[ELF] Convert GnuHashTableSection to input section

Differential revision: https://reviews.llvm.org/D26792

llvm-svn: 287322

1 files changed, 0 insertions, 152 deletions

diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index c98170dfc42..8270be0dc98 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -179,153 +179,6 @@ template <class ELFT> void HashTableSection<ELFT>::writeTo(uint8_t *Buf) {
   }
 }
 
-static uint32_t hashGnu(StringRef Name) {
-  uint32_t H = 5381;
-  for (uint8_t C : Name)
-    H = (H << 5) + H + C;
-  return H;
-}
-
-template <class ELFT>
-GnuHashTableSection<ELFT>::GnuHashTableSection()
-    : OutputSectionBase(".gnu.hash", SHT_GNU_HASH, SHF_ALLOC) {
-  this->Entsize = ELFT::Is64Bits ? 0 : 4;
-  this->Addralign = sizeof(uintX_t);
-}
-
-template <class ELFT>
-unsigned GnuHashTableSection<ELFT>::calcNBuckets(unsigned NumHashed) {
-  if (!NumHashed)
-    return 0;
-
-  // These values are prime numbers which are not greater than 2^(N-1) + 1.
-  // In result, for any particular NumHashed we return a prime number
-  // which is not greater than NumHashed.
-  static const unsigned Primes[] = {
-      1,   1,    3,    3,    7,    13,    31,    61,    127,   251,
-      509, 1021, 2039, 4093, 8191, 16381, 32749, 65521, 131071};
-
-  return Primes[std::min<unsigned>(Log2_32_Ceil(NumHashed),
-                                   array_lengthof(Primes) - 1)];
-}
-
-// Bloom filter estimation: at least 8 bits for each hashed symbol.
-// GNU Hash table requirement: it should be a power of 2,
-//   the minimum value is 1, even for an empty table.
-// Expected results for a 32-bit target:
-//   calcMaskWords(0..4)   = 1
-//   calcMaskWords(5..8)   = 2
-//   calcMaskWords(9..16)  = 4
-// For a 64-bit target:
-//   calcMaskWords(0..8)   = 1
-//   calcMaskWords(9..16)  = 2
-//   calcMaskWords(17..32) = 4
-template <class ELFT>
-unsigned GnuHashTableSection<ELFT>::calcMaskWords(unsigned NumHashed) {
-  if (!NumHashed)
-    return 1;
-  return NextPowerOf2((NumHashed - 1) / sizeof(Elf_Off));
-}
-
-template <class ELFT> void GnuHashTableSection<ELFT>::finalize() {
-  unsigned NumHashed = Symbols.size();
-  NBuckets = calcNBuckets(NumHashed);
-  MaskWords = calcMaskWords(NumHashed);
-  // Second hash shift estimation: just predefined values.
-  Shift2 = ELFT::Is64Bits ? 6 : 5;
-
-  this->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
-  this->Size = sizeof(Elf_Word) * 4            // Header
-               + sizeof(Elf_Off) * MaskWords   // Bloom Filter
-               + sizeof(Elf_Word) * NBuckets   // Hash Buckets
-               + sizeof(Elf_Word) * NumHashed; // Hash Values
-}
-
-template <class ELFT> void GnuHashTableSection<ELFT>::writeTo(uint8_t *Buf) {
-  writeHeader(Buf);
-  if (Symbols.empty())
-    return;
-  writeBloomFilter(Buf);
-  writeHashTable(Buf);
-}
-
-template <class ELFT>
-void GnuHashTableSection<ELFT>::writeHeader(uint8_t *&Buf) {
-  auto *P = reinterpret_cast<Elf_Word *>(Buf);
-  *P++ = NBuckets;
-  *P++ = In<ELFT>::DynSymTab->getNumSymbols() - Symbols.size();
-  *P++ = MaskWords;
-  *P++ = Shift2;
-  Buf = reinterpret_cast<uint8_t *>(P);
-}
-
-template <class ELFT>
-void GnuHashTableSection<ELFT>::writeBloomFilter(uint8_t *&Buf) {
-  unsigned C = sizeof(Elf_Off) * 8;
-
-  auto *Masks = reinterpret_cast<Elf_Off *>(Buf);
-  for (const SymbolData &Sym : Symbols) {
-    size_t Pos = (Sym.Hash / C) & (MaskWords - 1);
-    uintX_t V = (uintX_t(1) << (Sym.Hash % C)) |
-                (uintX_t(1) << ((Sym.Hash >> Shift2) % C));
-    Masks[Pos] |= V;
-  }
-  Buf += sizeof(Elf_Off) * MaskWords;
-}
-
-template <class ELFT>
-void GnuHashTableSection<ELFT>::writeHashTable(uint8_t *Buf) {
-  Elf_Word *Buckets = reinterpret_cast<Elf_Word *>(Buf);
-  Elf_Word *Values = Buckets + NBuckets;
-
-  int PrevBucket = -1;
-  int I = 0;
-  for (const SymbolData &Sym : Symbols) {
-    int Bucket = Sym.Hash % NBuckets;
-    assert(PrevBucket <= Bucket);
-    if (Bucket != PrevBucket) {
-      Buckets[Bucket] = Sym.Body->DynsymIndex;
-      PrevBucket = Bucket;
-      if (I > 0)
-        Values[I - 1] |= 1;
-    }
-    Values[I] = Sym.Hash & ~1;
-    ++I;
-  }
-  if (I > 0)
-    Values[I - 1] |= 1;
-}
-
-// Add symbols to this symbol hash table. Note that this function
-// destructively sort a given vector -- which is needed because
-// GNU-style hash table places some sorting requirements.
-template <class ELFT>
-void GnuHashTableSection<ELFT>::addSymbols(std::vector<SymbolTableEntry> &V) {
-  // Ideally this will just be 'auto' but GCC 6.1 is not able
-  // to deduce it correctly.
-  std::vector<SymbolTableEntry>::iterator Mid =
-      std::stable_partition(V.begin(), V.end(), [](const SymbolTableEntry &S) {
-        return S.Symbol->isUndefined();
-      });
-  if (Mid == V.end())
-    return;
-  for (auto I = Mid, E = V.end(); I != E; ++I) {
-    SymbolBody *B = I->Symbol;
-    size_t StrOff = I->StrTabOffset;
-    Symbols.push_back({B, StrOff, hashGnu(B->getName())});
-  }
-
-  unsigned NBuckets = calcNBuckets(Symbols.size());
-  std::stable_sort(Symbols.begin(), Symbols.end(),
-                   [&](const SymbolData &L, const SymbolData &R) {
-                     return L.Hash % NBuckets < R.Hash % NBuckets;
-                   });
-
-  V.erase(Mid, V.end());
-  for (const SymbolData &Sym : Symbols)
-    V.push_back({Sym.Body, Sym.STName});
-}
-
 // Returns the number of version definition entries. Because the first entry
 // is for the version definition itself, it is the number of versioned symbols
 // plus one. Note that we don't support multiple versions yet.
@@ -1085,11 +938,6 @@ template class PltSection<ELF32BE>;
 template class PltSection<ELF64LE>;
 template class PltSection<ELF64BE>;
 
-template class GnuHashTableSection<ELF32LE>;
-template class GnuHashTableSection<ELF32BE>;
-template class GnuHashTableSection<ELF64LE>;
-template class GnuHashTableSection<ELF64BE>;
-
 template class HashTableSection<ELF32LE>;
 template class HashTableSection<ELF32BE>;
 template class HashTableSection<ELF64LE>;