[PowerPC][ELF] Place .got2 in the same COMDAT group as the target object

[MaskRay]

Better fix

[MaskRay]

Test. Add comments

[MaskRay]

OK... I believe that the problem in .got2 is inherent and cannot be fixed...

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

 
 #define DEBUG_TYPE "asmprinter"
 
 namespace {
 
 class PPCAsmPrinter : public AsmPrinter {
 protected:
   MapVector<const MCSymbol *, MCSymbol *> TOC;
+  // PPC32 .got2 used in PIC.
+  MapVector<const MCSymbol *, int> Got2;
   const PPCSubtarget *Subtarget = nullptr;
   StackMaps SM;
 
   virtual MCSymbol *getMCSymbolForTOCPseudoMO(const MachineOperand &MO);
 
 public:
   explicit PPCAsmPrinter(TargetMachine &TM,
                          std::unique_ptr<MCStreamer> Streamer)
if (PL == PICLevel::SmallPIC && !IsAIX) {
       EmitToStreamer(*OutStreamer, TmpInst);
       return;
     }
 
     // Otherwise, use the TOC. 'TOCEntry' is a label used to reference the
     // storage allocated in the TOC which contains the address of
     // 'MOSymbol'. Said TOC entry will be synthesized later.
     MCSymbol *TOCEntry = lookUpOrCreateTOCEntry(MOSymbol);
-    const MCExpr *Exp =
-        MCSymbolRefExpr::create(TOCEntry, MCSymbolRefExpr::VK_None, OutContext);
 
     // AIX uses the label directly as the lwz displacement operand for
     // references into the toc section. The displacement value will be generated
     // relative to the toc-base.
     if (IsAIX) {
       assert(
           TM.getCodeModel() == CodeModel::Small &&
           "This pseudo should only be selected for 32-bit small code model.");
+      const MCExpr *Exp = MCSymbolRefExpr::create(
+          TOCEntry, MCSymbolRefExpr::VK_None, OutContext);
       TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
       EmitToStreamer(*OutStreamer, TmpInst);
       return;
     }
 
     // Create an explicit subtract expression between the local symbol and
     // '.LTOC' to manifest the toc-relative offset.
-    const MCExpr *PB = MCSymbolRefExpr::create(
-        OutContext.getOrCreateSymbol(Twine(".LTOC")), OutContext);
-    Exp = MCBinaryExpr::createSub(Exp, PB, OutContext);
+    int Ordinal =
+        Got2.insert(std::make_pair(MOSymbol, (int)Got2.size())).first->second;
+    const auto *Exp = MCConstantExpr::create(Ordinal * 4 - 0x8000, OutContext);
     TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
     EmitToStreamer(*OutStreamer, TmpInst);
     return;
   }
   case PPC::LDtocJTI:
   case PPC::LDtocCPT:
   case PPC::LDtocBA:
   case PPC::LDtoc: {
OutStreamer->emitValue(
     MCSymbolRefExpr::create(Symbol2, MCSymbolRefExpr::VK_PPC_TOCBASE, OutContext),
     8/*size*/);
   // Emit a null environment pointer.
   OutStreamer->emitIntValue(0, 8 /* size */);
   OutStreamer->SwitchSection(Current.first, Current.second);
 }
 
 void PPCLinuxAsmPrinter::emitEndOfAsmFile(Module &M) {
-  const DataLayout &DL = getDataLayout();
-
-  bool isPPC64 = DL.getPointerSizeInBits() == 64;
-
   PPCTargetStreamer &TS =
       static_cast<PPCTargetStreamer &>(*OutStreamer->getTargetStreamer());
 
   if (!TOC.empty()) {
-    const char *Name = isPPC64 ? ".toc" : ".got2";
     MCSectionELF *CurSection = nullptr, *Section;
+    // Emit PPC32 .got2 entries.
+    for (const auto &It : Got2) {
+      const MCSymbol *Sym = It.first;
+      const MCSymbolELF *Group = nullptr;
+      if (Sym->isInSection())
+        Group = cast<MCSectionELF>(Sym->getSection()).getGroup();
+      Section = OutStreamer->getContext().getELFSection(
+          ".got2", ELF::SHT_PROGBITS,
+          ELF::SHF_WRITE | ELF::SHF_ALLOC | (Group ? ELF::SHF_GROUP : 0), 0,
+          Group, MCSection::NonUniqueID, nullptr);
+      if (Section != CurSection) {
+        OutStreamer->SwitchSection(Section);
+        CurSection = Section;
+        OutStreamer->emitValueToAlignment(4);
+      }
+      OutStreamer->emitSymbolValue(Sym, 4);
+    }
+    // Emit PPC64 .toc entries.
     for (const auto &TOCMapPair : TOC) {
       const MCSymbol *const TOCEntryTarget = TOCMapPair.first;
       MCSymbol *const TOCEntryLabel = TOCMapPair.second;
       const MCSymbolELF *Group = nullptr;
-      if (isPPC64 && TOCEntryTarget->isInSection())
+      if (TOCEntryTarget->isInSection())
         Group = cast<MCSectionELF>(TOCEntryTarget->getSection()).getGroup();
       Section = OutStreamer->getContext().getELFSection(
-          Name, ELF::SHT_PROGBITS,
+          ".toc", ELF::SHT_PROGBITS,
           ELF::SHF_WRITE | ELF::SHF_ALLOC | (Group ? ELF::SHF_GROUP : 0), 0,
           Group, MCSection::NonUniqueID, nullptr);
       if (Section != CurSection) {
         OutStreamer->SwitchSection(Section);
         CurSection = Section;
-        if (!isPPC64)
-          OutStreamer->emitValueToAlignment(4);
       }
 
       OutStreamer->emitLabel(TOCEntryLabel);
-      if (isPPC64)
-        TS.emitTCEntry(*TOCEntryTarget);
-      else
-        OutStreamer->emitSymbolValue(TOCEntryTarget, 4);
     }
   }
 
   PPCAsmPrinter::emitEndOfAsmFile(M);
 }
 
 /// EmitFunctionBodyStart - Emit a global entry point prefix for ELFv2.
 void PPCLinuxAsmPrinter::emitFunctionBodyStart() {