lld/COFF/MinGW.cpp

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