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Convert SimplifyDemandedMask and ShrinkDemandedConstant to use APInt.

Browse Source 
Change several cases in SimplifyDemandedMask that don't ever do any
simplifying to reuse the logic in ComputeMaskedBits instead of
duplicating it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47648 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2008-02-27 00:25:32 +00:00
parent cc4831849e
commit 7b8d4a9eef
3 changed files with 156 additions and 144 deletions
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6
include/llvm/Target/TargetLowering.h
View File

@ -610,7 +610,7 @@ public:
/// 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);
bool ShrinkDemandedConstant(SDOperand Op, const APInt &Demanded);
};
/// SimplifyDemandedBits - Look at Op. At this point, we know that only the
@ -621,8 +621,8 @@ public:
/// 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,
bool SimplifyDemandedBits(SDOperand Op, const APInt &DemandedMask,
APInt &KnownZero, APInt &KnownOne,
TargetLoweringOpt &TLO, unsigned Depth = 0) const;
/// computeMaskedBitsForTargetNode - Determine which of the bits specified in

17
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -118,7 +118,12 @@ namespace {
/// SimplifyDemandedBits - Check the specified integer node value to see if
/// it can be simplified or if things it uses can be simplified by bit
/// propagation. If so, return true.
bool SimplifyDemandedBits(SDOperand Op, uint64_t Demanded = ~0ULL);
bool SimplifyDemandedBits(SDOperand Op) {
APInt Demanded = APInt::getAllOnesValue(Op.getValueSizeInBits());
return SimplifyDemandedBits(Op, Demanded);
}
bool SimplifyDemandedBits(SDOperand Op, const APInt &Demanded);
bool CombineToPreIndexedLoadStore(SDNode *N);
bool CombineToPostIndexedLoadStore(SDNode *N);
@ -534,10 +539,9 @@ SDOperand DAGCombiner::CombineTo(SDNode *N, const SDOperand *To, unsigned NumTo,
/// SimplifyDemandedBits - Check the specified integer node value to see if
/// it can be simplified or if things it uses can be simplified by bit
/// propagation. If so, return true.
bool DAGCombiner::SimplifyDemandedBits(SDOperand Op, uint64_t Demanded) {
bool DAGCombiner::SimplifyDemandedBits(SDOperand Op, const APInt &Demanded) {
TargetLowering::TargetLoweringOpt TLO(DAG, AfterLegalize);
uint64_t KnownZero, KnownOne;
Demanded &= MVT::getIntVTBitMask(Op.getValueType());
APInt KnownZero, KnownOne;
if (!TLI.SimplifyDemandedBits(Op, Demanded, KnownZero, KnownOne, TLO))
return false;
@ -4501,7 +4505,10 @@ SDOperand DAGCombiner::visitSTORE(SDNode *N) {
// Otherwise, see if we can simplify the operation with
// SimplifyDemandedBits, which only works if the value has a single use.
if (SimplifyDemandedBits(Value, MVT::getIntVTBitMask(ST->getMemoryVT())))
if (SimplifyDemandedBits(Value,
APInt::getLowBitsSet(
Value.getValueSizeInBits(),
MVT::getSizeInBits(ST->getMemoryVT()))))
return SDOperand(N, 0);
}

277
lib/CodeGen/SelectionDAG/TargetLowering.cpp
View File

@ -443,7 +443,7 @@ SDOperand TargetLowering::getPICJumpTableRelocBase(SDOperand Table,
/// 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) {
const APInt &Demanded) {
// FIXME: ISD::SELECT, ISD::SELECT_CC
switch(Op.getOpcode()) {
default: break;
@ -451,10 +451,11 @@ bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDOperand Op,
case ISD::OR:
case ISD::XOR:
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1)))
if ((~Demanded & C->getValue()) != 0) {
if (C->getAPIntValue().intersects(~Demanded)) {
MVT::ValueType VT = Op.getValueType();
SDOperand New = DAG.getNode(Op.getOpcode(), VT, Op.getOperand(0),
DAG.getConstant(Demanded & C->getValue(),
DAG.getConstant(Demanded &
C->getAPIntValue(),
VT));
return CombineTo(Op, New);
}
@ -470,17 +471,20 @@ bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDOperand Op,
/// 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,
bool TargetLowering::SimplifyDemandedBits(SDOperand Op,
const APInt &DemandedMask,
APInt &KnownZero,
APInt &KnownOne,
TargetLoweringOpt &TLO,
unsigned Depth) const {
KnownZero = KnownOne = 0; // Don't know anything.
unsigned BitWidth = DemandedMask.getBitWidth();
assert(Op.getValueSizeInBits() == BitWidth &&
"Mask size mismatches value type size!");
APInt NewMask = DemandedMask;
// Don't know anything.
KnownZero = KnownOne = APInt(BitWidth, 0);
// 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) {
@ -490,8 +494,8 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
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());
// just set the NewMask to all bits.
NewMask = APInt::getAllOnesValue(BitWidth);
} else if (DemandedMask == 0) {
// Not demanding any bits from Op.
if (Op.getOpcode() != ISD::UNDEF)
@ -501,12 +505,12 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
return false;
}
uint64_t KnownZero2, KnownOne2, KnownZeroOut, KnownOneOut;
APInt 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;
KnownOne = cast<ConstantSDNode>(Op)->getAPIntValue() & NewMask;
KnownZero = ~KnownOne & NewMask;
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
@ -514,38 +518,38 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
// 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;
TLO.DAG.ComputeMaskedBits(Op.getOperand(0), DemandedMask,
APInt LHSZero, LHSOne;
TLO.DAG.ComputeMaskedBits(Op.getOperand(0), NewMask,
LHSZero, LHSOne, Depth+1);
// If the LHS already has zeros where RHSC does, this and is dead.
if ((LHSZero & DemandedMask) == (~RHSC->getValue() & DemandedMask))
if ((LHSZero & NewMask) == (~RHSC->getAPIntValue() & NewMask))
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))
if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & NewMask))
return true;
}
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
if (SimplifyDemandedBits(Op.getOperand(1), NewMask, 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,
if (SimplifyDemandedBits(Op.getOperand(0), ~KnownZero & NewMask,
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))
if ((NewMask & ~KnownZero2 & KnownOne) == (~KnownZero2 & NewMask))
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & ~KnownZero & KnownOne2)==(DemandedMask & ~KnownZero))
if ((NewMask & ~KnownZero & KnownOne2) == (~KnownZero & NewMask))
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)
if ((NewMask & (KnownZero|KnownZero2)) == NewMask)
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))
if (TLO.ShrinkDemandedConstant(Op, ~KnownZero2 & NewMask))
return true;
// Output known-1 bits are only known if set in both the LHS & RHS.
@ -554,31 +558,29 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
KnownZero |= KnownZero2;
break;
case ISD::OR:
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
if (SimplifyDemandedBits(Op.getOperand(1), NewMask, 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,
if (SimplifyDemandedBits(Op.getOperand(0), ~KnownOne & NewMask,
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))
if ((NewMask & ~KnownOne2 & KnownZero) == (~KnownOne2 & NewMask))
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne))
if ((NewMask & ~KnownOne & KnownZero2) == (~KnownOne & NewMask))
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)))
if ((NewMask & ~KnownZero & KnownOne2) == (~KnownZero & NewMask))
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & (~KnownZero2) & KnownOne) ==
(DemandedMask & (~KnownZero2)))
if ((NewMask & ~KnownZero2 & KnownOne) == (~KnownZero2 & NewMask))
return TLO.CombineTo(Op, Op.getOperand(1));
// If the RHS is a constant, see if we can simplify it.
if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
if (TLO.ShrinkDemandedConstant(Op, NewMask))
return true;
// Output known-0 bits are only known if clear in both the LHS & RHS.
@ -587,26 +589,26 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
KnownOne |= KnownOne2;
break;
case ISD::XOR:
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
if (SimplifyDemandedBits(Op.getOperand(1), NewMask, 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,
if (SimplifyDemandedBits(Op.getOperand(0), NewMask, 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)
if ((KnownZero & NewMask) == NewMask)
return TLO.CombineTo(Op, Op.getOperand(0));
if ((DemandedMask & KnownZero2) == DemandedMask)
if ((KnownZero2 & NewMask) == NewMask)
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)
if ((NewMask & ~KnownZero & ~KnownZero2) == 0)
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, Op.getValueType(),
Op.getOperand(0),
Op.getOperand(1)));
@ -620,10 +622,10 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
// 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 ((NewMask & (KnownZero|KnownOne)) == NewMask) { // all known
if ((KnownOne & KnownOne2) == KnownOne) {
MVT::ValueType VT = Op.getValueType();
SDOperand ANDC = TLO.DAG.getConstant(~KnownOne & DemandedMask, VT);
SDOperand ANDC = TLO.DAG.getConstant(~KnownOne & NewMask, VT);
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::AND, VT, Op.getOperand(0),
ANDC));
}
@ -631,29 +633,24 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
// 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))
if (TLO.ShrinkDemandedConstant(Op, NewMask))
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,
if (SimplifyDemandedBits(Op.getOperand(2), NewMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero2,
if (SimplifyDemandedBits(Op.getOperand(1), NewMask, 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))
if (TLO.ShrinkDemandedConstant(Op, NewMask))
return true;
// Only known if known in both the LHS and RHS.
@ -661,17 +658,17 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
KnownZero &= KnownZero2;
break;
case ISD::SELECT_CC:
if (SimplifyDemandedBits(Op.getOperand(3), DemandedMask, KnownZero,
if (SimplifyDemandedBits(Op.getOperand(3), NewMask, KnownZero,
KnownOne, TLO, Depth+1))
return true;
if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero2,
if (SimplifyDemandedBits(Op.getOperand(2), NewMask, 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))
if (TLO.ShrinkDemandedConstant(Op, NewMask))
return true;
// Only known if known in both the LHS and RHS.
@ -683,12 +680,16 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
unsigned ShAmt = SA->getValue();
SDOperand InOp = Op.getOperand(0);
// If the shift count is an invalid immediate, don't do anything.
if (ShAmt >= BitWidth)
break;
// 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) {
if (ShAmt && (NewMask & APInt::getLowBitsSet(BitWidth, ShAmt)) == 0) {
unsigned C1 = cast<ConstantSDNode>(InOp.getOperand(1))->getValue();
unsigned Opc = ISD::SHL;
int Diff = ShAmt-C1;
@ -705,28 +706,32 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
}
}
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask >> ShAmt,
if (SimplifyDemandedBits(Op.getOperand(0), NewMask.lshr(ShAmt),
KnownZero, KnownOne, TLO, Depth+1))
return true;
KnownZero <<= SA->getValue();
KnownOne <<= SA->getValue();
KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
// low bits known zero.
KnownZero |= APInt::getLowBitsSet(BitWidth, SA->getValue());
}
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 the shift count is an invalid immediate, don't do anything.
if (ShAmt >= BitWidth)
break;
// 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) {
if (ShAmt && (NewMask & APInt::getHighBitsSet(VTSize, ShAmt)) == 0) {
unsigned C1 = cast<ConstantSDNode>(InOp.getOperand(1))->getValue();
unsigned Opc = ISD::SRL;
int Diff = ShAmt-C1;
@ -743,17 +748,14 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
}
// Compute the new bits that are at the top now.
if (SimplifyDemandedBits(InOp, (DemandedMask << ShAmt) & TypeMask,
if (SimplifyDemandedBits(InOp, (NewMask << ShAmt),
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;
KnownZero = KnownZero.lshr(ShAmt);
KnownOne = KnownOne.lshr(ShAmt);
uint64_t HighBits = (1ULL << ShAmt)-1;
HighBits <<= VTSize - ShAmt;
APInt HighBits = APInt::getHighBitsSet(BitWidth, ShAmt);
KnownZero |= HighBits; // High bits known zero.
}
break;
@ -762,37 +764,34 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
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 the shift count is an invalid immediate, don't do anything.
if (ShAmt >= BitWidth)
break;
APInt InDemandedMask = (NewMask << ShAmt);
// 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);
APInt HighBits = APInt::getHighBitsSet(BitWidth, ShAmt);
if (HighBits.intersects(NewMask))
InDemandedMask |= APInt::getSignBit(MVT::getSizeInBits(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;
KnownZero = KnownZero.lshr(ShAmt);
KnownOne = KnownOne.lshr(ShAmt);
// Handle the sign bits.
uint64_t SignBit = MVT::getIntVTSignBit(VT);
SignBit >>= ShAmt; // Adjust to where it is now in the mask.
// Handle the sign bit, adjusted to where it is now in the mask.
APInt SignBit = APInt::getSignBit(BitWidth).lshr(ShAmt);
// 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) {
if (KnownZero.intersects(SignBit) || (HighBits & ~NewMask) == 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.
} else if (KnownOne.intersects(SignBit)) { // New bits are known one.
KnownOne |= HighBits;
}
}
@ -802,14 +801,19 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
// Sign extension. Compute the demanded bits in the result that are not
// present in the input.
uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & DemandedMask;
APInt NewBits = APInt::getHighBitsSet(BitWidth,
BitWidth - MVT::getSizeInBits(EVT)) &
NewMask;
// 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);
APInt InSignBit = APInt::getSignBit(MVT::getSizeInBits(EVT));
InSignBit.zext(BitWidth);
APInt InputDemandedBits = APInt::getLowBitsSet(BitWidth,
MVT::getSizeInBits(EVT)) &
NewMask;
// Since the sign extended bits are demanded, we know that the sign
// bit is demanded.
@ -824,11 +828,11 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
// top bits of the result.
// If the input sign bit is known zero, convert this into a zero extension.
if (KnownZero & InSignBit)
if (KnownZero.intersects(InSignBit))
return TLO.CombineTo(Op,
TLO.DAG.getZeroExtendInReg(Op.getOperand(0), EVT));
if (KnownOne & InSignBit) { // Input sign bit known set
if (KnownOne.intersects(InSignBit)) { // Input sign bit known set
KnownOne |= NewBits;
KnownZero &= ~NewBits;
} else { // Input sign bit unknown
@ -837,45 +841,34 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
}
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->getMemoryVT();
KnownZero |= ~MVT::getIntVTBitMask(VT) & DemandedMask;
}
break;
}
case ISD::ZERO_EXTEND: {
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
unsigned OperandBitWidth = Op.getOperand(0).getValueSizeInBits();
APInt InMask = NewMask;
InMask.trunc(OperandBitWidth);
// If none of the top bits are demanded, convert this into an any_extend.
uint64_t NewBits = (~InMask) & DemandedMask;
if (NewBits == 0)
APInt NewBits =
APInt::getHighBitsSet(BitWidth, BitWidth - OperandBitWidth) & NewMask;
if (!NewBits.intersects(NewMask))
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND,
Op.getValueType(),
Op.getOperand(0)));
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
if (SimplifyDemandedBits(Op.getOperand(0), InMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero.zext(BitWidth);
KnownOne.zext(BitWidth);
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;
unsigned InBits = MVT::getSizeInBits(InVT);
APInt InMask = APInt::getLowBitsSet(BitWidth, InBits);
APInt InSignBit = APInt::getLowBitsSet(BitWidth, InBits);
APInt NewBits = ~InMask & NewMask;
// If none of the top bits are demanded, convert this into an any_extend.
if (NewBits == 0)
@ -884,21 +877,24 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
// Since some of the sign extended bits are demanded, we know that the sign
// bit is demanded.
uint64_t InDemandedBits = DemandedMask & InMask;
APInt InDemandedBits = InMask & NewMask;
InDemandedBits |= InSignBit;
InDemandedBits.trunc(InBits);
if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, KnownZero,
KnownOne, TLO, Depth+1))
return true;
KnownZero.zext(BitWidth);
KnownOne.zext(BitWidth);
// If the sign bit is known zero, convert this to a zero extend.
if (KnownZero & InSignBit)
if (KnownZero.intersects(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) {
if (KnownOne.intersects(InSignBit)) {
KnownOne |= NewBits;
KnownZero &= ~NewBits;
} else { // Otherwise, top bits aren't known.
@ -908,36 +904,45 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
break;
}
case ISD::ANY_EXTEND: {
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
unsigned OperandBitWidth = Op.getOperand(0).getValueSizeInBits();
APInt InMask = NewMask;
InMask.trunc(OperandBitWidth);
if (SimplifyDemandedBits(Op.getOperand(0), InMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero.zext(BitWidth);
KnownOne.zext(BitWidth);
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,
APInt TruncMask = NewMask;
TruncMask.zext(Op.getOperand(0).getValueSizeInBits());
if (SimplifyDemandedBits(Op.getOperand(0), TruncMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
KnownZero.trunc(BitWidth);
KnownOne.trunc(BitWidth);
// 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);
unsigned InBitWidth = In.getValueSizeInBits();
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();
APInt HighBits = APInt::getHighBitsSet(InBitWidth,
InBitWidth - BitWidth);
HighBits = HighBits.lshr(ShAmt->getValue());
HighBits.trunc(BitWidth);
if (ShAmt->getValue() < MVT::getSizeInBits(Op.getValueType()) &&
(DemandedMask & HighBits) == 0) {
if (ShAmt->getValue() < BitWidth && !(HighBits & NewMask)) {
// 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,
@ -952,30 +957,24 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
}
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,
APInt InMask = APInt::getLowBitsSet(BitWidth,
MVT::getSizeInBits(VT));
if (SimplifyDemandedBits(Op.getOperand(0), InMask & NewMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero |= ~InMask & DemandedMask;
KnownZero |= ~InMask & NewMask;
break;
}
case ISD::FGETSIGN:
// All bits are zero except the low bit.
KnownZero = MVT::getIntVTBitMask(Op.getValueType()) ^ 1;
break;
case ISD::BIT_CONVERT:
#if 0
// If this is an FP->Int bitcast and if the sign bit is the only thing that
// is demanded, turn this into a FGETSIGN.
if (DemandedMask == MVT::getIntVTSignBit(Op.getValueType()) &&
if (NewMask == MVT::getIntVTSignBit(Op.getValueType()) &&
MVT::isFloatingPoint(Op.getOperand(0).getValueType()) &&
!MVT::isVector(Op.getOperand(0).getValueType())) {
// Only do this xform if FGETSIGN is valid or if before legalize.
@ -998,14 +997,20 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
case ISD::INTRINSIC_WO_CHAIN:
case ISD::INTRINSIC_W_CHAIN:
case ISD::INTRINSIC_VOID:
case ISD::CTTZ:
case ISD::CTLZ:
case ISD::CTPOP:
case ISD::LOAD:
case ISD::SETCC:
case ISD::FGETSIGN:
// Just use ComputeMaskedBits to compute output bits.
TLO.DAG.ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
TLO.DAG.ComputeMaskedBits(Op, NewMask, 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)
if ((NewMask & (KnownZero|KnownOne)) == NewMask)
return TLO.CombineTo(Op, TLO.DAG.getConstant(KnownOne, Op.getValueType()));
return false;