Add an -object-path-prefix option to dsymutil

[aprantl]

Summary

to remap object file paths (but no source paths) before
processing. This is meant to be used for Clang objects where the
module cache location was remapped using `-fdebug-prefix-map`; to
help dsymutil find the Clang module cache.

rdar://problem/55685132

[JDevlieghere]

LGTM

llvm/docs/CommandGuide/dsymutil.rst

 
  Specifies an alternate ``path`` to place the dSYM bundle. The default dSYM
  bundle path is created by appending ``.dSYM`` to the executable name.
 
 .. option:: --oso-prepend-path=<path>
 
  Specifies a ``path`` to prepend to all debug symbol object file paths.
 
+.. option:: --object-prefix-map=<prefix=remapped>
+
+ Remap object file paths (but no source paths) before processing.  Use
+ this for Clang objects where the module cache location was remapped using
+ ``-fdebug-prefix-map``; to help dsymutil find the Clang module cache.
+ 
 .. option:: --papertrail
 
  When running dsymutil as part of your build system, it can be desirable for
  warnings to be part of the end product, rather than just being emitted to the
  output stream. When enabled warnings are embedded in the linked DWARF debug
  information.
 
 .. option:: -s, --symtab

llvm/include/llvm/DWARFLinker/DWARFLinker.h

 
 typedef std::function<void(const Twine &Warning, StringRef Context,
                            const DWARFDie *DIE)>
     messageHandler;
 typedef std::function<ErrorOr<DwarfFile &>(StringRef ContainerName,
                                            StringRef Path)>
     objFileLoader;
 typedef std::map<std::string, std::string> swiftInterfacesMap;
+typedef std::map<std::string, std::string> objectPrefixMap;
 
 /// The core of the Dwarf linking logic.
 ///
 /// The generation of the dwarf information from the object files will be
 /// driven by the selection of 'root DIEs', which are DIEs that
 /// describe variables or functions that resolves to the corresponding
 /// code section(and thus have entries in the Addresses map). All the debug
 /// information that will be generated(the DIEs, but also the line
void setObjFileLoader(objFileLoader Loader) {
     Options.ObjFileLoader = Loader;
   }
 
   /// Set map for Swift interfaces.
   void setSwiftInterfacesMap(swiftInterfacesMap *Map) {
     Options.ParseableSwiftInterfaces = Map;
   }
 
+  /// Set prefix map for objects.
+  void setObjectPrefixMap(objectPrefixMap *Map) {
+    Options.ObjectPrefixMap = Map;
+  }
+
 private:
   /// Flags passed to DwarfLinker::lookForDIEsToKeep
   enum TraversalFlags {
     TF_Keep = 1 << 0,            ///< Mark the traversed DIEs as kept.
     TF_InFunctionScope = 1 << 1, ///< Current scope is a function scope.
     TF_DependencyWalk = 1 << 2,  ///< Walking the dependencies of a kept DIE.
     TF_ParentWalk = 1 << 3,      ///< Walking up the parents of a kept DIE.
     TF_ODR = 1 << 4,             ///< Use the ODR while keeping dependents.
struct DWARFLinkerOptions {
     objFileLoader ObjFileLoader = nullptr;
 
     /// A list of all .swiftinterface files referenced by the debug
     /// info, mapping Module name to path on disk. The entries need to
     /// be uniqued and sorted and there are only few entries expected
     /// per compile unit, which is why this is a std::map.
     /// this is dsymutil specific fag.
     swiftInterfacesMap *ParseableSwiftInterfaces = nullptr;
+
+    /// A list of remappings to apply to file paths.
+    objectPrefixMap *ObjectPrefixMap = nullptr;
   } Options;
 };
 
 } // end namespace llvm
 
 #endif // LLVM_DWARFLINKER_DWARFLINKER_H

llvm/lib/DWARFLinker/DWARFLinker.cpp

 static uint64_t getDwoId(const DWARFDie &CUDie, const DWARFUnit &Unit) {
   auto DwoId = dwarf::toUnsigned(
       CUDie.find({dwarf::DW_AT_dwo_id, dwarf::DW_AT_GNU_dwo_id}));
   if (DwoId)
     return *DwoId;
   return 0;
 }
 
+static std::string remapPath(StringRef Path,
+                             const objectPrefixMap &ObjectPrefixMap) {
+  for (const auto &Entry : ObjectPrefixMap)
+    if (Path.startswith(Entry.first))
+      return (Twine(Entry.second) + Path.substr(Entry.first.size())).str();
+  return Path.str();
+}
+
 bool DWARFLinker::registerModuleReference(
     DWARFDie CUDie, const DWARFUnit &Unit, const DwarfFile &File,
     OffsetsStringPool &StringPool, UniquingStringPool &UniquingStringPool,
     DeclContextTree &ODRContexts, uint64_t ModulesEndOffset, unsigned &UnitID,
     bool IsLittleEndian, unsigned Indent, bool Quiet) {
   std::string PCMfile = dwarf::toString(
       CUDie.find({dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}), "");
   if (PCMfile.empty())
     return false;
+  if (Options.ObjectPrefixMap)
+    PCMfile = remapPath(PCMfile, *Options.ObjectPrefixMap);
 
   // Clang module DWARF skeleton CUs abuse this for the path to the module.
   uint64_t DwoId = getDwoId(CUDie, Unit);
 
   std::string Name = dwarf::toString(CUDie.find(dwarf::DW_AT_name), "");
   if (Name.empty()) {
     if (!Quiet)
       reportWarning("Anonymous module skeleton CU for " + PCMfile, File);

llvm/test/tools/dsymutil/X86/object-prefix-path.test

+RUN: rm -rf %t.dir && mkdir %t.dir && mkdir %t.dir/ModuleCacheRenamed
+RUN: cp %p/../Inputs/module-warnings/1.o %t.dir
+RUN: cp %p/../Inputs/module-warnings/Foo.pcm %t.dir/ModuleCacheRenamed
+
+RUN: dsymutil -verify -f -oso-prepend-path=%t.dir -y \
+RUN:   %p/dummy-debug-map.map -o %t \
+RUN:   -object-prefix-map=/ModuleCache=/ModuleCacheRenamed \
+RUN:   2>&1 | FileCheck %s
+
+CHECK:     warning: {{.*}}Bar.pcm:
+CHECK-NOT: warning: {{.*}}Foo.pcm:

llvm/test/tools/dsymutil/cmdline.test

 RUN: dsymutil -help 2>&1 | FileCheck --check-prefix=HELP %s
 HELP: OVERVIEW: manipulate archived DWARF debug symbol files.
 HELP: USAGE: {{.*}}dsymutil{{[^ ]*}} [options] <input files>
 HELP-NOT: -reverse-iterate
 HELP: Dsymutil Options:
 HELP: -accelerator
 HELP: -arch <arch>
 HELP: -dump-debug-map
 HELP: -flat
 HELP: -minimize
 HELP: -no-odr
 HELP: -no-output
 HELP: -no-swiftmodule-timestamp
 HELP: -num-threads <threads>
+HELP: -object-prefix-map <prefix=remapped>
 HELP: -oso-prepend-path <path>
 HELP: -o <filename>
 HELP: -papertrail
 HELP: -remarks-output-format <format>
 HELP: -remarks-prepend-path <path>
 HELP: -symbol-map
 HELP: -symtab
 HELP: -toolchain

llvm/tools/dsymutil/DwarfLinkerForBinary.cpp

bool DwarfLinkerForBinary::link(const DebugMap &Map) {
 
   DebugMap DebugMap(Map.getTriple(), Map.getBinaryPath());
 
   DWARFLinker GeneralLinker(Streamer.get(), DwarfLinkerClient::Dsymutil);
 
   remarks::RemarkLinker RL;
   if (!Options.RemarksPrependPath.empty())
     RL.setExternalFilePrependPath(Options.RemarksPrependPath);
+  GeneralLinker.setObjectPrefixMap(&Options.ObjectPrefixMap);
 
   std::function<StringRef(StringRef)> TranslationLambda = [&](StringRef Input) {
     assert(Options.Translator);
     return Options.Translator(Input);
   };
 
   GeneralLinker.setVerbosity(Options.Verbose);
   GeneralLinker.setNoOutput(Options.NoOutput);

llvm/tools/dsymutil/LinkUtils.h

struct LinkOptions {
   OutputFileType FileType = OutputFileType::Object;
 
   /// The accelerator table kind
   AccelTableKind TheAccelTableKind;
 
   /// -oso-prepend-path
   std::string PrependPath;
 
+  /// The -object-prefix-map.
+  std::map<std::string, std::string> ObjectPrefixMap;
+
   /// The Resources directory in the .dSYM bundle.
   Optional<std::string> ResourceDir;
 
   /// Symbol map translator.
   SymbolMapTranslator Translator;
 
   /// Fields used for linking and placing remarks into the .dSYM bundle.
   /// @{

llvm/tools/dsymutil/Options.td

 def: Joined<["--", "-"], "o=">, Alias<output>;
 
 def oso_prepend_path: Separate<["--", "-"], "oso-prepend-path">,
   MetaVarName<"<path>">,
   HelpText<"Specify a directory to prepend to the paths of object files.">,
   Group<grp_general>;
 def: Joined<["--", "-"], "oso-prepend-path=">, Alias<oso_prepend_path>;
 
+def object_prefix_map: Separate<["--", "-"], "object-prefix-map">,
+    MetaVarName<"<prefix=remapped>">,
+    HelpText<"Remap object file paths (but no source paths) before processing."
+             "Use this for Clang objects where the module cache location was"
+             "remapped using -fdebug-prefix-map; to help dsymutil"
+             "find the Clang module cache.">,
+    Group<grp_general>;
+def: Joined<["--", "-"], "object-prefix-map=">, Alias<object_prefix_map>;
+
 def symbolmap: Separate<["--", "-"], "symbol-map">,
   MetaVarName<"<bcsymbolmap>">,
   HelpText<"Updates the existing dSYMs inplace using symbol map specified.">,
   Group<grp_general>;
 def: Joined<["--", "-"], "symbol-map=">, Alias<symbolmap>;
 
 def arch: Separate<["--", "-"], "arch">,
   MetaVarName<"<arch>">,

llvm/tools/dsymutil/dsymutil.cpp

static Expected<DsymutilOptions> getOptions(opt::InputArgList &Args) {
   }
 
   for (auto *Arch : Args.filtered(OPT_arch))
     Options.Archs.push_back(Arch->getValue());
 
   if (opt::Arg *OsoPrependPath = Args.getLastArg(OPT_oso_prepend_path))
     Options.LinkOpts.PrependPath = OsoPrependPath->getValue();
 
+  for (const auto &Arg : Args.getAllArgValues(OPT_object_prefix_map)) {
+    auto Split = StringRef(Arg).split('=');
+    Options.LinkOpts.ObjectPrefixMap.insert(
+        {std::string(Split.first), std::string(Split.second)});
+  }
+
   if (opt::Arg *OutputFile = Args.getLastArg(OPT_output))
     Options.OutputFile = OutputFile->getValue();
 
   if (opt::Arg *Toolchain = Args.getLastArg(OPT_toolchain))
     Options.Toolchain = Toolchain->getValue();
 
   if (Args.hasArg(OPT_assembly))
     Options.LinkOpts.FileType = OutputFileType::Assembly;