[dsymutil] Pass LinkOptions by value instead of const ref.

When looping over the difference architectures in a fat binary, we
modify the link options before dispatching the link step to a different
thread. Passing the options by cont reference is not thread safe, as we
might modify its fields before the whole sturct is copied over.

Given that the link options are already stored in the DwarfLinker, we
can easily fix this by passing a copy of the link options instead of a
reference, which would just get copied later on.

llvm-svn: 367348

tools/dsymutil/DwarfLinker.cpp

@@ -2850,8 +2850,8 @@ bool DwarfLinker::link(const DebugMap &Map) {
 } // namespace dsymutil
 
 bool linkDwarf(raw_fd_ostream &OutFile, BinaryHolder &BinHolder,
-               const DebugMap &DM, const LinkOptions &Options) {
-  DwarfLinker Linker(OutFile, BinHolder, Options);
+               const DebugMap &DM, LinkOptions Options) {
+  DwarfLinker Linker(OutFile, BinHolder, std::move(Options));
   return Linker.link(DM);
 }
 

tools/dsymutil/DwarfLinker.h

@@ -56,8 +56,8 @@ using UnitListTy = std::vector<std::unique_ptr<CompileUnit>>;
 class DwarfLinker {
 public:
   DwarfLinker(raw_fd_ostream &OutFile, BinaryHolder &BinHolder,
-              const LinkOptions &Options)
-      : OutFile(OutFile), BinHolder(BinHolder), Options(Options) {}
+              LinkOptions Options)
+      : OutFile(OutFile), BinHolder(BinHolder), Options(std::move(Options)) {}
 
   /// Link the contents of the DebugMap.
   bool link(const DebugMap &);

tools/dsymutil/dsymutil.h

@@ -46,7 +46,7 @@ bool dumpStab(StringRef InputFile, ArrayRef<std::string> Archs,
 /// Link the Dwarf debug info as directed by the passed DebugMap \p DM into a
 /// DwarfFile named \p OutputFilename. \returns false if the link failed.
 bool linkDwarf(raw_fd_ostream &OutFile, BinaryHolder &BinHolder,
-               const DebugMap &DM, const LinkOptions &Options);
+               const DebugMap &DM, LinkOptions Options);
 
 } // end namespace dsymutil
 } // end namespace llvm