Fix code-gen crash on Power9 for insert_vector_elt with variable index (PR30189)

This patch corresponds to review:
https://reviews.llvm.org/D24021

In the initial implementation of this instruction, I forgot to account for
variable indices. This patch fixes PR30189 and should probably be merged into
3.9.1 (I'll open a bug according to the new instructions).

llvm-svn: 281479

1 files changed, 15 insertions, 2 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 170704958d4..4aed89ecbe9 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -667,9 +667,10 @@ PPCTargetLowering::PPCTargetLowering(const PPCTargetMachine &TM,
       addRegisterClass(MVT::v2i64, &PPC::VRRCRegClass);
       addRegisterClass(MVT::v1i128, &PPC::VRRCRegClass);
     }
+
     if (Subtarget.hasP9Vector()) {
-      setOperationAction(ISD::INSERT_VECTOR_ELT, MVT::v4i32, Legal);
-      setOperationAction(ISD::INSERT_VECTOR_ELT, MVT::v4f32, Legal);
+      setOperationAction(ISD::INSERT_VECTOR_ELT, MVT::v4i32, Custom);
+      setOperationAction(ISD::INSERT_VECTOR_ELT, MVT::v4f32, Custom);
     }
   }
 
@@ -7879,6 +7880,17 @@ SDValue PPCTargetLowering::LowerSCALAR_TO_VECTOR(SDValue Op,
   return DAG.getLoad(Op.getValueType(), dl, Store, FIdx, MachinePointerInfo());
 }
 
+SDValue PPCTargetLowering::LowerINSERT_VECTOR_ELT(SDValue Op,
+                                                  SelectionDAG &DAG) const {
+  assert(Op.getOpcode() == ISD::INSERT_VECTOR_ELT &&
+         "Should only be called for ISD::INSERT_VECTOR_ELT");
+  ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(2));
+  // We have legal lowering for constant indices but not for variable ones.
+  if (C)
+    return Op;
+  return SDValue();
+}
+
 SDValue PPCTargetLowering::LowerEXTRACT_VECTOR_ELT(SDValue Op,
                                                    SelectionDAG &DAG) const {
   SDLoc dl(Op);
@@ -8284,6 +8296,7 @@ SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   case ISD::SCALAR_TO_VECTOR:   return LowerSCALAR_TO_VECTOR(Op, DAG);
   case ISD::SIGN_EXTEND_INREG:  return LowerSIGN_EXTEND_INREG(Op, DAG);
   case ISD::EXTRACT_VECTOR_ELT: return LowerEXTRACT_VECTOR_ELT(Op, DAG);
+  case ISD::INSERT_VECTOR_ELT:  return LowerINSERT_VECTOR_ELT(Op, DAG);
   case ISD::MUL:                return LowerMUL(Op, DAG);
 
   // For counter-based loop handling.