6 files changed, 25 insertions, 9 deletions
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index c3ab95550e0..6f425721c1b 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -715,6 +715,13 @@ static bool isValidVisibilityForLinkage(unsigned V, unsigned L) {
          (GlobalValue::VisibilityTypes)V == GlobalValue::DefaultVisibility;
 }
 
+// If there was an explicit dso_local, update GV. In the absence of an explicit
+// dso_local we keep the default value.
+static void maybeSetDSOLocal(bool DSOLocal, GlobalValue &GV) {
+  if (DSOLocal)
+    GV.setDSOLocal(true);
+}
+
 /// parseIndirectSymbol:
 ///   ::= GlobalVar '=' OptionalLinkage OptionalPreemptionSpecifier 
 ///                     OptionalVisibility OptionalDLLStorageClass
@@ -826,7 +833,7 @@ bool LLParser::parseIndirectSymbol(const std::string &Name, LocTy NameLoc,
   GA->setVisibility((GlobalValue::VisibilityTypes)Visibility);
   GA->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
   GA->setUnnamedAddr(UnnamedAddr);
-  GA->setDSOLocal(DSOLocal);
+  maybeSetDSOLocal(DSOLocal, *GA);
 
   if (Name.empty())
     NumberedVals.push_back(GA.get());
@@ -947,7 +954,7 @@ bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
     GV->setInitializer(Init);
   GV->setConstant(IsConstant);
   GV->setLinkage((GlobalValue::LinkageTypes)Linkage);
-  GV->setDSOLocal(DSOLocal);
+  maybeSetDSOLocal(DSOLocal, *GV);
   GV->setVisibility((GlobalValue::VisibilityTypes)Visibility);
   GV->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
   GV->setExternallyInitialized(IsExternallyInitialized);
@@ -4923,7 +4930,7 @@ bool LLParser::ParseFunctionHeader(Function *&Fn, bool isDefine) {
     NumberedVals.push_back(Fn);
 
   Fn->setLinkage((GlobalValue::LinkageTypes)Linkage);
-  Fn->setDSOLocal(DSOLocal);
+  maybeSetDSOLocal(DSOLocal, *Fn);
   Fn->setVisibility((GlobalValue::VisibilityTypes)Visibility);
   Fn->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
   Fn->setCallingConv(CC);
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 0fafe82404e..27a75927832 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2497,8 +2497,10 @@ static void PrintVisibility(GlobalValue::VisibilityTypes Vis,
   }
 }
 
-static void PrintDSOLocation(bool IsDSOLocal, formatted_raw_ostream &Out){
-  if (IsDSOLocal)
+static void PrintDSOLocation(const GlobalValue &GV,
+                             formatted_raw_ostream &Out) {
+  // GVs with local linkage are implicitly dso_local, so we don't print it.
+  if (GV.isDSOLocal() && !GV.hasLocalLinkage())
     Out << "dso_local ";
 }
 
@@ -2572,7 +2574,7 @@ void AssemblyWriter::printGlobal(const GlobalVariable *GV) {
     Out << "external ";
 
   Out << getLinkagePrintName(GV->getLinkage());
-  PrintDSOLocation(GV->isDSOLocal(), Out);
+  PrintDSOLocation(*GV, Out);
   PrintVisibility(GV->getVisibility(), Out);
   PrintDLLStorageClass(GV->getDLLStorageClass(), Out);
   PrintThreadLocalModel(GV->getThreadLocalMode(), Out);
@@ -2619,7 +2621,7 @@ void AssemblyWriter::printIndirectSymbol(const GlobalIndirectSymbol *GIS) {
   Out << " = ";
 
   Out << getLinkagePrintName(GIS->getLinkage());
-  PrintDSOLocation(GIS->isDSOLocal(), Out);
+  PrintDSOLocation(*GIS, Out);
   PrintVisibility(GIS->getVisibility(), Out);
   PrintDLLStorageClass(GIS->getDLLStorageClass(), Out);
   PrintThreadLocalModel(GIS->getThreadLocalMode(), Out);
@@ -2731,7 +2733,7 @@ void AssemblyWriter::printFunction(const Function *F) {
     Out << "define ";
 
   Out << getLinkagePrintName(F->getLinkage());
-  PrintDSOLocation(F->isDSOLocal(), Out);
+  PrintDSOLocation(*F, Out);
   PrintVisibility(F->getVisibility(), Out);
   PrintDLLStorageClass(F->getDLLStorageClass(), Out);
 
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index b83201f982f..1a964dfb731 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -570,6 +570,11 @@ void Verifier::visitGlobalValue(const GlobalValue &GV) {
     Assert(!GV.isDSOLocal(),
            "GlobalValue with DLLImport Storage is dso_local!", &GV);
 
+  if (GV.hasLocalLinkage())
+    Assert(GV.isDSOLocal(),
+           "GlobalValue with private or internal linkage must be dso_local!",
+           &GV);
+
   forEachUser(&GV, GlobalValueVisited, [&](const Value *V) -> bool {
     if (const Instruction *I = dyn_cast<Instruction>(V)) {
       if (!I->getParent() || !I->getParent()->getParent())
diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index c4c0dd22ee0..8e3a818690f 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -146,7 +146,7 @@ bool TargetMachine::shouldAssumeDSOLocal(const Module &M,
       GV->hasExternalWeakLinkage())
     return false;
 
-  if (GV && (GV->hasLocalLinkage() || !GV->hasDefaultVisibility()))
+  if (GV && !GV->hasDefaultVisibility())
     return true;
 
   if (TT.isOSBinFormatMachO()) {
diff --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 122f51a0d21..4a69fbfe435 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -265,6 +265,7 @@ static Function *createClone(Function &F, Twine Suffix, coro::Shape &Shape,
   SmallVector<ReturnInst *, 4> Returns;
 
   CloneFunctionInto(NewF, &F, VMap, /*ModuleLevelChanges=*/true, Returns);
+  NewF->setDSOLocal(true);
 
   // Remove old returns.
   for (ReturnInst *Return : Returns)
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 4bb2984e3b4..65dcd281009 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2486,6 +2486,7 @@ OptimizeGlobalAliases(Module &M,
       // Give the aliasee the name, linkage and other attributes of the alias.
       Target->takeName(&*J);
       Target->setLinkage(J->getLinkage());
+      Target->setDSOLocal(J->isDSOLocal());
       Target->setVisibility(J->getVisibility());
       Target->setDLLStorageClass(J->getDLLStorageClass());