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Fix a bug in the 'shuffle(undef,x,mask) -> shuffle(x, undef,mask')' xform

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Make the insert/extract elt -> shuffle code more aggressive.

This fixes CodeGen/PowerPC/vec_shuffle.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27728 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-04-16 00:51:47 +00:00
parent 706126dac1
commit 7f6cc0ccb5
1 changed files with 84 additions and 17 deletions
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101
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -6916,12 +6916,72 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
return 0;
}
/// CollectShuffleElements - We are building a shuffle between V and RHSVec,
/// which are both packed values with identical types. Return a shuffle mask
/// that computes V.
/// 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 (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();
// 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 *RHSVec) {
assert(isa<PackedType>(V->getType()) && V->getType() == RHSVec->getType() &&
Value *&RHS) {
assert(isa<PackedType>(V->getType()) &&
(RHS == 0 || V->getType() == RHS->getType()) &&
"Invalid shuffle!");
unsigned NumElts = cast<PackedType>(V->getType())->getNumElements();
@ -6946,15 +7006,16 @@ static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
// 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) == RHSVec) {
Value *V = CollectShuffleElements(VecOp, Mask, RHSVec);
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 == RHSVec) {
Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHSVec);
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)
@ -6962,10 +7023,16 @@ static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
}
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)
@ -7023,11 +7090,11 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
// (and any insertelements it points to), into one big shuffle.
if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
std::vector<Constant*> Mask;
Value *InVecA = CollectShuffleElements(&IE, Mask, EI->getOperand(0));
// We now have a shuffle of InVecA, VecOp, Mask.
return new ShuffleVectorInst(InVecA, EI->getOperand(0),
ConstantPacked::get(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));
}
}
}
@ -7088,8 +7155,8 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
Elts.push_back(CPM->getOperand(i));
else {
unsigned EltNo = cast<ConstantUInt>(CPM->getOperand(i))->getRawValue();
if (EltNo >= e/2)
Elts.push_back(ConstantUInt::get(Type::UIntTy, EltNo-e/2));
if (EltNo >= e)
Elts.push_back(ConstantUInt::get(Type::UIntTy, EltNo-e));
else // Referring to the undef.
Elts.push_back(UndefValue::get(Type::UIntTy));
}