[SDAG] At the suggestion of Hal, switch to an output parameter that
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.
llvm-svn: 212581
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d58824a..7497feb 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -655,13 +655,13 @@
return CN;
if (BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(N)) {
- bool HasUndefElements;
- ConstantSDNode *CN = BV->getConstantSplatNode(HasUndefElements);
+ BitVector UndefElements;
+ ConstantSDNode *CN = BV->getConstantSplatNode(&UndefElements);
// BuildVectors can truncate their operands. Ignore that case here.
// FIXME: We blindly ignore splats which include undef which is overly
// pessimistic.
- if (CN && !HasUndefElements &&
+ if (CN && UndefElements.none() &&
CN->getValueType(0) == N.getValueType().getScalarType())
return CN;
}
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 15baf14..c2cb0d8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1521,15 +1521,15 @@
// 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 @@
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 @@
}
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 {
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 9aee389..578821a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1158,11 +1158,11 @@
return false;
IsVec = true;
- bool HasUndefElements;
- CN = BV->getConstantSplatNode(HasUndefElements);
+ BitVector UndefElements;
+ CN = BV->getConstantSplatNode(&UndefElements);
// Only interested in constant splats, and we don't try to handle undef
// elements in identifying boolean constants.
- if (!CN || HasUndefElements)
+ if (!CN || UndefElements.none())
return false;
}
@@ -1190,11 +1190,11 @@
return false;
IsVec = true;
- bool HasUndefElements;
- CN = BV->getConstantSplatNode(HasUndefElements);
+ BitVector UndefElements;
+ CN = BV->getConstantSplatNode(&UndefElements);
// Only interested in constant splats, and we don't try to handle undef
// elements in identifying boolean constants.
- if (!CN || HasUndefElements)
+ if (!CN || UndefElements.none())
return false;
}