llvm/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 #include "llvm/Object/Wasm.h"
  15 #include "llvm/Object/XCOFFObjectFile.h"
  16
  17 using namespace llvm;
  18 using namespace object;
  19
  20 // Orders increasingly by (SectionID, Address).
  21 int llvm::object::compareAddress(const SymEntry *A, const SymEntry *B) {
  22   if (A->SectionID != B->SectionID)
  23     return A->SectionID < B->SectionID ? -1 : 1;
  24   if (A->Address != B->Address)
  25     return A->Address < B->Address ? -1 : 1;
  26   return 0;
  27 }
  28
  29 static unsigned getSectionID(const ObjectFile &O, SectionRef Sec) {
  30   if (auto *M = dyn_cast<MachOObjectFile>(&O))
  31     return M->getSectionID(Sec);
  32   if (isa<WasmObjectFile>(&O))
  33     return Sec.getIndex();
  34   if (isa<XCOFFObjectFile>(&O))
  35     return Sec.getIndex();
  36   return cast<COFFObjectFile>(O).getSectionID(Sec);
  37 }
  38
  39 static unsigned getSymbolSectionID(const ObjectFile &O, SymbolRef Sym) {
  40   if (auto *M = dyn_cast<MachOObjectFile>(&O))
  41     return M->getSymbolSectionID(Sym);
  42   if (const auto *M = dyn_cast<WasmObjectFile>(&O))
  43     return M->getSymbolSectionId(Sym);
  44   if (const auto *M = dyn_cast<XCOFFObjectFile>(&O))
  45     return M->getSymbolSectionID(Sym);
  46   return cast<COFFObjectFile>(O).getSymbolSectionID(Sym);
  47 }
  48
  49 std::vector<std::pair<SymbolRef, uint64_t>>
  50 llvm::object::computeSymbolSizes(const ObjectFile &O) {
  51   std::vector<std::pair<SymbolRef, uint64_t>> Ret;
  52
  53   if (const auto *E = dyn_cast<ELFObjectFileBase>(&O)) {
  54     auto Syms = E->symbols();
  55     if (Syms.empty())
  56       Syms = E->getDynamicSymbolIterators();
  57     for (ELFSymbolRef Sym : Syms)
  58       Ret.push_back({Sym, Sym.getSize()});
  59     return Ret;
  60   }
  61
  62   // Collect sorted symbol addresses. Include dummy addresses for the end
  63   // of each section.
  64   std::vector<SymEntry> Addresses;
  65   unsigned SymNum = 0;
  66   for (symbol_iterator I = O.symbol_begin(), E = O.symbol_end(); I != E; ++I) {
  67     SymbolRef Sym = *I;
  68     Expected<uint64_t> ValueOrErr = Sym.getValue();
  69     if (!ValueOrErr)
  70       // TODO: Actually report errors helpfully.
  71       report_fatal_error(ValueOrErr.takeError());
  72     Addresses.push_back({I, *ValueOrErr, SymNum, getSymbolSectionID(O, Sym)});
  73     ++SymNum;
  74   }
  75   for (SectionRef Sec : O.sections()) {
  76     uint64_t Address = Sec.getAddress();
  77     uint64_t Size = Sec.getSize();
  78     Addresses.push_back(
  79         {O.symbol_end(), Address + Size, 0, getSectionID(O, Sec)});
  80   }
  81
  82   if (Addresses.empty())
  83     return Ret;
  84
  85   array_pod_sort(Addresses.begin(), Addresses.end(), compareAddress);
  86
  87   // Compute the size as the gap to the next symbol. If multiple symbols have
  88   // the same address, give both the same size. Because Addresses is sorted,
  89   // use two pointers to keep track of the current symbol vs. the next symbol
  90   // that doesn't have the same address for size computation.
  91   for (unsigned I = 0, NextI = 0, N = Addresses.size() - 1; I < N; ++I) {
  92     auto &P = Addresses[I];
  93     if (P.I == O.symbol_end())
  94       continue;
  95
  96     // If the next pointer is behind, update it to the next symbol.
  97     if (NextI <= I) {
  98       NextI = I + 1;
  99       while (NextI < N && Addresses[NextI].Address == P.Address)
 100         ++NextI;
 101     }
 102
 103     uint64_t Size = Addresses[NextI].Address - P.Address;
 104     P.Address = Size;
 105   }
 106
 107   // Assign the sorted symbols in the original order.
 108   Ret.resize(SymNum);
 109   for (SymEntry &P : Addresses) {
 110     if (P.I == O.symbol_end())
 111       continue;
 112     Ret[P.Number] = {*P.I, P.Address};
 113   }
 114   return Ret;
 115 }