[DAG] Fix an assertion failure caused by an invalid cast in method 'BuildVectorSDNode::isConstantSplat'
This patch renames method 'isConstantSplat' as 'getConstantSplatValue'
(mainly for consistency reasons), and rewrites its logic to ensure
that we always perform a legal 'cast<ConstantSDNode>'.
Added test shift-combine-crash.ll to verify that DAGCombiner no longer crashes with an assertion failure in the attempt to simplify a vector shift by a vector of all undef counts.
llvm-svn: 204536
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 2b2bbf9..a9983c7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -667,7 +667,7 @@
return CN;
if (BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(N))
- return BV->isConstantSplat();
+ return BV->getConstantSplatValue();
return nullptr;
}
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index df8d423..029011c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6573,15 +6573,14 @@
return true;
}
-ConstantSDNode *BuildVectorSDNode::isConstantSplat() const {
+ConstantSDNode *BuildVectorSDNode::getConstantSplatValue() const {
SDValue Op0 = getOperand(0);
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- SDValue Opi = getOperand(i);
- unsigned Opc = Opi.getOpcode();
- if ((Opc != ISD::UNDEF && Opc != ISD::Constant && Opc != ISD::ConstantFP) ||
- Opi != Op0)
+ if (Op0.getOpcode() != ISD::Constant)
+ return nullptr;
+
+ for (unsigned i = 1, e = getNumOperands(); i != e; ++i)
+ if (getOperand(i) != Op0)
return nullptr;
- }
return cast<ConstantSDNode>(Op0);
}