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[X86] Refactored getTargetConstantBitsFromNode to allow for expansion. NFCI. 

getTargetConstantBitsFromNode currently only extracts constant pool vector data, but it will need to be generalized to support broadcast and scalar constant pool data as well.

Converted Constant bit extraction and Bitset splitting to helper lambda functions.

llvm-svn: 288496
This commit is contained in:
Simon Pilgrim 2016-12-02 11:58:05 +00:00
parent 4bf67af2d5
commit b3ae416839
1 changed files with 60 additions and 48 deletions
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108
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -5131,7 +5131,7 @@ static const Constant *getTargetConstantFromNode(SDValue Op) {
return dyn_cast<Constant>(CNode->getConstVal());
}
// Extract constant bits from constant pool vector.
// Extract raw constant bits from constant pools.
static bool getTargetConstantBitsFromNode(SDValue Op, unsigned EltSizeInBits,
SmallBitVector &UndefElts,
SmallVectorImpl<APInt> &EltBits) {
@ -5143,63 +5143,75 @@ static bool getTargetConstantBitsFromNode(SDValue Op, unsigned EltSizeInBits,
assert((SizeInBits % EltSizeInBits) == 0 && "Can't split constant!");
unsigned NumElts = SizeInBits / EltSizeInBits;
auto *Cst = getTargetConstantFromNode(Op);
if (!Cst)
return false;
Type *CstTy = Cst->getType();
if (!CstTy->isVectorTy() || (SizeInBits != CstTy->getPrimitiveSizeInBits()))
return false;
// Extract all the undef/constant element data and pack into single bitsets.
APInt UndefBits(SizeInBits, 0);
APInt MaskBits(SizeInBits, 0);
unsigned CstEltSizeInBits = CstTy->getScalarSizeInBits();
for (unsigned i = 0, e = CstTy->getVectorNumElements(); i != e; ++i) {
auto *COp = Cst->getAggregateElement(i);
if (!COp ||
!(isa<UndefValue>(COp) || isa<ConstantInt>(COp) ||
isa<ConstantFP>(COp)))
// Split the undef/constant single bitset data into the target elements.
auto SplitBitData = [&]() {
UndefElts = SmallBitVector(NumElts, false);
EltBits.resize(NumElts, APInt(EltSizeInBits, 0));
for (unsigned i = 0; i != NumElts; ++i) {
APInt UndefEltBits = UndefBits.lshr(i * EltSizeInBits);
UndefEltBits = UndefEltBits.zextOrTrunc(EltSizeInBits);
// Only treat an element as UNDEF if all bits are UNDEF, otherwise
// treat it as zero.
if (UndefEltBits.isAllOnesValue()) {
UndefElts[i] = true;
continue;
}
APInt Bits = MaskBits.lshr(i * EltSizeInBits);
Bits = Bits.zextOrTrunc(EltSizeInBits);
EltBits[i] = Bits.getZExtValue();
}
return true;
};
// Extract constant bits from constant pool scalar/vector.
if (auto *Cst = getTargetConstantFromNode(Op)) {
Type *CstTy = Cst->getType();
if (!CstTy->isVectorTy() || (SizeInBits != CstTy->getPrimitiveSizeInBits()))
return false;
if (isa<UndefValue>(COp)) {
APInt EltUndef = APInt::getLowBitsSet(SizeInBits, CstEltSizeInBits);
UndefBits |= EltUndef.shl(i * CstEltSizeInBits);
continue;
auto ExtractConstantBits = [SizeInBits](const Constant *Cst, APInt &Mask,
APInt &Undefs) {
if (!Cst)
return false;
unsigned CstSizeInBits = Cst->getType()->getPrimitiveSizeInBits();
if (isa<UndefValue>(Cst)) {
Mask = APInt::getNullValue(SizeInBits);
Undefs = APInt::getLowBitsSet(SizeInBits, CstSizeInBits);
return true;
}
if (auto *CInt = dyn_cast<ConstantInt>(Cst)) {
Mask = CInt->getValue().zextOrTrunc(SizeInBits);
Undefs = APInt::getNullValue(SizeInBits);
return true;
}
if (auto *CFP = dyn_cast<ConstantFP>(Cst)) {
Mask = CFP->getValueAPF().bitcastToAPInt().zextOrTrunc(SizeInBits);
Undefs = APInt::getNullValue(SizeInBits);
return true;
}
return false;
};
unsigned CstEltSizeInBits = CstTy->getScalarSizeInBits();
for (unsigned i = 0, e = CstTy->getVectorNumElements(); i != e; ++i) {
APInt Bits, Undefs;
if (!ExtractConstantBits(Cst->getAggregateElement(i), Bits, Undefs))
return false;
MaskBits |= Bits.shl(i * CstEltSizeInBits);
UndefBits |= Undefs.shl(i * CstEltSizeInBits);
}
APInt Bits;
if (auto *CInt = dyn_cast<ConstantInt>(COp))
Bits = CInt->getValue();
else if (auto *CFP = dyn_cast<ConstantFP>(COp))
Bits = CFP->getValueAPF().bitcastToAPInt();
Bits = Bits.zextOrTrunc(SizeInBits);
MaskBits |= Bits.shl(i * CstEltSizeInBits);
return SplitBitData();
}
UndefElts = SmallBitVector(NumElts, false);
EltBits.resize(NumElts, APInt(EltSizeInBits, 0));
// Now extract the undef/constant bit data into the target elts.
for (unsigned i = 0; i != NumElts; ++i) {
APInt UndefEltBits = UndefBits.lshr(i * EltSizeInBits);
UndefEltBits = UndefEltBits.zextOrTrunc(EltSizeInBits);
// Only treat the element as UNDEF if all bits are UNDEF, otherwise
// treat it as zero.
if (UndefEltBits.isAllOnesValue()) {
UndefElts[i] = true;
continue;
}
APInt Bits = MaskBits.lshr(i * EltSizeInBits);
Bits = Bits.zextOrTrunc(EltSizeInBits);
EltBits[i] = Bits.getZExtValue();
}
return true;
return false;
}
static bool getTargetShuffleMaskIndices(SDValue MaskNode,