1 files changed, 41 insertions, 1 deletions
diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index 66df23bab1b..70626682d55 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -347,6 +347,12 @@ applyRestriction(GlobalValue &GV,
   if (isa<Function>(GV) &&
       std::binary_search(Libcalls.begin(), Libcalls.end(), GV.getName()))
     AsmUsed.insert(&GV);
+
+  // Record the linkage type of non-local symbols so they can be restored prior
+  // to module splitting.
+  if (ShouldRestoreGlobalsLinkage && !GV.hasAvailableExternallyLinkage() &&
+      !GV.hasLocalLinkage() && GV.hasName())
+    ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
 }
 
 static void findUsedValues(GlobalVariable *LLVMUsed,
@@ -454,6 +460,35 @@ void LTOCodeGenerator::applyScopeRestrictions() {
   ScopeRestrictionsDone = true;
 }
 
+/// Restore original linkage for symbols that may have been internalized
+void LTOCodeGenerator::restoreLinkageForExternals() {
+  if (!ShouldInternalize || !ShouldRestoreGlobalsLinkage)
+    return;
+
+  assert(ScopeRestrictionsDone &&
+         "Cannot externalize without internalization!");
+
+  if (ExternalSymbols.empty())
+    return;
+
+  auto externalize = [this](GlobalValue &GV) {
+    if (!GV.hasLocalLinkage() || !GV.hasName())
+      return;
+
+    auto I = ExternalSymbols.find(GV.getName());
+    if (I == ExternalSymbols.end())
+      return;
+
+    GV.setLinkage(I->second);
+  };
+
+  std::for_each(MergedModule->begin(), MergedModule->end(), externalize);
+  std::for_each(MergedModule->global_begin(), MergedModule->global_end(),
+                externalize);
+  std::for_each(MergedModule->alias_begin(), MergedModule->alias_end(),
+                externalize);
+}
+
 /// Optimize merged modules using various IPO passes
 bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
                                 bool DisableGVNLoadPRE,
@@ -504,6 +539,10 @@ bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
   preCodeGenPasses.add(createObjCARCContractPass());
   preCodeGenPasses.run(*MergedModule);
 
+  // Re-externalize globals that may have been internalized to increase scope
+  // for splitting
+  restoreLinkageForExternals();
+
   // Do code generation. We need to preserve the module in case the client calls
   // writeMergedModules() after compilation, but we only need to allow this at
   // parallelism level 1. This is achieved by having splitCodeGen return the
@@ -511,7 +550,8 @@ bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
   // MergedModule.
   MergedModule =
       splitCodeGen(std::move(MergedModule), Out, MCpu, FeatureStr, Options,
-                   RelocModel, CodeModel::Default, CGOptLevel, FileType);
+                   RelocModel, CodeModel::Default, CGOptLevel, FileType,
+                   ShouldRestoreGlobalsLinkage);
 
   return true;
 }