COFF: Support both /lldmap and /lldmap:<file>

[hans]

Summary

The former option bases the filename on the output name, e.g. if the
link output is a.exe, the map will be written to a.exe. This the
behaviour of link.exe's /MAP option and is useful for creating a map
file of each executable when building a large project.

[hans]

Oh, and what do you think about just spelling the option /map, like for link.exe? Maybe the output format isn't exactly the same, but the functionality is.

[ruiu]

IIRC, the reason why I chose a different name than /map is because the output format is different. If some build system is using /map, it is likely that it reads a result file afterwards using a script, so I chose to fail early. In that sense, I think keeping the different name still makes sense.

COFF/Driver.cpp

778–779

Pass Args and call getLastArg in getMapFile. Since Config is a global variable, you don't need to pass it to the function.

[hans]

In D27595#617733, @ruiu wrote:

IIRC, the reason why I chose a different name than /map is because the output format is different. If some build system is using /map, it is likely that it reads a result file afterwards using a script, so I chose to fail early. In that sense, I think keeping the different name still makes sense.

Sounds reasonable.

COFF/Driver.cpp

778–779

Thanks! That's nicer.

[hans]

Addressing comments.

[ruiu]

LGTM

COFF/Driver.cpp

static unsigned parseDebugType(StringRef Arg) {
   for (StringRef Type : Types)
     DebugTypes |= StringSwitch<unsigned>(Type.lower())
                       .Case("cv", static_cast<unsigned>(DebugType::CV))
                       .Case("pdata", static_cast<unsigned>(DebugType::PData))
                       .Case("fixup", static_cast<unsigned>(DebugType::Fixup));
   return DebugTypes;
 }
 
+static std::string getMapFile(const opt::InputArgList &Args) {
+  auto *Arg = Args.getLastArg(OPT_lldmap, OPT_lldmap_file);
+  if (!Arg)
+    return "";
+  if (Arg->getOption().getID() == OPT_lldmap_file)
+    return Arg->getValue();
+
+  assert(Arg->getOption().getID() == OPT_lldmap);
+  StringRef OutFile = Config->OutputFile;
+  return (OutFile.substr(0, OutFile.rfind('.')) + ".map").str();
+}
+
 void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   // If the first command line argument is "/lib", link.exe acts like lib.exe.
   // We call our own implementation of lib.exe that understands bitcode files.
   if (ArgsArr.size() > 1 && StringRef(ArgsArr[1]).equals_lower("/lib")) {
     if (llvm::libDriverMain(ArgsArr.slice(1)) != 0)
       fatal("lib failed");
     return;
   }
void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   if (Config->DoICF)
     doICF(Symtab.getChunks());
 
   // Write the result.
   writeResult(&Symtab);
 
   // Create a symbol map file containing symbol VAs and their names
   // to help debugging.
-  if (auto *Arg = Args.getLastArg(OPT_lldmap)) {
+  std::string MapFile = getMapFile(Args);
+  if (!MapFile.empty()) {
     std::error_code EC;
-    raw_fd_ostream Out(Arg->getValue(), EC, OpenFlags::F_Text);
+    raw_fd_ostream Out(MapFile, EC, OpenFlags::F_Text);
     if (EC)
-      fatal(EC, "could not create the symbol map");
+      fatal(EC, "could not create the symbol map " + MapFile);
     Symtab.printMap(Out);
   }
+
   // Call exit to avoid calling destructors.
   exit(0);
 }
 
 } // namespace coff
 } // namespace lld

COFF/Options.td

 def help : F<"help">;
 def help_q : Flag<["/?", "-?"], "">, Alias<help>;
 
 // LLD extensions
 def nosymtab : F<"nosymtab">;
 
 // Flags for debugging
 def dumppdb : Joined<["/", "-"], "dumppdb">;
-def lldmap : Joined<["/", "-"], "lldmap:">;
+def lldmap : F<"lldmap">;
+def lldmap_file : Joined<["/", "-"], "lldmap:">;
 
 //==============================================================================
 // The flags below do nothing. They are defined only for link.exe compatibility.
 //==============================================================================
 
 class QF<string name> : Joined<["/", "-", "-?"], name#":">;
 
 multiclass QB<string name> {

test/COFF/lldmap.test

 # RUN: yaml2obj < %p/Inputs/ret42.yaml > %t.obj
-# RUN: lld-link /out:%t.exe /entry:main /lldmap:%t.map %t.obj
-# RUN: FileCheck %s < %t.map
+# RUN: lld-link /out:%t.exe /entry:main /lldmap:%T/foo.map %t.obj
+# RUN: FileCheck %s < %T/foo.map
+# RUN: lld-link /out:%T/bar.exe /entry:main /lldmap %t.obj
+# RUN: FileCheck %s < %T/bar.map
 
 # CHECK: .obj:
 # CHECK-NEXT: 140001000 .text$mn
 # CHECK-NEXT: 140001000 .data
 # CHECK-NEXT: 140001000 main