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[SDAG] At the suggestion of Hal, switch to an output parameter that

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tracks which elements of the build vector are in fact undef.

This should make actually inpsecting them (likely in my next patch)
reasonably pretty. Also makes the output parameter optional as it is
clear now that *most* users are happy with undefs in their splats.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212581 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth
2014-07-09 00:41:34 +00:00
parent bab04b583c
commit d0de9868a6
4 changed files with 42 additions and 25 deletions
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31
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@@ -1521,15 +1521,15 @@ SDValue SelectionDAG::getVectorShuffle(EVT VT, SDLoc dl, SDValue N1,
// A splat should always show up as a build vector node.
if (auto *BV = dyn_cast<BuildVectorSDNode>(V)) {
bool SplatHasUndefs;
SDValue Splat = BV->getSplatValue(SplatHasUndefs);
BitVector UndefElements;
SDValue Splat = BV->getSplatValue(&UndefElements);
// If this is a splat of an undef, shuffling it is also undef.
if (Splat && Splat.getOpcode() == ISD::UNDEF)
return getUNDEF(VT);
// We only have a splat which can skip shuffles if there is a splatted
// value and no undef lanes rearranged by the shuffle.
if (Splat && !SplatHasUndefs) {
if (Splat && UndefElements.none()) {
// Splat of <x, x, ..., x>, return <x, x, ..., x>, provided that the
// number of elements match or the value splatted is a zero constant.
if (V.getValueType().getVectorNumElements() ==
@@ -6635,17 +6635,22 @@ bool BuildVectorSDNode::isConstantSplat(APInt &SplatValue,
return true;
}
SDValue BuildVectorSDNode::getSplatValue(bool &HasUndefElements) const {
HasUndefElements = false;
SDValue BuildVectorSDNode::getSplatValue(BitVector *UndefElements) const {
if (UndefElements) {
UndefElements->clear();
UndefElements->resize(getNumOperands());
}
SDValue Splatted;
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
SDValue Op = getOperand(i);
if (Op.getOpcode() == ISD::UNDEF)
HasUndefElements = true;
else if (!Splatted)
if (Op.getOpcode() == ISD::UNDEF) {
if (UndefElements)
(*UndefElements)[i] = true;
} else if (!Splatted) {
Splatted = Op;
else if (Splatted != Op)
} else if (Splatted != Op) {
return SDValue();
}
}
if (!Splatted) {
@@ -6658,15 +6663,15 @@ SDValue BuildVectorSDNode::getSplatValue(bool &HasUndefElements) const {
}
ConstantSDNode *
BuildVectorSDNode::getConstantSplatNode(bool &HasUndefElements) const {
BuildVectorSDNode::getConstantSplatNode(BitVector *UndefElements) const {
return dyn_cast_or_null<ConstantSDNode>(
getSplatValue(HasUndefElements).getNode());
getSplatValue(UndefElements).getNode());
}
ConstantFPSDNode *
BuildVectorSDNode::getConstantFPSplatNode(bool &HasUndefElements) const {
BuildVectorSDNode::getConstantFPSplatNode(BitVector *UndefElements) const {
return dyn_cast_or_null<ConstantFPSDNode>(
getSplatValue(HasUndefElements).getNode());
getSplatValue(UndefElements).getNode());
}
bool BuildVectorSDNode::isConstant() const {