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
88   for (unsigned I = 0, N = Addresses.size() - 1; I < N; ++I) {
89     auto &P = Addresses[I];
90     if (P.I == O.symbol_end())
91       continue;
92 
93     // If multiple symbol have the same address, give both the same size.
94     unsigned NextI = I + 1;
95     while (NextI < N && Addresses[NextI].Address == P.Address)
96       ++NextI;
97 
98     uint64_t Size = Addresses[NextI].Address - P.Address;
99     P.Address = Size;
100   }
101 
102   // Assign the sorted symbols in the original order.
103   Ret.resize(SymNum);
104   for (SymEntry &P : Addresses) {
105     if (P.I == O.symbol_end())
106       continue;
107     Ret[P.Number] = {*P.I, P.Address};
108   }
109   return Ret;
110 }
111