contrib/llvm-project/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       "libclang_rt.profile",
  38       "libclang_rt.profile-aarch64",
  39       "libclang_rt.profile-arm",
  40       "libclang_rt.profile-i386",
  41       "libclang_rt.profile-x86_64",
  42       "libc++",
  43       "libc++abi",
  44       "libunwind",
  45       "libmsvcrt",
  46       "libucrtbase",
  47   };
  48
  49   excludeObjects = {
  50       "crt0.o",    "crt1.o",  "crt1u.o", "crt2.o",  "crt2u.o",    "dllcrt1.o",
  51       "dllcrt2.o", "gcrt0.o", "gcrt1.o", "gcrt2.o", "crtbegin.o", "crtend.o",
  52   };
  53
  54   excludeSymbolPrefixes = {
  55       // Import symbols
  56       "__imp_",
  57       "__IMPORT_DESCRIPTOR_",
  58       // Extra import symbols from GNU import libraries
  59       "__nm_",
  60       // C++ symbols
  61       "__rtti_",
  62       "__builtin_",
  63       // Artificial symbols such as .refptr
  64       ".",
  65       // profile generate symbols
  66       "__profc_",
  67       "__profd_",
  68       "__profvp_",
  69   };
  70
  71   excludeSymbolSuffixes = {
  72       "_iname",
  73       "_NULL_THUNK_DATA",
  74   };
  75
  76   if (config->machine == I386) {
  77     excludeSymbols = {
  78         "__NULL_IMPORT_DESCRIPTOR",
  79         "__pei386_runtime_relocator",
  80         "_do_pseudo_reloc",
  81         "_impure_ptr",
  82         "__impure_ptr",
  83         "__fmode",
  84         "_environ",
  85         "___dso_handle",
  86         // These are the MinGW names that differ from the standard
  87         // ones (lacking an extra underscore).
  88         "_DllMain@12",
  89         "_DllEntryPoint@12",
  90         "_DllMainCRTStartup@12",
  91     };
  92     excludeSymbolPrefixes.insert("__head_");
  93   } else {
  94     excludeSymbols = {
  95         "__NULL_IMPORT_DESCRIPTOR",
  96         "_pei386_runtime_relocator",
  97         "do_pseudo_reloc",
  98         "impure_ptr",
  99         "_impure_ptr",
 100         "_fmode",
 101         "environ",
 102         "__dso_handle",
 103         // These are the MinGW names that differ from the standard
 104         // ones (lacking an extra underscore).
 105         "DllMain",
 106         "DllEntryPoint",
 107         "DllMainCRTStartup",
 108     };
 109     excludeSymbolPrefixes.insert("_head_");
 110   }
 111 }
 112
 113 void AutoExporter::addWholeArchive(StringRef path) {
 114   StringRef libName = sys::path::filename(path);
 115   // Drop the file extension, to match the processing below.
 116   libName = libName.substr(0, libName.rfind('.'));
 117   excludeLibs.erase(libName);
 118 }
 119
 120 bool AutoExporter::shouldExport(Defined *sym) const {
 121   if (!sym || !sym->isLive() || !sym->getChunk())
 122     return false;
 123
 124   // Only allow the symbol kinds that make sense to export; in particular,
 125   // disallow import symbols.
 126   if (!isa<DefinedRegular>(sym) && !isa<DefinedCommon>(sym))
 127     return false;
 128   if (excludeSymbols.count(sym->getName()))
 129     return false;
 130
 131   for (StringRef prefix : excludeSymbolPrefixes.keys())
 132     if (sym->getName().startswith(prefix))
 133       return false;
 134   for (StringRef suffix : excludeSymbolSuffixes.keys())
 135     if (sym->getName().endswith(suffix))
 136       return false;
 137
 138   // If a corresponding __imp_ symbol exists and is defined, don't export it.
 139   if (symtab->find(("__imp_" + sym->getName()).str()))
 140     return false;
 141
 142   // Check that file is non-null before dereferencing it, symbols not
 143   // originating in regular object files probably shouldn't be exported.
 144   if (!sym->getFile())
 145     return false;
 146
 147   StringRef libName = sys::path::filename(sym->getFile()->parentName);
 148
 149   // Drop the file extension.
 150   libName = libName.substr(0, libName.rfind('.'));
 151   if (!libName.empty())
 152     return !excludeLibs.count(libName);
 153
 154   StringRef fileName = sys::path::filename(sym->getFile()->getName());
 155   return !excludeObjects.count(fileName);
 156 }
 157
 158 void lld::coff::writeDefFile(StringRef name) {
 159   std::error_code ec;
 160   raw_fd_ostream os(name, ec, sys::fs::OF_None);
 161   if (ec)
 162     fatal("cannot open " + name + ": " + ec.message());
 163
 164   os << "EXPORTS\n";
 165   for (Export &e : config->exports) {
 166     os << "    " << e.exportName << " "
 167        << "@" << e.ordinal;
 168     if (auto *def = dyn_cast_or_null<Defined>(e.sym)) {
 169       if (def && def->getChunk() &&
 170           !(def->getChunk()->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE))
 171         os << " DATA";
 172     }
 173     os << "\n";
 174   }
 175 }