[CloneFunction] Don't remove unrelated nodes from the CGSSC

CGSCC use a WeakVH to track call sites.  RAUW a call within a function
can result in that WeakVH getting confused about whether or not the call
site is still around.

llvm-svn: 279268
diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 4f1052d..4d33e22 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -566,6 +566,12 @@
     if (!I)
       continue;
 
+    // Skip over non-intrinsic callsites, we don't want to remove any nodes from
+    // the CGSCC.
+    CallSite CS = CallSite(I);
+    if (CS && CS.getCalledFunction() && !CS.getCalledFunction()->isIntrinsic())
+      continue;
+
     // See if this instruction simplifies.
     Value *SimpleV = SimplifyInstruction(I, DL);
     if (!SimpleV)