Refactor code from inlining and globalopt that checks whether a function definition is unused, and enhance it so it can tell that functions which are only used by a blockaddress are in fact dead.  This probably doesn't happen much on most code, but the Linux kernel's _THIS_IP_ can trigger this issue with blockaddress.  (GlobalDCE can also handle the given tescase, but we only run that at -O3.)  Found while looking at PR11180.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142572 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/BasicInliner.cpp b/lib/Transforms/Utils/BasicInliner.cpp
index 23a30cc..50c91b6 100644
--- a/lib/Transforms/Utils/BasicInliner.cpp
+++ b/lib/Transforms/Utils/BasicInliner.cpp
@@ -131,8 +131,8 @@
         // Inline
         InlineFunctionInfo IFI(0, TD);
         if (InlineFunction(CS, IFI)) {
-          if (Callee->use_empty() && (Callee->hasLocalLinkage() ||
-                                      Callee->hasAvailableExternallyLinkage()))
+          Callee->removeDeadConstantUsers();
+          if (Callee->isDefTriviallyDead())
             DeadFunctions.insert(Callee);
           Changed = true;
           CallSites.erase(CallSites.begin() + index);