MinGW.cpp revision 360784 
1//===- MinGW.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 "MinGW.h"
10#include "SymbolTable.h"
11#include "lld/Common/ErrorHandler.h"
12#include "llvm/Object/COFF.h"
13#include "llvm/Support/Path.h"
14#include "llvm/Support/raw_ostream.h"
15
16using namespace llvm;
17using namespace llvm::COFF;
18
19namespace lld {
20namespace coff {
21
22AutoExporter::AutoExporter() {
23  excludeLibs = {
24      "libgcc",
25      "libgcc_s",
26      "libstdc++",
27      "libmingw32",
28      "libmingwex",
29      "libg2c",
30      "libsupc++",
31      "libobjc",
32      "libgcj",
33      "libclang_rt.builtins",
34      "libclang_rt.builtins-aarch64",
35      "libclang_rt.builtins-arm",
36      "libclang_rt.builtins-i386",
37      "libclang_rt.builtins-x86_64",
38      "libc++",
39      "libc++abi",
40      "libunwind",
41      "libmsvcrt",
42      "libucrtbase",
43  };
44
45  excludeObjects = {
46      "crt0.o",    "crt1.o",  "crt1u.o", "crt2.o",  "crt2u.o",    "dllcrt1.o",
47      "dllcrt2.o", "gcrt0.o", "gcrt1.o", "gcrt2.o", "crtbegin.o", "crtend.o",
48  };
49
50  excludeSymbolPrefixes = {
51      // Import symbols
52      "__imp_",
53      "__IMPORT_DESCRIPTOR_",
54      // Extra import symbols from GNU import libraries
55      "__nm_",
56      // C++ symbols
57      "__rtti_",
58      "__builtin_",
59      // Artificial symbols such as .refptr
60      ".",
61  };
62
63  excludeSymbolSuffixes = {
64      "_iname",
65      "_NULL_THUNK_DATA",
66  };
67
68  if (config->machine == I386) {
69    excludeSymbols = {
70        "__NULL_IMPORT_DESCRIPTOR",
71        "__pei386_runtime_relocator",
72        "_do_pseudo_reloc",
73        "_impure_ptr",
74        "__impure_ptr",
75        "__fmode",
76        "_environ",
77        "___dso_handle",
78        // These are the MinGW names that differ from the standard
79        // ones (lacking an extra underscore).
80        "_DllMain@12",
81        "_DllEntryPoint@12",
82        "_DllMainCRTStartup@12",
83    };
84    excludeSymbolPrefixes.insert("__head_");
85  } else {
86    excludeSymbols = {
87        "__NULL_IMPORT_DESCRIPTOR",
88        "_pei386_runtime_relocator",
89        "do_pseudo_reloc",
90        "impure_ptr",
91        "_impure_ptr",
92        "_fmode",
93        "environ",
94        "__dso_handle",
95        // These are the MinGW names that differ from the standard
96        // ones (lacking an extra underscore).
97        "DllMain",
98        "DllEntryPoint",
99        "DllMainCRTStartup",
100    };
101    excludeSymbolPrefixes.insert("_head_");
102  }
103}
104
105void AutoExporter::addWholeArchive(StringRef path) {
106  StringRef libName = sys::path::filename(path);
107  // Drop the file extension, to match the processing below.
108  libName = libName.substr(0, libName.rfind('.'));
109  excludeLibs.erase(libName);
110}
111
112bool AutoExporter::shouldExport(Defined *sym) const {
113  if (!sym || !sym->isLive() || !sym->getChunk())
114    return false;
115
116  // Only allow the symbol kinds that make sense to export; in particular,
117  // disallow import symbols.
118  if (!isa<DefinedRegular>(sym) && !isa<DefinedCommon>(sym))
119    return false;
120  if (excludeSymbols.count(sym->getName()))
121    return false;
122
123  for (StringRef prefix : excludeSymbolPrefixes.keys())
124    if (sym->getName().startswith(prefix))
125      return false;
126  for (StringRef suffix : excludeSymbolSuffixes.keys())
127    if (sym->getName().endswith(suffix))
128      return false;
129
130  // If a corresponding __imp_ symbol exists and is defined, don't export it.
131  if (symtab->find(("__imp_" + sym->getName()).str()))
132    return false;
133
134  // Check that file is non-null before dereferencing it, symbols not
135  // originating in regular object files probably shouldn't be exported.
136  if (!sym->getFile())
137    return false;
138
139  StringRef libName = sys::path::filename(sym->getFile()->parentName);
140
141  // Drop the file extension.
142  libName = libName.substr(0, libName.rfind('.'));
143  if (!libName.empty())
144    return !excludeLibs.count(libName);
145
146  StringRef fileName = sys::path::filename(sym->getFile()->getName());
147  return !excludeObjects.count(fileName);
148}
149
150void writeDefFile(StringRef name) {
151  std::error_code ec;
152  raw_fd_ostream os(name, ec, sys::fs::OF_None);
153  if (ec)
154    fatal("cannot open " + name + ": " + ec.message());
155
156  os << "EXPORTS\n";
157  for (Export &e : config->exports) {
158    os << "    " << e.exportName << " "
159       << "@" << e.ordinal;
160    if (auto *def = dyn_cast_or_null<Defined>(e.sym)) {
161      if (def && def->getChunk() &&
162          !(def->getChunk()->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE))
163        os << " DATA";
164    }
165    os << "\n";
166  }
167}
168
169} // namespace coff
170} // namespace lld
171