contrib/llvm/tools/lld/COFF/MinGW.cpp

   1 //===- MinGW.cpp ----------------------------------------------------------===//
   2 //
   3 //                             The LLVM Linker
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "MinGW.h"
  11 #include "SymbolTable.h"
  12 #include "lld/Common/ErrorHandler.h"
  13 #include "llvm/Object/COFF.h"
  14 #include "llvm/Support/Path.h"
  15 #include "llvm/Support/raw_ostream.h"
  16
  17 using namespace lld;
  18 using namespace lld::coff;
  19 using namespace llvm;
  20 using namespace llvm::COFF;
  21
  22 void AutoExporter::initSymbolExcludes() {
  23   ExcludeSymbolPrefixes = {
  24       // Import symbols
  25       "__imp_",
  26       "__IMPORT_DESCRIPTOR_",
  27       // Extra import symbols from GNU import libraries
  28       "__nm_",
  29       // C++ symbols
  30       "__rtti_",
  31       "__builtin_",
  32       // Artifical symbols such as .refptr
  33       ".",
  34   };
  35   ExcludeSymbolSuffixes = {
  36       "_iname",
  37       "_NULL_THUNK_DATA",
  38   };
  39   if (Config->Machine == I386) {
  40     ExcludeSymbols = {
  41         "__NULL_IMPORT_DESCRIPTOR",
  42         "__pei386_runtime_relocator",
  43         "_do_pseudo_reloc",
  44         "_impure_ptr",
  45         "__impure_ptr",
  46         "__fmode",
  47         "_environ",
  48         "___dso_handle",
  49         // These are the MinGW names that differ from the standard
  50         // ones (lacking an extra underscore).
  51         "_DllMain@12",
  52         "_DllEntryPoint@12",
  53         "_DllMainCRTStartup@12",
  54     };
  55     ExcludeSymbolPrefixes.insert("__head_");
  56   } else {
  57     ExcludeSymbols = {
  58         "__NULL_IMPORT_DESCRIPTOR",
  59         "_pei386_runtime_relocator",
  60         "do_pseudo_reloc",
  61         "impure_ptr",
  62         "_impure_ptr",
  63         "_fmode",
  64         "environ",
  65         "__dso_handle",
  66         // These are the MinGW names that differ from the standard
  67         // ones (lacking an extra underscore).
  68         "DllMain",
  69         "DllEntryPoint",
  70         "DllMainCRTStartup",
  71     };
  72     ExcludeSymbolPrefixes.insert("_head_");
  73   }
  74 }
  75
  76 AutoExporter::AutoExporter() {
  77   ExcludeLibs = {
  78       "libgcc",
  79       "libgcc_s",
  80       "libstdc++",
  81       "libmingw32",
  82       "libmingwex",
  83       "libg2c",
  84       "libsupc++",
  85       "libobjc",
  86       "libgcj",
  87       "libclang_rt.builtins",
  88       "libclang_rt.builtins-aarch64",
  89       "libclang_rt.builtins-arm",
  90       "libclang_rt.builtins-i386",
  91       "libclang_rt.builtins-x86_64",
  92       "libc++",
  93       "libc++abi",
  94       "libunwind",
  95       "libmsvcrt",
  96       "libucrtbase",
  97   };
  98   ExcludeObjects = {
  99       "crt0.o",
 100       "crt1.o",
 101       "crt1u.o",
 102       "crt2.o",
 103       "crt2u.o",
 104       "dllcrt1.o",
 105       "dllcrt2.o",
 106       "gcrt0.o",
 107       "gcrt1.o",
 108       "gcrt2.o",
 109       "crtbegin.o",
 110       "crtend.o",
 111   };
 112 }
 113
 114 void AutoExporter::addWholeArchive(StringRef Path) {
 115   StringRef LibName = sys::path::filename(Path);
 116   // Drop the file extension, to match the processing below.
 117   LibName = LibName.substr(0, LibName.rfind('.'));
 118   ExcludeLibs.erase(LibName);
 119 }
 120
 121 bool AutoExporter::shouldExport(Defined *Sym) const {
 122   if (!Sym || !Sym->isLive() || !Sym->getChunk())
 123     return false;
 124
 125   // Only allow the symbol kinds that make sense to export; in particular,
 126   // disallow import symbols.
 127   if (!isa<DefinedRegular>(Sym) && !isa<DefinedCommon>(Sym))
 128     return false;
 129   if (ExcludeSymbols.count(Sym->getName()))
 130     return false;
 131
 132   for (StringRef Prefix : ExcludeSymbolPrefixes.keys())
 133     if (Sym->getName().startswith(Prefix))
 134       return false;
 135   for (StringRef Suffix : ExcludeSymbolSuffixes.keys())
 136     if (Sym->getName().endswith(Suffix))
 137       return false;
 138
 139   // If a corresponding __imp_ symbol exists and is defined, don't export it.
 140   if (Symtab->find(("__imp_" + Sym->getName()).str()))
 141     return false;
 142
 143   // Check that file is non-null before dereferencing it, symbols not
 144   // originating in regular object files probably shouldn't be exported.
 145   if (!Sym->getFile())
 146     return false;
 147
 148   StringRef LibName = sys::path::filename(Sym->getFile()->ParentName);
 149
 150   // Drop the file extension.
 151   LibName = LibName.substr(0, LibName.rfind('.'));
 152   if (!LibName.empty())
 153     return !ExcludeLibs.count(LibName);
 154
 155   StringRef FileName = sys::path::filename(Sym->getFile()->getName());
 156   return !ExcludeObjects.count(FileName);
 157 }
 158
 159 void coff::writeDefFile(StringRef Name) {
 160   std::error_code EC;
 161   raw_fd_ostream OS(Name, EC, sys::fs::F_None);
 162   if (EC)
 163     fatal("cannot open " + Name + ": " + EC.message());
 164
 165   OS << "EXPORTS\n";
 166   for (Export &E : Config->Exports) {
 167     OS << "    " << E.ExportName << " "
 168        << "@" << E.Ordinal;
 169     if (auto *Def = dyn_cast_or_null<Defined>(E.Sym)) {
 170       if (Def && Def->getChunk() &&
 171           !(Def->getChunk()->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE))
 172         OS << " DATA";
 173     }
 174     OS << "\n";
 175   }
 176 }