[SystemZ] Check for presence of vector support in SystemZISelLowering

A test case was found with llvm-stress that caused DAGCombiner to crash
when compiling for an older subtarget without vector support.

SystemZTargetLowering::combineTruncateExtract() should do nothing for older
subtargets.

This check was placed in canTreatAsByteVector(), which also helps in a few
other places.

Review: Ulrich Weigand
llvm-svn: 299763

2 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
index 7f0cb11dc35..140ee29e5f1 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -4736,8 +4736,11 @@ const char *SystemZTargetLowering::getTargetNodeName(unsigned Opcode) const {
 }
 
 // Return true if VT is a vector whose elements are a whole number of bytes
-// in width.
-static bool canTreatAsByteVector(EVT VT) {
+// in width. Also check for presence of vector support.
+bool SystemZTargetLowering::canTreatAsByteVector(EVT VT) const {
+  if (!Subtarget.hasVector())
+    return false;
+
   return VT.isVector() && VT.getScalarSizeInBits() % 8 == 0 && VT.isSimple();
 }
 
diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.h b/llvm/lib/Target/SystemZ/SystemZISelLowering.h
index 7a21a474c11..7d92a735587 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.h
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.h
@@ -537,6 +537,7 @@ private:
                                  unsigned UnpackHigh) const;
   SDValue lowerShift(SDValue Op, SelectionDAG &DAG, unsigned ByScalar) const;
 
+  bool canTreatAsByteVector(EVT VT) const;
   SDValue combineExtract(const SDLoc &DL, EVT ElemVT, EVT VecVT, SDValue OrigOp,
                          unsigned Index, DAGCombinerInfo &DCI,
                          bool Force) const;