lib/Object/SymbolSize.cpp

   1 //===- SymbolSize.cpp -----------------------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/Object/SymbolSize.h"
  11 #include "llvm/ADT/STLExtras.h"
  12 #include "llvm/Object/COFF.h"
  13 #include "llvm/Object/ELFObjectFile.h"
  14 #include "llvm/Object/MachO.h"
  15
  16 using namespace llvm;
  17 using namespace object;
  18
  19 // Orders increasingly by (SectionID, Address).
  20 int llvm::object::compareAddress(const SymEntry *A, const SymEntry *B) {
  21   if (A->SectionID != B->SectionID)
  22     return A->SectionID < B->SectionID ? -1 : 1;
  23   if (A->Address != B->Address)
  24     return A->Address < B->Address ? -1 : 1;
  25   return 0;
  26 }
  27
  28 static unsigned getSectionID(const ObjectFile &O, SectionRef Sec) {
  29   if (auto *M = dyn_cast<MachOObjectFile>(&O))
  30     return M->getSectionID(Sec);
  31   return cast<COFFObjectFile>(O).getSectionID(Sec);
  32 }
  33
  34 static unsigned getSymbolSectionID(const ObjectFile &O, SymbolRef Sym) {
  35   if (auto *M = dyn_cast<MachOObjectFile>(&O))
  36     return M->getSymbolSectionID(Sym);
  37   return cast<COFFObjectFile>(O).getSymbolSectionID(Sym);
  38 }
  39
  40 std::vector<std::pair<SymbolRef, uint64_t>>
  41 llvm::object::computeSymbolSizes(const ObjectFile &O) {
  42   std::vector<std::pair<SymbolRef, uint64_t>> Ret;
  43
  44   if (const auto *E = dyn_cast<ELFObjectFileBase>(&O)) {
  45     auto Syms = E->symbols();
  46     if (Syms.begin() == Syms.end())
  47       Syms = E->getDynamicSymbolIterators();
  48     for (ELFSymbolRef Sym : Syms)
  49       Ret.push_back({Sym, Sym.getSize()});
  50     return Ret;
  51   }
  52
  53   // Collect sorted symbol addresses. Include dummy addresses for the end
  54   // of each section.
  55   std::vector<SymEntry> Addresses;
  56   unsigned SymNum = 0;
  57   for (symbol_iterator I = O.symbol_begin(), E = O.symbol_end(); I != E; ++I) {
  58     SymbolRef Sym = *I;
  59     uint64_t Value = Sym.getValue();
  60     Addresses.push_back({I, Value, SymNum, getSymbolSectionID(O, Sym)});
  61     ++SymNum;
  62   }
  63   for (SectionRef Sec : O.sections()) {
  64     uint64_t Address = Sec.getAddress();
  65     uint64_t Size = Sec.getSize();
  66     Addresses.push_back(
  67         {O.symbol_end(), Address + Size, 0, getSectionID(O, Sec)});
  68   }
  69
  70   if (Addresses.empty())
  71     return Ret;
  72
  73   array_pod_sort(Addresses.begin(), Addresses.end(), compareAddress);
  74
  75   // Compute the size as the gap to the next symbol
  76   for (unsigned I = 0, N = Addresses.size() - 1; I < N; ++I) {
  77     auto &P = Addresses[I];
  78     if (P.I == O.symbol_end())
  79       continue;
  80
  81     // If multiple symbol have the same address, give both the same size.
  82     unsigned NextI = I + 1;
  83     while (NextI < N && Addresses[NextI].Address == P.Address)
  84       ++NextI;
  85
  86     uint64_t Size = Addresses[NextI].Address - P.Address;
  87     P.Address = Size;
  88   }
  89
  90   // Assign the sorted symbols in the original order.
  91   Ret.resize(SymNum);
  92   for (SymEntry &P : Addresses) {
  93     if (P.I == O.symbol_end())
  94       continue;
  95     Ret[P.Number] = {*P.I, P.Address};
  96   }
  97   return Ret;
  98 }