3 files changed, 55 insertions, 3 deletions
diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
index 6fe2804e30a..04b804209a7 100644
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -109,6 +109,10 @@ MCAsmInfo::MCAsmInfo() {
 MCAsmInfo::~MCAsmInfo() {
 }
 
+bool MCAsmInfo::isSectionAtomizableBySymbols(const MCSection &Section) const {
+  return false;
+}
+
 const MCExpr *
 MCAsmInfo::getExprForPersonalitySymbol(const MCSymbol *Sym,
                                        unsigned Encoding,
diff --git a/llvm/lib/MC/MCAsmInfoDarwin.cpp b/llvm/lib/MC/MCAsmInfoDarwin.cpp
index 66a138b90c6..04cc0ff4a86 100644
--- a/llvm/lib/MC/MCAsmInfoDarwin.cpp
+++ b/llvm/lib/MC/MCAsmInfoDarwin.cpp
@@ -15,10 +15,57 @@
 #include "llvm/MC/MCAsmInfoDarwin.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCStreamer.h"
 using namespace llvm;
 
-void MCAsmInfoDarwin::anchor() { }
+bool MCAsmInfoDarwin::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() == "__TEXT" &&
+      SMO.getSectionName() == "__objc_classname" &&
+      SMO.getType() == MachO::S_CSTRING_LITERALS)
+    return false;
+
+  if (SMO.getSegmentName() == "__TEXT" &&
+      SMO.getSectionName() == "__objc_methname" &&
+      SMO.getType() == MachO::S_CSTRING_LITERALS)
+    return false;
+
+  if (SMO.getSegmentName() == "__TEXT" &&
+      SMO.getSectionName() == "__objc_methtype" &&
+      SMO.getType() == MachO::S_CSTRING_LITERALS)
+    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 MachO::S_4BYTE_LITERALS:
+  case MachO::S_8BYTE_LITERALS:
+  case MachO::S_16BYTE_LITERALS:
+  case MachO::S_LITERAL_POINTERS:
+  case MachO::S_NON_LAZY_SYMBOL_POINTERS:
+  case MachO::S_LAZY_SYMBOL_POINTERS:
+  case MachO::S_MOD_INIT_FUNC_POINTERS:
+  case MachO::S_MOD_TERM_FUNC_POINTERS:
+  case MachO::S_INTERPOSING:
+    return false;
+  }
+}
 
 MCAsmInfoDarwin::MCAsmInfoDarwin() {
   // Common settings for all Darwin targets.
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index 85d0c13c710..459488bfe15 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -12,6 +12,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCAsmLayout.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCContext.h"
@@ -448,8 +449,8 @@ const MCSymbolData *MCAssembler::getAtom(const MCSymbolData *SD) const {
 
   // Non-linker visible symbols in sections which can't be atomized have no
   // defining atom.
-  if (!getBackend().isSectionAtomizable(
-        SD->getFragment()->getParent()->getSection()))
+  if (!getContext().getAsmInfo()->isSectionAtomizableBySymbols(
+          SD->getFragment()->getParent()->getSection()))
     return nullptr;
 
   // Otherwise, return the atom for the containing fragment.