Fix a bug that would cause subzero to fail when --threads=0.

src/IceELFObjectWriter.cpp

 //===- subzero/src/IceELFObjectWriter.cpp - ELF object file writer --------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the writer for ELF relocatable object files.
@@ skipping 267 matching lines @@
       size_t Section = classifyGlobalSection(Var);
       assert(Section < ELFObjectWriter::NumSectionTypes);
       VarsBySection[Section].push_back(Var);
     }
   }
 }
 
 } // end of anonymous namespace
 
 void ELFObjectWriter::writeDataSection(const VariableDeclarationList &Vars,
-                                       FixupKind RelocationKind) {
+                                       FixupKind RelocationKind,
+                                       const IceString &SectionSuffix) {
   assert(!SectionNumbersAssigned);
   VariableDeclarationList VarsBySection[ELFObjectWriter::NumSectionTypes];
   for (auto &SectionList : VarsBySection)
     SectionList.reserve(Vars.size());
   partitionGlobalsBySection(Vars, VarsBySection,
                             Ctx.getFlags().getTranslateOnly());
   size_t I = 0;
   for (auto &SectionList : VarsBySection) {
-    writeDataOfType(static_cast<SectionType>(I++), SectionList, RelocationKind);
+    writeDataOfType(static_cast<SectionType>(I++), SectionList, RelocationKind,
+                    SectionSuffix);
   }
 }
 
+namespace {
+IceString MangleSectionName(const char Base[], const IceString &Suffix) {
+  if (Suffix.empty())
+    return Base;
+  return Base + ("." + Suffix);
+}
+} // end of anonymous namespace
+
+// TODO(jvoung): Handle fdata-sections.
 void ELFObjectWriter::writeDataOfType(SectionType ST,
                                       const VariableDeclarationList &Vars,
-                                      FixupKind RelocationKind) {
+                                      FixupKind RelocationKind,
+                                      const IceString &SectionSuffix) {
   if (Vars.empty())
     return;
   ELFDataSection *Section;
   ELFRelocationSection *RelSection;
-  // TODO(jvoung): Handle fdata-sections.
   IceString SectionName;
   Elf64_Xword ShAddralign = 1;
   for (VariableDeclaration *Var : Vars) {
     Elf64_Xword Align = Var->getAlignment();
     ShAddralign = std::max(ShAddralign, Align);
   }
   const Elf64_Xword ShEntsize = 0; // non-uniform data element size.
   // Lift this out, so it can be re-used if we do fdata-sections?
   switch (ST) {
   case ROData: {
-    SectionName = ".rodata";
-    // Only expecting to write the data sections all in one shot for now.
-    assert(RODataSections.empty());
+    const IceString SectionName = MangleSectionName(".rodata", SectionSuffix);
     const Elf64_Xword ShFlags = SHF_ALLOC;
     Section = createSection<ELFDataSection>(SectionName, SHT_PROGBITS, ShFlags,
                                             ShAddralign, ShEntsize);
     Section->setFileOffset(alignFileOffset(ShAddralign));
     RODataSections.push_back(Section);
     RelSection = createRelocationSection(Section);
     RelRODataSections.push_back(RelSection);
     break;
   }
   case Data: {
-    SectionName = ".data";
-    assert(DataSections.empty());
+    const IceString SectionName = MangleSectionName(".data", SectionSuffix);
     const Elf64_Xword ShFlags = SHF_ALLOC | SHF_WRITE;
     Section = createSection<ELFDataSection>(SectionName, SHT_PROGBITS, ShFlags,
                                             ShAddralign, ShEntsize);
     Section->setFileOffset(alignFileOffset(ShAddralign));
     DataSections.push_back(Section);
     RelSection = createRelocationSection(Section);
     RelDataSections.push_back(RelSection);
     break;
   }
   case BSS: {
-    SectionName = ".bss";
-    assert(BSSSections.empty());
+    const IceString SectionName = MangleSectionName(".bss", SectionSuffix);
     const Elf64_Xword ShFlags = SHF_ALLOC | SHF_WRITE;
     Section = createSection<ELFDataSection>(SectionName, SHT_NOBITS, ShFlags,
                                             ShAddralign, ShEntsize);
     Section->setFileOffset(alignFileOffset(ShAddralign));
     BSSSections.push_back(Section);
     break;
   }
   case NumSectionTypes:
     llvm::report_fatal_error("Unknown SectionType");
     break;
@@ skipping 20 matching lines @@
       assert(ST == BSS || ST == ROData);
       if (ST == ROData)
         Section->appendZeros(Str, SymbolSize);
       else
         Section->setSize(Section->getCurrentSize() + SymbolSize);
     } else {
       assert(ST != BSS);
       for (VariableDeclaration::Initializer *Init : Var->getInitializers()) {
         switch (Init->getKind()) {
         case VariableDeclaration::Initializer::DataInitializerKind: {
-          const auto Data =
-              llvm::cast<VariableDeclaration::DataInitializer>(Init)
-                  ->getContents();
+          const auto Data = llvm::cast<VariableDeclaration::DataInitializer>(
+                                Init)->getContents();
           Section->appendData(Str, llvm::StringRef(Data.data(), Data.size()));
           break;
         }
         case VariableDeclaration::Initializer::ZeroInitializerKind:
           Section->appendZeros(Str, Init->getNumBytes());
           break;
         case VariableDeclaration::Initializer::RelocInitializerKind: {
           const auto Reloc =
               llvm::cast<VariableDeclaration::RelocInitializer>(Init);
           AssemblerFixup NewFixup;
@@ skipping 209 matching lines @@
   if (ELF64) {
     writeELFHeaderInternal<true>(ShOffset, ShStrTab->getNumber(),
                                  AllSections.size());
   } else {
     writeELFHeaderInternal<false>(ShOffset, ShStrTab->getNumber(),
                                   AllSections.size());
   }
 }
 
 } // end of namespace Ice