Add an -object-path-prefix option to dsymutil

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>

Differential Revision: https://reviews.llvm.org/D76391

llvm/docs/CommandGuide/dsymutil.rst

@@ -71,6 +71,12 @@ OPTIONS
 
  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

llvm/include/llvm/DWARFLinker/DWARFLinker.h

@@ -226,6 +226,7 @@ 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.
 ///
@@ -311,6 +312,11 @@ public:
     Options.ParseableSwiftInterfaces = Map;
   }
 
+  /// Set prefix map for objects.
+  void setObjectPrefixMap(objectPrefixMap *Map) {
+    Options.ObjectPrefixMap = Map;
+  }
+
 private:
   /// Flags passed to DwarfLinker::lookForDIEsToKeep
   enum TraversalFlags {
@@ -783,6 +789,9 @@ private:
     /// 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;
 };
 

llvm/lib/DWARFLinker/DWARFLinker.cpp

@@ -1918,6 +1918,14 @@ static uint64_t getDwoId(const DWARFDie &CUDie, const DWARFUnit &Unit) {
   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,
@@ -1927,6 +1935,8 @@ bool DWARFLinker::registerModuleReference(
       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);

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

@@ -0,0 +1,11 @@
+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

@@ -12,6 +12,7 @@ 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

llvm/tools/dsymutil/DwarfLinkerForBinary.cpp

@@ -297,6 +297,7 @@ bool DwarfLinkerForBinary::link(const DebugMap &Map) {
   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);

llvm/tools/dsymutil/LinkUtils.h

@@ -57,6 +57,9 @@ struct LinkOptions {
   /// -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;
 

llvm/tools/dsymutil/Options.td

@@ -110,6 +110,15 @@ def oso_prepend_path: Separate<["--", "-"], "oso-prepend-path">,
   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.">,

llvm/tools/dsymutil/dsymutil.cpp

@@ -246,6 +246,12 @@ static Expected<DsymutilOptions> getOptions(opt::InputArgList &Args) {
   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();