[ELF] - Prepare GnuHashTableSection<ELFT> for detemplation.

[grimar]

Summary

This patch changes GnuHashTableSection implementation
to avoid depend on uintX_t and other ELFT stuff, reducing amount of
changes for following patch(es).

[ruiu]

ELF/SyntheticSections.cpp

1493–1494

Just like writeUint, you want to define readUint.

1514

&Buckets[I] -> Buckets + I

1525–1526

&Values[I++] -> Values + I++

[grimar]

• Addressed review comments, rebased.

ELF/SyntheticSections.cpp

1493–1494

Done.

1514

Done.

1525–1526

Done.

[grimar]

Ping.

[ruiu]

LGTM

ELF/SyntheticSections.h

private:
 
   StringTableSection &StrTabSec;
 };
 
 // Outputs GNU Hash section. For detailed explanation see:
 // https://blogs.oracle.com/ali/entry/gnu_hash_elf_sections
 template <class ELFT>
 class GnuHashTableSection final : public SyntheticSection {
-  typedef typename ELFT::uint uintX_t;
-
 public:
   GnuHashTableSection();
   void finalizeContents() override;
   void writeTo(uint8_t *Buf) override;
   size_t getSize() const override { return Size; }
 
   // Adds symbols to the hash table.
   // Sorts the input to satisfy GNU hash section requirements.
   void addSymbols(std::vector<SymbolTableEntry> &Symbols);
 
 private:
-  size_t getShift2() const { return ELFT::Is64Bits ? 6 : 5; }
+  size_t getShift2() const { return (Config->Wordsize == 8) ? 6 : 5; }
 
   void writeBloomFilter(uint8_t *Buf);
   void writeHashTable(uint8_t *Buf);
 
   struct Entry {
     SymbolBody *Body;
     size_t StrTabOffset;
     uint32_t Hash;

ELF/SyntheticSections.cpp

 // and .gnu.hash. They are for the same purpose, and .gnu.hash is a new
 // and better version of .hash. .hash is just an on-disk hash table, but
 // .gnu.hash has a bloom filter in addition to a hash table to skip
 // DSOs very quickly. If you are sure that your dynamic linker knows
 // about .gnu.hash, you want to specify -hash-style=gnu. Otherwise, a
 // safe bet is to specify -hash-style=both for backward compatibilty.
 template <class ELFT>
 GnuHashTableSection<ELFT>::GnuHashTableSection()
-    : SyntheticSection(SHF_ALLOC, SHT_GNU_HASH, sizeof(uintX_t), ".gnu.hash") {
-  this->Entsize = ELFT::Is64Bits ? 0 : 4;
+    : SyntheticSection(SHF_ALLOC, SHT_GNU_HASH, Config->Wordsize, ".gnu.hash") {
+  // 64 bit .gnu.hash sections have mixed element size, sh_entsize is 0.
+  this->Entsize = (Config->Wordsize == 8) ? 0 : 4;
 }
 
 template <class ELFT> void GnuHashTableSection<ELFT>::finalizeContents() {
   this->OutSec->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
 
   // Computes bloom filter size in word size. We want to allocate 8
   // bits for each symbol. It must be a power of two.
   if (Symbols.empty())
     MaskWords = 1;
   else
-    MaskWords = NextPowerOf2((Symbols.size() - 1) / sizeof(uintX_t));
+    MaskWords = NextPowerOf2((Symbols.size() - 1) / Config->Wordsize);
 
-  Size = 16;                           // Header
-  Size += sizeof(uintX_t) * MaskWords; // Bloom filter
-  Size += NBuckets * 4;                // Hash buckets
-  Size += Symbols.size() * 4;          // Hash values
+  Size = 16;                            // Header
+  Size += Config->Wordsize * MaskWords; // Bloom filter
+  Size += NBuckets * 4;                 // Hash buckets
+  Size += Symbols.size() * 4;           // Hash values
 }
 
-template <class ELFT> void GnuHashTableSection<ELFT>::writeTo(uint8_t *Buf) {
+template <class ELFT>
+void GnuHashTableSection<ELFT>::writeTo(uint8_t *Buf) {
   // Write a header.
-  const endianness E = ELFT::TargetEndianness;
-  write32<E>(Buf, NBuckets);
-  write32<E>(Buf + 4, In<ELFT>::DynSymTab->getNumSymbols() - Symbols.size());
-  write32<E>(Buf + 8, MaskWords);
-  write32<E>(Buf + 12, getShift2());
+  support::endianness E =
+      Config->IsLE ? support::endianness::little : support::endianness::big;
+  write32(Buf, NBuckets, E);
+  write32(Buf + 4, In<ELFT>::DynSymTab->getNumSymbols() - Symbols.size(), E);
+  write32(Buf + 8, MaskWords, E);
+  write32(Buf + 12, getShift2(), E);
   Buf += 16;
 
   // Write a bloom filter and a hash table.
   writeBloomFilter(Buf);
-  Buf += sizeof(uintX_t) * MaskWords;
+  Buf += Config->Wordsize * MaskWords;
   writeHashTable(Buf);
 }
 
 // This function writes a 2-bit bloom filter. This bloom filter alone
 // usually filters out 80% or more of all symbol lookups [1].
 // The dynamic linker uses the hash table only when a symbol is not
 // filtered out by a bloom filter.
 //
 // [1] Ulrich Drepper (2011), "How To Write Shared Libraries" (Ver. 4.1.2),
 //     p.9, https://www.akkadia.org/drepper/dsohowto.pdf
 template <class ELFT>
 void GnuHashTableSection<ELFT>::writeBloomFilter(uint8_t *Buf) {
-  typedef typename ELFT::Off Elf_Off;
-  const unsigned C = sizeof(uintX_t) * 8;
-
-  auto *Filter = reinterpret_cast<Elf_Off *>(Buf);
+  support::endianness E =
+      Config->IsLE ? support::endianness::little : support::endianness::big;
+  const unsigned C = Config->Wordsize * 8;
   for (const Entry &Sym : Symbols) {
     size_t I = (Sym.Hash / C) & (MaskWords - 1);
-    Filter[I] |= uintX_t(1) << (Sym.Hash % C);
-    Filter[I] |= uintX_t(1) << ((Sym.Hash >> getShift2()) % C);
+    uint64_t Val = (Config->Wordsize == 8) ? read64(&((uint64_t *)Buf)[I], E)
+                                           : read32(&((uint32_t *)Buf)[I], E);
+    Val |= uint64_t(1) << (Sym.Hash % C);
+    Val |= uint64_t(1) << ((Sym.Hash >> getShift2()) % C);
+    writeUint(Buf + I * Config->Wordsize, Val);
   }
 }
 
 template <class ELFT>
 void GnuHashTableSection<ELFT>::writeHashTable(uint8_t *Buf) {
-  // A 32-bit integer type in the target endianness.
-  typedef typename ELFT::Word Elf_Word;
-
+  const endianness E = Config->IsLE ? endianness::little : endianness::big;
   // Group symbols by hash value.
   std::vector<std::vector<Entry>> Syms(NBuckets);
   for (const Entry &Ent : Symbols)
     Syms[Ent.Hash % NBuckets].push_back(Ent);
 
   // Write hash buckets. Hash buckets contain indices in the following
   // hash value table.
-  Elf_Word *Buckets = reinterpret_cast<Elf_Word *>(Buf);
+  uint32_t *Buckets = reinterpret_cast<uint32_t *>(Buf);
   for (size_t I = 0; I < NBuckets; ++I)
     if (!Syms[I].empty())
-      Buckets[I] = Syms[I][0].Body->DynsymIndex;
+      write32(&Buckets[I], Syms[I][0].Body->DynsymIndex, E);
 
   // Write a hash value table. It represents a sequence of chains that
   // share the same hash modulo value. The last element of each chain
   // is terminated by LSB 1.
-  Elf_Word *Values = Buckets + NBuckets;
+  uint32_t *Values = Buckets + NBuckets;
   size_t I = 0;
   for (std::vector<Entry> &Vec : Syms) {
     if (Vec.empty())
       continue;
     for (const Entry &Ent : makeArrayRef(Vec).drop_back())
-      Values[I++] = Ent.Hash & ~1;
-    Values[I++] = Vec.back().Hash | 1;
+      write32(&Values[I++], Ent.Hash & ~1, E);
+    write32(&Values[I++], Vec.back().Hash | 1, E);
   }
 }
 
 static uint32_t hashGnu(StringRef Name) {
   uint32_t H = 5381;
   for (uint8_t C : Name)
     H = (H << 5) + H + C;
   return H;