Add back r201608, r201622, r201624 and r201625

r201608 made llvm corretly handle private globals with MachO. r201622 fixed
a bug in it and r201624 and r201625 were changes for using private linkage,
assuming that llvm would do the right thing.

They all got reverted because r201608 introduced a crash in LTO. This patch
includes a fix for that. The issue was that TargetLoweringObjectFile now has
to be initialized before we can mangle names of private globals. This is
trivially true during the normal codegen pipeline (the asm printer does it),
but LTO has to do it manually.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201700 91177308-0d34-0410-b5e6-96231b3b80d8

21 files changed, 232 insertions, 134 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 63b4bb4296..6c4cddc3f6 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -311,8 +311,13 @@ void AsmPrinter::EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
   llvm_unreachable("Unknown linkage type!");
 }
 
+void AsmPrinter::getNameWithPrefix(SmallVectorImpl<char> &Name,
+                                   const GlobalValue *GV) const {
+  TM.getTargetLowering()->getNameWithPrefix(Name, GV, *Mang);
+}
+
 MCSymbol *AsmPrinter::getSymbol(const GlobalValue *GV) const {
-  return getObjFileLowering().getSymbol(GV, *Mang);
+  return TM.getTargetLowering()->getSymbol(GV, *Mang);
 }
 
 /// EmitGlobalVariable - Emit the specified global variable to the .s file.
@@ -1369,7 +1374,7 @@ void AsmPrinter::EmitLLVMUsedList(const ConstantArray *InitList) {
   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
     const GlobalValue *GV =
       dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
-    if (GV && getObjFileLowering().shouldEmitUsedDirectiveFor(GV, *Mang))
+    if (GV && getObjFileLowering().shouldEmitUsedDirectiveFor(GV, *Mang, TM))
       OutStreamer.EmitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip);
   }
 }
@@ -1574,7 +1579,8 @@ static const MCExpr *lowerConstant(const Constant *CV, AsmPrinter &AP) {
   }
 
   if (const MCExpr *RelocExpr =
-          AP.getObjFileLowering().getExecutableRelativeSymbol(CE, *AP.Mang))
+          AP.getObjFileLowering().getExecutableRelativeSymbol(CE, *AP.Mang,
+                                                              AP.TM))
     return RelocExpr;
 
   switch (CE->getOpcode()) {
@@ -2103,7 +2109,8 @@ MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
 
 MCSymbol *AsmPrinter::getSymbolWithGlobalValueBase(const GlobalValue *GV,
                                                    StringRef Suffix) const {
-  return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, *Mang);
+  return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, *Mang,
+                                                           TM);
 }
 
 /// GetExternalSymbolSymbol - Return the MCSymbol for the specified
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp b/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
index 94198c4af1..5f23e12eac 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
@@ -143,7 +143,7 @@ void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
     const TargetLoweringObjectFile &TLOF = getObjFileLowering();
 
     const MCExpr *Exp =
-        TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, MMI, OutStreamer);
+        TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI, OutStreamer);
     OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
   } else
     OutStreamer.EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
diff --git a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index ed51f50c40..30312ac2e2 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -119,7 +119,8 @@ void DwarfCFIException::beginFunction(const MachineFunction *MF) {
   if (!shouldEmitPersonality)
     return;
 
-  const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, MMI);
+  const MCSymbol *Sym =
+      TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
   Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
 
   Asm->OutStreamer.EmitDebugLabel
diff --git a/lib/CodeGen/AsmPrinter/Win64Exception.cpp b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
index eda444bd69..17d8bff609 100644
--- a/lib/CodeGen/AsmPrinter/Win64Exception.cpp
+++ b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
@@ -101,7 +101,8 @@ void Win64Exception::endFunction(const MachineFunction *) {
   if (shouldEmitPersonality) {
     const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
     const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
-    const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, MMI);
+    const MCSymbol *Sym =
+        TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
 
     Asm->OutStreamer.PushSection();
     Asm->OutStreamer.EmitWin64EHHandlerData();
diff --git a/lib/CodeGen/TargetLoweringBase.cpp b/lib/CodeGen/TargetLoweringBase.cpp
index bdcb7216a5..d3c42be5e6 100644
--- a/lib/CodeGen/TargetLoweringBase.cpp
+++ b/lib/CodeGen/TargetLoweringBase.cpp
@@ -24,7 +24,9 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/Mangler.h"
 #include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1426,3 +1428,30 @@ bool TargetLoweringBase::isLegalAddressingMode(const AddrMode &AM,
 
   return true;
 }
+
+void TargetLoweringBase::getNameWithPrefix(SmallVectorImpl<char> &Name,
+                                           const GlobalValue *GV,
+                                           Mangler &Mang,
+                                           bool MayAlwaysUsePrivate) const {
+  if (MayAlwaysUsePrivate || !GV->hasPrivateLinkage()) {
+    // Simple case: If GV is not private, it is not important to find out if
+    // private labels are legal in this case or not.
+    Mang.getNameWithPrefix(Name, GV, false);
+    return;
+  }
+  SectionKind GVKind =
+    TargetLoweringObjectFile::getKindForGlobal(GV, getTargetMachine());
+  const TargetLoweringObjectFile &TLOF = getObjFileLowering();
+  const MCSection *TheSection =
+    TLOF.SectionForGlobal(GV, GVKind, Mang, getTargetMachine());
+  bool CannotUsePrivateLabel = TLOF.isSectionAtomizableBySymbols(*TheSection);
+  Mang.getNameWithPrefix(Name, GV, CannotUsePrivateLabel);
+}
+
+MCSymbol *TargetLoweringBase::getSymbol(const GlobalValue *GV,
+                                        Mangler &Mang) const {
+  SmallString<60> NameStr;
+  getNameWithPrefix(NameStr, GV, Mang);
+  const TargetLoweringObjectFile &TLOF = getObjFileLowering();
+  return TLOF.getContext().GetOrCreateSymbol(NameStr.str());
+}
diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 127b2aa324..bd54a871ca 100644
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -36,6 +36,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetLowering.h"
 using namespace llvm;
 using namespace dwarf;
 
@@ -43,19 +44,18 @@ using namespace dwarf;
 //                                  ELF
 //===----------------------------------------------------------------------===//
 
-MCSymbol *
-TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV,
-                                                     Mangler &Mang,
-                                                MachineModuleInfo *MMI) const {
+MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
+    const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
+    MachineModuleInfo *MMI) const {
   unsigned Encoding = getPersonalityEncoding();
   switch (Encoding & 0x70) {
   default:
     report_fatal_error("We do not support this DWARF encoding yet!");
   case dwarf::DW_EH_PE_absptr:
-    return getSymbol(GV, Mang);
+    return TM.getTargetLowering()->getSymbol(GV, Mang);
   case dwarf::DW_EH_PE_pcrel: {
     return getContext().GetOrCreateSymbol(StringRef("DW.ref.") +
-                                          getSymbol(GV, Mang)->getName());
+                        TM.getTargetLowering()->getSymbol(GV, Mang)->getName());
   }
   }
 }
@@ -89,18 +89,19 @@ void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
 
 const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
-    MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+    const TargetMachine &TM, MachineModuleInfo *MMI,
+    MCStreamer &Streamer) const {
 
   if (Encoding & dwarf::DW_EH_PE_indirect) {
     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 
-    MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang);
+    MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang, TM);
 
     // Add information about the stub reference to ELFMMI so that the stub
     // gets emitted by the asmprinter.
     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
     if (StubSym.getPointer() == 0) {
-      MCSymbol *Sym = getSymbol(GV, Mang);
+      MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
     }
 
@@ -109,8 +110,8 @@ const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference(
                         Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
   }
 
-  return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang,
-                                                           MMI, Streamer);
+  return TargetLoweringObjectFile::
+    getTTypeGlobalReference(GV, Encoding, Mang, TM, MMI, Streamer);
 }
 
 static SectionKind
@@ -195,10 +196,9 @@ getELFSectionFlags(SectionKind K) {
   return Flags;
 }
 
-
-const MCSection *TargetLoweringObjectFileELF::
-getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
-                         Mangler &Mang, const TargetMachine &TM) const {
+const MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
+    const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
+    const TargetMachine &TM) const {
   StringRef SectionName = GV->getSection();
 
   // Infer section flags from the section name if we can.
@@ -248,12 +248,12 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
     Prefix = getSectionPrefixForGlobal(Kind);
 
     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
-    MCSymbol *Sym = getSymbol(GV, Mang);
-    Name.append(Sym->getName().begin(), Sym->getName().end());
+    TM.getTargetLowering()->getNameWithPrefix(Name, GV, Mang, true);
+
     StringRef Group = "";
     unsigned Flags = getELFSectionFlags(Kind);
     if (GV->isWeakForLinker()) {
-      Group = Sym->getName();
+      Group = Name.substr(strlen(Prefix));
       Flags |= ELF::SHF_GROUP;
     }
 
@@ -487,9 +487,9 @@ emitModuleFlags(MCStreamer &Streamer,
   Streamer.AddBlankLine();
 }
 
-const MCSection *TargetLoweringObjectFileMachO::
-getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
-                         Mangler &Mang, const TargetMachine &TM) const {
+const MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
+    const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
+    const TargetMachine &TM) const {
   // Parse the section specifier and create it if valid.
   StringRef Segment, Section;
   unsigned TAA = 0, StubSize = 0;
@@ -526,6 +526,41 @@ getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
   return S;
 }
 
+bool TargetLoweringObjectFileMachO::isSectionAtomizableBySymbols(
+    const MCSection &Section) const {
+    const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section);
+
+    // Sections holding 1 byte strings are atomized based on the data
+    // they contain.
+    // Sections holding 2 byte strings require symbols in order to be
+    // atomized.
+    // There is no dedicated section for 4 byte strings.
+    if (SMO.getKind().isMergeable1ByteCString())
+      return false;
+
+    if (SMO.getSegmentName() == "__DATA" &&
+        SMO.getSectionName() == "__cfstring")
+      return false;
+
+    switch (SMO.getType()) {
+    default:
+      return true;
+
+      // These sections are atomized at the element boundaries without using
+      // symbols.
+    case MCSectionMachO::S_4BYTE_LITERALS:
+    case MCSectionMachO::S_8BYTE_LITERALS:
+    case MCSectionMachO::S_16BYTE_LITERALS:
+    case MCSectionMachO::S_LITERAL_POINTERS:
+    case MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS:
+    case MCSectionMachO::S_LAZY_SYMBOL_POINTERS:
+    case MCSectionMachO::S_MOD_INIT_FUNC_POINTERS:
+    case MCSectionMachO::S_MOD_TERM_FUNC_POINTERS:
+    case MCSectionMachO::S_INTERPOSING:
+      return false;
+    }
+}
+
 const MCSection *TargetLoweringObjectFileMachO::
 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
                        Mangler &Mang, const TargetMachine &TM) const {
@@ -606,21 +641,17 @@ TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
   return ReadOnlySection;  // .const
 }
 
-/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
-/// not to emit the UsedDirective for some symbols in llvm.used.
+/// This hook allows targets to selectively decide not to emit the UsedDirective
+/// for some symbols in llvm.used.
 // FIXME: REMOVE this (rdar://7071300)
-bool TargetLoweringObjectFileMachO::
-shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler &Mang) const {
-  /// On Darwin, internally linked data beginning with "L" or "l" does not have
-  /// the directive emitted (this occurs in ObjC metadata).
-  if (!GV) return false;
-
+bool TargetLoweringObjectFileMachO::shouldEmitUsedDirectiveFor(
+    const GlobalValue *GV, Mangler &Mang, TargetMachine &TM) const {
   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
     // FIXME: ObjC metadata is currently emitted as internal symbols that have
     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
     // this horrible hack can go away.
-    MCSymbol *Sym = getSymbol(GV, Mang);
+    MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
       return false;
   }
@@ -630,14 +661,16 @@ shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler &Mang) const {
 
 const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
-    MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+    const TargetMachine &TM, MachineModuleInfo *MMI,
+    MCStreamer &Streamer) const {
   // The mach-o version of this method defaults to returning a stub reference.
 
   if (Encoding & DW_EH_PE_indirect) {
     MachineModuleInfoMachO &MachOMMI =
       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 
-    MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang);
+    MCSymbol *SSym =
+        getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
 
     // Add information about the stub reference to MachOMMI so that the stub
     // gets emitted by the asmprinter.
@@ -645,7 +678,7 @@ const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
       GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
                                   MachOMMI.getGVStubEntry(SSym);
     if (StubSym.getPointer() == 0) {
-      MCSymbol *Sym = getSymbol(GV, Mang);
+      MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
     }
 
@@ -654,24 +687,24 @@ const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
                         Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
   }
 
-  return TargetLoweringObjectFile::
-    getTTypeGlobalReference(GV, Encoding, Mang, MMI, Streamer);
+  return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang,
+                                                           TM, MMI, Streamer);
 }
 
-MCSymbol *TargetLoweringObjectFileMachO::
-getCFIPersonalitySymbol(const GlobalValue *GV, Mangler &Mang,
-                        MachineModuleInfo *MMI) const {
+MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
+    const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
+    MachineModuleInfo *MMI) const {
   // The mach-o version of this method defaults to returning a stub reference.
   MachineModuleInfoMachO &MachOMMI =
     MMI->getObjFileInfo<MachineModuleInfoMachO>();
 
-  MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang);
+  MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
 
   // Add information about the stub reference to MachOMMI so that the stub
   // gets emitted by the asmprinter.
   MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
   if (StubSym.getPointer() == 0) {
-    MCSymbol *Sym = getSymbol(GV, Mang);
+    MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
     StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
   }
 
@@ -717,9 +750,9 @@ getCOFFSectionFlags(SectionKind K) {
   return Flags;
 }
 
-const MCSection *TargetLoweringObjectFileCOFF::
-getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
-                         Mangler &Mang, const TargetMachine &TM) const {
+const MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
+    const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
+    const TargetMachine &TM) const {
   int Selection = 0;
   unsigned Characteristics = getCOFFSectionFlags(Kind);
   StringRef Name = GV->getSection();
@@ -727,7 +760,7 @@ getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
   if (GV->isWeakForLinker()) {
     Selection = COFF::IMAGE_COMDAT_SELECT_ANY;
     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
-    MCSymbol *Sym = getSymbol(GV, Mang);
+    MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
     COMDATSymName = Sym->getName();
   }
   return getContext().getCOFFSection(Name,
@@ -761,7 +794,7 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
     unsigned Characteristics = getCOFFSectionFlags(Kind);
 
     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
-    MCSymbol *Sym = getSymbol(GV, Mang);
+    MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
     return getContext().getCOFFSection(Name, Characteristics,
                                        Kind, Sym->getName(),
                                        COFF::IMAGE_COMDAT_SELECT_ANY);
diff --git a/lib/ExecutionEngine/MCJIT/MCJIT.cpp b/lib/ExecutionEngine/MCJIT/MCJIT.cpp
index 4eaeb7a1d5..4d5723a7a1 100644
--- a/lib/ExecutionEngine/MCJIT/MCJIT.cpp
+++ b/lib/ExecutionEngine/MCJIT/MCJIT.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/MutexGuard.h"
+#include "llvm/Target/TargetLowering.h"
 
 using namespace llvm;
 
@@ -371,7 +372,7 @@ void *MCJIT::getPointerToFunction(Function *F) {
   // load address of the symbol, not the local address.
   Mangler Mang(TM->getDataLayout());
   SmallString<128> Name;
-  Mang.getNameWithPrefix(Name, F);
+  TM->getTargetLowering()->getNameWithPrefix(Name, F, Mang);
   return (void*)Dyld.getSymbolLoadAddress(Name);
 }
 
diff --git a/lib/IR/Mangler.cpp b/lib/IR/Mangler.cpp
index 9c18e6f300..4ee2cd2c93 100644
--- a/lib/IR/Mangler.cpp
+++ b/lib/IR/Mangler.cpp
@@ -76,12 +76,18 @@ static void AddFastCallStdCallSuffix(raw_ostream &OS, const Function *F,
   OS << '@' << ArgWords;
 }
 
-void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV) const {
+void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
+                                bool CannotUsePrivateLabel) const {
   ManglerPrefixTy PrefixTy = Mangler::Default;
-  if (GV->hasPrivateLinkage())
-    PrefixTy = Mangler::Private;
-  else if (GV->hasLinkerPrivateLinkage() || GV->hasLinkerPrivateWeakLinkage())
+  if (GV->hasPrivateLinkage()) {
+    if (CannotUsePrivateLabel)
+      PrefixTy = Mangler::LinkerPrivate;
+    else
+      PrefixTy = Mangler::Private;
+  } else if (GV->hasLinkerPrivateLinkage() ||
+             GV->hasLinkerPrivateWeakLinkage()) {
     PrefixTy = Mangler::LinkerPrivate;
+  }
 
   if (!GV->hasName()) {
     // Get the ID for the global, assigning a new one if we haven't got one
@@ -134,7 +140,8 @@ void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV) const {
 }
 
 void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
-                                const GlobalValue *GV) const {
+                                const GlobalValue *GV,
+                                bool CannotUsePrivateLabel) const {
   raw_svector_ostream OS(OutName);
-  getNameWithPrefix(OS, GV);
+  getNameWithPrefix(OS, GV, CannotUsePrivateLabel);
 }
diff --git a/lib/LTO/LTOCodeGenerator.cpp b/lib/LTO/LTOCodeGenerator.cpp
index 073947055a..b03b1da01a 100644
--- a/lib/LTO/LTOCodeGenerator.cpp
+++ b/lib/LTO/LTOCodeGenerator.cpp
@@ -335,11 +335,17 @@ applyRestriction(GlobalValue &GV,
                  std::vector<const char*> &MustPreserveList,
                  SmallPtrSet<GlobalValue*, 8> &AsmUsed,
                  Mangler &Mangler) {
-  SmallString<64> Buffer;
-  Mangler.getNameWithPrefix(Buffer, &GV);
-
+  // There are no restrictions to apply to declarations.
   if (GV.isDeclaration())
     return;
+
+  // There is nothing more restrictive than private linkage.
+  if (GV.hasPrivateLinkage())
+    return;
+
+  SmallString<64> Buffer;
+  TargetMach->getTargetLowering()->getNameWithPrefix(Buffer, &GV, Mangler);
+
   if (MustPreserveSymbols.count(Buffer))
     MustPreserveList.push_back(GV.getName().data());
   if (AsmUndefinedRefs.count(Buffer))
diff --git a/lib/LTO/LTOModule.cpp b/lib/LTO/LTOModule.cpp
index 909b92e888..86b67ef205 100644
--- a/lib/LTO/LTOModule.cpp
+++ b/lib/LTO/LTOModule.cpp
@@ -176,6 +176,16 @@ LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
   m->materializeAllPermanently();
 
   LTOModule *Ret = new LTOModule(m.take(), target);
+
+  // We need a MCContext set up in order to get mangled names of private
+  // symbols. It is a bit odd that we need to report uses and definitions
+  // of private symbols, but it does look like ld64 expects to be informed
+  // of at least the ones with an 'l' prefix.
+  MCContext &Context = Ret->_context;
+  const TargetLoweringObjectFile &TLOF =
+      target->getTargetLowering()->getObjFileLowering();
+  const_cast<TargetLoweringObjectFile &>(TLOF).Initialize(Context, *target);
+
   if (Ret->parseSymbols(errMsg)) {
     delete Ret;
     return NULL;
@@ -381,7 +391,7 @@ void LTOModule::addDefinedSymbol(const GlobalValue *def, bool isFunction) {
 
   // string is owned by _defines
   SmallString<64> Buffer;
-  _mangler.getNameWithPrefix(Buffer, def);
+  _target->getTargetLowering()->getNameWithPrefix(Buffer, def, _mangler);
 
   // set alignment part log2() can have rounding errors
   uint32_t align = def->getAlignment();
@@ -517,7 +527,7 @@ LTOModule::addPotentialUndefinedSymbol(const GlobalValue *decl, bool isFunc) {
     return;
 
   SmallString<64> name;
-  _mangler.getNameWithPrefix(name, decl);
+  _target->getTargetLowering()->getNameWithPrefix(name, decl, _mangler);
 
   StringMap<NameAndAttributes>::value_type &entry =
     _undefines.GetOrCreateValue(name);
diff --git a/lib/Target/ARM/ARMTargetObjectFile.cpp b/lib/Target/ARM/ARMTargetObjectFile.cpp
index f9d71acf11..4e81fcdc3a 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.cpp
+++ b/lib/Target/ARM/ARMTargetObjectFile.cpp
@@ -16,7 +16,7 @@
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/ELF.h"
-#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetLowering.h"
 using namespace llvm;
 using namespace dwarf;
 
@@ -43,12 +43,12 @@ void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,
 
 const MCExpr *ARMElfTargetObjectFile::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
-    MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+    const TargetMachine &TM, MachineModuleInfo *MMI,
+    MCStreamer &Streamer) const {
   assert(Encoding == DW_EH_PE_absptr && "Can handle absptr encoding only");
 
-  return MCSymbolRefExpr::Create(getSymbol(GV, Mang),
-                                 MCSymbolRefExpr::VK_ARM_TARGET2,
-                                 getContext());
+  return MCSymbolRefExpr::Create(TM.getTargetLowering()->getSymbol(GV, Mang),
+                                 MCSymbolRefExpr::VK_ARM_TARGET2, getContext());
 }
 
 const MCExpr *ARMElfTargetObjectFile::
diff --git a/lib/Target/ARM/ARMTargetObjectFile.h b/lib/Target/ARM/ARMTargetObjectFile.h
index c703f2fafa..aee5836141 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.h
+++ b/lib/Target/ARM/ARMTargetObjectFile.h
@@ -28,10 +28,10 @@ public:
 
   void Initialize(MCContext &Ctx, const TargetMachine &TM) LLVM_OVERRIDE;
 
-  const MCExpr *getTTypeGlobalReference(const GlobalValue *GV,
-                                        unsigned Encoding, Mangler &Mang,
-                                        MachineModuleInfo *MMI,
-                                        MCStreamer &Streamer) const
+  const MCExpr *
+  getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding,
+                          Mangler &Mang, const TargetMachine &TM,
+                          MachineModuleInfo *MMI, MCStreamer &Streamer) const
       LLVM_OVERRIDE;
 
   /// \brief Describe a TLS variable address within debug info.
diff --git a/lib/Target/PowerPC/PPCMCInstLower.cpp b/lib/Target/PowerPC/PPCMCInstLower.cpp
index fed254d799..cc40361cfc 100644
--- a/lib/Target/PowerPC/PPCMCInstLower.cpp
+++ b/lib/Target/PowerPC/PPCMCInstLower.cpp
@@ -25,7 +25,8 @@
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
-#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
 using namespace llvm;
 
 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
@@ -34,7 +35,9 @@ static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
 
 
 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
-  const DataLayout *DL = AP.TM.getDataLayout();
+  const TargetMachine &TM = AP.TM;
+  Mangler *Mang = AP.Mang;
+  const DataLayout *DL = TM.getDataLayout();
   MCContext &Ctx = AP.OutContext;
 
   SmallString<128> Name;
@@ -51,10 +54,10 @@ static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
 
   if (!MO.isGlobal()) {
     assert(MO.isSymbol() && "Isn't a symbol reference");
-    AP.Mang->getNameWithPrefix(Name, MO.getSymbolName());
+    Mang->getNameWithPrefix(Name, MO.getSymbolName());
   } else {
     const GlobalValue *GV = MO.getGlobal();
-    AP.Mang->getNameWithPrefix(Name, GV);
+    TM.getTargetLowering()->getNameWithPrefix(Name, GV, *Mang);
   }
 
   unsigned OrigLen = Name.size() - PrefixLen;
diff --git a/lib/Target/Sparc/SparcTargetObjectFile.cpp b/lib/Target/Sparc/SparcTargetObjectFile.cpp
index 11cc41f8c6..b732e18d81 100644
--- a/lib/Target/Sparc/SparcTargetObjectFile.cpp
+++ b/lib/Target/Sparc/SparcTargetObjectFile.cpp
@@ -11,23 +11,25 @@
 #include "MCTargetDesc/SparcMCExpr.h"
 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
 #include "llvm/Support/Dwarf.h"
+#include "llvm/Target/TargetLowering.h"
 
 using namespace llvm;
 
 const MCExpr *SparcELFTargetObjectFile::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
-    MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+    const TargetMachine &TM, MachineModuleInfo *MMI,
+    MCStreamer &Streamer) const {
 
   if (Encoding & dwarf::DW_EH_PE_pcrel) {
     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 
-    MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang);
+    MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang, TM);
 
     // Add information about the stub reference to ELFMMI so that the stub
     // gets emitted by the asmprinter.
     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
     if (StubSym.getPointer() == 0) {
-      MCSymbol *Sym = getSymbol(GV, Mang);
+      MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
     }
 
@@ -37,5 +39,5 @@ const MCExpr *SparcELFTargetObjectFile::getTTypeGlobalReference(
   }
 
   return TargetLoweringObjectFileELF::getTTypeGlobalReference(
-      GV, Encoding, Mang, MMI, Streamer);
+      GV, Encoding, Mang, TM, MMI, Streamer);
 }
diff --git a/lib/Target/Sparc/SparcTargetObjectFile.h b/lib/Target/Sparc/SparcTargetObjectFile.h
index 933d758f76..cce4a78690 100644
--- a/lib/Target/Sparc/SparcTargetObjectFile.h
+++ b/lib/Target/Sparc/SparcTargetObjectFile.h
@@ -23,10 +23,10 @@ public:
     TargetLoweringObjectFileELF()
   {}
 
-  const MCExpr *getTTypeGlobalReference(const GlobalValue *GV,
-                                        unsigned Encoding, Mangler &Mang,
-                                        MachineModuleInfo *MMI,
-                                        MCStreamer &Streamer) const
+  const MCExpr *
+  getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding,
+                          Mangler &Mang, const TargetMachine &TM,
+                          MachineModuleInfo *MMI, MCStreamer &Streamer) const
       LLVM_OVERRIDE;
 };
 
diff --git a/lib/Target/TargetLoweringObjectFile.cpp b/lib/Target/TargetLoweringObjectFile.cpp
index a0218a83df..9fff220d47 100644
--- a/lib/Target/TargetLoweringObjectFile.cpp
+++ b/lib/Target/TargetLoweringObjectFile.cpp
@@ -28,6 +28,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetOptions.h"
 using namespace llvm;
 
@@ -99,30 +100,22 @@ static bool IsNullTerminatedString(const Constant *C) {
   return false;
 }
 
-/// Return the MCSymbol for the specified global value.  This
-/// symbol is the main label that is the address of the global.
-MCSymbol *TargetLoweringObjectFile::getSymbol(const GlobalValue *GV,
-                                              Mangler &M) const {
-  SmallString<60> NameStr;
-  M.getNameWithPrefix(NameStr, GV);
-  return Ctx->GetOrCreateSymbol(NameStr.str());
-}
-
 MCSymbol *TargetLoweringObjectFile::getSymbolWithGlobalValueBase(
-    const GlobalValue *GV, StringRef Suffix, Mangler &M) const {
+    const GlobalValue *GV, StringRef Suffix, Mangler &Mang,
+    const TargetMachine &TM) const {
   assert(!Suffix.empty());
 
   SmallString<60> NameStr;
   NameStr += DL->getPrivateGlobalPrefix();
-  M.getNameWithPrefix(NameStr, GV);
+  TM.getTargetLowering()->getNameWithPrefix(NameStr, GV, Mang);
   NameStr.append(Suffix.begin(), Suffix.end());
   return Ctx->GetOrCreateSymbol(NameStr.str());
 }
 
-MCSymbol *TargetLoweringObjectFile::
-getCFIPersonalitySymbol(const GlobalValue *GV, Mangler &Mang,
-                        MachineModuleInfo *MMI) const {
-  return getSymbol(GV, Mang);
+MCSymbol *TargetLoweringObjectFile::getCFIPersonalitySymbol(
+    const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
+    MachineModuleInfo *MMI) const {
+  return TM.getTargetLowering()->getSymbol(GV, Mang);
 }
 
 void TargetLoweringObjectFile::emitPersonalityValue(MCStreamer &Streamer,
@@ -275,6 +268,10 @@ SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
   return SelectSectionForGlobal(GV, Kind, Mang, TM);
 }
 
+bool TargetLoweringObjectFile::isSectionAtomizableBySymbols(
+    const MCSection &Section) const {
+  return false;
+}
 
 // Lame default implementation. Calculate the section name for global.
 const MCSection *
@@ -312,9 +309,11 @@ TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
 /// handling information.
 const MCExpr *TargetLoweringObjectFile::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
-    MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+    const TargetMachine &TM, MachineModuleInfo *MMI,
+    MCStreamer &Streamer) const {
   const MCSymbolRefExpr *Ref =
-      MCSymbolRefExpr::Create(getSymbol(GV, Mang), getContext());
+    MCSymbolRefExpr::Create(TM.getTargetLowering()->getSymbol(GV, Mang),
+                            getContext());
 
   return getTTypeReference(Ref, Encoding, Streamer);
 }
diff --git a/lib/Target/X86/X86MCInstLower.cpp b/lib/Target/X86/X86MCInstLower.cpp
index 6f88cf1059..3dabbd72ed 100644
--- a/lib/Target/X86/X86MCInstLower.cpp
+++ b/lib/Target/X86/X86MCInstLower.cpp
@@ -98,7 +98,7 @@ GetSymbolFromOperand(const MachineOperand &MO) const {
 
   if (MO.isGlobal()) {
     const GlobalValue *GV = MO.getGlobal();
-    getMang()->getNameWithPrefix(Name, GV);
+    AsmPrinter.getNameWithPrefix(Name, GV);
   } else if (MO.isSymbol()) {
     getMang()->getNameWithPrefix(Name, MO.getSymbolName());
   } else if (MO.isMBB()) {
diff --git a/lib/Target/X86/X86TargetObjectFile.cpp b/lib/Target/X86/X86TargetObjectFile.cpp
index c5ba3ecd91..95fccba48a 100644
--- a/lib/Target/X86/X86TargetObjectFile.cpp
+++ b/lib/Target/X86/X86TargetObjectFile.cpp
@@ -14,18 +14,20 @@
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/Support/Dwarf.h"
+#include "llvm/Target/TargetLowering.h"
 
 using namespace llvm;
 using namespace dwarf;
 
 const MCExpr *X86_64MachoTargetObjectFile::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
-    MachineModuleInfo *MMI, MCStreamer &Streamer) const {
+    const TargetMachine &TM, MachineModuleInfo *MMI,
+    MCStreamer &Streamer) const {
 
   // On Darwin/X86-64, we can reference dwarf symbols with foo@GOTPCREL+4, which
   // is an indirect pc-relative reference.
   if (Encoding & (DW_EH_PE_indirect | DW_EH_PE_pcrel)) {
-    const MCSymbol *Sym = getSymbol(GV, Mang);
+    const MCSymbol *Sym = TM.getTargetLowering()->getSymbol(GV, Mang);
     const MCExpr *Res =
       MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOTPCREL, getContext());
     const MCExpr *Four = MCConstantExpr::Create(4, getContext());
@@ -33,13 +35,13 @@ const MCExpr *X86_64MachoTargetObjectFile::getTTypeGlobalReference(
   }
 
   return TargetLoweringObjectFileMachO::getTTypeGlobalReference(
-      GV, Encoding, Mang, MMI, Streamer);
+      GV, Encoding, Mang, TM, MMI, Streamer);
 }
 
-MCSymbol *X86_64MachoTargetObjectFile::
-getCFIPersonalitySymbol(const GlobalValue *GV, Mangler &Mang,
-                        MachineModuleInfo *MMI) const {
-  return getSymbol(GV, Mang);
+MCSymbol *X86_64MachoTargetObjectFile::getCFIPersonalitySymbol(
+    const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
+    MachineModuleInfo *MMI) const {
+  return TM.getTargetLowering()->getSymbol(GV, Mang);
 }
 
 void
@@ -54,9 +56,8 @@ X86LinuxTargetObjectFile::getDebugThreadLocalSymbol(
   return MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext());
 }
 
-const MCExpr *
-X86WindowsTargetObjectFile::getExecutableRelativeSymbol(const ConstantExpr *CE,
-                                                        Mangler &Mang) const {
+const MCExpr *X86WindowsTargetObjectFile::getExecutableRelativeSymbol(
+    const ConstantExpr *CE, Mangler &Mang, const TargetMachine &TM) const {
   // We are looking for the difference of two symbols, need a subtraction
   // operation.
   const SubOperator *Sub = dyn_cast<SubOperator>(CE);
@@ -101,6 +102,7 @@ X86WindowsTargetObjectFile::getExecutableRelativeSymbol(const ConstantExpr *CE,
   if (GVLHS->isThreadLocal())
     return 0;
 
-  return MCSymbolRefExpr::Create(
-      getSymbol(GVLHS, Mang), MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
+  return MCSymbolRefExpr::Create(TM.getTargetLowering()->getSymbol(GVLHS, Mang),
+                                 MCSymbolRefExpr::VK_COFF_IMGREL32,
+                                 getContext());
 }
diff --git a/lib/Target/X86/X86TargetObjectFile.h b/lib/Target/X86/X86TargetObjectFile.h
index 45739475f8..22f3e572d9 100644
--- a/lib/Target/X86/X86TargetObjectFile.h
+++ b/lib/Target/X86/X86TargetObjectFile.h
@@ -20,15 +20,16 @@ namespace llvm {
   /// x86-64.
   class X86_64MachoTargetObjectFile : public TargetLoweringObjectFileMachO {
   public:
-    const MCExpr *getTTypeGlobalReference(const GlobalValue *GV,
-                                          unsigned Encoding, Mangler &Mang,
-                                          MachineModuleInfo *MMI,
-                                          MCStreamer &Streamer) const
+    const MCExpr *
+    getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding,
+                            Mangler &Mang, const TargetMachine &TM,
+                            MachineModuleInfo *MMI, MCStreamer &Streamer) const
         LLVM_OVERRIDE;
 
     // getCFIPersonalitySymbol - The symbol that gets passed to
     // .cfi_personality.
     MCSymbol *getCFIPersonalitySymbol(const GlobalValue *GV, Mangler &Mang,
+                                      const TargetMachine &TM,
                                       MachineModuleInfo *MMI) const
         LLVM_OVERRIDE;
   };
@@ -46,7 +47,8 @@ namespace llvm {
   /// \brief This implementation is used for Windows targets on x86 and x86-64.
   class X86WindowsTargetObjectFile : public TargetLoweringObjectFileCOFF {
     const MCExpr *getExecutableRelativeSymbol(const ConstantExpr *CE,
-                                              Mangler &Mang) const
+                                              Mangler &Mang,
+                                              const TargetMachine &TM) const
         LLVM_OVERRIDE;
   };
 
diff --git a/lib/Target/XCore/XCoreTargetObjectFile.cpp b/lib/Target/XCore/XCoreTargetObjectFile.cpp
index 6584ee2d13..ab0f7ad47d 100644
--- a/lib/Target/XCore/XCoreTargetObjectFile.cpp
+++ b/lib/Target/XCore/XCoreTargetObjectFile.cpp
@@ -118,9 +118,10 @@ static unsigned getXCoreSectionFlags(SectionKind K, bool IsCPRel) {
   return Flags;
 }
 
-const MCSection *XCoreTargetObjectFile::
-getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
-                         Mangler &Mang, const TargetMachine &TM) const {
+const MCSection *
+XCoreTargetObjectFile::getExplicitSectionGlobal(const GlobalValue *GV,
+                                                SectionKind Kind, Mangler &Mang,
+                                                const TargetMachine &TM) const {
   StringRef SectionName = GV->getSection();
   // Infer section flags from the section name if we can.
   bool IsCPRel = SectionName.startswith(".cp.");
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index cf10af61d2..ee2692dced 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -561,19 +561,13 @@ static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
 static GlobalVariable *createPrivateGlobalForString(
     Module &M, StringRef Str, bool AllowMerging) {
   Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
-  // For module-local strings that can be merged with another one we set the
-  // private linkage and the unnamed_addr attribute.
-  // Non-mergeable strings are made linker_private to remove them from the
-  // symbol table. "private" linkage doesn't work for Darwin, where the
-  // "L"-prefixed globals  end up in __TEXT,__const section
-  // (see http://llvm.org/bugs/show_bug.cgi?id=17976 for more info).
-  GlobalValue::LinkageTypes linkage =
-      AllowMerging ? GlobalValue::PrivateLinkage
-                   : GlobalValue::LinkerPrivateLinkage;
+  // We use private linkage for module-local strings. If they can be merged
+  // with another one, we set the unnamed_addr attribute.
   GlobalVariable *GV =
       new GlobalVariable(M, StrConst->getType(), true,
-                         linkage, StrConst, kAsanGenPrefix);
-  if (AllowMerging) GV->setUnnamedAddr(true);
+                         GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
+  if (AllowMerging)
+    GV->setUnnamedAddr(true);
   GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
   return GV;
 }