[DAG] Fix wrong canonicalization performed on shuffle nodes.
This fixes a regression introduced by r226816.
When replacing a splat shuffle node with a constant build_vector,
make sure that the new build_vector has a valid number of elements.
Thanks to Patrik Hagglund for reporting this problem and providing a
small reproducible.
llvm-svn: 227002
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index c354155..565e4bb 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1538,13 +1538,15 @@
if (Splat && Splat.getOpcode() == ISD::UNDEF)
return getUNDEF(VT);
+ bool SameNumElts =
+ V.getValueType().getVectorNumElements() == VT.getVectorNumElements();
+
// 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 && 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() ==
- VT.getVectorNumElements())
+ if (SameNumElts)
return N1;
if (auto *C = dyn_cast<ConstantSDNode>(Splat))
if (C->isNullValue())
@@ -1553,15 +1555,15 @@
// If the shuffle itself creates a constant splat, build the vector
// directly.
- if (AllSame) {
+ if (AllSame && SameNumElts) {
const SDValue &Splatted = BV->getOperand(MaskVec[0]);
if (isa<ConstantSDNode>(Splatted) || isa<ConstantFPSDNode>(Splatted)) {
SmallVector<SDValue, 8> Ops;
- for (unsigned i = 0; i != NElts; ++i) {
+ for (unsigned i = 0; i != NElts; ++i)
Ops.push_back(Splatted);
- }
- SDValue NewBV = getNode(ISD::BUILD_VECTOR, dl,
- BV->getValueType(0), Ops);
+
+ SDValue NewBV =
+ getNode(ISD::BUILD_VECTOR, dl, BV->getValueType(0), Ops);
// We may have jumped through bitcasts, so the type of the
// BUILD_VECTOR may not match the type of the shuffle.