[lld-macho] Use separate tablegen file for LC_LINKER_OPTION

[keith]

Summary

This cuts another 5 seconds off the top it takes lld to link our large
project. I assume because the parsing of the larger tablegen file
happened many times, when we actually only wanted to handle these 2
options. This is a bit more work to maintain these arguments in 2 places
but they shouldn't change too much to be a big problem.

[keith]

lld/MachO/DriverUtils.cpp

54

I assume there is another, better, way for me to define 2 OptTables in the same file, I would appreciate pointers!

[int3]

lld/MachO/DriverUtils.cpp

54

idk if there are more elegant ways of working with OptTables, but I was wondering if it would be simpler to not use an OptTable altogether. Given that there are only two unique prefixes that we need to check for, we could do it by hand -- something like if (s.startswith("-l")) { ... }.

[keith]

lld/MachO/DriverUtils.cpp

54

Yea I was considering that too. I do think that would be much simpler. It looks like we're only missing 2 so it shouldn't grow much https://github.com/keith/ld64/blob/2ff40b093f1b20dad35d48480da016bc380707dd/src/ld/Resolver.cpp#L324-L363

[keith]

lld/MachO/DriverUtils.cpp

54

Submitted https://reviews.llvm.org/D113235 for discussion

[thakis]

Oh, interesting. Any opinion on how this compares to the alternate approach taken for this in D78845 for the COFF linker?

[keith]

Actually landed https://reviews.llvm.org/D113235 instead, lmk what you think there!

lld/MachO/CMakeLists.txt

 set(LLVM_TARGET_DEFINITIONS Options.td)
 tablegen(LLVM Options.inc -gen-opt-parser-defs)
 add_public_tablegen_target(MachOOptionsTableGen)
 
+set(LLVM_TARGET_DEFINITIONS LCLinkerOptions.td)
+tablegen(LLVM LCLinkerOptions.inc -gen-opt-parser-defs)
+add_public_tablegen_target(MachOLCLinkerOptionsTableGen)
+
 include_directories(${LLVM_MAIN_SRC_DIR}/../libunwind/include)
 
 add_lld_library(lldMachO
   Arch/ARM.cpp
   Arch/ARM64.cpp
   Arch/ARM64Common.cpp
   Arch/ARM64_32.cpp
   Arch/X86_64.cpp
add_lld_library(lldMachO
 
   LINK_LIBS
   lldCommon
   ${LLVM_PTHREAD_LIB}
   ${XAR_LIB}
 
   DEPENDS
   MachOOptionsTableGen
+  MachOLCLinkerOptionsTableGen
   ${tablegen_deps}
   )
 
 if(LLVM_HAVE_LIBXAR)
   target_link_libraries(lldMachO PRIVATE ${XAR_LIB})
 endif()

lld/MachO/Driver.h

 // Create enum with OPT_xxx values for each option in Options.td
 enum {
   OPT_INVALID = 0,
 #define OPTION(_1, _2, ID, _4, _5, _6, _7, _8, _9, _10, _11, _12) OPT_##ID,
 #include "Options.inc"
 #undef OPTION
 };
 
+class MachOLCLinkerOptTable : public llvm::opt::OptTable {
+public:
+  MachOLCLinkerOptTable();
+  // llvm::opt::InputArgList parse(ArrayRef<const char *> argv);
+};
+
+// Create enum with OPT_xxx values for each option in Options.td
+enum {
+  OPT_LC_INVALID = 0,
+#define OPTION(_1, _2, ID, _4, _5, _6, _7, _8, _9, _10, _11, _12) OPT_lc_##ID,
+#include "LCLinkerOptions.inc"
+#undef OPTION
+};
+
 void parseLCLinkerOption(InputFile *, unsigned argc, StringRef data);
 
 std::string createResponseFile(const llvm::opt::InputArgList &args);
 
 // Check for both libfoo.dylib and libfoo.tbd (in that order).
 llvm::Optional<StringRef> resolveDylibPath(llvm::StringRef path);
 
 DylibFile *loadDylib(llvm::MemoryBufferRef mbref, DylibFile *umbrella = nullptr,

lld/MachO/Driver.cpp

void macho::parseLCLinkerOption(InputFile *f, unsigned argc, StringRef data) {
   size_t offset = 0;
   for (unsigned i = 0; i < argc && offset < data.size(); ++i) {
     argv.push_back(data.data() + offset);
     offset += strlen(data.data() + offset) + 1;
   }
   if (argv.size() != argc || offset > data.size())
     fatal(toString(f) + ": invalid LC_LINKER_OPTION");
 
-  MachOOptTable table;
+  MachOLCLinkerOptTable table;
   unsigned missingIndex, missingCount;
   InputArgList args = table.ParseArgs(argv, missingIndex, missingCount);
   if (missingCount)
     fatal(Twine(args.getArgString(missingIndex)) + ": missing argument");
   for (const Arg *arg : args.filtered(OPT_UNKNOWN))
     error("unknown argument: " + arg->getAsString(args));
 
   for (const Arg *arg : args) {
     switch (arg->getOption().getID()) {
-    case OPT_l: {
+    case OPT_lc_l: {
       StringRef name = arg->getValue();
       ForceLoad forceLoadArchive =
           config->forceLoadSwift && name.startswith("swift") ? ForceLoad::Yes
                                                              : ForceLoad::No;
       addLibrary(name, /*isNeeded=*/false, /*isWeak=*/false,
                  /*isReexport=*/false, /*isExplicit=*/false, forceLoadArchive);
       break;
     }
-    case OPT_framework:
+    case OPT_lc_framework:
       addFramework(arg->getValue(), /*isNeeded=*/false, /*isWeak=*/false,
                    /*isReexport=*/false, /*isExplicit=*/false, ForceLoad::No);
       break;
     default:
       error(arg->getSpelling() + " is not allowed in LC_LINKER_OPTION");
     }
   }
 }

lld/MachO/DriverUtils.cpp

#define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
   {X1, X2, X10,         X11,         OPT_##ID, Option::KIND##Class,            \
    X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
 #include "Options.inc"
 #undef OPTION
 };
 
 MachOOptTable::MachOOptTable() : OptTable(optInfo) {}
 
+namespace LCLinkerOptInfo {
+// Create prefix string literals used in LCLinkerOptions.td
+#define PREFIX(NAME, VALUE) const char *NAME[] = VALUE;
+#include "LCLinkerOptions.inc"
+#undef PREFIX
+
+// Create table mapping all options defined in Options.td
+static const OptTable::Info lcLinkerOptInfo[] = {
+#define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
+  {X1,                                                                         \
+   X2,                                                                         \
+   X10,                                                                        \
+   X11,                                                                        \
+   OPT_lc_##ID,                                                                \
+   Option::KIND##Class,                                                        \
+   X9,                                                                         \
+   X8,                                                                         \
+   OPT_LC_##GROUP,                                                             \
+   OPT_LC_##ALIAS,                                                             \
+   X7,                                                                         \
+   X12},
+#include "LCLinkerOptions.inc"
+#undef OPTION
+};
+} // namespace LCLinkerOptInfo
+MachOLCLinkerOptTable::MachOLCLinkerOptTable()
+    : OptTable(LCLinkerOptInfo::lcLinkerOptInfo) {}
+
 // Set color diagnostics according to --color-diagnostics={auto,always,never}
 // or --no-color-diagnostics flags.
 static void handleColorDiagnostics(InputArgList &args) {
   const Arg *arg =
       args.getLastArg(OPT_color_diagnostics, OPT_color_diagnostics_eq,
                       OPT_no_color_diagnostics);
   if (!arg)
     return;

lld/MachO/LCLinkerOptions.td

+include "llvm/Option/OptParser.td"
+
+// Flags that can be used in the LC_LINKER_OPTION load command
+
+def l : Joined<["-"], "l">,
+    MetaVarName<"<name>">,
+    HelpText<"Search for lib<name>.dylib or lib<name>.a on the library search path">;
+def framework : Separate<["-"], "framework">,
+    MetaVarName<"<name>">,
+    HelpText<"Search for <name>.framework/<name> on the framework search path">;