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).
compareAddress(const SymEntry * A,const SymEntry * B)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
getSectionID(const ObjectFile & O,SectionRef Sec)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
getSymbolSectionID(const ObjectFile & O,SymbolRef Sym)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>>
computeSymbolSizes(const ObjectFile & O)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 if (const auto *E = dyn_cast<XCOFFObjectFile>(&O)) {
63 for (XCOFFSymbolRef Sym : E->symbols())
64 Ret.push_back({Sym, Sym.getSize()});
65 return Ret;
66 }
67
68 // Collect sorted symbol addresses. Include dummy addresses for the end
69 // of each section.
70 std::vector<SymEntry> Addresses;
71 unsigned SymNum = 0;
72 for (symbol_iterator I = O.symbol_begin(), E = O.symbol_end(); I != E; ++I) {
73 SymbolRef Sym = *I;
74 Expected<uint64_t> ValueOrErr = Sym.getValue();
75 if (!ValueOrErr)
76 // TODO: Actually report errors helpfully.
77 report_fatal_error(ValueOrErr.takeError());
78 Addresses.push_back({I, *ValueOrErr, SymNum, getSymbolSectionID(O, Sym)});
79 ++SymNum;
80 }
81 for (SectionRef Sec : O.sections()) {
82 uint64_t Address = Sec.getAddress();
83 uint64_t Size = Sec.getSize();
84 Addresses.push_back(
85 {O.symbol_end(), Address + Size, 0, getSectionID(O, Sec)});
86 }
87
88 if (Addresses.empty())
89 return Ret;
90
91 array_pod_sort(Addresses.begin(), Addresses.end(), compareAddress);
92
93 // Compute the size as the gap to the next symbol. If multiple symbols have
94 // the same address, give both the same size. Because Addresses is sorted,
95 // use two pointers to keep track of the current symbol vs. the next symbol
96 // that doesn't have the same address for size computation.
97 for (unsigned I = 0, NextI = 0, N = Addresses.size() - 1; I < N; ++I) {
98 auto &P = Addresses[I];
99 if (P.I == O.symbol_end())
100 continue;
101
102 // If the next pointer is behind, update it to the next symbol.
103 if (NextI <= I) {
104 NextI = I + 1;
105 while (NextI < N && Addresses[NextI].Address == P.Address)
106 ++NextI;
107 }
108
109 uint64_t Size = Addresses[NextI].Address - P.Address;
110 P.Address = Size;
111 }
112
113 // Assign the sorted symbols in the original order.
114 Ret.resize(SymNum);
115 for (SymEntry &P : Addresses) {
116 if (P.I == O.symbol_end())
117 continue;
118 Ret[P.Number] = {*P.I, P.Address};
119 }
120 return Ret;
121 }
122