[X86][AVX] createVariablePermute - fix v2i64/v2f64 VPERMILPD index creation.

The input indices vector will put the index in bit0, but VPERMILPD actually selects off bit1 - so we need to scale accordingly.

llvm-svn: 327159

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index e8265e7e643..b5649707cc5 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -7963,6 +7963,8 @@ SDValue createVariablePermute(MVT VT, SDValue SrcVec, SDValue IndicesVec,
   case MVT::v2f64:
   case MVT::v2i64:
     if (Subtarget.hasAVX()) {
+      // VPERMILPD selects using bit#1 of the index vector, so scale IndicesVec.
+      IndicesVec = DAG.getNode(ISD::ADD, DL, IndicesVT, IndicesVec, IndicesVec);
       Opcode = X86ISD::VPERMILPV;
       ShuffleVT = MVT::v2f64;
     }