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 
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   if (isa<WasmObjectFile>(&O))
32     return Sec.getIndex();
33 
34   return cast<COFFObjectFile>(O).getSectionID(Sec);
35 }
36 
37 static unsigned getSymbolSectionID(const ObjectFile &O, SymbolRef Sym) {
38   if (auto *M = dyn_cast<MachOObjectFile>(&O))
39     return M->getSymbolSectionID(Sym);
40   if (const auto *M = dyn_cast<WasmObjectFile>(&O))
41     return M->getSymbolSectionId(Sym);
42   return cast<COFFObjectFile>(O).getSymbolSectionID(Sym);
43 }
44 
45 std::vector<std::pair<SymbolRef, uint64_t>>
46 llvm::object::computeSymbolSizes(const ObjectFile &O) {
47   std::vector<std::pair<SymbolRef, uint64_t>> Ret;
48 
49   if (const auto *E = dyn_cast<ELFObjectFileBase>(&O)) {
50     auto Syms = E->symbols();
51     if (Syms.begin() == Syms.end())
52       Syms = E->getDynamicSymbolIterators();
53     for (ELFSymbolRef Sym : Syms)
54       Ret.push_back({Sym, Sym.getSize()});
55     return Ret;
56   }
57 
58   // Collect sorted symbol addresses. Include dummy addresses for the end
59   // of each section.
60   std::vector<SymEntry> Addresses;
61   unsigned SymNum = 0;
62   for (symbol_iterator I = O.symbol_begin(), E = O.symbol_end(); I != E; ++I) {
63     SymbolRef Sym = *I;
64     uint64_t Value = Sym.getValue();
65     Addresses.push_back({I, Value, SymNum, getSymbolSectionID(O, Sym)});
66     ++SymNum;
67   }
68   for (SectionRef Sec : O.sections()) {
69     uint64_t Address = Sec.getAddress();
70     uint64_t Size = Sec.getSize();
71     Addresses.push_back(
72         {O.symbol_end(), Address + Size, 0, getSectionID(O, Sec)});
73   }
74 
75   if (Addresses.empty())
76     return Ret;
77 
78   array_pod_sort(Addresses.begin(), Addresses.end(), compareAddress);
79 
80   // Compute the size as the gap to the next symbol
81   for (unsigned I = 0, N = Addresses.size() - 1; I < N; ++I) {
82     auto &P = Addresses[I];
83     if (P.I == O.symbol_end())
84       continue;
85 
86     // If multiple symbol have the same address, give both the same size.
87     unsigned NextI = I + 1;
88     while (NextI < N && Addresses[NextI].Address == P.Address)
89       ++NextI;
90 
91     uint64_t Size = Addresses[NextI].Address - P.Address;
92     P.Address = Size;
93   }
94 
95   // Assign the sorted symbols in the original order.
96   Ret.resize(SymNum);
97   for (SymEntry &P : Addresses) {
98     if (P.I == O.symbol_end())
99       continue;
100     Ret[P.Number] = {*P.I, P.Address};
101   }
102   return Ret;
103 }
104