// Transform trunc(lshr (sext A), Cst) to ashr A, Cst to eliminate type
// conversion.
// It works because bits coming from sign extension have the same value as
- // sign bit of the original value; performing ashr instead of lshr
+ // the sign bit of the original value; performing ashr instead of lshr
// generates bits of the same value as the sign bit.
if (Src->hasOneUse() &&
match(Src, m_LShr(m_SExt(m_Value(A)), m_ConstantInt(Cst))) &&
const unsigned ASize = A->getType()->getPrimitiveSizeInBits();
// This optimization can be only performed when zero bits generated by
// the original lshr aren't pulled into the value after truncation, so we
- // can only shift by values smaller then the size of destination type (in
+ // can only shift by values smaller than the size of destination type (in
// bits).
if (Cst->getValue().ult(ASize)) {
Value *Shift = Builder->CreateAShr(A, Cst->getZExtValue());
if (Instruction *I = commonCastTransforms(CI))
return I;
// If we have fptrunc(OpI (fpextend x), (fpextend y)), we would like to
- // simpilify this expression to avoid one or more of the trunc/extend
+ // simplify this expression to avoid one or more of the trunc/extend
// operations if we can do so without changing the numerical results.
//
// The exact manner in which the widths of the operands interact to limit
return Result;
}
+/// Canonicalize scalar bitcasts of extracted elements into a bitcast of the
+/// vector followed by extract element. The backend tends to handle bitcasts of
+/// vectors better than bitcasts of scalars because vector registers are
+/// usually not type-specific like scalar integer or scalar floating-point.
+static Instruction *canonicalizeBitCastExtElt(BitCastInst &BitCast,
+ InstCombiner &IC,
+ const DataLayout &DL) {
+ // TODO: Create and use a pattern matcher for ExtractElementInst.
+ auto *ExtElt = dyn_cast<ExtractElementInst>(BitCast.getOperand(0));
+ if (!ExtElt || !ExtElt->hasOneUse())
+ return nullptr;
+
+ // The bitcast must be to a vectorizable type, otherwise we can't make a new
+ // type to extract from.
+ Type *DestType = BitCast.getType();
+ if (!VectorType::isValidElementType(DestType))
+ return nullptr;
+
+ unsigned NumElts = ExtElt->getVectorOperandType()->getNumElements();
+ auto *NewVecType = VectorType::get(DestType, NumElts);
+ auto *NewBC = IC.Builder->CreateBitCast(ExtElt->getVectorOperand(),
+ NewVecType, "bc");
+ return ExtractElementInst::Create(NewBC, ExtElt->getIndexOperand());
+}
+
+static Instruction *foldVecTruncToExtElt(Value *VecInput, Type *DestTy,
+ unsigned ShiftAmt, InstCombiner &IC,
+ const DataLayout &DL) {
+ VectorType *VecTy = cast<VectorType>(VecInput->getType());
+ unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
+ unsigned VecWidth = VecTy->getPrimitiveSizeInBits();
+
+ if ((VecWidth % DestWidth != 0) || (ShiftAmt % DestWidth != 0))
+ return nullptr;
+
+ // If the element type of the vector doesn't match the result type,
+ // bitcast it to be a vector type we can extract from.
+ unsigned NumVecElts = VecWidth / DestWidth;
+ if (VecTy->getElementType() != DestTy) {
+ VecTy = VectorType::get(DestTy, NumVecElts);
+ VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
+ }
+
+ unsigned Elt = ShiftAmt / DestWidth;
+ if (DL.isBigEndian())
+ Elt = NumVecElts - 1 - Elt;
+
+ return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
+}
/// See if we can optimize an integer->float/double bitcast.
/// The various long double bitcasts can't get in here.
static Instruction *optimizeIntToFloatBitCast(BitCastInst &CI, InstCombiner &IC,
const DataLayout &DL) {
Value *Src = CI.getOperand(0);
- Type *DestTy = CI.getType();
+ Type *DstTy = CI.getType();
// If this is a bitcast from int to float, check to see if the int is an
// extraction from a vector.
Value *VecInput = nullptr;
// bitcast(trunc(bitcast(somevector)))
if (match(Src, m_Trunc(m_BitCast(m_Value(VecInput)))) &&
- isa<VectorType>(VecInput->getType())) {
- VectorType *VecTy = cast<VectorType>(VecInput->getType());
- unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
-
- if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0) {
- // If the element type of the vector doesn't match the result type,
- // bitcast it to be a vector type we can extract from.
- if (VecTy->getElementType() != DestTy) {
- VecTy = VectorType::get(DestTy,
- VecTy->getPrimitiveSizeInBits() / DestWidth);
- VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
- }
-
- unsigned Elt = 0;
- if (DL.isBigEndian())
- Elt = VecTy->getPrimitiveSizeInBits() / DestWidth - 1;
- return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
- }
- }
+ isa<VectorType>(VecInput->getType()))
+ return foldVecTruncToExtElt(VecInput, DstTy, 0, IC, DL);
// bitcast(trunc(lshr(bitcast(somevector), cst))
ConstantInt *ShAmt = nullptr;
if (match(Src, m_Trunc(m_LShr(m_BitCast(m_Value(VecInput)),
m_ConstantInt(ShAmt)))) &&
- isa<VectorType>(VecInput->getType())) {
- VectorType *VecTy = cast<VectorType>(VecInput->getType());
- unsigned DestWidth = DestTy->getPrimitiveSizeInBits();
- if (VecTy->getPrimitiveSizeInBits() % DestWidth == 0 &&
- ShAmt->getZExtValue() % DestWidth == 0) {
- // If the element type of the vector doesn't match the result type,
- // bitcast it to be a vector type we can extract from.
- if (VecTy->getElementType() != DestTy) {
- VecTy = VectorType::get(DestTy,
- VecTy->getPrimitiveSizeInBits() / DestWidth);
- VecInput = IC.Builder->CreateBitCast(VecInput, VecTy);
- }
+ isa<VectorType>(VecInput->getType()))
+ return foldVecTruncToExtElt(VecInput, DstTy, ShAmt->getZExtValue(), IC, DL);
- unsigned Elt = ShAmt->getZExtValue() / DestWidth;
- if (DL.isBigEndian())
- Elt = VecTy->getPrimitiveSizeInBits() / DestWidth - 1 - Elt;
- return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
- }
- }
return nullptr;
}
}
}
+ if (Instruction *I = canonicalizeBitCastExtElt(CI, *this, DL))
+ return I;
+
if (SrcTy->isPointerTy())
return commonPointerCastTransforms(CI);
return commonCastTransforms(CI);
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