[X86ISelLowering] Provide a more informative assert message.

I stumbled upon this while debugging a lowering bug.

llvm-svn: 261371

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index ddbbf0297ac..bdae495903a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -16567,7 +16567,7 @@ static SDValue getTargetVShiftByConstNode(unsigned Opc, SDLoc dl, MVT VT,
     ConstantSDNode *ND;
 
     switch(Opc) {
-    default: llvm_unreachable(nullptr);
+    default: llvm_unreachable("Unknown opcode!");
     case X86ISD::VSHLI:
       for (unsigned i=0; i!=NumElts; ++i) {
         SDValue CurrentOp = SrcOp->getOperand(i);