//===----------------------------------------------------------------------===//
#include "InstCombine.h"
+#include "llvm/Support/PatternMatch.h"
using namespace llvm;
+using namespace PatternMatch;
/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
/// is to leave as a vector operation. isConstant indicates whether we're
return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
}
+ // Extract a value from a vector add operation with a constant zero.
+ Value *Val = 0; Constant *Con = 0;
+ if (match(V, m_Add(m_Value(Val), m_Constant(Con)))) {
+ if (Con->getAggregateElement(EltNo)->isNullValue())
+ return FindScalarElement(Val, EltNo);
+ }
+
// Otherwise, we don't know.
return 0;
}
+// If we have a PHI node with a vector type that has only 2 uses: feed
+// itself and be an operand of extractelement at a constant location,
+// try to replace the PHI of the vector type with a PHI of a scalar type.
+Instruction *InstCombiner::scalarizePHI(ExtractElementInst &EI, PHINode *PN) {
+ // Verify that the PHI node has exactly 2 uses. Otherwise return NULL.
+ if (!PN->hasNUses(2))
+ return NULL;
+
+ // If so, it's known at this point that one operand is PHI and the other is
+ // an extractelement node. Find the PHI user that is not the extractelement
+ // node.
+ Value::use_iterator iu = PN->use_begin();
+ Instruction *PHIUser = dyn_cast<Instruction>(*iu);
+ if (PHIUser == cast<Instruction>(&EI))
+ PHIUser = cast<Instruction>(*(++iu));
+
+ // Verify that this PHI user has one use, which is the PHI itself,
+ // and that it is a binary operation which is cheap to scalarize.
+ // otherwise return NULL.
+ if (!PHIUser->hasOneUse() || !(PHIUser->use_back() == PN) ||
+ !(isa<BinaryOperator>(PHIUser)) || !CheapToScalarize(PHIUser, true))
+ return NULL;
+
+ // Create a scalar PHI node that will replace the vector PHI node
+ // just before the current PHI node.
+ PHINode *scalarPHI = cast<PHINode>(InsertNewInstWith(
+ PHINode::Create(EI.getType(), PN->getNumIncomingValues(), ""), *PN));
+ // Scalarize each PHI operand.
+ for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) {
+ Value *PHIInVal = PN->getIncomingValue(i);
+ BasicBlock *inBB = PN->getIncomingBlock(i);
+ Value *Elt = EI.getIndexOperand();
+ // If the operand is the PHI induction variable:
+ if (PHIInVal == PHIUser) {
+ // Scalarize the binary operation. Its first operand is the
+ // scalar PHI and the second operand is extracted from the other
+ // vector operand.
+ BinaryOperator *B0 = cast<BinaryOperator>(PHIUser);
+ unsigned opId = (B0->getOperand(0) == PN) ? 1 : 0;
+ Value *Op = InsertNewInstWith(
+ ExtractElementInst::Create(B0->getOperand(opId), Elt,
+ B0->getOperand(opId)->getName() + ".Elt"),
+ *B0);
+ Value *newPHIUser = InsertNewInstWith(
+ BinaryOperator::Create(B0->getOpcode(), scalarPHI, Op), *B0);
+ scalarPHI->addIncoming(newPHIUser, inBB);
+ } else {
+ // Scalarize PHI input:
+ Instruction *newEI = ExtractElementInst::Create(PHIInVal, Elt, "");
+ // Insert the new instruction into the predecessor basic block.
+ Instruction *pos = dyn_cast<Instruction>(PHIInVal);
+ BasicBlock::iterator InsertPos;
+ if (pos && !isa<PHINode>(pos)) {
+ InsertPos = pos;
+ ++InsertPos;
+ } else {
+ InsertPos = inBB->getFirstInsertionPt();
+ }
+
+ InsertNewInstWith(newEI, *InsertPos);
+
+ scalarPHI->addIncoming(newEI, inBB);
+ }
+ }
+ return ReplaceInstUsesWith(EI, scalarPHI);
+}
+
Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
// If vector val is constant with all elements the same, replace EI with
// that element. We handle a known element # below.
if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
return new BitCastInst(Elt, EI.getType());
}
+
+ // If there's a vector PHI feeding a scalar use through this extractelement
+ // instruction, try to scalarize the PHI.
+ if (PHINode *PN = dyn_cast<PHINode>(EI.getOperand(0))) {
+ Instruction *scalarPHI = scalarizePHI(EI, PN);
+ if (scalarPHI)
+ return scalarPHI;
+ }
}
if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
} else if (CastInst *CI = dyn_cast<CastInst>(I)) {
// Canonicalize extractelement(cast) -> cast(extractelement)
// bitcasts can change the number of vector elements and they cost nothing
- if (CI->hasOneUse() && EI.hasOneUse() &&
- (CI->getOpcode() != Instruction::BitCast)) {
+ if (CI->hasOneUse() && (CI->getOpcode() != Instruction::BitCast)) {
Value *EE = Builder->CreateExtractElement(CI->getOperand(0),
EI.getIndexOperand());
+ Worklist.AddValue(EE);
return CastInst::Create(CI->getOpcode(), EE, EI.getType());
}
+ } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
+ if (SI->hasOneUse()) {
+ // TODO: For a select on vectors, it might be useful to do this if it
+ // has multiple extractelement uses. For vector select, that seems to
+ // fight the vectorizer.
+
+ // If we are extracting an element from a vector select or a select on
+ // vectors, a select on the scalars extracted from the vector arguments.
+ Value *TrueVal = SI->getTrueValue();
+ Value *FalseVal = SI->getFalseValue();
+
+ Value *Cond = SI->getCondition();
+ if (Cond->getType()->isVectorTy()) {
+ Cond = Builder->CreateExtractElement(Cond,
+ EI.getIndexOperand(),
+ Cond->getName() + ".elt");
+ }
+
+ Value *V1Elem
+ = Builder->CreateExtractElement(TrueVal,
+ EI.getIndexOperand(),
+ TrueVal->getName() + ".elt");
+
+ Value *V2Elem
+ = Builder->CreateExtractElement(FalseVal,
+ EI.getIndexOperand(),
+ FalseVal->getName() + ".elt");
+ return SelectInst::Create(Cond,
+ V1Elem,
+ V2Elem,
+ SI->getName() + ".elt");
+ }
}
}
return 0;
SmallVectorImpl<Constant*> &Mask) {
assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
"Invalid CollectSingleShuffleElements");
- unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+ unsigned NumElts = V->getType()->getVectorNumElements();
if (isa<UndefValue>(V)) {
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
return V;
}
-
+
if (isa<ConstantAggregateZero>(V)) {
Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
return V;
}
-
+
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);
if (VecOp == RHS) {
Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
+ // Update Mask to reflect that `ScalarOp' has been inserted at
+ // position `InsertedIdx' within the vector returned by IEI.
+ Mask[InsertedIdx % NumElts] = Mask[ExtractedIdx];
+
// Everything but the extracted element is replaced with the RHS.
for (unsigned i = 0; i != NumElts; ++i) {
if (i != InsertedIdx)
return 0;
}
+/// Return true if we can evaluate the specified expression tree if the vector
+/// elements were shuffled in a different order.
+static bool CanEvaluateShuffled(Value *V, ArrayRef<int> Mask,
+ unsigned Depth = 5) {
+ // We can always reorder the elements of a constant.
+ if (isa<Constant>(V))
+ return true;
+
+ // We won't reorder vector arguments. No IPO here.
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false;
+
+ // Two users may expect different orders of the elements. Don't try it.
+ if (!I->hasOneUse())
+ return false;
+
+ if (Depth == 0) return false;
+
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::FAdd:
+ case Instruction::Sub:
+ case Instruction::FSub:
+ case Instruction::Mul:
+ case Instruction::FMul:
+ case Instruction::UDiv:
+ case Instruction::SDiv:
+ case Instruction::FDiv:
+ case Instruction::URem:
+ case Instruction::SRem:
+ case Instruction::FRem:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::ICmp:
+ case Instruction::FCmp:
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::UIToFP:
+ case Instruction::SIToFP:
+ case Instruction::FPTrunc:
+ case Instruction::FPExt:
+ case Instruction::GetElementPtr: {
+ for (int i = 0, e = I->getNumOperands(); i != e; ++i) {
+ if (!CanEvaluateShuffled(I->getOperand(i), Mask, Depth-1))
+ return false;
+ }
+ return true;
+ }
+ case Instruction::InsertElement: {
+ ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(2));
+ if (!CI) return false;
+ int ElementNumber = CI->getLimitedValue();
+
+ // Verify that 'CI' does not occur twice in Mask. A single 'insertelement'
+ // can't put an element into multiple indices.
+ bool SeenOnce = false;
+ for (int i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] == ElementNumber) {
+ if (SeenOnce)
+ return false;
+ SeenOnce = true;
+ }
+ }
+ return CanEvaluateShuffled(I->getOperand(0), Mask, Depth-1);
+ }
+ }
+ return false;
+}
+
+/// Rebuild a new instruction just like 'I' but with the new operands given.
+/// In the event of type mismatch, the type of the operands is correct.
+static Value *BuildNew(Instruction *I, ArrayRef<Value*> NewOps) {
+ // We don't want to use the IRBuilder here because we want the replacement
+ // instructions to appear next to 'I', not the builder's insertion point.
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::FAdd:
+ case Instruction::Sub:
+ case Instruction::FSub:
+ case Instruction::Mul:
+ case Instruction::FMul:
+ case Instruction::UDiv:
+ case Instruction::SDiv:
+ case Instruction::FDiv:
+ case Instruction::URem:
+ case Instruction::SRem:
+ case Instruction::FRem:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor: {
+ BinaryOperator *BO = cast<BinaryOperator>(I);
+ assert(NewOps.size() == 2 && "binary operator with #ops != 2");
+ BinaryOperator *New =
+ BinaryOperator::Create(cast<BinaryOperator>(I)->getOpcode(),
+ NewOps[0], NewOps[1], "", BO);
+ if (isa<OverflowingBinaryOperator>(BO)) {
+ New->setHasNoUnsignedWrap(BO->hasNoUnsignedWrap());
+ New->setHasNoSignedWrap(BO->hasNoSignedWrap());
+ }
+ if (isa<PossiblyExactOperator>(BO)) {
+ New->setIsExact(BO->isExact());
+ }
+ return New;
+ }
+ case Instruction::ICmp:
+ assert(NewOps.size() == 2 && "icmp with #ops != 2");
+ return new ICmpInst(I, cast<ICmpInst>(I)->getPredicate(),
+ NewOps[0], NewOps[1]);
+ case Instruction::FCmp:
+ assert(NewOps.size() == 2 && "fcmp with #ops != 2");
+ return new FCmpInst(I, cast<FCmpInst>(I)->getPredicate(),
+ NewOps[0], NewOps[1]);
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::UIToFP:
+ case Instruction::SIToFP:
+ case Instruction::FPTrunc:
+ case Instruction::FPExt: {
+ // It's possible that the mask has a different number of elements from
+ // the original cast. We recompute the destination type to match the mask.
+ Type *DestTy =
+ VectorType::get(I->getType()->getScalarType(),
+ NewOps[0]->getType()->getVectorNumElements());
+ assert(NewOps.size() == 1 && "cast with #ops != 1");
+ return CastInst::Create(cast<CastInst>(I)->getOpcode(), NewOps[0], DestTy,
+ "", I);
+ }
+ case Instruction::GetElementPtr: {
+ Value *Ptr = NewOps[0];
+ ArrayRef<Value*> Idx = NewOps.slice(1);
+ GetElementPtrInst *GEP = GetElementPtrInst::Create(Ptr, Idx, "", I);
+ GEP->setIsInBounds(cast<GetElementPtrInst>(I)->isInBounds());
+ return GEP;
+ }
+ }
+ llvm_unreachable("failed to rebuild vector instructions");
+}
+
+Value *
+InstCombiner::EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask) {
+ // Mask.size() does not need to be equal to the number of vector elements.
+
+ assert(V->getType()->isVectorTy() && "can't reorder non-vector elements");
+ if (isa<UndefValue>(V)) {
+ return UndefValue::get(VectorType::get(V->getType()->getScalarType(),
+ Mask.size()));
+ }
+ if (isa<ConstantAggregateZero>(V)) {
+ return ConstantAggregateZero::get(
+ VectorType::get(V->getType()->getScalarType(),
+ Mask.size()));
+ }
+ if (Constant *C = dyn_cast<Constant>(V)) {
+ SmallVector<Constant *, 16> MaskValues;
+ for (int i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] == -1)
+ MaskValues.push_back(UndefValue::get(Builder->getInt32Ty()));
+ else
+ MaskValues.push_back(Builder->getInt32(Mask[i]));
+ }
+ return ConstantExpr::getShuffleVector(C, UndefValue::get(C->getType()),
+ ConstantVector::get(MaskValues));
+ }
+
+ Instruction *I = cast<Instruction>(V);
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::FAdd:
+ case Instruction::Sub:
+ case Instruction::FSub:
+ case Instruction::Mul:
+ case Instruction::FMul:
+ case Instruction::UDiv:
+ case Instruction::SDiv:
+ case Instruction::FDiv:
+ case Instruction::URem:
+ case Instruction::SRem:
+ case Instruction::FRem:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::ICmp:
+ case Instruction::FCmp:
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::UIToFP:
+ case Instruction::SIToFP:
+ case Instruction::FPTrunc:
+ case Instruction::FPExt:
+ case Instruction::Select:
+ case Instruction::GetElementPtr: {
+ SmallVector<Value*, 8> NewOps;
+ bool NeedsRebuild = (Mask.size() != I->getType()->getVectorNumElements());
+ for (int i = 0, e = I->getNumOperands(); i != e; ++i) {
+ Value *V = EvaluateInDifferentElementOrder(I->getOperand(i), Mask);
+ NewOps.push_back(V);
+ NeedsRebuild |= (V != I->getOperand(i));
+ }
+ if (NeedsRebuild) {
+ return BuildNew(I, NewOps);
+ }
+ return I;
+ }
+ case Instruction::InsertElement: {
+ int Element = cast<ConstantInt>(I->getOperand(2))->getLimitedValue();
+
+ // The insertelement was inserting at Element. Figure out which element
+ // that becomes after shuffling. The answer is guaranteed to be unique
+ // by CanEvaluateShuffled.
+ bool Found = false;
+ int Index = 0;
+ for (int e = Mask.size(); Index != e; ++Index) {
+ if (Mask[Index] == Element) {
+ Found = true;
+ break;
+ }
+ }
+
+ if (!Found)
+ return UndefValue::get(
+ VectorType::get(V->getType()->getScalarType(), Mask.size()));
+
+ Value *V = EvaluateInDifferentElementOrder(I->getOperand(0), Mask);
+ return InsertElementInst::Create(V, I->getOperand(1),
+ Builder->getInt32(Index), "", I);
+ }
+ }
+ llvm_unreachable("failed to reorder elements of vector instruction!");
+}
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
Value *LHS = SVI.getOperand(0);
if (LHS == RHS || isa<UndefValue>(LHS)) {
if (isa<UndefValue>(LHS) && LHS == RHS) {
// shuffle(undef,undef,mask) -> undef.
- Value* result = (VWidth == LHSWidth)
+ Value *Result = (VWidth == LHSWidth)
? LHS : UndefValue::get(SVI.getType());
- return ReplaceInstUsesWith(SVI, result);
+ return ReplaceInstUsesWith(SVI, Result);
}
// Remap any references to RHS to use LHS.
if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
}
+ if (isa<UndefValue>(RHS) && CanEvaluateShuffled(LHS, Mask)) {
+ Value *V = EvaluateInDifferentElementOrder(LHS, Mask);
+ return ReplaceInstUsesWith(SVI, V);
+ }
+
// If the LHS is a shufflevector itself, see if we can combine it with this
// one without producing an unusual shuffle.
// Cases that might be simplified:
// ShuffleVectorInst is equivalent to the original one.
for (unsigned i = 0; i < VWidth; ++i) {
int eltMask;
- if (Mask[i] == -1) {
+ if (Mask[i] < 0) {
// 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) {
// with a -1 mask value.
if (eltMask >= (int)LHSOp0Width && isa<UndefValue>(LHSOp1))
eltMask = -1;
- }
- else
+ } else
eltMask = Mask[i];
} else {
// This element is from right hand side vector operand
&& "should have been check above");
eltMask = -1;
}
- }
- else
+ } else
eltMask = Mask[i]-LHSWidth;
// If LHS's width is changed, shift the mask value accordingly.
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