[ELF] - Step to combine LinkerScript and LinkerScriptBase

[grimar]

Summary

We can move all not templated functionality to LinkerScriptBase.
Patch do that for hasPhdrsCommands() and shows how it helps to detemplate
things in other places.

Probably we should be able to merge these 2 classes into single one after such steps.
Even if not, it still looks as reasonable cleanup for me.

[ruiu]

LGTM

ELF/LinkerScript.h

239–240

Why two "public" labels?

ELF/LinkerScript.h

struct MemoryRegion {
   std::string Name;
   uint64_t Origin;
   uint64_t Length;
   uint64_t Offset;
   uint32_t Flags;
   uint32_t NegFlags;
 };
 
-class LinkerScriptBase {
-protected:
-  ~LinkerScriptBase() = default;
-  OutputSection *Aether;
-
-public:
-  virtual uint64_t getSymbolValue(const Twine &Loc, StringRef S) = 0;
-  uint64_t getDot() { return getSymbolValue("", "."); }
-  virtual bool isDefined(StringRef S) = 0;
-  virtual bool isAbsolute(StringRef S) = 0;
-  virtual OutputSection *getSymbolSection(StringRef S) = 0;
-  virtual OutputSection *getOutputSection(const Twine &Loc, StringRef S) = 0;
-  virtual uint64_t getOutputSectionSize(StringRef S) = 0;
-};
 
 // ScriptConfiguration holds linker script parse results.
 struct ScriptConfiguration {
   // Used to assign addresses to sections.
   std::vector<std::unique_ptr<BaseCommand>> Commands;
 
   // Used to assign sections to headers.
   std::vector<PhdrsCommand> PhdrsCommands;
 
   bool HasSections = false;
 
   // List of section patterns specified with KEEP commands. They will
   // be kept even if they are unused and --gc-sections is specified.
   std::vector<InputSectionDescription *> KeptSections;
 
   // A map from memory region name to a memory region descriptor.
   llvm::DenseMap<llvm::StringRef, MemoryRegion> MemoryRegions;
 };
 
 extern ScriptConfiguration *ScriptConfig;
 
+class LinkerScriptBase {
+protected:
+  ~LinkerScriptBase() = default;
+  OutputSection *Aether;
+
+  // "ScriptConfig" is a bit too long, so define a short name for it.
+  ScriptConfiguration &Opt = *ScriptConfig;
+
+public:
+  bool hasPhdrsCommands() { return !Opt.PhdrsCommands.empty(); }
+
+public:
+  virtual uint64_t getSymbolValue(const Twine &Loc, StringRef S) = 0;
+  uint64_t getDot() { return getSymbolValue("", "."); }
+  virtual bool isDefined(StringRef S) = 0;
+  virtual bool isAbsolute(StringRef S) = 0;
+  virtual OutputSection *getSymbolSection(StringRef S) = 0;
+  virtual OutputSection *getOutputSection(const Twine &Loc, StringRef S) = 0;
+  virtual uint64_t getOutputSectionSize(StringRef S) = 0;
+};
+
 // This is a runner of the linker script.
 template <class ELFT> class LinkerScript final : public LinkerScriptBase {
   typedef typename ELFT::uint uintX_t;
 
 public:
   LinkerScript();
   ~LinkerScript();
 
   void processCommands(OutputSectionFactory &Factory);
   void addOrphanSections(OutputSectionFactory &Factory);
   void removeEmptyCommands();
   void adjustSectionsBeforeSorting();
   void adjustSectionsAfterSorting();
 
   std::vector<PhdrEntry> createPhdrs();
   bool ignoreInterpSection();
 
   uint32_t getFiller(StringRef Name);
   void writeDataBytes(StringRef Name, uint8_t *Buf);
   bool hasLMA(StringRef Name);
   bool shouldKeep(InputSectionBase *S);
   void assignOffsets(OutputSectionCommand *Cmd);
   void placeOrphanSections();
   void assignAddresses(std::vector<PhdrEntry> &Phdrs);
-  bool hasPhdrsCommands();
   uint64_t getSymbolValue(const Twine &Loc, StringRef S) override;
   bool isDefined(StringRef S) override;
   bool isAbsolute(StringRef S) override;
   OutputSection *getSymbolSection(StringRef S) override;
   OutputSection *getOutputSection(const Twine &Loc, StringRef S) override;
   uint64_t getOutputSectionSize(StringRef S) override;
 
   std::vector<OutputSection *> *OutputSections;
 
   int getSectionIndex(StringRef Name);
 
 private:
   void assignSymbol(SymbolAssignment *Cmd, bool InSec = false);
   void addSymbol(SymbolAssignment *Cmd);
   void computeInputSections(InputSectionDescription *);
   void setDot(Expr E, const Twine &Loc, bool InSec = false);
 
   void discard(ArrayRef<InputSectionBase *> V);
 
   std::vector<InputSectionBase *>
   createInputSectionList(OutputSectionCommand &Cmd);
 
-  // "ScriptConfig" is a bit too long, so define a short name for it.
-  ScriptConfiguration &Opt = *ScriptConfig;
-
   std::vector<size_t> getPhdrIndices(StringRef SectionName);
   size_t getPhdrIndex(const Twine &Loc, StringRef PhdrName);
 
   MemoryRegion *findMemoryRegion(OutputSectionCommand *Cmd, OutputSection *Sec);
 
   uintX_t Dot;
   std::function<uint64_t()> LMAOffset;
   OutputSection *CurOutSec = nullptr;

ELF/LinkerScript.cpp

void LinkerScript<ELFT>::assignAddresses(std::vector<PhdrEntry> &Phdrs) {
   uintX_t MinVA = std::numeric_limits<uintX_t>::max();
   for (OutputSection *Sec : *OutputSections) {
     if (Sec->Flags & SHF_ALLOC)
       MinVA = std::min<uint64_t>(MinVA, Sec->Addr);
     else
       Sec->Addr = 0;
   }
 
-  allocateHeaders<ELFT>(Phdrs, *OutputSections, MinVA);
+  allocateHeaders(Phdrs, *OutputSections, MinVA);
 }
 
 // Creates program headers as instructed by PHDRS linker script command.
 template <class ELFT> std::vector<PhdrEntry> LinkerScript<ELFT>::createPhdrs() {
   std::vector<PhdrEntry> Ret;
 
   // Process PHDRS and FILEHDR keywords because they are not
   // real output sections and cannot be added in the following loop.

 template <class ELFT> int LinkerScript<ELFT>::getSectionIndex(StringRef Name) {
   for (int I = 0, E = Opt.Commands.size(); I != E; ++I)
     if (auto *Cmd = dyn_cast<OutputSectionCommand>(Opt.Commands[I].get()))
       if (Cmd->Name == Name)
         return I;
   return INT_MAX;
 }
 
-template <class ELFT> bool LinkerScript<ELFT>::hasPhdrsCommands() {
-  return !Opt.PhdrsCommands.empty();
-}
-
 template <class ELFT>
 OutputSection *LinkerScript<ELFT>::getOutputSection(const Twine &Loc,
                                                     StringRef Name) {
   static OutputSection FakeSec("", 0, 0);
 
   for (OutputSection *Sec : *OutputSections)
     if (Sec->Name == Name)
       return Sec;

ELF/Writer.h

struct PhdrEntry {
 
   OutputSection *First = nullptr;
   OutputSection *Last = nullptr;
   bool HasLMA = false;
 };
 
 llvm::StringRef getOutputSectionName(llvm::StringRef Name);
 
-template <class ELFT>
 bool allocateHeaders(std::vector<PhdrEntry> &, llvm::ArrayRef<OutputSection *>,
                      uint64_t Min);
 
 template <class ELFT> uint32_t getMipsEFlags();
 
 uint8_t getMipsFpAbiFlag(uint8_t OldFlag, uint8_t NewFlag,
                          llvm::StringRef FileName);
 
 bool isMipsN32Abi(const InputFile *F);
 }
 }
 
 #endif

ELF/Writer.cpp

for (const PhdrEntry &P : Phdrs) {
     if (I == End || (I + 1) == End)
       continue;
     OutputSection *Sec = *(I + 1);
     if (needsPtLoad<ELFT>(Sec))
       Sec->PageAlign = true;
   }
 }
 
-template <class ELFT>
 bool elf::allocateHeaders(std::vector<PhdrEntry> &Phdrs,
                           ArrayRef<OutputSection *> OutputSections,
                           uint64_t Min) {
   auto FirstPTLoad =
       std::find_if(Phdrs.begin(), Phdrs.end(),
                    [](const PhdrEntry &E) { return E.p_type == PT_LOAD; });
   if (FirstPTLoad == Phdrs.end())
     return false;
bool elf::allocateHeaders(std::vector<PhdrEntry> &Phdrs,
   Min = alignDown(Min - HeaderSize, Config->MaxPageSize);
 
   if (!ScriptConfig->HasSections)
     Config->ImageBase = Min = std::min(Min, Config->ImageBase);
 
   Out::ElfHeader->Addr = Min;
   Out::ProgramHeaders->Addr = Min + Out::ElfHeader->Size;
 
-  if (Script<ELFT>::X->hasPhdrsCommands())
+  if (ScriptBase->hasPhdrsCommands())
     return true;
 
   if (FirstPTLoad->First)
     for (OutputSection *Sec : OutputSections)
       if (Sec->FirstInPtLoad == FirstPTLoad->First)
         Sec->FirstInPtLoad = Out::ElfHeader;
   FirstPTLoad->First = Out::ElfHeader;
   if (!FirstPTLoad->Last)
template <class ELFT> void Writer<ELFT>::fixHeaders() {
 
   // When -T<section> option is specified, lower the base to make room for those
   // sections.
   uint64_t Min = -1;
   if (!Config->SectionStartMap.empty())
     for (const auto &P : Config->SectionStartMap)
       Min = std::min(Min, P.second);
 
-  AllocateHeader = allocateHeaders<ELFT>(Phdrs, OutputSections, Min);
+  AllocateHeader = allocateHeaders(Phdrs, OutputSections, Min);
 }
 
 // Assign VAs (addresses at run-time) to output sections.
 template <class ELFT> void Writer<ELFT>::assignAddresses() {
   uintX_t VA = Config->ImageBase;
   if (AllocateHeader)
     VA += getHeaderSize();
   uintX_t ThreadBssOffset = 0;
template <class ELFT> void Writer<ELFT>::writeBuildId() {
   In<ELFT>::BuildId->writeBuildId({Start, End});
 }
 
 template void elf::writeResult<ELF32LE>();
 template void elf::writeResult<ELF32BE>();
 template void elf::writeResult<ELF64LE>();
 template void elf::writeResult<ELF64BE>();
 
-template bool elf::allocateHeaders<ELF32LE>(std::vector<PhdrEntry> &,
-                                            ArrayRef<OutputSection *>,
-                                            uint64_t);
-template bool elf::allocateHeaders<ELF32BE>(std::vector<PhdrEntry> &,
-                                            ArrayRef<OutputSection *>,
-                                            uint64_t);
-template bool elf::allocateHeaders<ELF64LE>(std::vector<PhdrEntry> &,
-                                            ArrayRef<OutputSection *>,
-                                            uint64_t);
-template bool elf::allocateHeaders<ELF64BE>(std::vector<PhdrEntry> &,
-                                            ArrayRef<OutputSection *>,
-                                            uint64_t);
-
 template bool elf::isRelroSection<ELF32LE>(const OutputSection *);
 template bool elf::isRelroSection<ELF32BE>(const OutputSection *);
 template bool elf::isRelroSection<ELF64LE>(const OutputSection *);
 template bool elf::isRelroSection<ELF64BE>(const OutputSection *);