1 files changed, 12 insertions, 34 deletions

diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 99d9323d9d2..f8209e0ccf0 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -68,12 +68,11 @@ private:
   void writeSections();
   void writeBuildId();
 
-  void addCommonSymbols(std::vector<DefinedCommon *> &Syms);
-
   std::unique_ptr<FileOutputBuffer> Buffer;
 
   BumpPtrAllocator Alloc;
   std::vector<OutputSectionBase<ELFT> *> OutputSections;
+  std::unique_ptr<CommonInputSection<ELFT>> CommonSection;
   OutputSectionFactory<ELFT> Factory;
 
   void addRelIpltSymbols();
@@ -223,9 +222,11 @@ template <class ELFT> void Writer<ELFT>::run() {
     copyLocalSymbols();
   addReservedSymbols();
 
-  OutputSections = ScriptConfig->DoLayout
-                       ? Script<ELFT>::X->createSections(Factory)
-                       : createSections();
+  CommonSection = llvm::make_unique<CommonInputSection<ELFT>>();
+  OutputSections =
+      ScriptConfig->DoLayout
+          ? Script<ELFT>::X->createSections(Factory, CommonSection.get())
+          : createSections();
   finalizeSections();
   if (HasError)
     return;
@@ -490,30 +491,6 @@ void PhdrEntry<ELFT>::add(OutputSectionBase<ELFT> *Sec) {
   H.p_align = std::max<typename ELFT::uint>(H.p_align, Sec->getAlignment());
 }
 
-// Until this function is called, common symbols do not belong to any section.
-// This function adds them to end of BSS section.
-template <class ELFT>
-void Writer<ELFT>::addCommonSymbols(std::vector<DefinedCommon *> &Syms) {
-  if (Syms.empty())
-    return;
-
-  // Sort the common symbols by alignment as an heuristic to pack them better.
-  std::stable_sort(Syms.begin(), Syms.end(),
-                   [](const DefinedCommon *A, const DefinedCommon *B) {
-                     return A->Alignment > B->Alignment;
-                   });
-
-  uintX_t Off = Out<ELFT>::Bss->getSize();
-  for (DefinedCommon *C : Syms) {
-    Off = alignTo(Off, C->Alignment);
-    Out<ELFT>::Bss->updateAlignment(C->Alignment);
-    C->OffsetInBss = Off;
-    Off += C->Size;
-  }
-
-  Out<ELFT>::Bss->setSize(Off);
-}
-
 template <class ELFT>
 static Symbol *addOptionalSynthetic(SymbolTable<ELFT> &Table, StringRef Name,
                                     OutputSectionBase<ELFT> *Sec,
@@ -734,7 +711,6 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
 
   // Now that we have defined all possible symbols including linker-
   // synthesized ones. Visit all symbols to give the finishing touches.
-  std::vector<DefinedCommon *> CommonSymbols;
   for (Symbol *S : Symtab.getSymbols()) {
     SymbolBody *Body = S->body();
 
@@ -743,9 +719,6 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
     if (S->IsUsedInRegularObj && Body->isUndefined() && !S->isWeak())
       reportUndefined<ELFT>(Symtab, Body);
 
-    if (auto *C = dyn_cast<DefinedCommon>(Body))
-      CommonSymbols.push_back(C);
-
     if (!includeInSymtab<ELFT>(*Body))
       continue;
     if (Out<ELFT>::SymTab)
@@ -763,7 +736,12 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
   if (HasError)
     return;
 
-  addCommonSymbols(CommonSymbols);
+  // If linker script processor hasn't added common symbol section yet,
+  // then add it to .bss now.
+  if (!CommonSection->OutSec) {
+    Out<ELFT>::Bss->addSection(CommonSection.get());
+    Out<ELFT>::Bss->assignOffsets();
+  }
 
   // So far we have added sections from input object files.
   // This function adds linker-created Out<ELFT>::* sections.