[FuzzMutate] Don't crash when we can't remove instruction from empty function

Differential Revision: https://reviews.llvm.org/D40393

llvm-svn: 319438
diff --git a/llvm/lib/FuzzMutate/IRMutator.cpp b/llvm/lib/FuzzMutate/IRMutator.cpp
index 6545446..59f9471 100644
--- a/llvm/lib/FuzzMutate/IRMutator.cpp
+++ b/llvm/lib/FuzzMutate/IRMutator.cpp
@@ -147,7 +147,9 @@
   for (Instruction &Inst : instructions(F))
     if (!Inst.isTerminator())
       RS.sample(&Inst, /*Weight=*/1);
-  assert(!RS.isEmpty() && "No instructions to delete");
+  if (RS.isEmpty())
+    return;
+
   // Delete the instruction.
   mutate(*RS.getSelection(), IB);
   // Clean up any dead code that's left over after removing the instruction.