[InlineSpiller] Don't call TargetInstrInfo::foldMemoryOperand with an empty list.

Since r287792 if we try to do that we will hit an assert.

llvm-svn: 289001
diff --git a/llvm/lib/CodeGen/InlineSpiller.cpp b/llvm/lib/CodeGen/InlineSpiller.cpp
index 3e5ae5f..422f2dc 100644
--- a/llvm/lib/CodeGen/InlineSpiller.cpp
+++ b/llvm/lib/CodeGen/InlineSpiller.cpp
@@ -768,6 +768,11 @@
       FoldOps.push_back(Idx);
   }
 
+  // If we only have implicit uses, we won't be able to fold that.
+  // Moreover, TargetInstrInfo::foldMemoryOperand will assert if we try!
+  if (FoldOps.empty())
+    return false;
+
   MachineInstrSpan MIS(MI);
 
   MachineInstr *FoldMI =