/// getShuffleMask - Read and decode a shufflevector mask.
/// Turn undef elements into negative values.
-static std::vector<int> getShuffleMask(const ShuffleVectorInst *SVI) {
+static SmallVector<int, 16> getShuffleMask(const ShuffleVectorInst *SVI) {
unsigned NElts = SVI->getType()->getNumElements();
if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
- return std::vector<int>(NElts, 0);
+ return SmallVector<int, 16>(NElts, 0);
if (isa<UndefValue>(SVI->getOperand(2)))
- return std::vector<int>(NElts, -1);
+ return SmallVector<int, 16>(NElts, -1);
- std::vector<int> Result;
+ SmallVector<int, 16> Result;
const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
if (isa<UndefValue>(*i))
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
Value *LHS = SVI.getOperand(0);
Value *RHS = SVI.getOperand(1);
- std::vector<int> Mask = getShuffleMask(&SVI);
+ SmallVector<int, 16> Mask = getShuffleMask(&SVI);
bool MadeChange = false;
unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
- if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
- return 0;
-
APInt UndefElts(VWidth, 0);
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
if (Value *V = SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
MadeChange = true;
}
+ unsigned LHSWidth = cast<VectorType>(LHS->getType())->getNumElements();
+
// Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
// Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
if (LHS == RHS || isa<UndefValue>(LHS)) {
if (isa<UndefValue>(LHS) && LHS == RHS) {
// shuffle(undef,undef,mask) -> undef.
- return ReplaceInstUsesWith(SVI, LHS);
+ Value* result = (VWidth == LHSWidth)
+ ? LHS : UndefValue::get(SVI.getType());
+ return ReplaceInstUsesWith(SVI, result);
}
// Remap any references to RHS to use LHS.
std::vector<Constant*> Elts;
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ for (unsigned i = 0, e = LHSWidth; i != VWidth; ++i) {
if (Mask[i] < 0)
Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
else {
MadeChange = true;
}
- // Analyze the shuffle, are the LHS or RHS and identity shuffles?
- bool isLHSID = true, isRHSID = true;
+ if (VWidth == LHSWidth) {
+ // Analyze the shuffle, are the LHS or RHS and identity shuffles?
+ bool isLHSID = true, isRHSID = true;
+
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] < 0) continue; // Ignore undef values.
+ // Is this an identity shuffle of the LHS value?
+ isLHSID &= (Mask[i] == (int)i);
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
- if (Mask[i] < 0) continue; // Ignore undef values.
- // Is this an identity shuffle of the LHS value?
- isLHSID &= (Mask[i] == (int)i);
+ // Is this an identity shuffle of the RHS value?
+ isRHSID &= (Mask[i]-e == i);
+ }
- // Is this an identity shuffle of the RHS value?
- isRHSID &= (Mask[i]-e == i);
+ // Eliminate identity shuffles.
+ if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
+ if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
}
- // Eliminate identity shuffles.
- if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
- if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
-
// If the LHS is a shufflevector itself, see if we can combine it with this
- // one without producing an unusual shuffle. Here we are really conservative:
+ // one without producing an unusual shuffle.
+ // Cases that might be simplified:
+ // 1.
+ // x1=shuffle(v1,v2,mask1)
+ // x=shuffle(x1,undef,mask)
+ // ==>
+ // x=shuffle(v1,undef,newMask)
+ // newMask[i] = (mask[i] < x1.size()) ? mask1[mask[i]] : -1
+ // 2.
+ // x1=shuffle(v1,undef,mask1)
+ // x=shuffle(x1,x2,mask)
+ // where v1.size() == mask1.size()
+ // ==>
+ // x=shuffle(v1,x2,newMask)
+ // newMask[i] = (mask[i] < x1.size()) ? mask1[mask[i]] : mask[i]
+ // 3.
+ // x2=shuffle(v2,undef,mask2)
+ // x=shuffle(x1,x2,mask)
+ // where v2.size() == mask2.size()
+ // ==>
+ // x=shuffle(x1,v2,newMask)
+ // newMask[i] = (mask[i] < x1.size())
+ // ? mask[i] : mask2[mask[i]-x1.size()]+x1.size()
+ // 4.
+ // x1=shuffle(v1,undef,mask1)
+ // x2=shuffle(v2,undef,mask2)
+ // x=shuffle(x1,x2,mask)
+ // where v1.size() == v2.size()
+ // ==>
+ // x=shuffle(v1,v2,newMask)
+ // newMask[i] = (mask[i] < x1.size())
+ // ? mask1[mask[i]] : mask2[mask[i]-x1.size()]+v1.size()
+ //
+ // Here we are really conservative:
// we are absolutely afraid of producing a shuffle mask not in the input
// program, because the code gen may not be smart enough to turn a merged
// shuffle into two specific shuffles: it may produce worse code. As such,
// we only merge two shuffles if the result is either a splat or one of the
- // two input shuffle masks. In this case, merging the shuffles just removes
+ // input shuffle masks. In this case, merging the shuffles just removes
// one instruction, which we know is safe. This is good for things like
- // turning: (splat(splat)) -> splat.
- if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
+ // turning: (splat(splat)) -> splat, or
+ // merge(V[0..n], V[n+1..2n]) -> V[0..2n]
+ ShuffleVectorInst* LHSShuffle = dyn_cast<ShuffleVectorInst>(LHS);
+ ShuffleVectorInst* RHSShuffle = dyn_cast<ShuffleVectorInst>(RHS);
+ if (LHSShuffle)
+ if (!isa<UndefValue>(LHSShuffle->getOperand(1)) && !isa<UndefValue>(RHS))
+ LHSShuffle = NULL;
+ if (RHSShuffle)
+ if (!isa<UndefValue>(RHSShuffle->getOperand(1)))
+ RHSShuffle = NULL;
+ if (!LHSShuffle && !RHSShuffle)
+ return MadeChange ? &SVI : 0;
+
+ Value* LHSOp0 = NULL;
+ Value* LHSOp1 = NULL;
+ Value* RHSOp0 = NULL;
+ unsigned LHSOp0Width = 0;
+ unsigned RHSOp0Width = 0;
+ if (LHSShuffle) {
+ LHSOp0 = LHSShuffle->getOperand(0);
+ LHSOp1 = LHSShuffle->getOperand(1);
+ LHSOp0Width = cast<VectorType>(LHSOp0->getType())->getNumElements();
+ }
+ if (RHSShuffle) {
+ RHSOp0 = RHSShuffle->getOperand(0);
+ RHSOp0Width = cast<VectorType>(RHSOp0->getType())->getNumElements();
+ }
+ Value* newLHS = LHS;
+ Value* newRHS = RHS;
+ if (LHSShuffle) {
+ // case 1
if (isa<UndefValue>(RHS)) {
- std::vector<int> LHSMask = getShuffleMask(LHSSVI);
-
- if (LHSMask.size() == Mask.size()) {
- std::vector<int> NewMask;
- bool isSplat = true;
- int SplatElt = -1; // undef
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
- int MaskElt;
- if (Mask[i] < 0 || Mask[i] >= (int)e)
- MaskElt = -1; // undef
- else
- MaskElt = LHSMask[Mask[i]];
- // Check if this could still be a splat.
- if (MaskElt >= 0) {
- if (SplatElt >=0 && SplatElt != MaskElt)
- isSplat = false;
- SplatElt = MaskElt;
- }
- NewMask.push_back(MaskElt);
- }
+ newLHS = LHSOp0;
+ newRHS = LHSOp1;
+ }
+ // case 2 or 4
+ else if (LHSOp0Width == LHSWidth) {
+ newLHS = LHSOp0;
+ }
+ }
+ // case 3 or 4
+ if (RHSShuffle && RHSOp0Width == LHSWidth) {
+ newRHS = RHSOp0;
+ }
+ // case 4
+ if (LHSOp0 == RHSOp0) {
+ newLHS = LHSOp0;
+ newRHS = NULL;
+ }
- // If the result mask is equal to the src shuffle or this
- // shuffle mask, do the replacement.
- if (isSplat || NewMask == LHSMask || NewMask == Mask) {
- std::vector<Constant*> Elts;
- Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
- for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
- if (NewMask[i] < 0) {
- Elts.push_back(UndefValue::get(Int32Ty));
- } else {
- Elts.push_back(ConstantInt::get(Int32Ty, NewMask[i]));
- }
- }
- return new ShuffleVectorInst(LHSSVI->getOperand(0),
- LHSSVI->getOperand(1),
- ConstantVector::get(Elts));
+ if (newLHS == LHS && newRHS == RHS)
+ return MadeChange ? &SVI : 0;
+
+ SmallVector<int, 16> LHSMask;
+ SmallVector<int, 16> RHSMask;
+ if (newLHS != LHS) {
+ LHSMask = getShuffleMask(LHSShuffle);
+ }
+ if (RHSShuffle && newRHS != RHS) {
+ RHSMask = getShuffleMask(RHSShuffle);
+ }
+ unsigned newLHSWidth = (newLHS != LHS) ? LHSOp0Width : LHSWidth;
+ SmallVector<int, 16> newMask;
+ bool isSplat = true;
+ int SplatElt = -1;
+ // Create a new mask for the new ShuffleVectorInst so that the new
+ // ShuffleVectorInst is equivalent to the original one.
+ for (unsigned i = 0; i < VWidth; ++i) {
+ int eltMask;
+ if (Mask[i] == -1) {
+ // This element is an undef value.
+ eltMask = -1;
+ } else if (Mask[i] < (int)LHSWidth) {
+ // This element is from left hand side vector operand.
+ //
+ // If LHS is going to be replaced (case 1, 2, or 4), calculate the
+ // new mask value for the element.
+ if (newLHS != LHS) {
+ eltMask = LHSMask[Mask[i]];
+ // If the value selected is an undef value, explicitly specify it
+ // with a -1 mask value.
+ if (eltMask >= (int)LHSOp0Width && isa<UndefValue>(LHSOp1))
+ eltMask = -1;
+ }
+ else
+ eltMask = Mask[i];
+ } else {
+ // This element is from right hand side vector operand
+ //
+ // If the value selected is an undef value, explicitly specify it
+ // with a -1 mask value. (case 1)
+ if (isa<UndefValue>(RHS))
+ eltMask = -1;
+ // If RHS is going to be replaced (case 3 or 4), calculate the
+ // new mask value for the element.
+ else if (newRHS != RHS) {
+ eltMask = RHSMask[Mask[i]-LHSWidth];
+ // If the value selected is an undef value, explicitly specify it
+ // with a -1 mask value.
+ if (eltMask >= (int)RHSOp0Width) {
+ assert(isa<UndefValue>(RHSShuffle->getOperand(1))
+ && "should have been check above");
+ eltMask = -1;
}
}
+ else
+ eltMask = Mask[i]-LHSWidth;
+
+ // If LHS's width is changed, shift the mask value accordingly.
+ // If newRHS == NULL, i.e. LHSOp0 == RHSOp0, we want to remap any
+ // references to RHSOp0 to LHSOp0, so we don't need to shift the mask.
+ if (eltMask >= 0 && newRHS != NULL)
+ eltMask += newLHSWidth;
+ }
+
+ // Check if this could still be a splat.
+ if (eltMask >= 0) {
+ if (SplatElt >= 0 && SplatElt != eltMask)
+ isSplat = false;
+ SplatElt = eltMask;
+ }
+
+ newMask.push_back(eltMask);
+ }
+
+ // If the result mask is equal to one of the original shuffle masks,
+ // or is a splat, do the replacement.
+ if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask) {
+ SmallVector<Constant*, 16> Elts;
+ Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
+ for (unsigned i = 0, e = newMask.size(); i != e; ++i) {
+ if (newMask[i] < 0) {
+ Elts.push_back(UndefValue::get(Int32Ty));
+ } else {
+ Elts.push_back(ConstantInt::get(Int32Ty, newMask[i]));
+ }
}
+ if (newRHS == NULL)
+ newRHS = UndefValue::get(newLHS->getType());
+ return new ShuffleVectorInst(newLHS, newRHS, ConstantVector::get(Elts));
}
return MadeChange ? &SVI : 0;
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