1 files changed, 19 insertions, 4 deletions
diff --git a/lib/Transforms/IPO/GlobalDCE.cpp b/lib/Transforms/IPO/GlobalDCE.cpp
index 0c081f1ba5..9decddcff8 100644
--- a/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/lib/Transforms/IPO/GlobalDCE.cpp
@@ -15,15 +15,18 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "globaldce"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/ADT/SmallPtrSet.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/Pass.h"
 using namespace llvm;
 
+#define DEBUG_TYPE "globaldce"
+
 STATISTIC(NumAliases  , "Number of global aliases removed");
 STATISTIC(NumFunctions, "Number of functions removed");
 STATISTIC(NumVariables, "Number of global variables removed");
@@ -53,6 +56,15 @@ namespace {
   };
 }
 
+/// Returns true if F contains only a single "ret" instruction.
+static bool isEmptyFunction(Function *F) {
+  BasicBlock &Entry = F->getEntryBlock();
+  if (Entry.size() != 1 || !isa<ReturnInst>(Entry.front()))
+    return false;
+  ReturnInst &RI = cast<ReturnInst>(Entry.front());
+  return RI.getReturnValue() == NULL;
+}
+
 char GlobalDCE::ID = 0;
 INITIALIZE_PASS(GlobalDCE, "globaldce",
                 "Dead Global Elimination", false, false)
@@ -61,7 +73,10 @@ ModulePass *llvm::createGlobalDCEPass() { return new GlobalDCE(); }
 
 bool GlobalDCE::runOnModule(Module &M) {
   bool Changed = false;
-  
+
+  // Remove empty functions from the global ctors list.
+  Changed |= optimizeGlobalCtorsList(M, isEmptyFunction);
+
   // Loop over the module, adding globals which are obviously necessary.
   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
     Changed |= RemoveUnusedGlobalValue(*I);
@@ -99,7 +114,7 @@ bool GlobalDCE::runOnModule(Module &M) {
        I != E; ++I)
     if (!AliveGlobals.count(I)) {
       DeadGlobalVars.push_back(I);         // Keep track of dead globals
-      I->setInitializer(0);
+      I->setInitializer(nullptr);
     }
 
   // The second pass drops the bodies of functions which are dead...
@@ -117,7 +132,7 @@ bool GlobalDCE::runOnModule(Module &M) {
        ++I)
     if (!AliveGlobals.count(I)) {
       DeadAliases.push_back(I);
-      I->setAliasee(0);
+      I->setAliasee(nullptr);
     }
 
   if (!DeadFunctions.empty()) {