[ThinLTO] Add code comment. NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375500 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/FunctionImport.cpp

diff --git a/lib/Transforms/IPO/FunctionImport.cpp b/lib/Transforms/IPO/FunctionImport.cpp
index 2ce8c92..3f5cc07 100644
--- a/lib/Transforms/IPO/FunctionImport.cpp
+++ b/lib/Transforms/IPO/FunctionImport.cpp
@@ -952,6 +952,9 @@
     if (NewLinkage == GV.getLinkage())
       return;
     if (GlobalValue::isLocalLinkage(GV.getLinkage()) ||
+        // Don't internalize anything here, because the code below
+        // lacks necessary correctness checks. Leave this job to
+        // LLVM 'internalize' pass.
         GlobalValue::isLocalLinkage(NewLinkage) ||
         // In case it was dead and already converted to declaration.
         GV.isDeclaration())