Minor extension to llvm.experimental.patchpoint: don't require a call.

If a null call target is provided, don't emit a dummy call. This
allows the runtime to reserve as little nop space as it needs without
the requirement of emitting a call.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194676 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 98e067e..e80b630 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6826,7 +6826,7 @@
 /// \brief Lower llvm.experimental.patchpoint directly to its target opcode.
 void SelectionDAGBuilder::visitPatchpoint(const CallInst &CI) {
   // void|i64 @llvm.experimental.patchpoint.void|i64(i32 <id>,
-  //                                                 i32 <numNopBytes>,
+  //                                                 i32 <numBytes>,
   //                                                 i8* <target>,
   //                                                 i32 <numArgs>,
   //                                                 [Args...],