Fix a crash in the dag combiner caused by ConstantFoldBIT_CONVERTofBUILD_VECTOR calling itself

recursively and returning a SCALAR_TO_VECTOR node, but assuming the input was always a BUILD_VECTOR.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109519 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 16 insertions, 2 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index e671752464..7ffbf8d791 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4489,6 +4489,16 @@ ConstantFoldBIT_CONVERTofBUILD_VECTOR(SDNode *BV, EVT DstEltVT) {
   // If this is a conversion of N elements of one type to N elements of another
   // type, convert each element.  This handles FP<->INT cases.
   if (SrcBitSize == DstBitSize) {
+    EVT VT = EVT::getVectorVT(*DAG.getContext(), DstEltVT,
+                              BV->getValueType(0).getVectorNumElements());
+
+    // Due to the FP element handling below calling this routine recursively,
+    // we can end up with a scalar-to-vector node here.
+    if (BV->getOpcode() == ISD::SCALAR_TO_VECTOR)
+      return DAG.getNode(ISD::SCALAR_TO_VECTOR, BV->getDebugLoc(), VT, 
+                         DAG.getNode(ISD::BIT_CONVERT, BV->getDebugLoc(),
+                                     DstEltVT, BV->getOperand(0)));
+      
     SmallVector<SDValue, 8> Ops;
     for (unsigned i = 0, e = BV->getNumOperands(); i != e; ++i) {
       SDValue Op = BV->getOperand(i);
@@ -4500,8 +4510,6 @@ ConstantFoldBIT_CONVERTofBUILD_VECTOR(SDNode *BV, EVT DstEltVT) {
                                 DstEltVT, Op));
       AddToWorkList(Ops.back().getNode());
     }
-    EVT VT = EVT::getVectorVT(*DAG.getContext(), DstEltVT,
-                              BV->getValueType(0).getVectorNumElements());
     return DAG.getNode(ISD::BUILD_VECTOR, BV->getDebugLoc(), VT,
                        &Ops[0], Ops.size());
   }
diff --git a/test/CodeGen/Generic/2010-07-27-DAGCombineCrash.ll b/test/CodeGen/Generic/2010-07-27-DAGCombineCrash.ll
new file mode 100644
index 0000000000..a2945aaec3
--- /dev/null
+++ b/test/CodeGen/Generic/2010-07-27-DAGCombineCrash.ll
@@ -0,0 +1,6 @@
+; RUN: llc < %s
+
+define float @test1()
+{
+	ret float extractelement (<2 x float> bitcast (<1 x double> <double 0x3f800000> to <2 x float>), i32 1);
+}