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[InstCombine] add getNegativeIsTrueBoolVec() helper function; NFC

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Originally part of:
http://reviews.llvm.org/D17485

We need this when simplifying masked memory ops too.

llvm-svn: 261483
This commit is contained in:
Sanjay Patel 2016-02-21 17:29:33 +00:00
parent 7fe777fc31
commit 67805931c5
1 changed files with 20 additions and 22 deletions
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42
lib/Transforms/InstCombine/InstCombineCalls.cpp
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@ -60,6 +60,24 @@ static Type *reduceToSingleValueType(Type *T) {
return T;
}
/// Return a constant boolean vector that has true elements in all positions
/// where the input constant integer vector has an element with the sign bit
/// set.
static Constant *getNegativeIsTrueBoolVec(ConstantDataVector *V) {
SmallVector<Constant *, 32> BoolVec;
IntegerType *BoolTy = Type::getInt1Ty(V->getContext());
for (unsigned I = 0, E = V->getNumElements(); I != E; ++I) {
Constant *Elt = V->getElementAsConstant(I);
assert((isa<ConstantInt>(Elt) || isa<ConstantFP>(Elt)) &&
"Unexpected constant data vector element type");
bool Sign = V->getElementType()->isIntegerTy()
? cast<ConstantInt>(Elt)->isNegative()
: cast<ConstantFP>(Elt)->isNegative();
BoolVec.push_back(ConstantInt::get(BoolTy, Sign));
}
return ConstantVector::get(BoolVec);
}
Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), DL, MI, AC, DT);
unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), DL, MI, AC, DT);
@ -1476,28 +1494,8 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
return replaceInstUsesWith(CI, Op0);
// Constant Mask - select 1st/2nd argument lane based on top bit of mask.
if (auto C = dyn_cast<ConstantDataVector>(Mask)) {
auto Tyi1 = Builder->getInt1Ty();
auto SelectorType = cast<VectorType>(Mask->getType());
auto EltTy = SelectorType->getElementType();
unsigned Size = SelectorType->getNumElements();
unsigned BitWidth =
EltTy->isFloatTy()
? 32
: (EltTy->isDoubleTy() ? 64 : EltTy->getIntegerBitWidth());
assert((BitWidth == 64 || BitWidth == 32 || BitWidth == 8) &&
"Wrong arguments for variable blend intrinsic");
SmallVector<Constant *, 32> Selectors;
for (unsigned I = 0; I < Size; ++I) {
// The intrinsics only read the top bit
uint64_t Selector;
if (BitWidth == 8)
Selector = C->getElementAsInteger(I);
else
Selector = C->getElementAsAPFloat(I).bitcastToAPInt().getZExtValue();
Selectors.push_back(ConstantInt::get(Tyi1, Selector >> (BitWidth - 1)));
}
auto NewSelector = ConstantVector::get(Selectors);
if (auto *ConstantMask = dyn_cast<ConstantDataVector>(Mask)) {
Constant *NewSelector = getNegativeIsTrueBoolVec(ConstantMask);
return SelectInst::Create(NewSelector, Op1, Op0, "blendv");
}
break;