Instruction *visitStoreInst(StoreInst &SI);
Instruction *visitBranchInst(BranchInst &BI);
Instruction *visitSwitchInst(SwitchInst &SI);
+ Instruction *visitInsertElementInst(InsertElementInst &IE);
Instruction *visitExtractElementInst(ExtractElementInst &EI);
+ Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
// visitInstruction - Specify what to return for unhandled instructions...
Instruction *visitInstruction(Instruction &I) { return 0; }
Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
if (V->getType() == Ty) return V;
+ if (Constant *CV = dyn_cast<Constant>(V))
+ return ConstantExpr::getCast(CV, Ty);
+
Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
WorkList.push_back(C);
return C;
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return;
+ Mask &= V->getType()->getIntegralTypeMask();
+
switch (I->getOpcode()) {
case Instruction::And:
// If either the LHS or the RHS are Zero, the result is zero.
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return false; // Only analyze instructions.
+ DemandedMask &= V->getType()->getIntegralTypeMask();
+
uint64_t KnownZero2, KnownOne2;
switch (I->getOpcode()) {
default: break;
}
}
+ // fold (and (cast A), (cast B)) -> (cast (and A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOperand(0)->getType() == Op1C->getOperand(0)->getType() &&
+ Op0C->getOperand(0)->getType()->isIntegral()) {
+ Instruction *NewOp = BinaryOperator::createAnd(Op0C->getOperand(0),
+ Op1C->getOperand(0),
+ I.getName());
+ InsertNewInstBefore(NewOp, I);
+ return new CastInst(NewOp, I.getType());
+ }
+ }
+
return Changed ? &I : 0;
}
}
}
}
+
+ // fold (or (cast A), (cast B)) -> (cast (or A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOperand(0)->getType() == Op1C->getOperand(0)->getType() &&
+ Op0C->getOperand(0)->getType()->isIntegral()) {
+ Instruction *NewOp = BinaryOperator::createOr(Op0C->getOperand(0),
+ Op1C->getOperand(0),
+ I.getName());
+ InsertNewInstBefore(NewOp, I);
+ return new CastInst(NewOp, I.getType());
+ }
+ }
+
return Changed ? &I : 0;
}
if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
return R;
+ // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOperand(0)->getType() == Op1C->getOperand(0)->getType() &&
+ Op0C->getOperand(0)->getType()->isIntegral()) {
+ Instruction *NewOp = BinaryOperator::createXor(Op0C->getOperand(0),
+ Op1C->getOperand(0),
+ I.getName());
+ InsertNewInstBefore(NewOp, I);
+ return new CastInst(NewOp, I.getType());
+ }
+ }
+
return Changed ? &I : 0;
}
// this case, C1 == C2 and C1 is 8, 16, or 32.
if (ShiftAmt1 == ShiftAmt2) {
const Type *SExtType = 0;
- switch (ShiftAmt1) {
+ switch (Op0->getType()->getPrimitiveSizeInBits() - ShiftAmt1) {
case 8 : SExtType = Type::SByteTy; break;
case 16: SExtType = Type::ShortTy; break;
case 32: SExtType = Type::IntTy; break;
SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
return true;
+ // Packed type conversions don't modify bits.
+ if (isa<PackedType>(SrcTy) && isa<PackedType>(MidTy) &&isa<PackedType>(DstTy))
+ return true;
+
return false;
}
if (isa<PHINode>(Src))
if (Instruction *NV = FoldOpIntoPhi(CI))
return NV;
+
+ // If the source and destination are pointers, and this cast is equivalent to
+ // a getelementptr X, 0, 0, 0... turn it into the appropriate getelementptr.
+ // This can enhance SROA and other transforms that want type-safe pointers.
+ if (const PointerType *DstPTy = dyn_cast<PointerType>(CI.getType()))
+ if (const PointerType *SrcPTy = dyn_cast<PointerType>(Src->getType())) {
+ const Type *DstTy = DstPTy->getElementType();
+ const Type *SrcTy = SrcPTy->getElementType();
+
+ Constant *ZeroUInt = Constant::getNullValue(Type::UIntTy);
+ unsigned NumZeros = 0;
+ while (SrcTy != DstTy &&
+ isa<CompositeType>(SrcTy) && !isa<PointerType>(SrcTy)) {
+ SrcTy = cast<CompositeType>(SrcTy)->getTypeAtIndex(ZeroUInt);
+ ++NumZeros;
+ }
+ // If we found a path from the src to dest, create the getelementptr now.
+ if (SrcTy == DstTy) {
+ std::vector<Value*> Idxs(NumZeros+1, ZeroUInt);
+ return new GetElementPtrInst(Src, Idxs);
+ }
+ }
+
// If the source value is an instruction with only this use, we can attempt to
// propagate the cast into the instruction. Also, only handle integral types
// for now.
default: break;
case Intrinsic::ppc_altivec_lvx:
case Intrinsic::ppc_altivec_lvxl:
- // Turn lvx -> load if the pointer is known aligned.
+ case Intrinsic::x86_sse_loadu_ps:
+ case Intrinsic::x86_sse2_loadu_pd:
+ case Intrinsic::x86_sse2_loadu_dq:
+ // Turn PPC lvx -> load if the pointer is known aligned.
+ // Turn X86 loadups -> load if the pointer is known aligned.
if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
- Instruction *Ptr = new CastInst(II->getOperand(1),
- PointerType::get(II->getType()), "tmp");
- InsertNewInstBefore(Ptr, CI);
+ Value *Ptr = InsertCastBefore(II->getOperand(1),
+ PointerType::get(II->getType()), CI);
return new LoadInst(Ptr);
}
break;
case Intrinsic::ppc_altivec_stvxl:
// Turn stvx -> store if the pointer is known aligned.
if (GetKnownAlignment(II->getOperand(2), TD) >= 16) {
- const Type *OpTy = II->getOperand(1)->getType();
- Instruction *Ptr = new CastInst(II->getOperand(2),
- PointerType::get(OpTy), "tmp");
- InsertNewInstBefore(Ptr, CI);
+ const Type *OpPtrTy = PointerType::get(II->getOperand(1)->getType());
+ Value *Ptr = InsertCastBefore(II->getOperand(2), OpPtrTy, CI);
return new StoreInst(II->getOperand(1), Ptr);
}
break;
-
+ case Intrinsic::x86_sse_storeu_ps:
+ case Intrinsic::x86_sse2_storeu_pd:
+ case Intrinsic::x86_sse2_storeu_dq:
+ case Intrinsic::x86_sse2_storel_dq:
+ // Turn X86 storeu -> store if the pointer is known aligned.
+ if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
+ const Type *OpPtrTy = PointerType::get(II->getOperand(2)->getType());
+ Value *Ptr = InsertCastBefore(II->getOperand(1), OpPtrTy, CI);
+ return new StoreInst(II->getOperand(2), Ptr);
+ }
+ break;
+ case Intrinsic::ppc_altivec_vperm:
+ // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
+ if (ConstantPacked *Mask = dyn_cast<ConstantPacked>(II->getOperand(3))) {
+ assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
+
+ // Check that all of the elements are integer constants or undefs.
+ bool AllEltsOk = true;
+ for (unsigned i = 0; i != 16; ++i) {
+ if (!isa<ConstantInt>(Mask->getOperand(i)) &&
+ !isa<UndefValue>(Mask->getOperand(i))) {
+ AllEltsOk = false;
+ break;
+ }
+ }
+
+ if (AllEltsOk) {
+ // Cast the input vectors to byte vectors.
+ Value *Op0 = InsertCastBefore(II->getOperand(1), Mask->getType(), CI);
+ Value *Op1 = InsertCastBefore(II->getOperand(2), Mask->getType(), CI);
+ Value *Result = UndefValue::get(Op0->getType());
+
+ // Only extract each element once.
+ Value *ExtractedElts[32];
+ memset(ExtractedElts, 0, sizeof(ExtractedElts));
+
+ for (unsigned i = 0; i != 16; ++i) {
+ if (isa<UndefValue>(Mask->getOperand(i)))
+ continue;
+ unsigned Idx =cast<ConstantInt>(Mask->getOperand(i))->getRawValue();
+ Idx &= 31; // Match the hardware behavior.
+
+ if (ExtractedElts[Idx] == 0) {
+ Instruction *Elt =
+ new ExtractElementInst(Idx < 16 ? Op0 : Op1,
+ ConstantUInt::get(Type::UIntTy, Idx&15),
+ "tmp");
+ InsertNewInstBefore(Elt, CI);
+ ExtractedElts[Idx] = Elt;
+ }
+
+ // Insert this value into the result vector.
+ Result = new InsertElementInst(Result, ExtractedElts[Idx],
+ ConstantUInt::get(Type::UIntTy, i),
+ "tmp");
+ InsertNewInstBefore(cast<Instruction>(Result), CI);
+ }
+ return new CastInst(Result, CI.getType());
+ }
+ }
+ break;
+
case Intrinsic::stackrestore: {
// If the save is right next to the restore, remove the restore. This can
// happen when variable allocas are DCE'd.
// Check to see if we are changing the return type...
if (OldRetTy != FT->getReturnType()) {
if (Callee->isExternal() &&
- !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
- !Caller->use_empty())
+ !(OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) ||
+ (isa<PointerType>(FT->getReturnType()) &&
+ TD->getIntPtrType()->isLosslesslyConvertibleTo(OldRetTy)))
+ && !Caller->use_empty())
return false; // Cannot transform this return value...
// If the callsite is an invoke instruction, and the return value is used by
static Value *FindScalarElement(Value *V, unsigned EltNo) {
assert(isa<PackedType>(V->getType()) && "Not looking at a vector?");
const PackedType *PTy = cast<PackedType>(V->getType());
- if (EltNo >= PTy->getNumElements()) // Out of range access.
+ unsigned Width = PTy->getNumElements();
+ if (EltNo >= Width) // Out of range access.
return UndefValue::get(PTy->getElementType());
if (isa<UndefValue>(V))
// Otherwise, the insertelement doesn't modify the value, recurse on its
// vector input.
return FindScalarElement(III->getOperand(0), EltNo);
+ } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
+ if (isa<ConstantAggregateZero>(SVI->getOperand(2))) {
+ return FindScalarElement(SVI->getOperand(0), 0);
+ } else if (ConstantPacked *CP =
+ dyn_cast<ConstantPacked>(SVI->getOperand(2))) {
+ if (isa<UndefValue>(CP->getOperand(EltNo)))
+ return UndefValue::get(PTy->getElementType());
+ unsigned InEl = cast<ConstantUInt>(CP->getOperand(EltNo))->getValue();
+ if (InEl < Width)
+ return FindScalarElement(SVI->getOperand(0), InEl);
+ else
+ return FindScalarElement(SVI->getOperand(1), InEl - Width);
+ }
}
// Otherwise, we don't know.
// If extracting a specified index from the vector, see if we can recursively
// find a previously computed scalar that was inserted into the vector.
- if (ConstantUInt *IdxC = dyn_cast<ConstantUInt>(EI.getOperand(1)))
+ if (ConstantUInt *IdxC = dyn_cast<ConstantUInt>(EI.getOperand(1))) {
if (Value *Elt = FindScalarElement(EI.getOperand(0), IdxC->getValue()))
return ReplaceInstUsesWith(EI, Elt);
+ }
if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0)))
if (I->hasOneUse()) {
return 0;
}
+/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
+/// elements from either LHS or RHS, return the shuffle mask and true.
+/// Otherwise, return false.
+static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
+ std::vector<Constant*> &Mask) {
+ assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
+ "Invalid CollectSingleShuffleElements");
+ unsigned NumElts = cast<PackedType>(V->getType())->getNumElements();
+
+ if (isa<UndefValue>(V)) {
+ Mask.assign(NumElts, UndefValue::get(Type::UIntTy));
+ return true;
+ } else if (V == LHS) {
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantUInt::get(Type::UIntTy, i));
+ return true;
+ } else if (V == RHS) {
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantUInt::get(Type::UIntTy, i+NumElts));
+ return true;
+ } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert of an extract from some other vector, include it.
+ Value *VecOp = IEI->getOperand(0);
+ Value *ScalarOp = IEI->getOperand(1);
+ Value *IdxOp = IEI->getOperand(2);
+
+ if (!isa<ConstantInt>(IdxOp))
+ return false;
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getRawValue();
+
+ if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
+ // Okay, we can handle this if the vector we are insertinting into is
+ // transitively ok.
+ if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
+ // If so, update the mask to reflect the inserted undef.
+ Mask[InsertedIdx] = UndefValue::get(Type::UIntTy);
+ return true;
+ }
+ } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
+ if (isa<ConstantInt>(EI->getOperand(1)) &&
+ EI->getOperand(0)->getType() == V->getType()) {
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getRawValue();
+
+ // This must be extracting from either LHS or RHS.
+ if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
+ // Okay, we can handle this if the vector we are insertinting into is
+ // transitively ok.
+ if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
+ // If so, update the mask to reflect the inserted value.
+ if (EI->getOperand(0) == LHS) {
+ Mask[InsertedIdx & (NumElts-1)] =
+ ConstantUInt::get(Type::UIntTy, ExtractedIdx);
+ } else {
+ assert(EI->getOperand(0) == RHS);
+ Mask[InsertedIdx & (NumElts-1)] =
+ ConstantUInt::get(Type::UIntTy, ExtractedIdx+NumElts);
+
+ }
+ return true;
+ }
+ }
+ }
+ }
+ }
+ // TODO: Handle shufflevector here!
+
+ return false;
+}
+
+/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
+/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
+/// that computes V and the LHS value of the shuffle.
+static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
+ Value *&RHS) {
+ assert(isa<PackedType>(V->getType()) &&
+ (RHS == 0 || V->getType() == RHS->getType()) &&
+ "Invalid shuffle!");
+ unsigned NumElts = cast<PackedType>(V->getType())->getNumElements();
+
+ if (isa<UndefValue>(V)) {
+ Mask.assign(NumElts, UndefValue::get(Type::UIntTy));
+ return V;
+ } else if (isa<ConstantAggregateZero>(V)) {
+ Mask.assign(NumElts, ConstantUInt::get(Type::UIntTy, 0));
+ return V;
+ } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert of an extract from some other vector, include it.
+ Value *VecOp = IEI->getOperand(0);
+ Value *ScalarOp = IEI->getOperand(1);
+ Value *IdxOp = IEI->getOperand(2);
+
+ if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+ if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+ EI->getOperand(0)->getType() == V->getType()) {
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getRawValue();
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getRawValue();
+
+ // Either the extracted from or inserted into vector must be RHSVec,
+ // otherwise we'd end up with a shuffle of three inputs.
+ if (EI->getOperand(0) == RHS || RHS == 0) {
+ RHS = EI->getOperand(0);
+ Value *V = CollectShuffleElements(VecOp, Mask, RHS);
+ Mask[InsertedIdx & (NumElts-1)] =
+ ConstantUInt::get(Type::UIntTy, NumElts+ExtractedIdx);
+ return V;
+ }
+
+ if (VecOp == RHS) {
+ Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
+ // Everything but the extracted element is replaced with the RHS.
+ for (unsigned i = 0; i != NumElts; ++i) {
+ if (i != InsertedIdx)
+ Mask[i] = ConstantUInt::get(Type::UIntTy, NumElts+i);
+ }
+ return V;
+ }
+
+ // If this insertelement is a chain that comes from exactly these two
+ // vectors, return the vector and the effective shuffle.
+ if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
+ return EI->getOperand(0);
+
+ }
+ }
+ }
+ // TODO: Handle shufflevector here!
+
+ // Otherwise, can't do anything fancy. Return an identity vector.
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantUInt::get(Type::UIntTy, i));
+ return V;
+}
+
+Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
+ Value *VecOp = IE.getOperand(0);
+ Value *ScalarOp = IE.getOperand(1);
+ Value *IdxOp = IE.getOperand(2);
+
+ // If the inserted element was extracted from some other vector, and if the
+ // indexes are constant, try to turn this into a shufflevector operation.
+ if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+ if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+ EI->getOperand(0)->getType() == IE.getType()) {
+ unsigned NumVectorElts = IE.getType()->getNumElements();
+ unsigned ExtractedIdx=cast<ConstantInt>(EI->getOperand(1))->getRawValue();
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getRawValue();
+
+ if (ExtractedIdx >= NumVectorElts) // Out of range extract.
+ return ReplaceInstUsesWith(IE, VecOp);
+
+ if (InsertedIdx >= NumVectorElts) // Out of range insert.
+ return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
+
+ // If we are extracting a value from a vector, then inserting it right
+ // back into the same place, just use the input vector.
+ if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
+ return ReplaceInstUsesWith(IE, VecOp);
+
+ // We could theoretically do this for ANY input. However, doing so could
+ // turn chains of insertelement instructions into a chain of shufflevector
+ // instructions, and right now we do not merge shufflevectors. As such,
+ // only do this in a situation where it is clear that there is benefit.
+ if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
+ // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of
+ // the values of VecOp, except then one read from EIOp0.
+ // Build a new shuffle mask.
+ std::vector<Constant*> Mask;
+ if (isa<UndefValue>(VecOp))
+ Mask.assign(NumVectorElts, UndefValue::get(Type::UIntTy));
+ else {
+ assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
+ Mask.assign(NumVectorElts, ConstantUInt::get(Type::UIntTy,
+ NumVectorElts));
+ }
+ Mask[InsertedIdx] = ConstantUInt::get(Type::UIntTy, ExtractedIdx);
+ return new ShuffleVectorInst(EI->getOperand(0), VecOp,
+ ConstantPacked::get(Mask));
+ }
+
+ // If this insertelement isn't used by some other insertelement, turn it
+ // (and any insertelements it points to), into one big shuffle.
+ if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
+ std::vector<Constant*> Mask;
+ Value *RHS = 0;
+ Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
+ if (RHS == 0) RHS = UndefValue::get(LHS->getType());
+ // We now have a shuffle of LHS, RHS, Mask.
+ return new ShuffleVectorInst(LHS, RHS, ConstantPacked::get(Mask));
+ }
+ }
+ }
+
+ return 0;
+}
+
+
+Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
+ Value *LHS = SVI.getOperand(0);
+ Value *RHS = SVI.getOperand(1);
+ Constant *Mask = cast<Constant>(SVI.getOperand(2));
+
+ bool MadeChange = false;
+
+ if (isa<UndefValue>(Mask))
+ return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
+
+ // TODO: If we have shuffle(x, undef, mask) and any elements of mask refer to
+ // the undef, change them to undefs.
+
+ // Canonicalize shuffle(x,x) -> shuffle(x,undef)
+ if (LHS == RHS) {
+ if (isa<UndefValue>(LHS)) {
+ // shuffle(undef,undef,mask) -> undef.
+ return ReplaceInstUsesWith(SVI, LHS);
+ }
+
+ if (!isa<ConstantAggregateZero>(Mask)) {
+ // Remap any references to RHS to use LHS.
+ ConstantPacked *CP = cast<ConstantPacked>(Mask);
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
+ Elts.push_back(CP->getOperand(i));
+ if (isa<UndefValue>(CP->getOperand(i)))
+ continue;
+ unsigned MV = cast<ConstantInt>(CP->getOperand(i))->getRawValue();
+ if (MV >= e)
+ Elts.back() = ConstantUInt::get(Type::UIntTy, MV & (e-1));
+ }
+ Mask = ConstantPacked::get(Elts);
+ }
+ SVI.setOperand(1, UndefValue::get(RHS->getType()));
+ SVI.setOperand(2, Mask);
+ MadeChange = true;
+ }
+
+ // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
+ if (isa<UndefValue>(LHS)) {
+ // shuffle(undef,x,<0,0,0,0>) -> undef.
+ if (isa<ConstantAggregateZero>(Mask))
+ return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
+
+ ConstantPacked *CPM = cast<ConstantPacked>(Mask);
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = CPM->getNumOperands(); i != e; ++i) {
+ if (isa<UndefValue>(CPM->getOperand(i)))
+ Elts.push_back(CPM->getOperand(i));
+ else {
+ unsigned EltNo = cast<ConstantUInt>(CPM->getOperand(i))->getRawValue();
+ if (EltNo >= e)
+ Elts.push_back(ConstantUInt::get(Type::UIntTy, EltNo-e));
+ else // Referring to the undef.
+ Elts.push_back(UndefValue::get(Type::UIntTy));
+ }
+ }
+ return new ShuffleVectorInst(RHS, LHS, ConstantPacked::get(Elts));
+ }
+
+ if (ConstantPacked *CP = dyn_cast<ConstantPacked>(Mask)) {
+ bool isLHSID = true, isRHSID = true;
+
+ // Analyze the shuffle.
+ for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
+ if (isa<UndefValue>(CP->getOperand(i)))
+ continue;
+ unsigned MV = cast<ConstantInt>(CP->getOperand(i))->getRawValue();
+
+ // Is this an identity shuffle of the LHS value?
+ isLHSID &= (MV == i);
+
+ // Is this an identity shuffle of the RHS value?
+ isRHSID &= (MV-e == i);
+ }
+
+ // Eliminate identity shuffles.
+ if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
+ if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
+ }
+
+ return MadeChange ? &SVI : 0;
+}
+
+
void InstCombiner::removeFromWorkList(Instruction *I) {
WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
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