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 }
98