPerMemcpy = maxStoresPerMemmove = 8;
allowUnalignedMemoryAccesses = false;
UseUnderscoreSetJmp = false;
UseUnderscoreLongJmp = false;
SelectIsExpensive = false;
IntDivIsCheap = false;
Pow2DivIsCheap = false;
StackPointerRegisterToSaveRestore = 0;
ExceptionPointerRegister = 0;
ExceptionSelectorRegister = 0;
SchedPreferenceInfo = SchedulingForLatency;
JumpBufSize = 0;
JumpBufAlignment = 0;
IfCvtBlockSizeLimit = 2;
InitLibcallNames(LibcallRoutineNames);
InitCmpLibcallCCs(CmpLibcallCCs);
}
TargetLowering::~TargetLowering() {}
/// setValueTypeAction - Set the action for a particular value type. This
/// assumes an action has not already been set for this value type.
static void SetValueTypeAction(MVT::ValueType VT,
TargetLowering::LegalizeAction Action,
TargetLowering &TLI,
MVT::ValueType *TransformToType,
TargetLowering::ValueTypeActionImpl &ValueTypeActions) {
ValueTypeActions.setTypeAction(VT, Action);
if (Action == TargetLowering::Promote) {
MVT::ValueType PromoteTo;
if (VT == MVT::f32)
PromoteTo = MVT::f64;
else {
unsigned LargerReg = VT+1;
while (!TLI.isTypeLegal((MVT::ValueType)LargerReg)) {
++LargerReg;
assert(MVT::isInteger((MVT::ValueType)LargerReg) &&
"Nothing to promote to??");
}
PromoteTo = (MVT::ValueType)LargerReg;
}
assert(MVT::isInteger(VT) == MVT::isInteger(PromoteTo) &&
MVT::isFloatingPoint(VT) == MVT::isFloatingPoint(PromoteTo) &&
"Can only promote from int->int or fp->fp!");
assert(VT < PromoteTo && "Must promote to a larger type!");
TransformToType[VT] = PromoteTo;
} else if (Action == TargetLowering::Expand) {
// f32 and f64 is each expanded to corresponding integer type of same size.
if (VT == MVT::f32)
TransformToType[VT] = MVT::i32;
else if (VT == MVT::f64)
TransformToType[VT] = MVT::i64;
else {
assert((VT == MVT::Vector || MVT::isInteger(VT)) && VT > MVT::i8 &&
"Cannot expand this type: target must support SOME integer reg!");
// Expand to the next smaller integer type!
TransformToType[VT] = (MVT::ValueType)(VT-1);
}
}
}
/// computeRegisterProperties - Once all of the register classes are added,
/// this allows us to compute derived properties we expose.
void TargetLowering::computeRegisterProperties() {
assert(MVT::LAST_VALUETYPE <= 32 &&
"Too many value types for ValueTypeActions to hold!");
// Everything defaults to one.
for (unsigned i = 0; i != MVT::LAST_VALUETYPE; ++i)
NumRegistersForVT[i] = 1;
// Find the largest integer register class.
unsigned LargestIntReg = MVT::i128;
for (; RegClassForVT[LargestIntReg] == 0; --LargestIntReg)
assert(LargestIntReg != MVT::i1 && "No integer registers defined!");
// Every integer value type larger than this largest register takes twice as
// many registers to represent as the previous ValueType.
unsigned ExpandedReg = LargestIntReg; ++LargestIntReg;
for (++ExpandedReg; MVT::isInteger((MVT::ValueType)ExpandedReg);++ExpandedReg)
NumRegistersForVT[ExpandedReg] = 2*NumRegistersForVT[ExpandedReg-1];
// Inspect all of the ValueType's possible, deciding how to process them.
for (unsigned IntReg = MVT::i1; IntReg <= MVT::i128; ++IntReg)
// If we are expanding this type, expand it!
if (getNumRegisters((MVT::ValueType)IntReg) != 1)
SetValueTypeAction((MVT::ValueType)IntReg, Expand, *this, TransformToType,
ValueTypeActions);
else if (!isTypeLegal((MVT::ValueType)IntReg))
// Otherwise, if we don't have native support, we must promote to a
// larger type.
SetValueTypeAction((MVT::ValueType)IntReg, Promote, *this,
TransformToType, ValueTypeActions);
else
TransformToType[(MVT::ValueType)IntReg] = (MVT::ValueType)IntReg;
// If the target does not have native f64 support, expand it to i64. We will
// be generating soft float library calls. If the target does not have native
// support for f32, promote it to f64 if it is legal. Otherwise, expand it to
// i32.
if (isTypeLegal(MVT::f64))
TransformToType[MVT::f64] = MVT::f64;
else {
NumRegistersForVT[MVT::f64] = NumRegistersForVT[MVT::i64];
SetValueTypeAction(MVT::f64, Expand, *this, TransformToType,
ValueTypeActions);
}
if (isTypeLegal(MVT::f32))
TransformToType[MVT::f32] = MVT::f32;
else if (isTypeLegal(MVT::f64))
SetValueTypeAction(MVT::f32, Promote, *this, TransformToType,
ValueTypeActions);
else {
NumRegistersForVT[MVT::f32] = NumRegistersForVT[MVT::i32];
SetValueTypeAction(MVT::f32, Expand, *this, TransformToType,
ValueTypeActions);
}
// Set MVT::Vector to always be Expanded
SetValueTypeAction(MVT::Vector, Expand, *this, TransformToType,
ValueTypeActions);
// Loop over all of the legal vector value types, specifying an identity type
// transformation.
for (unsigned i = MVT::FIRST_VECTOR_VALUETYPE;
i <= MVT::LAST_VECTOR_VALUETYPE; ++i) {
if (isTypeLegal((MVT::ValueType)i))
TransformToType[i] = (MVT::ValueType)i;
}
}
const char *TargetLowering::getTargetNodeName(unsigned Opcode) const {
return NULL;
}
/// getVectorTypeBreakdown - Packed types are broken down into some number of
/// legal first class types. For example, <8 x float> maps to 2 MVT::v4f32
/// with Altivec or SSE1, or 8 promoted MVT::f64 values with the X86 FP stack.
///
/// This method returns the number and type of the resultant breakdown.
///
unsigned TargetLowering::getVectorTypeBreakdown(const VectorType *PTy,
MVT::ValueType &PTyElementVT,
MVT::ValueType &PTyLegalElementVT) const {
// Figure out the right, legal destination reg to copy into.
unsigned NumElts = PTy->getNumElements();
MVT::ValueType EltTy = getValueType(PTy->getElementType());
unsigned NumVectorRegs = 1;
// Divide the input until we get to a supported size. This will always
// end with a scalar if the target doesn't support vectors.
while (NumElts > 1 && !isTypeLegal(MVT::getVectorType(EltTy, NumElts))) {
NumElts >>= 1;
NumVectorRegs <<= 1;
}
MVT::ValueType VT = MVT::getVectorType(EltTy, NumElts);
if (!isTypeLegal(VT))
VT = EltTy;
PTyElementVT = VT;
MVT::ValueType DestVT = getTypeToTransformTo(VT);
PTyLegalElementVT = DestVT;
if (DestVT < VT) {
// Value is expanded, e.g. i64 -> i16.
return NumVectorRegs*(MVT::getSizeInBits(VT)/MVT::getSizeInBits(DestVT));
} else {
// Otherwise, promotion or legal types use the same number of registers as
// the vector decimated to the appropriate level.
return NumVectorRegs;
}
return 1;
}
//===----------------------------------------------------------------------===//
// Optimization Methods
//===----------------------------------------------------------------------===//
/// 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 TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDOperand Op,
uint64_t Demanded) {
// FIXME: ISD::SELECT, ISD::SELECT_CC
switch(Op.getOpcode()) {
default: break;
case ISD::AND:
case ISD::OR:
case ISD::XOR:
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1)))
if ((~Demanded & C->getValue()) != 0) {
MVT::ValueType VT = Op.getValueType();
SDOperand New = DAG.getNode(Op.getOpcode(), VT, Op.getOperand(0),
DAG.getConstant(Demanded & C->getValue(),
VT));
return CombineTo(Op, New);
}
break;
}
return false;
}
/// 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 TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
uint64_t &KnownZero,
uint64_t &KnownOne,
TargetLoweringOpt &TLO,
unsigned Depth) const {
KnownZero = KnownOne = 0; // Don't know anything.
// The masks are not wide enough to represent this type! Should use APInt.
if (Op.getValueType() == MVT::i128)
return false;
// Other users may use these bits.
if (!Op.Val->hasOneUse()) {
if (Depth != 0) {
// If not at the root, Just compute the KnownZero/KnownOne bits to
// simplify things downstream.
ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
return false;
}
// If this is the root being simplified, allow it to have multiple uses,
// just set the DemandedMask to all bits.
DemandedMask = MVT::getIntVTBitMask(Op.getValueType());
} else if (DemandedMask == 0) {
// Not demanding any bits from Op.
if (Op.getOpcode() != ISD::UNDEF)
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::UNDEF, Op.getValueType()));
return false;
} else if (Depth == 6) { // Limit search depth.
return false;
}
uint64_t KnownZero2, KnownOne2, KnownZeroOut, KnownOneOut;
switch (Op.getOpcode()) {
case ISD::Constant:
// We know all of the bits for a constant!
KnownOne = cast<ConstantSDNode>(Op)->getValue() & DemandedMask;
KnownZero = ~KnownOne & DemandedMask;
return false; // Don't fall through, will infinitely loop.
case ISD::AND:
// If the RHS is a constant, check to see if the LHS would be zero without
// using the bits from the RHS. Below, we use knowledge about the RHS to
// simplify the LHS, here we're using information from the LHS to simplify
// the RHS.
if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
uint64_t LHSZero, LHSOne;
ComputeMaskedBits(Op.getOperand(0), DemandedMask,
LHSZero, LHSOne, Depth+1);
// If the LHS already has zeros where RHSC does, this and is dead.
if ((LHSZero & DemandedMask) == (~RHSC->getValue() & DemandedMask))
return TLO.CombineTo(Op, Op.getOperand(0));
// If any of the set bits in the RHS are known zero on the LHS, shrink
// the constant.
if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & DemandedMask))
return true;
}
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & ~KnownZero,
KnownZero2, KnownOne2, TLO, Depth+1))
return true;
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// If all of the demanded bits are known one on one side, return the other.
// These bits cannot contribute to the result of the 'and'.
if ((DemandedMask & ~KnownZero2 & KnownOne)==(DemandedMask & ~KnownZero2))
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & ~KnownZero & KnownOne2)==(DemandedMask & ~KnownZero))
return TLO.CombineTo(Op, Op.getOperand(1));
// If all of the demanded bits in the inputs are known zeros, return zero.
if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask)
return TLO.CombineTo(Op, TLO.DAG.getConstant(0, Op.getValueType()));
// If the RHS is a constant, see if we can simplify it.
if (TLO.ShrinkDemandedConstant(Op, DemandedMask & ~KnownZero2))
return true;
// Output known-1 bits are only known if set in both the LHS & RHS.
KnownOne &= KnownOne2;
// Output known-0 are known to be clear if zero in either the LHS | RHS.
KnownZero |= KnownZero2;
break;
case ISD::OR:
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & ~KnownOne,
KnownZero2, KnownOne2, TLO, Depth+1))
return true;
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// If all of the demanded bits are known zero on one side, return the other.
// These bits cannot contribute to the result of the 'or'.
if ((DemandedMask & ~KnownOne2 & KnownZero) == (DemandedMask & ~KnownOne2))
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne))
return TLO.CombineTo(Op, Op.getOperand(1));
// If all of the potentially set bits on one side are known to be set on
// the other side, just use the 'other' side.
if ((DemandedMask & (~KnownZero) & KnownOne2) ==
(DemandedMask & (~KnownZero)))
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & (~KnownZero2) & KnownOne) ==
(DemandedMask & (~KnownZero2)))
return TLO.CombineTo(Op, Op.getOperand(1));
// If the RHS is a constant, see if we can simplify it.
if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
return true;
// Output known-0 bits are only known if clear in both the LHS & RHS.
KnownZero &= KnownZero2;
// Output known-1 are known to be set if set in either the LHS | RHS.
KnownOne |= KnownOne2;
break;
case ISD::XOR:
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask, KnownZero2,
KnownOne2, TLO, Depth+1))
return true;
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// If all of the demanded bits are known zero on one side, return the other.
// These bits cannot contribute to the result of the 'xor'.
if ((DemandedMask & KnownZero) == DemandedMask)
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & KnownZero2) == DemandedMask)
return TLO.CombineTo(Op, Op.getOperand(1));
// If all of the unknown bits are known to be zero on one side or the other
// (but not both) turn this into an *inclusive* or.
// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
if ((DemandedMask & ~KnownZero & ~KnownZero2) == 0)
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, Op.getValueType(),
Op.getOperand(0),
Op.getOperand(1)));
// Output known-0 bits are known if clear or set in both the LHS & RHS.
KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
// Output known-1 are known to be set if set in only one of the LHS, RHS.
KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
// If all of the demanded bits on one side are known, and all of the set
// bits on that side are also known to be set on the other side, turn this
// into an AND, as we know the bits will be cleared.
// e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) { // all known
if ((KnownOne & KnownOne2) == KnownOne) {
MVT::ValueType VT = Op.getValueType();
SDOperand ANDC = TLO.DAG.getConstant(~KnownOne & DemandedMask, VT);
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::AND, VT, Op.getOperand(0),
ANDC));
}
}
// If the RHS is a constant, see if we can simplify it.
// FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
return true;
KnownZero = KnownZeroOut;
KnownOne = KnownOneOut;
break;
case ISD::SETCC:
// If we know the result of a setcc has the top bits zero, use this info.
if (getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult)
KnownZero |= (MVT::getIntVTBitMask(Op.getValueType()) ^ 1ULL);
break;
case ISD::SELECT:
if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero2,
KnownOne2, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// If the operands are constants, see if we can simplify them.
if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
return true;
// Only known if known in both the LHS and RHS.
KnownOne &= KnownOne2;
KnownZero &= KnownZero2;
break;
case ISD::SELECT_CC:
if (SimplifyDemandedBits(Op.getOperand(3), DemandedMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero2,
KnownOne2, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// If the operands are constants, see if we can simplify them.
if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
return true;
// Only known if known in both the LHS and RHS.
KnownOne &= KnownOne2;
KnownZero &= KnownZero2;
break;
case ISD::SHL:
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
unsigned ShAmt = SA->getValue();
SDOperand InOp = Op.getOperand(0);
// If this is ((X >>u C1) << ShAmt), see if we can simplify this into a
// single shift. We can do this if the bottom bits (which are shifted
// out) are never demanded.
if (InOp.getOpcode() == ISD::SRL &&
isa<ConstantSDNode>(InOp.getOperand(1))) {
if (ShAmt && (DemandedMask & ((1ULL << ShAmt)-1)) == 0) {
unsigned C1 = cast<ConstantSDNode>(InOp.getOperand(1))->getValue();
unsigned Opc = ISD::SHL;
int Diff = ShAmt-C1;
if (Diff < 0) {
Diff = -Diff;
Opc = ISD::SRL;
}
SDOperand NewSA =
TLO.DAG.getConstant(Diff, Op.getOperand(1).getValueType());
MVT::ValueType VT = Op.getValueType();
return TLO.CombineTo(Op, TLO.DAG.getNode(Opc, VT,
InOp.getOperand(0), NewSA));
}
}
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask >> ShAmt,
KnownZero, KnownOne, TLO, Depth+1))
return true;
KnownZero <<= SA->getValue();
KnownOne <<= SA->getValue();
KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
}
break;
case ISD::SRL:
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
MVT::ValueType VT = Op.getValueType();
unsigned ShAmt = SA->getValue();
uint64_t TypeMask = MVT::getIntVTBitMask(VT);
unsigned VTSize = MVT::getSizeInBits(VT);
SDOperand InOp = Op.getOperand(0);
// If this is ((X << C1) >>u ShAmt), see if we can simplify this into a
// single shift. We can do this if the top bits (which are shifted out)
// are never demanded.
if (InOp.getOpcode() == ISD::SHL &&
isa<ConstantSDNode>(InOp.getOperand(1))) {
if (ShAmt && (DemandedMask & (~0ULL << (VTSize-ShAmt))) == 0) {
unsigned C1 = cast<ConstantSDNode>(InOp.getOperand(1))->getValue();
unsigned Opc = ISD::SRL;
int Diff = ShAmt-C1;
if (Diff < 0) {
Diff = -Diff;
Opc = ISD::SHL;
}
SDOperand NewSA =
TLO.DAG.getConstant(Diff, Op.getOperand(1).getValueType());
return TLO.CombineTo(Op, TLO.DAG.getNode(Opc, VT,
InOp.getOperand(0), NewSA));
}
}
// Compute the new bits that are at the top now.
if (SimplifyDemandedBits(InOp, (DemandedMask << ShAmt) & TypeMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero &= TypeMask;
KnownOne &= TypeMask;
KnownZero >>= ShAmt;
KnownOne >>= ShAmt;
uint64_t HighBits = (1ULL << ShAmt)-1;
HighBits <<= VTSize - ShAmt;
KnownZero |= HighBits; // High bits known zero.
}
break;
case ISD::SRA:
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
MVT::ValueType VT = Op.getValueType();
unsigned ShAmt = SA->getValue();
// Compute the new bits that are at the top now.
uint64_t TypeMask = MVT::getIntVTBitMask(VT);
uint64_t InDemandedMask = (DemandedMask << ShAmt) & TypeMask;
// If any of the demanded bits are produced by the sign extension, we also
// demand the input sign bit.
uint64_t HighBits = (1ULL << ShAmt)-1;
HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
if (HighBits & DemandedMask)
InDemandedMask |= MVT::getIntVTSignBit(VT);
if (SimplifyDemandedBits(Op.getOperand(0), InDemandedMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero &= TypeMask;
KnownOne &= TypeMask;
KnownZero >>= ShAmt;
KnownOne >>= ShAmt;
// Handle the sign bits.
uint64_t SignBit = MVT::getIntVTSignBit(VT);
SignBit >>= ShAmt; // Adjust to where it is now in the mask.
// If the input sign bit is known to be zero, or if none of the top bits
// are demanded, turn this into an unsigned shift right.
if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) {
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, VT, Op.getOperand(0),
Op.getOperand(1)));
} else if (KnownOne & SignBit) { // New bits are known one.
KnownOne |= HighBits;
}
}
break;
case ISD::SIGN_EXTEND_INREG: {
MVT::ValueType EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
// Sign extension. Compute the demanded bits in the result that are not
// present in the input.
uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & DemandedMask;
// If none of the extended bits are demanded, eliminate the sextinreg.
if (NewBits == 0)
return TLO.CombineTo(Op, Op.getOperand(0));
uint64_t InSignBit = MVT::getIntVTSignBit(EVT);
int64_t InputDemandedBits = DemandedMask & MVT::getIntVTBitMask(EVT);
// Since the sign extended bits are demanded, we know that the sign
// bit is demanded.
InputDemandedBits |= InSignBit;
if (SimplifyDemandedBits(Op.getOperand(0), InputDemandedBits,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
// If the sign bit of the input is known set or clear, then we know the
// top bits of the result.
// If the input sign bit is known zero, convert this into a zero extension.
if (KnownZero & InSignBit)
return TLO.CombineTo(Op,
TLO.DAG.getZeroExtendInReg(Op.getOperand(0), EVT));
if (KnownOne & InSignBit) { // Input sign bit known set
KnownOne |= NewBits;
KnownZero &= ~NewBits;
} else { // Input sign bit unknown
KnownZero &= ~NewBits;
KnownOne &= ~NewBits;
}
break;
}
case ISD::CTTZ:
case ISD::CTLZ:
case ISD::CTPOP: {
MVT::ValueType VT = Op.getValueType();
unsigned LowBits = Log2_32(MVT::getSizeInBits(VT))+1;
KnownZero = ~((1ULL << LowBits)-1) & MVT::getIntVTBitMask(VT);
KnownOne = 0;
break;
}
case ISD::LOAD: {
if (ISD::isZEXTLoad(Op.Val)) {
LoadSDNode *LD = cast<LoadSDNode>(Op);
MVT::ValueType VT = LD->getLoadedVT();
KnownZero |= ~MVT::getIntVTBitMask(VT) & DemandedMask;
}
break;
}
case ISD::ZERO_EXTEND: {
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
// If none of the top bits are demanded, convert this into an any_extend.
uint64_t NewBits = (~InMask) & DemandedMask;
if (NewBits == 0)
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND,
Op.getValueType(),
Op.getOperand(0)));
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero |= NewBits;
break;
}
case ISD::SIGN_EXTEND: {
MVT::ValueType InVT = Op.getOperand(0).getValueType();
uint64_t InMask = MVT::getIntVTBitMask(InVT);
uint64_t InSignBit = MVT::getIntVTSignBit(InVT);
uint64_t NewBits = (~InMask) & DemandedMask;
// If none of the top bits are demanded, convert this into an any_extend.
if (NewBits == 0)
return TLO.CombineTo(Op,TLO.DAG.getNode(ISD::ANY_EXTEND,Op.getValueType(),
Op.getOperand(0)));
// Since some of the sign extended bits are demanded, we know that the sign
// bit is demanded.
uint64_t InDemandedBits = DemandedMask & InMask;
InDemandedBits |= InSignBit;
if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, KnownZero,
KnownOne, TLO, Depth+1))
return true;
// If the sign bit is known zero, convert this to a zero extend.
if (KnownZero & InSignBit)
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ZERO_EXTEND,
Op.getValueType(),
Op.getOperand(0)));
// If the sign bit is known one, the top bits match.
if (KnownOne & InSignBit) {
KnownOne |= NewBits;
KnownZero &= ~NewBits;
} else { // Otherwise, top bits aren't known.
KnownOne &= ~NewBits;
KnownZero &= ~NewBits;
}
break;
}
case ISD::ANY_EXTEND: {
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
break;
}
case ISD::TRUNCATE: {
// Simplify the input, using demanded bit information, and compute the known
// zero/one bits live out.
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
// If the input is only used by this truncate, see if we can shrink it based
// on the known demanded bits.
if (Op.getOperand(0).Val->hasOneUse()) {
SDOperand In = Op.getOperand(0);
switch (In.getOpcode()) {
default: break;
case ISD::SRL:
// Shrink SRL by a constant if none of the high bits shifted in are
// demanded.
if (ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(In.getOperand(1))){
uint64_t HighBits = MVT::getIntVTBitMask(In.getValueType());
HighBits &= ~MVT::getIntVTBitMask(Op.getValueType());
HighBits >>= ShAmt->getValue();
if (ShAmt->getValue() < MVT::getSizeInBits(Op.getValueType()) &&
(DemandedMask & HighBits) == 0) {
// None of the shifted in bits are needed. Add a truncate of the
// shift input, then shift it.
SDOperand NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE,
Op.getValueType(),
In.getOperand(0));
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL,Op.getValueType(),
NewTrunc, In.getOperand(1)));
}
}
break;
}
}
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
uint64_t OutMask = MVT::getIntVTBitMask(Op.getValueType());
KnownZero &= OutMask;
KnownOne &= OutMask;
break;
}
case ISD::AssertZext: {
MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
uint64_t InMask = MVT::getIntVTBitMask(VT);
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero |= ~InMask & DemandedMask;
break;
}
case ISD::ADD:
case ISD::SUB:
case ISD::INTRINSIC_WO_CHAIN:
case ISD::INTRINSIC_W_CHAIN:
case ISD::INTRINSIC_VOID:
// Just use ComputeMaskedBits to compute output bits.
ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
break;
}
// If we know the value of all of the demanded bits, return this as a
// constant.
if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
return TLO.CombineTo(Op, TLO.DAG.getConstant(KnownOne, Op.getValueType()));
return false;
}
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
/// this predicate to simplify operations downstream. Mask is known to be zero
/// for bits that V cannot have.
bool TargetLowering::MaskedValueIsZero(SDOperand Op, uint64_t Mask,
unsigned Depth) const {
// The masks are not wide enough to represent this type! Should use APInt.
if (Op.getValueType() == MVT::i128)
return false;
uint64_t KnownZero, KnownOne;
ComputeMaskedBits(Op, Mask, KnownZero, KnownOne, Depth);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
return (KnownZero & Mask) == Mask;
}
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
/// known to be either zero or one and return them in the KnownZero/KnownOne
/// bitsets. This code only analyzes bits in Mask, in order to short-circuit
/// processing.
void TargetLowering::ComputeMaskedBits(SDOperand Op, uint64_t Mask,
uint64_t &KnownZero, uint64_t &KnownOne,
unsigned Depth) const {
KnownZero = KnownOne = 0; // Don't know anything.
if (Depth == 6 || Mask == 0)
return; // Limit search depth.
// The masks are not wide enough to represent this type! Should use APInt.
if (Op.getValueType() == MVT::i128)
return;
uint64_t KnownZero2, KnownOne2;
switch (Op.getOpcode()) {
case ISD::Constant:
// We know all of the bits for a constant!
KnownOne = cast<ConstantSDNode>(Op)->getValue() & Mask;
KnownZero = ~KnownOne & Mask;
return;
case ISD::AND:
// If either the LHS or the RHS are Zero, the result is zero.
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
Mask &= ~KnownZero;
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// Output known-1 bits are only known if set in both the LHS & RHS.
KnownOne &= KnownOne2;
// Output known-0 are known to be clear if zero in either the LHS | RHS.
KnownZero |= KnownZero2;
return;
case ISD::OR:
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
Mask &= ~KnownOne;
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// Output known-0 bits are only known if clear in both the LHS & RHS.
KnownZero &= KnownZero2;
// Output known-1 are known to be set if set in either the LHS | RHS.
KnownOne |= KnownOne2;
return;
case ISD::XOR: {
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// Output known-0 bits are known if clear or set in both the LHS & RHS.
uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
// Output known-1 are known to be set if set in only one of the LHS, RHS.
KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
KnownZero = KnownZeroOut;
return;
}
case ISD::SELECT:
ComputeMaskedBits(Op.getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// Only known if known in both the LHS and RHS.
KnownOne &= KnownOne2;
KnownZero &= KnownZero2;
return;
case ISD::SELECT_CC:
ComputeMaskedBits(Op.getOperand(3), Mask, KnownZero, KnownOne, Depth+1);
ComputeMaskedBits(Op.getOperand(2), Mask, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// Only known if known in both the LHS and RHS.
KnownOne &= KnownOne2;
KnownZero &= KnownZero2;
return;
case ISD::SETCC:
// If we know the result of a setcc has the top bits zero, use this info.
if (getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult)
KnownZero |= (MVT::getIntVTBitMask(Op.getValueType()) ^ 1ULL);
return;
case ISD::SHL:
// (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
ComputeMaskedBits(Op.getOperand(0), Mask >> SA->getValue(),
KnownZero, KnownOne, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero <<= SA->getValue();
KnownOne <<= SA->getValue();
KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
}
return;
case ISD::SRL:
// (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
MVT::ValueType VT = Op.getValueType();
unsigned ShAmt = SA->getValue();
uint64_t TypeMask = MVT::getIntVTBitMask(VT);
ComputeMaskedBits(Op.getOperand(0), (Mask << ShAmt) & TypeMask,
KnownZero, KnownOne, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero &= TypeMask;
KnownOne &= TypeMask;
KnownZero >>= ShAmt;
KnownOne >>= ShAmt;
uint64_t HighBits = (1ULL << ShAmt)-1;
HighBits <<= MVT::getSizeInBits(VT)-ShAmt;
KnownZero |= HighBits; // High bits known zero.
}
return;
case ISD::SRA:
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
MVT::ValueType VT = Op.getValueType();
unsigned ShAmt = SA->getValue();
// Compute the new bits that are at the top now.
uint64_t TypeMask = MVT::getIntVTBitMask(VT);
uint64_t InDemandedMask = (Mask << ShAmt) & TypeMask;
// If any of the demanded bits are produced by the sign extension, we also
// demand the input sign bit.
uint64_t HighBits = (1ULL << ShAmt)-1;
HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
if (HighBits & Mask)
InDemandedMask |= MVT::getIntVTSignBit(VT);
ComputeMaskedBits(Op.getOperand(0), InDemandedMask, KnownZero, KnownOne,
Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero &= TypeMask;
KnownOne &= TypeMask;
KnownZero >>= ShAmt;
KnownOne >>= ShAmt;
// Handle the sign bits.
uint64_t SignBit = MVT::getIntVTSignBit(VT);
SignBit >>= ShAmt; // Adjust to where it is now in the mask.
if (KnownZero & SignBit) {
KnownZero |= HighBits; // New bits are known zero.
} else if (KnownOne & SignBit) {
KnownOne |= HighBits; // New bits are known one.
}
}
return;
case ISD::SIGN_EXTEND_INREG: {
MVT::ValueType EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
// Sign extension. Compute the demanded bits in the result that are not
// present in the input.
uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & Mask;
uint64_t InSignBit = MVT::getIntVTSignBit(EVT);
int64_t InputDemandedBits = Mask & MVT::getIntVTBitMask(EVT);
// If the sign extended bits are demanded, we know that the sign
// bit is demanded.
if (NewBits)
InputDemandedBits |= InSignBit;
ComputeMaskedBits(Op.getOperand(0), InputDemandedBits,
KnownZero, KnownOne, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
// If the sign bit of the input is known set or clear, then we know the
// top bits of the result.
if (KnownZero & InSignBit) { // Input sign bit known clear
KnownZero |= NewBits;
KnownOne &= ~NewBits;
} else if (KnownOne & InSignBit) { // Input sign bit known set
KnownOne |= NewBits;
KnownZero &= ~NewBits;
} else { // Input sign bit unknown
KnownZero &= ~NewBits;
KnownOne &= ~NewBits;
}
return;
}
case ISD::CTTZ:
case ISD::CTLZ:
case ISD::CTPOP: {
MVT::ValueType VT = Op.getValueType();
unsigned LowBits = Log2_32(MVT::getSizeInBits(VT))+1;
KnownZero = ~((1ULL << LowBits)-1) & MVT::getIntVTBitMask(VT);
KnownOne = 0;
return;
}
case ISD::LOAD: {
if (ISD::isZEXTLoad(Op.Val)) {
LoadSDNode *LD = cast<LoadSDNode>(Op);
MVT::ValueType VT = LD->getLoadedVT();
KnownZero |= ~MVT::getIntVTBitMask(VT) & Mask;
}
return;
}
case ISD::ZERO_EXTEND: {
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
uint64_t NewBits = (~InMask) & Mask;
ComputeMaskedBits(Op.getOperand(0), Mask & InMask, KnownZero,
KnownOne, Depth+1);
KnownZero |= NewBits & Mask;
KnownOne &= ~NewBits;
return;
}
case ISD::SIGN_EXTEND: {
MVT::ValueType InVT = Op.getOperand(0).getValueType();
unsigned InBits = MVT::getSizeInBits(InVT);
uint64_t InMask = MVT::getIntVTBitMask(InVT);
uint64_t InSignBit = 1ULL << (InBits-1);
uint64_t NewBits = (~InMask) & Mask;
uint64_t InDemandedBits = Mask & InMask;
// If any of the sign extended bits are demanded, we know that the sign
// bit is demanded.
if (NewBits & Mask)
InDemandedBits |= InSignBit;
ComputeMaskedBits(Op.getOperand(0), InDemandedBits, KnownZero,
KnownOne, Depth+1);
// If the sign bit is known zero or one, the top bits match.
if (KnownZero & InSignBit) {
KnownZero |= NewBits;
KnownOne &= ~NewBits;
} else if (KnownOne & InSignBit) {
KnownOne |= NewBits;
KnownZero &= ~NewBits;
} else { // Otherwise, top bits aren't known.
KnownOne &= ~NewBits;
KnownZero &= ~NewBits;
}
return;
}
case ISD::ANY_EXTEND: {
MVT::ValueType VT = Op.getOperand(0).getValueType();
ComputeMaskedBits(Op.getOperand(0), Mask & MVT::getIntVTBitMask(VT),
KnownZero, KnownOne, Depth+1);
return;
}
case ISD::TRUNCATE: {
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
uint64_t OutMask = MVT::getIntVTBitMask(Op.getValueType());
KnownZero &= OutMask;
KnownOne &= OutMask;
break;
}
case ISD::AssertZext: {
MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
uint64_t InMask = MVT::getIntVTBitMask(VT);
ComputeMaskedBits(Op.getOperand(0), Mask & InMask, KnownZero,
KnownOne, Depth+1);
KnownZero |= (~InMask) & Mask;
return;
}
case ISD::ADD: {
// If either the LHS or the RHS are Zero, the result is zero.
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
// Output known-0 bits are known if clear or set in both the low clear bits
// common to both LHS & RHS. For example, 8+(X<<3) is known to have the
// low 3 bits clear.
uint64_t KnownZeroOut = std::min(CountTrailingZeros_64(~KnownZero),
CountTrailingZeros_64(~KnownZero2));
KnownZero = (1ULL << KnownZeroOut) - 1;
KnownOne = 0;
return;
}
case ISD::SUB: {
ConstantSDNode *CLHS = dyn_cast<ConstantSDNode>(Op.getOperand(0));
if (!CLHS) return;
// We know that the top bits of C-X are clear if X contains less bits
// than C (i.e. no wrap-around can happen). For example, 20-X is
// positive if we can prove that X is >= 0 and < 16.
MVT::ValueType VT = CLHS->getValueType(0);
if ((CLHS->getValue() & MVT::getIntVTSignBit(VT)) == 0) { // sign bit clear
unsigned NLZ = CountLeadingZeros_64(CLHS->getValue()+1);
uint64_t MaskV = (1ULL << (63-NLZ))-1; // NLZ can't be 64 with no sign bit
MaskV = ~MaskV & MVT::getIntVTBitMask(VT);
ComputeMaskedBits(Op.getOperand(1), MaskV, KnownZero, KnownOne, Depth+1);
// If all of the MaskV bits are known to be zero, then we know the output
// top bits are zero, because we now know that the output is from [0-C].
if ((KnownZero & MaskV) == MaskV) {
unsigned NLZ2 = CountLeadingZeros_64(CLHS->getValue());
KnownZero = ~((1ULL << (64-NLZ2))-1) & Mask; // Top bits known zero.
KnownOne = 0; // No one bits known.
} else {
KnownZero = KnownOne = 0; // Otherwise, nothing known.
}
}
return;
}
default:
// Allow the target to implement this method for its nodes.
if (Op.getOpcode() >= ISD::BUILTIN_OP_END) {
case ISD::INTRINSIC_WO_CHAIN:
case ISD::INTRINSIC_W_CHAIN:
case ISD::INTRINSIC_VOID:
computeMaskedBitsForTargetNode(Op, Mask, KnownZero, KnownOne);
}
return;
}
}
/// 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.
void TargetLowering::computeMaskedBitsForTargetNode(const SDOperand Op,
uint64_t Mask,
uint64_t &KnownZero,
uint64_t &KnownOne,
unsigned Depth) const {
assert((Op.getOpcode() >= ISD::BUILTIN_OP_END ||
Op.getOpcode() == ISD::INTRINSIC_WO_CHAIN ||
Op.getOpcode() == ISD::INTRINSIC_W_CHAIN ||
Op.getOpcode() == ISD::INTRINSIC_VOID) &&
"Should use MaskedValueIsZero if you don't know whether Op"
" is a target node!");
KnownZero = 0;
KnownOne = 0;
}
/// ComputeNumSignBits - Return the number of times the sign bit of the
/// register is replicated into the other bits. We know that at least 1 bit
/// is always equal to the sign bit (itself), but other cases can give us
/// information. For example, immediately after an "SRA X, 2", we know that
/// the top 3 bits are all equal to each other, so we return 3.
unsigned TargetLowering::ComputeNumSignBits(SDOperand Op, unsigned Depth) const{
MVT::ValueType VT = Op.getValueType();
assert(MVT::isInteger(VT) && "Invalid VT!");
unsigned VTBits = MVT::getSizeInBits(VT);
unsigned Tmp, Tmp2;
if (Depth == 6)
return 1; // Limit search depth.
switch (Op.getOpcode()) {
default: break;
case ISD::AssertSext:
Tmp = MVT::getSizeInBits(cast<VTSDNode>(Op.getOperand(1))->getVT());
return VTBits-Tmp+1;
case ISD::AssertZext:
Tmp = MVT::getSizeInBits(cast<VTSDNode>(Op.getOperand(1))->getVT());
return VTBits-Tmp;
case ISD::Constant: {
uint64_t Val = cast<ConstantSDNode>(Op)->getValue();
// If negative, invert the bits, then look at it.
if (Val & MVT::getIntVTSignBit(VT))
Val = ~Val;
// Shift the bits so they are the leading bits in the int64_t.
Val <<= 64-VTBits;
// Return # leading zeros. We use 'min' here in case Val was zero before
// shifting. We don't want to return '64' as for an i32 "0".
return std::min(VTBits, CountLeadingZeros_64(Val));
}
case ISD::SIGN_EXTEND:
Tmp = VTBits-MVT::getSizeInBits(Op.getOperand(0).getValueType());
return ComputeNumSignBits(Op.getOperand(0), Depth+1) + Tmp;
case ISD::SIGN_EXTEND_INREG:
// Max of the input and what this extends.
Tmp = MVT::getSizeInBits(cast<VTSDNode>(Op.getOperand(1))->getVT());
Tmp = VTBits-Tmp+1;
Tmp2 = ComputeNumSignBits(Op.getOperand(0), Depth+1);
return std::max(Tmp, Tmp2);
case ISD::SRA:
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
// SRA X, C -> adds C sign bits.
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
Tmp += C->getValue();
if (Tmp > VTBits) Tmp = VTBits;
}
return Tmp;
case ISD::SHL:
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
// shl destroys sign bits.
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
if (C->getValue() >= VTBits || // Bad shift.
C->getValue() >= Tmp) break; // Shifted all sign bits out.
return Tmp - C->getValue();
}
break;
case ISD::AND:
case ISD::OR:
case ISD::XOR: // NOT is handled here.
// Logical binary ops preserve the number of sign bits.
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
if (Tmp == 1) return 1; // Early out.
Tmp2 = ComputeNumSignBits(Op.getOperand(1), Depth+1);
return std::min(Tmp, Tmp2);
case ISD::SELECT:
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
if (Tmp == 1) return 1; // Early out.
Tmp2 = ComputeNumSignBits(Op.getOperand(1), Depth+1);
return std::min(Tmp, Tmp2);
case ISD::SETCC:
// If setcc returns 0/-1, all bits are sign bits.
if (getSetCCResultContents() == ZeroOrNegativeOneSetCCResult)
return VTBits;
break;
case ISD::ROTL:
case ISD::ROTR:
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
unsigned RotAmt = C->getValue() & (VTBits-1);
// Handle rotate right by N like a rotate left by 32-N.
if (Op.getOpcode() == ISD::ROTR)
RotAmt = (VTBits-RotAmt) & (VTBits-1);
// If we aren't rotating out all of the known-in sign bits, return the
// number that are left. This handles rotl(sext(x), 1) for example.
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
if (Tmp > RotAmt+1) return Tmp-RotAmt;
}
break;
case ISD::ADD:
// Add can have at most one carry bit. Thus we know that the output
// is, at worst, one more bit than the inputs.
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
if (Tmp == 1) return 1; // Early out.
// Special case decrementing a value (ADD X, -1):
if (ConstantSDNode *CRHS = dyn_cast<ConstantSDNode>(Op.getOperand(0)))
if (CRHS->isAllOnesValue()) {
uint64_t KnownZero, KnownOne;
uint64_t Mask = MVT::getIntVTBitMask(VT);
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
// If the input is known to be 0 or 1, the output is 0/-1, which is all
// sign bits set.
if ((KnownZero|1) == Mask)
return VTBits;
// If we are subtracting one from a positive number, there is no carry
// out of the result.
if (KnownZero & MVT::getIntVTSignBit(VT))
return Tmp;
}
Tmp2 = ComputeNumSignBits(Op.getOperand(1), Depth+1);
if (Tmp2 == 1) return 1;
return std::min(Tmp, Tmp2)-1;
break;
case ISD::SUB:
Tmp2 = ComputeNumSignBits(Op.getOperand(1), Depth+1);
if (Tmp2 == 1) return 1;
// Handle NEG.
if (ConstantSDNode *CLHS = dyn_cast<ConstantSDNode>(Op.getOperand(0)))
if (CLHS->getValue() == 0) {
uint64_t KnownZero, KnownOne;
uint64_t Mask = MVT::getIntVTBitMask(VT);
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
// If the input is known to be 0 or 1, the output is 0/-1, which is all
// sign bits set.
if ((KnownZero|1) == Mask)
return VTBits;
// If the input is known to be positive (the sign bit is known clear),
// the output of the NEG has the same number of sign bits as the input.
if (KnownZero & MVT::getIntVTSignBit(VT))
return Tmp2;
// Otherwise, we treat this like a SUB.
}
// Sub can have at most one carry bit. Thus we know that the output
// is, at worst, one more bit than the inputs.
Tmp = ComputeNumSignBits(Op.getOperand(0), Depth+1);
if (Tmp == 1) return 1; // Early out.
return std::min(Tmp, Tmp2)-1;
break;
case ISD::TRUNCATE:
// FIXME: it's tricky to do anything useful for this, but it is an important
// case for targets like X86.
break;
}
// Handle LOADX separately here. EXTLOAD case will fallthrough.
if (Op.getOpcode() == ISD::LOAD) {
LoadSDNode *LD = cast<LoadSDNode>(Op);
unsigned ExtType = LD->getExtensionType();
switch (ExtType) {
default: break;
case ISD::SEXTLOAD: // '17' bits known
Tmp = MVT::getSizeInBits(LD->getLoadedVT());
return VTBits-Tmp+1;
case ISD::ZEXTLOAD: // '16' bits known
Tmp = MVT::getSizeInBits(LD->getLoadedVT());
return VTBits-Tmp;
}
}
// Allow the target to implement this method for its nodes.
if (Op.getOpcode() >= ISD::BUILTIN_OP_END ||
Op.getOpcode() == ISD::INTRINSIC_WO_CHAIN ||
Op.getOpcode() == ISD::INTRINSIC_W_CHAIN ||
Op.getOpcode() == ISD::INTRINSIC_VOID) {
unsigned NumBits = ComputeNumSignBitsForTargetNode(Op, Depth);
if (NumBits > 1) return NumBits;
}
// Finally, if we can prove that the top bits of the result are 0's or 1's,
// use this information.
uint64_t KnownZero, KnownOne;
uint64_t Mask = MVT::getIntVTBitMask(VT);
ComputeMaskedBits(Op, Mask, KnownZero, KnownOne, Depth);
uint64_t SignBit = MVT::getIntVTSignBit(VT);
if (KnownZero & SignBit) { // SignBit is 0
Mask = KnownZero;
} else if (KnownOne & SignBit) { // SignBit is 1;
Mask = KnownOne;
} else {
// Nothing known.
return 1;
}
// Okay, we know that the sign bit in Mask is set. Use CLZ to determine
// the number of identical bits in the top of the input value.
Mask ^= ~0ULL;
Mask <<= 64-VTBits;
// Return # leading zeros. We use 'min' here in case Val was zero before
// shifting. We don't want to return '64' as for an i32 "0".
return std::min(VTBits, CountLeadingZeros_64(Mask));
}
/// ComputeNumSignBitsForTargetNode - This method can be implemented by
/// targets that want to expose additional information about sign bits to the
/// DAG Combiner.
unsigned TargetLowering::ComputeNumSignBitsForTargetNode(SDOperand Op,
unsigned Depth) const {
assert((Op.getOpcode() >= ISD::BUILTIN_OP_END ||
Op.getOpcode() == ISD::INTRINSIC_WO_CHAIN ||
Op.getOpcode() == ISD::INTRINSIC_W_CHAIN ||
Op.getOpcode() == ISD::INTRINSIC_VOID) &&
"Should use ComputeNumSignBits if you don't know whether Op"
" is a target node!");
return 1;
}
/// 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
TargetLowering::SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1,
ISD::CondCode Cond, bool foldBooleans,
DAGCombinerInfo &DCI) const {
SelectionDAG &DAG = DCI.DAG;
// These setcc operations always fold.
switch (Cond) {
default: break;
case ISD::SETFALSE:
case ISD::SETFALSE2: return DAG.getConstant(0, VT);
case ISD::SETTRUE:
case ISD::SETTRUE2: return DAG.getConstant(1, VT);
}
if (ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val)) {
uint64_t C1 = N1C->getValue();
if (isa<ConstantSDNode>(N0.Val)) {
return DAG.FoldSetCC(VT, N0, N1, Cond);
} else {
// If the LHS is '(srl (ctlz x), 5)', the RHS is 0/1, and this is an
// equality comparison, then we're just comparing whether X itself is
// zero.
if (N0.getOpcode() == ISD::SRL && (C1 == 0 || C1 == 1) &&
N0.getOperand(0).getOpcode() == ISD::CTLZ &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
unsigned ShAmt = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
ShAmt == Log2_32(MVT::getSizeInBits(N0.getValueType()))) {
if ((C1 == 0) == (Cond == ISD::SETEQ)) {
// (srl (ctlz x), 5) == 0 -> X != 0
// (srl (ctlz x), 5) != 1 -> X != 0
Cond = ISD::SETNE;
} else {
// (srl (ctlz x), 5) != 0 -> X == 0
// (srl (ctlz x), 5) == 1 -> X == 0
Cond = ISD::SETEQ;
}
SDOperand Zero = DAG.getConstant(0, N0.getValueType());
return DAG.getSetCC(VT, N0.getOperand(0).getOperand(0),
Zero, Cond);
}
}
// If the LHS is a ZERO_EXTEND, perform the comparison on the input.
if (N0.getOpcode() == ISD::ZERO_EXTEND) {
unsigned InSize = MVT::getSizeInBits(N0.getOperand(0).getValueType());
// If the comparison constant has bits in the upper part, the
// zero-extended value could never match.
if (C1 & (~0ULL << InSize)) {
unsigned VSize = MVT::getSizeInBits(N0.getValueType());
switch (Cond) {
case ISD::SETUGT:
case ISD::SETUGE:
case ISD::SETEQ: return DAG.getConstant(0, VT);
case ISD::SETULT:
case ISD::SETULE:
case ISD::SETNE: return DAG.getConstant(1, VT);
case ISD::SETGT:
case ISD::SETGE:
// True if the sign bit of C1 is set.
return DAG.getConstant((C1 & (1ULL << (VSize-1))) != 0, VT);
case ISD::SETLT:
case ISD::SETLE:
// True if the sign bit of C1 isn't set.
return DAG.getConstant((C1 & (1ULL << (VSize-1))) == 0, VT);
default:
break;
}
}
// Otherwise, we can perform the comparison with the low bits.
switch (Cond) {
case ISD::SETEQ:
case ISD::SETNE:
case ISD::SETUGT:
case ISD::SETUGE:
case ISD::SETULT:
case ISD::SETULE:
return DAG.getSetCC(VT, N0.getOperand(0),
DAG.getConstant(C1, N0.getOperand(0).getValueType()),
Cond);
default:
break; // todo, be more careful with signed comparisons
}
} else if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG &&
(Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
MVT::ValueType ExtSrcTy = cast<VTSDNode>(N0.getOperand(1))->getVT();
unsigned ExtSrcTyBits = MVT::getSizeInBits(ExtSrcTy);
MVT::ValueType ExtDstTy = N0.getValueType();
unsigned ExtDstTyBits = MVT::getSizeInBits(ExtDstTy);
// If the extended part has any inconsistent bits, it cannot ever
// compare equal. In other words, they have to be all ones or all
// zeros.
uint64_t ExtBits =
(~0ULL >> (64-ExtSrcTyBits)) & (~0ULL << (ExtDstTyBits-1));
if ((C1 & ExtBits) != 0 && (C1 & ExtBits) != ExtBits)
return DAG.getConstant(Cond == ISD::SETNE, VT);
SDOperand ZextOp;
MVT::ValueType Op0Ty = N0.getOperand(0).getValueType();
if (Op0Ty == ExtSrcTy) {
ZextOp = N0.getOperand(0);
} else {
int64_t Imm = ~0ULL >> (64-ExtSrcTyBits);
ZextOp = DAG.getNode(ISD::AND, Op0Ty, N0.getOperand(0),
DAG.getConstant(Imm, Op0Ty));
}
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(ZextOp.Val);
// Otherwise, make this a use of a zext.
return DAG.getSetCC(VT, ZextOp,
DAG.getConstant(C1 & (~0ULL>>(64-ExtSrcTyBits)),
ExtDstTy),
Cond);
} else if ((N1C->getValue() == 0 || N1C->getValue() == 1) &&
(Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
// SETCC (SETCC), [0|1], [EQ|NE] -> SETCC
if (N0.getOpcode() == ISD::SETCC) {
bool TrueWhenTrue = (Cond == ISD::SETEQ) ^ (N1C->getValue() != 1);
if (TrueWhenTrue)
return N0;
// Invert the condition.
ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
CC = ISD::getSetCCInverse(CC,
MVT::isInteger(N0.getOperand(0).getValueType()));
return DAG.getSetCC(VT, N0.getOperand(0), N0.getOperand(1), CC);
}
if ((N0.getOpcode() == ISD::XOR ||
(N0.getOpcode() == ISD::AND &&
N0.getOperand(0).getOpcode() == ISD::XOR &&
N0.getOperand(1) == N0.getOperand(0).getOperand(1))) &&
isa<ConstantSDNode>(N0.getOperand(1)) &&
cast<ConstantSDNode>(N0.getOperand(1))->getValue() == 1) {
// If this is (X^1) == 0/1, swap the RHS and eliminate the xor. We
// can only do this if the top bits are known zero.
if (MaskedValueIsZero(N0, MVT::getIntVTBitMask(N0.getValueType())-1)){
// Okay, get the un-inverted input value.
SDOperand Val;
if (N0.getOpcode() == ISD::XOR)
Val = N0.getOperand(0);
else {
assert(N0.getOpcode() == ISD::AND &&
N0.getOperand(0).getOpcode() == ISD::XOR);
// ((X^1)&1)^1 -> X & 1
Val = DAG.getNode(ISD::AND, N0.getValueType(),
N0.getOperand(0).getOperand(0),
N0.getOperand(1));
}
return DAG.getSetCC(VT, Val, N1,
Cond == ISD::SETEQ ? ISD::SETNE : ISD::SETEQ);
}
}
}
uint64_t MinVal, MaxVal;
unsigned OperandBitSize = MVT::getSizeInBits(N1C->getValueType(0));
if (ISD::isSignedIntSetCC(Cond)) {
MinVal = 1ULL << (OperandBitSize-1);
if (OperandBitSize != 1) // Avoid X >> 64, which is undefined.
MaxVal = ~0ULL >> (65-OperandBitSize);
else
MaxVal = 0;
} else {
MinVal = 0;
MaxVal = ~0ULL >> (64-OperandBitSize);
}
// Canonicalize GE/LE comparisons to use GT/LT comparisons.
if (Cond == ISD::SETGE || Cond == ISD::SETUGE) {
if (C1 == MinVal) return DAG.getConstant(1, VT); // X >= MIN --> true
--C1; // X >= C0 --> X > (C0-1)
return DAG.getSetCC(VT, N0, DAG.getConstant(C1, N1.getValueType()),
(Cond == ISD::SETGE) ? ISD::SETGT : ISD::SETUGT);
}
if (Cond == ISD::SETLE || Cond == ISD::SETULE) {
if (C1 == MaxVal) return DAG.getConstant(1, VT); // X <= MAX --> true
++C1; // X <= C0 --> X < (C0+1)
return DAG.getSetCC(VT, N0, DAG.getConstant(C1, N1.getValueType()),
(Cond == ISD::SETLE) ? ISD::SETLT : ISD::SETULT);
}
if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal)
return DAG.getConstant(0, VT); // X < MIN --> false
if ((Cond == ISD::SETGE || Cond == ISD::SETUGE) && C1 == MinVal)
return DAG.getConstant(1, VT); // X >= MIN --> true
if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MaxVal)
return DAG.getConstant(0, VT); // X > MAX --> false
if ((Cond == ISD::SETLE || Cond == ISD::SETULE) && C1 == MaxVal)
return DAG.getConstant(1, VT); // X <= MAX --> true
// Canonicalize setgt X, Min --> setne X, Min
if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MinVal)
return DAG.getSetCC(VT, N0, N1, ISD::SETNE);
// Canonicalize setlt X, Max --> setne X, Max
if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MaxVal)
return DAG.getSetCC(VT, N0, N1, ISD::SETNE);
// If we have setult X, 1, turn it into seteq X, 0
if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal+1)
return DAG.getSetCC(VT, N0, DAG.getConstant(MinVal, N0.getValueType()),
ISD::SETEQ);
// If we have setugt X, Max-1, turn it into seteq X, Max
else if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MaxVal-1)
return DAG.getSetCC(VT, N0, DAG.getConstant(MaxVal, N0.getValueType()),
ISD::SETEQ);
// If we have "setcc X, C0", check to see if we can shrink the immediate
// by changing cc.
// SETUGT X, SINTMAX -> SETLT X, 0
if (Cond == ISD::SETUGT && OperandBitSize != 1 &&
C1 == (~0ULL >> (65-OperandBitSize)))
return DAG.getSetCC(VT, N0, DAG.getConstant(0, N1.getValueType()),
ISD::SETLT);
// FIXME: Implement the rest of these.
// Fold bit comparisons when we can.
if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
VT == N0.getValueType() && N0.getOpcode() == ISD::AND)
if (ConstantSDNode *AndRHS =
dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
if (Cond == ISD::SETNE && C1 == 0) {// (X & 8) != 0 --> (X & 8) >> 3
// Perform the xform if the AND RHS is a single bit.
if (isPowerOf2_64(AndRHS->getValue())) {
return DAG.getNode(ISD::SRL, VT, N0,
DAG.getConstant(Log2_64(AndRHS->getValue()),
getShiftAmountTy()));
}
} else if (Cond == ISD::SETEQ && C1 == AndRHS->getValue()) {
// (X & 8) == 8 --> (X & 8) >> 3
// Perform the xform if C1 is a single bit.
if (isPowerOf2_64(C1)) {
return DAG.getNode(ISD::SRL, VT, N0,
DAG.getConstant(Log2_64(C1), getShiftAmountTy()));
}
}
}
}
} else if (isa<ConstantSDNode>(N0.Val)) {
// Ensure that the constant occurs on the RHS.
return DAG.getSetCC(VT, N1, N0, ISD::getSetCCSwappedOperands(Cond));
}
if (isa<ConstantFPSDNode>(N0.Val)) {
// Constant fold or commute setcc.
SDOperand O = DAG.FoldSetCC(VT, N0, N1, Cond);
if (O.Val) return O;
}
if (N0 == N1) {
// We can always fold X == X for integer setcc's.
if (MVT::isInteger(N0.getValueType()))
return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);
unsigned UOF = ISD::getUnorderedFlavor(Cond);
if (UOF == 2) // FP operators that are undefined on NaNs.
return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT);
if (UOF == unsigned(ISD::isTrueWhenEqual(Cond)))
return DAG.getConstant(UOF, VT);
// Otherwise, we can't fold it. However, we can simplify it to SETUO/SETO
// if it is not already.
ISD::CondCode NewCond = UOF == 0 ? ISD::SETO : ISD::SETUO;
if (NewCond != Cond)
return DAG.getSetCC(VT, N0, N1, NewCond);
}
if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
MVT::isInteger(N0.getValueType())) {
if (N0.getOpcode() == ISD::ADD || N0.getOpcode() == ISD::SUB ||
N0.getOpcode() == ISD::XOR) {
// Simplify (X+Y) == (X+Z) --> Y == Z
if (N0.getOpcode() == N1.getOpcode()) {
if (N0.getOperand(0) == N1.getOperand(0))
return DAG.getSetCC(VT, N0.getOperand(1), N1.getOperand(1), Cond);
if (N0.getOperand(1) == N1.getOperand(1))
return DAG.getSetCC(VT, N0.getOperand(0), N1.getOperand(0), Cond);
if (DAG.isCommutativeBinOp(N0.getOpcode())) {
// If X op Y == Y op X, try other combinations.
if (N0.getOperand(0) == N1.getOperand(1))
return DAG.getSetCC(VT, N0.getOperand(1), N1.getOperand(0), Cond);
if (N0.getOperand(1) == N1.getOperand(0))
return DAG.getSetCC(VT, N0.getOperand(0), N1.getOperand(1), Cond);
}
}
if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(N1)) {
if (ConstantSDNode *LHSR = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
// Turn (X+C1) == C2 --> X == C2-C1
if (N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse()) {
return DAG.getSetCC(VT, N0.getOperand(0),
DAG.getConstant(RHSC->getValue()-LHSR->getValue(),
N0.getValueType()), Cond);
}
// Turn (X^C1) == C2 into X == C1^C2 iff X&~C1 = 0.
if (N0.getOpcode() == ISD::XOR)
// If we know that all of the inverted bits are zero, don't bother
// performing the inversion.
if (MaskedValueIsZero(N0.getOperand(0), ~LHSR->getValue()))
return DAG.getSetCC(VT, N0.getOperand(0),
DAG.getConstant(LHSR->getValue()^RHSC->getValue(),
N0.getValueType()), Cond);
}
// Turn (C1-X) == C2 --> X == C1-C2
if (ConstantSDNode *SUBC = dyn_cast<ConstantSDNode>(N0.getOperand(0))) {
if (N0.getOpcode() == ISD::SUB && N0.Val->hasOneUse()) {
return DAG.getSetCC(VT, N0.getOperand(1),
DAG.getConstant(SUBC->getValue()-RHSC->getValue(),
N0.getValueType()), Cond);
}
}
}
// Simplify (X+Z) == X --> Z == 0
if (N0.getOperand(0) == N1)
return DAG.getSetCC(VT, N0.getOperand(1),
DAG.getConstant(0, N0.getValueType()), Cond);
if (N0.getOperand(1) == N1) {
if (DAG.isCommutativeBinOp(N0.getOpcode()))
return DAG.getSetCC(VT, N0.getOperand(0),
DAG.getConstant(0, N0.getValueType()), Cond);
else if (N0.Val->hasOneUse()) {
assert(N0.getOpcode() == ISD::SUB && "Unexpected operation!");
// (Z-X) == X --> Z == X<<1
SDOperand SH = DAG.getNode(ISD::SHL, N1.getValueType(),
N1,
DAG.getConstant(1, getShiftAmountTy()));
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(SH.Val);
return DAG.getSetCC(VT, N0.getOperand(0), SH, Cond);
}
}
}
if (N1.getOpcode() == ISD::ADD || N1.getOpcode() == ISD::SUB ||
N1.getOpcode() == ISD::XOR) {
// Simplify X == (X+Z) --> Z == 0
if (N1.getOperand(0) == N0) {
return DAG.getSetCC(VT, N1.getOperand(1),
DAG.getConstant(0, N1.getValueType()), Cond);
} else if (N1.getOperand(1) == N0) {
if (DAG.isCommutativeBinOp(N1.getOpcode())) {
return DAG.getSetCC(VT, N1.getOperand(0),
DAG.getConstant(0, N1.getValueType()), Cond);
} else if (N1.Val->hasOneUse()) {
assert(N1.getOpcode() == ISD::SUB && "Unexpected operation!");
// X == (Z-X) --> X<<1 == Z
SDOperand SH = DAG.getNode(ISD::SHL, N1.getValueType(), N0,
DAG.getConstant(1, getShiftAmountTy()));
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(SH.Val);
return DAG.getSetCC(VT, SH, N1.getOperand(0), Cond);
}
}
}
}
// Fold away ALL boolean setcc's.
SDOperand Temp;
if (N0.getValueType() == MVT::i1 && foldBooleans) {
switch (Cond) {
default: assert(0 && "Unknown integer setcc!");
case ISD::SETEQ: // X == Y -> (X^Y)^1
Temp = DAG.getNode(ISD::XOR, MVT::i1, N0, N1);
N0 = DAG.getNode(ISD::XOR, MVT::i1, Temp, DAG.getConstant(1, MVT::i1));
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(Temp.Val);
break;
case ISD::SETNE: // X != Y --> (X^Y)
N0 = DAG.getNode(ISD::XOR, MVT::i1, N0, N1);
break;
case ISD::SETGT: // X >s Y --> X == 0 & Y == 1 --> X^1 & Y
case ISD::SETULT: // X <u Y --> X == 0 & Y == 1 --> X^1 & Y
Temp = DAG.getNode(ISD::XOR, MVT::i1, N0, DAG.getConstant(1, MVT::i1));
N0 = DAG.getNode(ISD::AND, MVT::i1, N1, Temp);
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(Temp.Val);
break;
case ISD::SETLT: // X <s Y --> X == 1 & Y == 0 --> Y^1 & X
case ISD::SETUGT: // X >u Y --> X == 1 & Y == 0 --> Y^1 & X
Temp = DAG.getNode(ISD::XOR, MVT::i1, N1, DAG.getConstant(1, MVT::i1));
N0 = DAG.getNode(ISD::AND, MVT::i1, N0, Temp);
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(Temp.Val);
break;
case ISD::SETULE: // X <=u Y --> X == 0 | Y == 1 --> X^1 | Y
case ISD::SETGE: // X >=s Y --> X == 0 | Y == 1 --> X^1 | Y
Temp = DAG.getNode(ISD::XOR, MVT::i1, N0, DAG.getConstant(1, MVT::i1));
N0 = DAG.getNode(ISD::OR, MVT::i1, N1, Temp);
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(Temp.Val);
break;
case ISD::SETUGE: // X >=u Y --> X == 1 | Y == 0 --> Y^1 | X
case ISD::SETLE: // X <=s Y --> X == 1 | Y == 0 --> Y^1 | X
Temp = DAG.getNode(ISD::XOR, MVT::i1, N1, DAG.getConstant(1, MVT::i1));
N0 = DAG.getNode(ISD::OR, MVT::i1, N0, Temp);
break;
}
if (VT != MVT::i1) {
if (!DCI.isCalledByLegalizer())
DCI.AddToWorklist(N0.Val);
// FIXME: If running after legalize, we probably can't do this.
N0 = DAG.getNode(ISD::ZERO_EXTEND, VT, N0);
}
return N0;
}
// Could not fold it.
return SDOperand();
}
SDOperand TargetLowering::
PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const {
// Default implementation: no optimization.
return SDOperand();
}
//===----------------------------------------------------------------------===//
// Inline Assembler Implementation Methods
//===----------------------------------------------------------------------===//
TargetLowering::ConstraintType
TargetLowering::getConstraintType(const std::string &Constraint) const {
// FIXME: lots more standard ones to handle.
if (Constraint.size() == 1) {
switch (Constraint[0]) {
default: break;
case 'r': return C_RegisterClass;
case 'm': // memory
case 'o': // offsetable
case 'V': // not offsetable
return C_Memory;
case 'i': // Simple Integer or Relocatable Constant
case 'n': // Simple Integer
case 's': // Relocatable Constant
case 'X': // Allow ANY value.
case 'I': // Target registers.
case 'J':
case 'K':
case 'L':
case 'M':
case 'N':
case 'O':
case 'P':
return C_Other;
}
}
if (Constraint.size() > 1 && Constraint[0] == '{' &&
Constraint[Constraint.size()-1] == '}')
return C_Register;
return C_Unknown;
}
/// isOperandValidForConstraint - Return the specified operand (possibly
/// modified) if the specified SDOperand is valid for the specified target
/// constraint letter, otherwise return null.
SDOperand TargetLowering::isOperandValidForConstraint(SDOperand Op,
char ConstraintLetter,
SelectionDAG &DAG) {
switch (ConstraintLetter) {
default: break;
case 'i': // Simple Integer or Relocatable Constant
case 'n': // Simple Integer
case 's': // Relocatable Constant
case 'X': { // Allows any operand.
// These operands are interested in values of the form (GV+C), where C may
// be folded in as an offset of GV, or it may be explicitly added. Also, it
// is possible and fine if either GV or C are missing.
ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op);
GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op);
// If we have "(add GV, C)", pull out GV/C
if (Op.getOpcode() == ISD::ADD) {
C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
GA = dyn_cast<GlobalAddressSDNode>(Op.getOperand(0));
if (C == 0 || GA == 0) {
C = dyn_cast<ConstantSDNode>(Op.getOperand(0));
GA = dyn_cast<GlobalAddressSDNode>(Op.getOperand(1));
}
if (C == 0 || GA == 0)
C = 0, GA = 0;
}
// If we find a valid operand, map to the TargetXXX version so that the
// value itself doesn't get selected.
if (GA) { // Either &GV or &GV+C
if (ConstraintLetter != 'n') {
int64_t Offs = GA->getOffset();
if (C) Offs += C->getValue();
return DAG.getTargetGlobalAddress(GA->getGlobal(), Op.getValueType(),
Offs);
}
}
if (C) { // just C, no GV.
// Simple constants are not allowed for 's'.
if (ConstraintLetter != 's')
return DAG.getTargetConstant(C->getValue(), Op.getValueType());
}
break;
}
}
return SDOperand(0,0);
}
std::vector<unsigned> TargetLowering::
getRegClassForInlineAsmConstraint(const std::string &Constraint,
MVT::ValueType VT) const {
return std::vector<unsigned>();
}
std::pair<unsigned, const TargetRegisterClass*> TargetLowering::
getRegForInlineAsmConstraint(const std::string &Constraint,
MVT::ValueType VT) const {
if (Constraint[0] != '{')
return std::pair<unsigned, const TargetRegisterClass*>(0, 0);
assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
// Remove the braces from around the name.
std::string RegName(Constraint.begin()+1, Constraint.end()-1);
// Figure out which register class contains this reg.
const MRegisterInfo *RI = TM.getRegisterInfo();
for (MRegisterInfo::regclass_iterator RCI = RI->regclass_begin(),
E = RI->regclass_end(); RCI != E; ++RCI) {
const TargetRegisterClass *RC = *RCI;
// If none of the the value types for this register class are valid, we
// can't use it. For example, 64-bit reg classes on 32-bit targets.
bool isLegal = false;
for (TargetRegisterClass::vt_iterator I = RC->vt_begin(), E = RC->vt_end();
I != E; ++I) {
if (isTypeLegal(*I)) {
isLegal = true;
break;
}
}
if (!isLegal) continue;
for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
I != E; ++I) {
if (StringsEqualNoCase(RegName, RI->get(*I).Name))
return std::make_pair(*I, RC);
}
}
return std::pair<unsigned, const TargetRegisterClass*>(0, 0);
}
//===----------------------------------------------------------------------===//
// Loop Strength Reduction hooks
//===----------------------------------------------------------------------===//
/// isLegalAddressingMode - Return true if the addressing mode represented
/// by AM is legal for this target, for a load/store of the specified type.
bool TargetLowering::isLegalAddressingMode(const AddrMode &AM,
const Type *Ty) const {
// The default implementation of this implements a conservative RISCy, r+r and
// r+i addr mode.
// Allows a sign-extended 16-bit immediate field.
if (AM.BaseOffs <= -(1LL << 16) || AM.BaseOffs >= (1LL << 16)-1)
return false;
// No global is ever allowed as a base.
if (AM.BaseGV)
return false;
// Only support r+r,
switch (AM.Scale) {
case 0: // "r+i" or just "i", depending on HasBaseReg.
break;
case 1:
if (AM.HasBaseReg && AM.BaseOffs) // "r+r+i" is not allowed.
return false;
// Otherwise we have r+r or r+i.
break;
case 2:
if (AM.HasBaseReg || AM.BaseOffs) // 2*r+r or 2*r+i is not allowed.
return false;
// Allow 2*r as r+r.
break;
}
return true;
}
// Magic for divide replacement
struct ms {
int64_t m; // magic number
int64_t s; // shift amount
};
struct mu {
uint64_t m; // magic number
int64_t a; // add indicator
int64_t s; // shift amount
};
/// magic - calculate the magic numbers required to codegen an integer sdiv as
/// a sequence of multiply and shifts. Requires that the divisor not be 0, 1,
/// or -1.
static ms magic32(int32_t d) {
int32_t p;
uint32_t ad, anc, delta, q1, r1, q2, r2, t;
const uint32_t two31 = 0x80000000U;
struct ms mag;
ad = abs(d);
t = two31 + ((uint32_t)d >> 31);
anc = t - 1 - t%ad; // absolute value of nc
p = 31; // initialize p
q1 = two31/anc; // initialize q1 = 2p/abs(nc)
r1 = two31 - q1*anc; // initialize r1 = rem(2p,abs(nc))
q2 = two31/ad; // initialize q2 = 2p/abs(d)
r2 = two31 - q2*ad; // initialize r2 = rem(2p,abs(d))
do {
p = p + 1;
q1 = 2*q1; // update q1 = 2p/abs(nc)
r1 = 2*r1; // update r1 = rem(2p/abs(nc))
if (r1 >= anc) { // must be unsigned comparison
q1 = q1 + 1;
r1 = r1 - anc;
}
q2 = 2*q2; // update q2 = 2p/abs(d)
r2 = 2*r2; // update r2 = rem(2p/abs(d))
if (r2 >= ad) { // must be unsigned comparison
q2 = q2 + 1;
r2 = r2 - ad;
}
delta = ad - r2;
} while (q1 < delta || (q1 == delta && r1 == 0));
mag.m = (int32_t)(q2 + 1); // make sure to sign extend
if (d < 0) mag.m = -mag.m; // resulting magic number
mag.s = p - 32; // resulting shift
return mag;
}
/// magicu - calculate the magic numbers required to codegen an integer udiv as
/// a sequence of multiply, add and shifts. Requires that the divisor not be 0.
static mu magicu32(uint32_t d) {
int32_t p;
uint32_t nc, delta, q1, r1, q2, r2;
struct mu magu;
magu.a = 0; // initialize "add" indicator
nc = - 1 - (-d)%d;
p = 31; // initialize p
q1 = 0x80000000/nc; // initialize q1 = 2p/nc
r1 = 0x80000000 - q1*nc; // initialize r1 = rem(2p,nc)
q2 = 0x7FFFFFFF/d; // initialize q2 = (2p-1)/d
r2 = 0x7FFFFFFF - q2*d; // initialize r2 = rem((2p-1),d)
do {
p = p + 1;
if (r1 >= nc - r1 ) {
q1 = 2*q1 + 1; // update q1
r1 = 2*r1 - nc; // update r1
}
else {
q1 = 2*q1; // update q1
r1 = 2*r1; // update r1
}
if (r2 + 1 >= d - r2) {
if (q2 >= 0x7FFFFFFF) magu.a = 1;
q2 = 2*q2 + 1; // update q2
r2 = 2*r2 + 1 - d; // update r2
}
else {
if (q2 >= 0x80000000) magu.a = 1;
q2 = 2*q2; // update q2
r2 = 2*r2 + 1; // update r2
}
delta = d - 1 - r2;
} while (p < 64 && (q1 < delta || (q1 == delta && r1 == 0)));
magu.m = q2 + 1; // resulting magic number
magu.s = p - 32; // resulting shift
return magu;
}
/// magic - calculate the magic numbers required to codegen an integer sdiv as
/// a sequence of multiply and shifts. Requires that the divisor not be 0, 1,
/// or -1.
static ms magic64(int64_t d) {
int64_t p;
uint64_t ad, anc, delta, q1, r1, q2, r2, t;
const uint64_t two63 = 9223372036854775808ULL; // 2^63
struct ms mag;
ad = d >= 0 ? d : -d;
t = two63 + ((uint64_t)d >> 63);
anc = t - 1 - t%ad; // absolute value of nc
p = 63; // initialize p
q1 = two63/anc; // initialize q1 = 2p/abs(nc)
r1 = two63 - q1*anc; // initialize r1 = rem(2p,abs(nc))
q2 = two63/ad; // initialize q2 = 2p/abs(d)
r2 = two63 - q2*ad; // initialize r2 = rem(2p,abs(d))
do {
p = p + 1;
q1 = 2*q1; // update q1 = 2p/abs(nc)
r1 = 2*r1; // update r1 = rem(2p/abs(nc))
if (r1 >= anc) { // must be unsigned comparison
q1 = q1 + 1;
r1 = r1 - anc;
}
q2 = 2*q2; // update q2 = 2p/abs(d)
r2 = 2*r2; // update r2 = rem(2p/abs(d))
if (r2 >= ad) { // must be unsigned comparison
q2 = q2 + 1;
r2 = r2 - ad;
}
delta = ad - r2;
} while (q1 < delta || (q1 == delta && r1 == 0));
mag.m = q2 + 1;
if (d < 0) mag.m = -mag.m; // resulting magic number
mag.s = p - 64; // resulting shift
return mag;
}
/// magicu - calculate the magic numbers required to codegen an integer udiv as
/// a sequence of multiply, add and shifts. Requires that the divisor not be 0.
static mu magicu64(uint64_t d)
{
int64_t p;
uint64_t nc, delta, q1, r1, q2, r2;
struct mu magu;
magu.a = 0; // initialize "add" indicator
nc = - 1 - (-d)%d;
p = 63; // initialize p
q1 = 0x8000000000000000ull/nc; // initialize q1 = 2p/nc
r1 = 0x8000000000000000ull - q1*nc; // initialize r1 = rem(2p,nc)
q2 = 0x7FFFFFFFFFFFFFFFull/d; // initialize q2 = (2p-1)/d
r2 = 0x7FFFFFFFFFFFFFFFull - q2*d; // initialize r2 = rem((2p-1),d)
do {
p = p + 1;
if (r1 >= nc - r1 ) {
q1 = 2*q1 + 1; // update q1
r1 = 2*r1 - nc; // update r1
}
else {
q1 = 2*q1; // update q1
r1 = 2*r1; // update r1
}
if (r2 + 1 >= d - r2) {
if (q2 >= 0x7FFFFFFFFFFFFFFFull) magu.a = 1;
q2 = 2*q2 + 1; // update q2
r2 = 2*r2 + 1 - d; // update r2
}
else {
if (q2 >= 0x8000000000000000ull) magu.a = 1;
q2 = 2*q2; // update q2
r2 = 2*r2 + 1; // update r2
}
delta = d - 1 - r2;
} while (p < 128 && (q1 < delta || (q1 == delta && r1 == 0)));
magu.m = q2 + 1; // resulting magic number
magu.s = p - 64; // resulting shift
return magu;
}
/// BuildSDIVSequence - Given an ISD::SDIV node expressing a divide by constant,
/// return a DAG expression to select that will generate the same value by
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDOperand TargetLowering::BuildSDIV(SDNode *N, SelectionDAG &DAG,
std::vector<SDNode*>* Created) const {
MVT::ValueType VT = N->getValueType(0);
// Check to see if we can do this.
if (!isTypeLegal(VT) || (VT != MVT::i32 && VT != MVT::i64))
return SDOperand(); // BuildSDIV only operates on i32 or i64
if (!isOperationLegal(ISD::MULHS, VT))
return SDOperand(); // Make sure the target supports MULHS.
int64_t d = cast<ConstantSDNode>(N->getOperand(1))->getSignExtended();
ms magics = (VT == MVT::i32) ? magic32(d) : magic64(d);
// Multiply the numerator (operand 0) by the magic value
SDOperand Q = DAG.getNode(ISD::MULHS, VT, N->getOperand(0),
DAG.getConstant(magics.m, VT));
// If d > 0 and m < 0, add the numerator
if (d > 0 && magics.m < 0) {
Q = DAG.getNode(ISD::ADD, VT, Q, N->getOperand(0));
if (Created)
Created->push_back(Q.Val);
}
// If d < 0 and m > 0, subtract the numerator.
if (d < 0 && magics.m > 0) {
Q = DAG.getNode(ISD::SUB, VT, Q, N->getOperand(0));
if (Created)
Created->push_back(Q.Val);
}
// Shift right algebraic if shift value is nonzero
if (magics.s > 0) {
Q = DAG.getNode(ISD::SRA, VT, Q,
DAG.getConstant(magics.s, getShiftAmountTy()));
if (Created)
Created->push_back(Q.Val);
}
// Extract the sign bit and add it to the quotient
SDOperand T =
DAG.getNode(ISD::SRL, VT, Q, DAG.getConstant(MVT::getSizeInBits(VT)-1,
getShiftAmountTy()));
if (Created)
Created->push_back(T.Val);
return DAG.getNode(ISD::ADD, VT, Q, T);
}
/// BuildUDIVSequence - Given an ISD::UDIV node expressing a divide by constant,
/// return a DAG expression to select that will generate the same value by
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDOperand TargetLowering::BuildUDIV(SDNode *N, SelectionDAG &DAG,
std::vector<SDNode*>* Created) const {
MVT::ValueType VT = N->getValueType(0);
// Check to see if we can do this.
if (!isTypeLegal(VT) || (VT != MVT::i32 && VT != MVT::i64))
return SDOperand(); // BuildUDIV only operates on i32 or i64
if (!isOperationLegal(ISD::MULHU, VT))
return SDOperand(); // Make sure the target supports MULHU.
uint64_t d = cast<ConstantSDNode>(N->getOperand(1))->getValue();
mu magics = (VT == MVT::i32) ? magicu32(d) : magicu64(d);
// Multiply the numerator (operand 0) by the magic value
SDOperand Q = DAG.getNode(ISD::MULHU, VT, N->getOperand(0),
DAG.getConstant(magics.m, VT));
if (Created)
Created->push_back(Q.Val);
if (magics.a == 0) {
return DAG.getNode(ISD::SRL, VT, Q,
DAG.getConstant(magics.s, getShiftAmountTy()));
} else {
SDOperand NPQ = DAG.getNode(ISD::SUB, VT, N->getOperand(0), Q);
if (Created)
Created->push_back(NPQ.Val);
NPQ = DAG.getNode(ISD::SRL, VT, NPQ,
DAG.getConstant(1, getShiftAmountTy()));
if (Created)
Created->push_back(NPQ.Val);
NPQ = DAG.getNode(ISD::ADD, VT, NPQ, Q);
if (Created)
Created->push_back(NPQ.Val);
return DAG.getNode(ISD::SRL, VT, NPQ,
DAG.getConstant(magics.s-1, getShiftAmountTy()));
}
}
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