lld/MachO/MapFile.cpp

   1 //===- MapFile.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 // This file implements the -map option, which maps address ranges to their
  10 // respective contents, plus the input file these contents were originally from.
  11 // The contents (typically symbols) are listed in address order. Dead-stripped
  12 // contents are included as well.
  13 //
  14 // # Path: test
  15 // # Arch: x86_84
  16 // # Object files:
  17 // [  0] linker synthesized
  18 // [  1] a.o
  19 // # Sections:
  20 // # Address    Size       Segment  Section
  21 // 0x1000005C0  0x0000004C __TEXT   __text
  22 // # Symbols:
  23 // # Address    Size       File  Name
  24 // 0x1000005C0  0x00000001 [  1] _main
  25 // # Dead Stripped Symbols:
  26 // #            Size       File  Name
  27 // <<dead>>     0x00000001 [  1] _foo
  28 //
  29 //===----------------------------------------------------------------------===//
  30
  31 #include "MapFile.h"
  32 #include "ConcatOutputSection.h"
  33 #include "Config.h"
  34 #include "InputFiles.h"
  35 #include "InputSection.h"
  36 #include "OutputSegment.h"
  37 #include "Symbols.h"
  38 #include "SyntheticSections.h"
  39 #include "Target.h"
  40 #include "lld/Common/ErrorHandler.h"
  41 #include "llvm/ADT/DenseMap.h"
  42 #include "llvm/Support/Parallel.h"
  43 #include "llvm/Support/TimeProfiler.h"
  44
  45 using namespace llvm;
  46 using namespace llvm::sys;
  47 using namespace lld;
  48 using namespace lld::macho;
  49
  50 struct CStringInfo {
  51   uint32_t fileIndex;
  52   StringRef str;
  53 };
  54
  55 struct MapInfo {
  56   SmallVector<InputFile *> files;
  57   SmallVector<Defined *> deadSymbols;
  58   DenseMap<const OutputSection *,
  59            SmallVector<std::pair<uint64_t /*addr*/, CStringInfo>>>
  60       liveCStringsForSection;
  61   SmallVector<CStringInfo> deadCStrings;
  62 };
  63
  64 static MapInfo gatherMapInfo() {
  65   MapInfo info;
  66   for (InputFile *file : inputFiles) {
  67     bool isReferencedFile = false;
  68
  69     if (isa<ObjFile>(file) || isa<BitcodeFile>(file)) {
  70       uint32_t fileIndex = info.files.size() + 1;
  71
  72       // Gather the dead symbols. We don't have to bother with the live ones
  73       // because we will pick them up as we iterate over the OutputSections
  74       // later.
  75       for (Symbol *sym : file->symbols) {
  76         if (auto *d = dyn_cast_or_null<Defined>(sym))
  77           // Only emit the prevailing definition of a symbol. Also, don't emit
  78           // the symbol if it is part of a cstring section (we use the literal
  79           // value instead, similar to ld64)
  80           if (d->isec && d->getFile() == file &&
  81               !isa<CStringInputSection>(d->isec)) {
  82             isReferencedFile = true;
  83             if (!d->isLive())
  84               info.deadSymbols.push_back(d);
  85           }
  86       }
  87
  88       // Gather all the cstrings (both live and dead). A CString(Output)Section
  89       // doesn't provide us a way of figuring out which InputSections its
  90       // cstring contents came from, so we need to build up that mapping here.
  91       for (const Section *sec : file->sections) {
  92         for (const Subsection &subsec : sec->subsections) {
  93           if (auto isec = dyn_cast<CStringInputSection>(subsec.isec)) {
  94             auto &liveCStrings = info.liveCStringsForSection[isec->parent];
  95             for (const auto &[i, piece] : llvm::enumerate(isec->pieces)) {
  96               if (piece.live)
  97                 liveCStrings.push_back({isec->parent->addr + piece.outSecOff,
  98                                         {fileIndex, isec->getStringRef(i)}});
  99               else
 100                 info.deadCStrings.push_back({fileIndex, isec->getStringRef(i)});
 101               isReferencedFile = true;
 102             }
 103           } else {
 104             break;
 105           }
 106         }
 107       }
 108     } else if (const auto *dylibFile = dyn_cast<DylibFile>(file)) {
 109       isReferencedFile = dylibFile->isReferenced();
 110     }
 111
 112     if (isReferencedFile)
 113       info.files.push_back(file);
 114   }
 115
 116   // cstrings are not stored in sorted order in their OutputSections, so we sort
 117   // them here.
 118   for (auto &liveCStrings : info.liveCStringsForSection)
 119     parallelSort(liveCStrings.second, [](const auto &p1, const auto &p2) {
 120       return p1.first < p2.first;
 121     });
 122   return info;
 123 }
 124
 125 // We use this instead of `toString(const InputFile *)` as we don't want to
 126 // include the dylib install name in our output.
 127 static void printFileName(raw_fd_ostream &os, const InputFile *f) {
 128   if (f->archiveName.empty())
 129     os << f->getName();
 130   else
 131     os << f->archiveName << "(" << path::filename(f->getName()) + ")";
 132 }
 133
 134 // For printing the contents of the __stubs and __la_symbol_ptr sections.
 135 static void printStubsEntries(
 136     raw_fd_ostream &os,
 137     const DenseMap<lld::macho::InputFile *, uint32_t> &readerToFileOrdinal,
 138     const OutputSection *osec, size_t entrySize) {
 139   for (const Symbol *sym : in.stubs->getEntries())
 140     os << format("0x%08llX\t0x%08zX\t[%3u] %s\n",
 141                  osec->addr + sym->stubsIndex * entrySize, entrySize,
 142                  readerToFileOrdinal.lookup(sym->getFile()),
 143                  sym->getName().str().data());
 144 }
 145
 146 static void printNonLazyPointerSection(raw_fd_ostream &os,
 147                                        NonLazyPointerSectionBase *osec) {
 148   // ld64 considers stubs to belong to particular files, but considers GOT
 149   // entries to be linker-synthesized. Not sure why they made that decision, but
 150   // I think we can follow suit unless there's demand for better symbol-to-file
 151   // associations.
 152   for (const Symbol *sym : osec->getEntries())
 153     os << format("0x%08llX\t0x%08zX\t[  0] non-lazy-pointer-to-local: %s\n",
 154                  osec->addr + sym->gotIndex * target->wordSize,
 155                  target->wordSize, sym->getName().str().data());
 156 }
 157
 158 void macho::writeMapFile() {
 159   if (config->mapFile.empty())
 160     return;
 161
 162   TimeTraceScope timeScope("Write map file");
 163
 164   // Open a map file for writing.
 165   std::error_code ec;
 166   raw_fd_ostream os(config->mapFile, ec, sys::fs::OF_None);
 167   if (ec) {
 168     error("cannot open " + config->mapFile + ": " + ec.message());
 169     return;
 170   }
 171
 172   os << format("# Path: %s\n", config->outputFile.str().c_str());
 173   os << format("# Arch: %s\n",
 174                getArchitectureName(config->arch()).str().c_str());
 175
 176   MapInfo info = gatherMapInfo();
 177
 178   os << "# Object files:\n";
 179   os << format("[%3u] %s\n", 0, (const char *)"linker synthesized");
 180   uint32_t fileIndex = 1;
 181   DenseMap<lld::macho::InputFile *, uint32_t> readerToFileOrdinal;
 182   for (InputFile *file : info.files) {
 183     os << format("[%3u] ", fileIndex);
 184     printFileName(os, file);
 185     os << "\n";
 186     readerToFileOrdinal[file] = fileIndex++;
 187   }
 188
 189   os << "# Sections:\n";
 190   os << "# Address\tSize    \tSegment\tSection\n";
 191   for (OutputSegment *seg : outputSegments)
 192     for (OutputSection *osec : seg->getSections()) {
 193       if (osec->isHidden())
 194         continue;
 195
 196       os << format("0x%08llX\t0x%08llX\t%s\t%s\n", osec->addr, osec->getSize(),
 197                    seg->name.str().c_str(), osec->name.str().c_str());
 198     }
 199
 200   os << "# Symbols:\n";
 201   os << "# Address\tSize    \tFile  Name\n";
 202   for (const OutputSegment *seg : outputSegments) {
 203     for (const OutputSection *osec : seg->getSections()) {
 204       if (auto *concatOsec = dyn_cast<ConcatOutputSection>(osec)) {
 205         for (const InputSection *isec : concatOsec->inputs) {
 206           for (Defined *sym : isec->symbols)
 207             if (!(isPrivateLabel(sym->getName()) && sym->size == 0))
 208               os << format("0x%08llX\t0x%08llX\t[%3u] %s\n", sym->getVA(),
 209                            sym->size, readerToFileOrdinal[sym->getFile()],
 210                            sym->getName().str().data());
 211         }
 212       } else if (osec == in.cStringSection || osec == in.objcMethnameSection) {
 213         const auto &liveCStrings = info.liveCStringsForSection.lookup(osec);
 214         uint64_t lastAddr = 0; // strings will never start at address 0, so this
 215                                // is a sentinel value
 216         for (const auto &[addr, info] : liveCStrings) {
 217           uint64_t size = 0;
 218           if (addr != lastAddr)
 219             size = info.str.size() + 1; // include null terminator
 220           lastAddr = addr;
 221           os << format("0x%08llX\t0x%08llX\t[%3u] literal string: ", addr, size,
 222                        info.fileIndex);
 223           os.write_escaped(info.str) << "\n";
 224         }
 225       } else if (osec == (void *)in.unwindInfo) {
 226         os << format("0x%08llX\t0x%08llX\t[  0] compact unwind info\n",
 227                      osec->addr, osec->getSize());
 228       } else if (osec == in.stubs) {
 229         printStubsEntries(os, readerToFileOrdinal, osec, target->stubSize);
 230       } else if (osec == in.lazyPointers) {
 231         printStubsEntries(os, readerToFileOrdinal, osec, target->wordSize);
 232       } else if (osec == in.stubHelper) {
 233         // yes, ld64 calls it "helper helper"...
 234         os << format("0x%08llX\t0x%08llX\t[  0] helper helper\n", osec->addr,
 235                      osec->getSize());
 236       } else if (osec == in.got) {
 237         printNonLazyPointerSection(os, in.got);
 238       } else if (osec == in.tlvPointers) {
 239         printNonLazyPointerSection(os, in.tlvPointers);
 240       }
 241       // TODO print other synthetic sections
 242     }
 243   }
 244
 245   if (config->deadStrip) {
 246     os << "# Dead Stripped Symbols:\n";
 247     os << "#        \tSize    \tFile  Name\n";
 248     for (Defined *sym : info.deadSymbols) {
 249       assert(!sym->isLive());
 250       os << format("<<dead>>\t0x%08llX\t[%3u] %s\n", sym->size,
 251                    readerToFileOrdinal[sym->getFile()],
 252                    sym->getName().str().data());
 253     }
 254     for (CStringInfo &cstrInfo : info.deadCStrings) {
 255       os << format("<<dead>>\t0x%08zX\t[%3u] literal string: ",
 256                    cstrInfo.str.size() + 1, cstrInfo.fileIndex);
 257       os.write_escaped(cstrInfo.str) << "\n";
 258     }
 259   }
 260 }