Revert commit r239480 as it causes https://code.google.com/p/chromium/issues/detail?id=499508#c3.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239589 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -105,7 +105,6 @@ PassManagerBuilder::PassManagerBuilder() {
     VerifyInput = false;
     VerifyOutput = false;
     MergeFunctions = false;
-    PrepareForLTO = false;
 }
 
 PassManagerBuilder::~PassManagerBuilder() {
@@ -402,17 +401,6 @@ void PassManagerBuilder::populateModulePassManager(
     // GlobalOpt already deletes dead functions and globals, at -O2 try a
     // late pass of GlobalDCE.  It is capable of deleting dead cycles.
     if (OptLevel > 1) {
-      if (!PrepareForLTO) {
-        // Remove avail extern fns and globals definitions if we aren't
-        // compiling an object file for later LTO. For LTO we want to preserve
-        // these so they are eligible for inlining at link-time. Note if they
-        // are unreferenced they will be removed by GlobalDCE below, so
-        // this only impacts referenced available externally globals.
-        // Eventually they will be suppressed during codegen, but eliminating
-        // here enables more opportunity for GlobalDCE as it may make
-        // globals referenced by available external functions dead.
-        MPM.add(createEliminateAvailableExternallyPass());
-      }
       MPM.add(createGlobalDCEPass());         // Remove dead fns and globals.
       MPM.add(createConstantMergePass());     // Merge dup global constants
     }