text: //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  #include "LanaiTargetObjectFile.h"
  
  #include "LanaiSubtarget.h"
  #include "LanaiTargetMachine.h"
  #include "llvm/BinaryFormat/ELF.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/GlobalVariable.h"
  #include "llvm/MC/MCContext.h"
  #include "llvm/MC/MCSectionELF.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Target/TargetMachine.h"
  
  using namespace llvm;
  
  static cl::opt<unsigned> SSThreshold(
      "lanai-ssection-threshold", cl::Hidden,
      cl::desc("Small data and bss section threshold size (default=0)"),
      cl::init(0));
  
  void LanaiTargetObjectFile::Initialize(MCContext &Ctx,
                                         const TargetMachine &TM) {
    TargetLoweringObjectFileELF::Initialize(Ctx, TM);
  
    SmallDataSection = getContext().getELFSection(
        ".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
    SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
                                                 ELF::SHF_WRITE | ELF::SHF_ALLOC);
  }
  
  // A address must be loaded from a small section if its size is less than the
  // small section size threshold. Data in this section must be addressed using
  // gp_rel operator.
  static bool isInSmallSection(uint64_t Size) {
    // gcc has traditionally not treated zero-sized objects as small data, so this
    // is effectively part of the ABI.
    return Size > 0 && Size <= SSThreshold;
  }
  
  // Return true if this global address should be placed into small data/bss
  // section.
  bool LanaiTargetObjectFile::isGlobalInSmallSection(
      const GlobalObject *GO, const TargetMachine &TM) const {
    if (GO == nullptr) return TM.getCodeModel() == CodeModel::Small;
  
    // We first check the case where global is a declaration, because finding
    // section kind using getKindForGlobal() is only allowed for global
    // definitions.
    if (GO->isDeclaration() || GO->hasAvailableExternallyLinkage())
      return isGlobalInSmallSectionImpl(GO, TM);
  
    return isGlobalInSmallSection(GO, TM, getKindForGlobal(GO, TM));
  }
  
  // Return true if this global address should be placed into small data/bss
  // section.
  bool LanaiTargetObjectFile::isGlobalInSmallSection(const GlobalObject *GO,
                                                     const TargetMachine &TM,
                                                     SectionKind Kind) const {
    return isGlobalInSmallSectionImpl(GO, TM);
  }
  
  // Return true if this global address should be placed into small data/bss
  // section. This method does all the work, except for checking the section
  // kind.
  bool LanaiTargetObjectFile::isGlobalInSmallSectionImpl(
      const GlobalObject *GO, const TargetMachine &TM) const {
    const auto *GVA = dyn_cast<GlobalVariable>(GO);
  
    // If not a GlobalVariable, only consider the code model.
    if (!GVA) return TM.getCodeModel() == CodeModel::Small;
  
    // Global values placed in sections starting with .ldata do not fit in
    // 21-bits, so always use large memory access for them. FIXME: This is a
    // workaround for a tool limitation.
    if (GVA->getSection().startswith(".ldata"))
      return false;
  
    if (TM.getCodeModel() == CodeModel::Small)
      return true;
  
    if (GVA->hasLocalLinkage())
      return false;
  
    if (((GVA->hasExternalLinkage() && GVA->isDeclaration()) ||
         GVA->hasCommonLinkage()))
      return false;
  
    Type *Ty = GVA->getValueType();
    return isInSmallSection(
        GVA->getParent()->getDataLayout().getTypeAllocSize(Ty));
  }
  
  MCSection *LanaiTargetObjectFile::SelectSectionForGlobal(
      const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
    // Handle Small Section classification here.
    if (Kind.isBSS() && isGlobalInSmallSection(GO, TM, Kind))
      return SmallBSSSection;
    if (Kind.isData() && isGlobalInSmallSection(GO, TM, Kind))
      return SmallDataSection;
  
    // Otherwise, we work the same as ELF.
    return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
  }
  
  /// Return true if this constant should be placed into small data section.
  bool LanaiTargetObjectFile::isConstantInSmallSection(const DataLayout &DL,
                                                       const Constant *CN) const {
    return isInSmallSection(DL.getTypeAllocSize(CN->getType()));
  }
  
  MCSection *LanaiTargetObjectFile::getSectionForConstant(const DataLayout &DL,
                                                          SectionKind Kind,
                                                          const Constant *C,
                                                          unsigned &Align) const {
    if (isConstantInSmallSection(DL, C))
      return SmallDataSection;
  
    // Otherwise, we work the same as ELF.
    return TargetLoweringObjectFileELF::getSectionForConstant(DL, Kind, C, Align);
  }
  