lib/Object/SymbolSize.cpp

   1 //===- SymbolSize.cpp -----------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Object/SymbolSize.h"
  10 #include "llvm/ADT/STLExtras.h"
  11 #include "llvm/Object/COFF.h"
  12 #include "llvm/Object/ELFObjectFile.h"
  13 #include "llvm/Object/MachO.h"
  14
  15 using namespace llvm;
  16 using namespace object;
  17
  18 // Orders increasingly by (SectionID, Address).
  19 int llvm::object::compareAddress(const SymEntry *A, const SymEntry *B) {
  20   if (A->SectionID != B->SectionID)
  21     return A->SectionID < B->SectionID ? -1 : 1;
  22   if (A->Address != B->Address)
  23     return A->Address < B->Address ? -1 : 1;
  24   return 0;
  25 }
  26
  27 static unsigned getSectionID(const ObjectFile &O, SectionRef Sec) {
  28   if (auto *M = dyn_cast<MachOObjectFile>(&O))
  29     return M->getSectionID(Sec);
  30   return cast<COFFObjectFile>(O).getSectionID(Sec);
  31 }
  32
  33 static unsigned getSymbolSectionID(const ObjectFile &O, SymbolRef Sym) {
  34   if (auto *M = dyn_cast<MachOObjectFile>(&O))
  35     return M->getSymbolSectionID(Sym);
  36   return cast<COFFObjectFile>(O).getSymbolSectionID(Sym);
  37 }
  38
  39 std::vector<std::pair<SymbolRef, uint64_t>>
  40 llvm::object::computeSymbolSizes(const ObjectFile &O) {
  41   std::vector<std::pair<SymbolRef, uint64_t>> Ret;
  42
  43   if (const auto *E = dyn_cast<ELFObjectFileBase>(&O)) {
  44     auto Syms = E->symbols();
  45     if (Syms.begin() == Syms.end())
  46       Syms = E->getDynamicSymbolIterators();
  47     for (ELFSymbolRef Sym : Syms)
  48       Ret.push_back({Sym, Sym.getSize()});
  49     return Ret;
  50   }
  51
  52   // Collect sorted symbol addresses. Include dummy addresses for the end
  53   // of each section.
  54   std::vector<SymEntry> Addresses;
  55   unsigned SymNum = 0;
  56   for (symbol_iterator I = O.symbol_begin(), E = O.symbol_end(); I != E; ++I) {
  57     SymbolRef Sym = *I;
  58     uint64_t Value = Sym.getValue();
  59     Addresses.push_back({I, Value, SymNum, getSymbolSectionID(O, Sym)});
  60     ++SymNum;
  61   }
  62   for (SectionRef Sec : O.sections()) {
  63     uint64_t Address = Sec.getAddress();
  64     uint64_t Size = Sec.getSize();
  65     Addresses.push_back(
  66         {O.symbol_end(), Address + Size, 0, getSectionID(O, Sec)});
  67   }
  68
  69   if (Addresses.empty())
  70     return Ret;
  71
  72   array_pod_sort(Addresses.begin(), Addresses.end(), compareAddress);
  73
  74   // Compute the size as the gap to the next symbol
  75   for (unsigned I = 0, N = Addresses.size() - 1; I < N; ++I) {
  76     auto &P = Addresses[I];
  77     if (P.I == O.symbol_end())
  78       continue;
  79
  80     // If multiple symbol have the same address, give both the same size.
  81     unsigned NextI = I + 1;
  82     while (NextI < N && Addresses[NextI].Address == P.Address)
  83       ++NextI;
  84
  85     uint64_t Size = Addresses[NextI].Address - P.Address;
  86     P.Address = Size;
  87   }
  88
  89   // Assign the sorted symbols in the original order.
  90   Ret.resize(SymNum);
  91   for (SymEntry &P : Addresses) {
  92     if (P.I == O.symbol_end())
  93       continue;
  94     Ret[P.Number] = {*P.I, P.Address};
  95   }
  96   return Ret;
  97 }