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

llvm-svn: 239589

llvm/include/llvm/InitializePasses.h

@@ -130,7 +130,6 @@ void initializeSanitizerCoverageModulePass(PassRegistry&);
 void initializeDataFlowSanitizerPass(PassRegistry&);
 void initializeScalarizerPass(PassRegistry&);
 void initializeEarlyCSELegacyPassPass(PassRegistry &);
-void initializeEliminateAvailableExternallyPass(PassRegistry&);
 void initializeExpandISelPseudosPass(PassRegistry&);
 void initializeFunctionAttrsPass(PassRegistry&);
 void initializeGCMachineCodeAnalysisPass(PassRegistry&);

llvm/include/llvm/Transforms/IPO.h

@@ -70,12 +70,6 @@ ModulePass *createGlobalOptimizerPass();
 ///
 ModulePass *createGlobalDCEPass();
 
-//===----------------------------------------------------------------------===//
-/// This transform is designed to eliminate available external globals
-/// (functions or global variables)
-///
-ModulePass *createEliminateAvailableExternallyPass();
-
 //===----------------------------------------------------------------------===//
 /// createGVExtractionPass - If deleteFn is true, this pass deletes
 /// the specified global values. Otherwise, it deletes as much of the module as

llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h

@@ -121,7 +121,6 @@ public:
   bool VerifyInput;
   bool VerifyOutput;
   bool MergeFunctions;
-  bool PrepareForLTO;
 
 private:
   /// ExtensionList - This is list of all of the extensions that are registered.

llvm/lib/Transforms/IPO/CMakeLists.txt

@@ -3,7 +3,6 @@ add_llvm_library(LLVMipo
   BarrierNoopPass.cpp
   ConstantMerge.cpp
   DeadArgumentElimination.cpp
-  ElimAvailExtern.cpp
   ExtractGV.cpp
   FunctionAttrs.cpp
   GlobalDCE.cpp

llvm/lib/Transforms/IPO/ElimAvailExtern.cpp

@@ -1,96 +0,0 @@
-//===-- ElimAvailExtern.cpp - DCE unreachable internal functions ----------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This transform is designed to eliminate available external global
-// definitions from the program, turning them into declarations.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/IPO.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Transforms/Utils/CtorUtils.h"
-#include "llvm/Transforms/Utils/GlobalStatus.h"
-#include "llvm/Pass.h"
-using namespace llvm;
-
-#define DEBUG_TYPE "elim-avail-extern"
-
-STATISTIC(NumAliases  , "Number of global aliases removed");
-STATISTIC(NumFunctions, "Number of functions removed");
-STATISTIC(NumVariables, "Number of global variables removed");
-
-namespace {
-  struct EliminateAvailableExternally : public ModulePass {
-    static char ID; // Pass identification, replacement for typeid
-    EliminateAvailableExternally() : ModulePass(ID) {
-      initializeEliminateAvailableExternallyPass(
-          *PassRegistry::getPassRegistry());
-    }
-
-    // run - Do the EliminateAvailableExternally pass on the specified module,
-    // optionally updating the specified callgraph to reflect the changes.
-    //
-    bool runOnModule(Module &M) override;
-  };
-}
-
-char EliminateAvailableExternally::ID = 0;
-INITIALIZE_PASS(EliminateAvailableExternally, "elim-avail-extern",
-                "Eliminate Available Externally Globals", false, false)
-
-ModulePass *llvm::createEliminateAvailableExternallyPass() {
-  return new EliminateAvailableExternally();
-}
-
-bool EliminateAvailableExternally::runOnModule(Module &M) {
-  bool Changed = false;
-
-  // Drop initializers of available externally global variables.
-  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
-       I != E; ++I) {
-    if (!I->hasAvailableExternallyLinkage())
-      continue;
-    if (I->hasInitializer()) {
-      Constant *Init = I->getInitializer();
-      I->setInitializer(nullptr);
-      if (isSafeToDestroyConstant(Init))
-        Init->destroyConstant();
-    }
-    I->removeDeadConstantUsers();
-    I->setLinkage(GlobalValue::ExternalLinkage);
-    NumVariables++;
-  }
-
-  // Drop the bodies of available externally functions.
-  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
-    if (!I->hasAvailableExternallyLinkage())
-      continue;
-    if (!I->isDeclaration())
-      // This will set the linkage to external
-      I->deleteBody();
-    I->removeDeadConstantUsers();
-    NumFunctions++;
-  }
-
-  // Drop targets of available externally aliases.
-  for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); I != E;
-       ++I) {
-    if (!I->hasAvailableExternallyLinkage())
-      continue;
-    I->setAliasee(nullptr);
-    I->removeDeadConstantUsers();
-    I->setLinkage(GlobalValue::ExternalLinkage);
-    NumAliases++;
-  }
-
-  return Changed;
-}

llvm/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
     }