[LLD][COFF] Support /MAPINFO flag

[pzheng]

Summary

This patch adds support for link.exe's /MAPINFO flag to lld-link.exe.

Here is a description of the flag from Microsoft
(https://learn.microsoft.com/en-us/cpp/build/reference/mapinfo-include-information-in-mapfile?view=msvc-170):

The /MAPINFO option tells the linker to include the specified information in a
mapfile, which is created if you specify the /MAP option. EXPORTS tells the
linker to include exported functions.

[rnk]

lgtm

lld/COFF/Config.h

struct Configuration {
   llvm::StringMap<int> order;
 
   // Used for /lldmap.
   std::string lldmapFile;
 
   // Used for /map.
   std::string mapFile;
 
+  // Used for /mapinfo.
+  bool mapInfo = false;
+
   // Used for /thinlto-index-only:
   llvm::StringRef thinLTOIndexOnlyArg;
 
   // Used for /thinlto-object-prefix-replace:
   std::pair<llvm::StringRef, llvm::StringRef> thinLTOPrefixReplace;
 
   // Used for /thinlto-object-suffix-replace:
   std::pair<llvm::StringRef, llvm::StringRef> thinLTOObjectSuffixReplace;

lld/COFF/Driver.cpp

void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   // Don't warn about long section names, such as .debug_info, for mingw or
   // when -debug:dwarf is requested.
   if (config->mingw || config->debugDwarf)
     config->warnLongSectionNames = false;
 
   config->lldmapFile = getMapFile(args, OPT_lldmap, OPT_lldmap_file);
   config->mapFile = getMapFile(args, OPT_map, OPT_map_file);
 
+  if (config->mapFile != "" && args.hasArg(OPT_map_info)) {
+    for (auto *arg : args.filtered(OPT_map_info)) {
+      std::string s = StringRef(arg->getValue()).lower();
+      if (s == "exports")
+        config->mapInfo = true;
+      else
+        error("unknown option: /mapinfo:" + s);
+    }
+  }
+
   if (config->lldmapFile != "" && config->lldmapFile == config->mapFile) {
     warn("/lldmap and /map have the same output file '" + config->mapFile +
          "'.\n>>> ignoring /lldmap");
     config->lldmapFile.clear();
   }
 
   if (config->incremental && args.hasArg(OPT_profile)) {
     warn("ignoring '/incremental' due to '/profile' specification");

lld/COFF/MapFile.cpp

void lld::coff::writeMapFile(COFFLinkerContext &ctx) {
 
   // Print out the static symbols
   os << "\n";
   os << " Static symbols\n";
   os << "\n";
   for (Defined *sym : staticSyms)
     os << staticSymStr[sym] << '\n';
 
+  // Print out the exported functions
+  if (config->mapInfo) {
+    os << "\n";
+    os << " Exports\n";
+    os << "\n";
+    os << "  ordinal    name\n\n";
+    for (Export &e : config->exports) {
+      os << format("  %7d", e.ordinal) << "    " << e.name << "\n";
+      if (!e.extName.empty() && e.extName != e.name)
+        os << "               exported name: " << e.extName << "\n";
+    }
+  }
+
   t4.stop();
   t1.stop();
 }

lld/COFF/Options.td

 
 def vfsoverlay : P<"vfsoverlay", "Path to a vfsoverlay yaml file to optionally look for /defaultlib's in">;
 
 // Flags for debugging
 def lldmap : F<"lldmap">;
 def lldmap_file : P_priv<"lldmap">;
 def map : F<"map">;
 def map_file : P_priv<"map">;
+def map_info : P<"mapinfo", "Include the specified information in a map file">;
 def show_timing : F<"time">;
 def summary : F<"summary">;
 
 //==============================================================================
 // The flags below do nothing. They are defined only for link.exe compatibility.
 //==============================================================================
 
 def ignoreidl : F<"ignoreidl">;

lld/test/COFF/map.test

 # RUN: yaml2obj %p/Inputs/export.yaml -o %t-dll.obj
 # RUN: lld-link /out:%t.dll /dll %t-dll.obj /implib:%t-dll.lib \
 # RUN:   /export:exportfn1 /export:exportfn2
 # RUN: yaml2obj %p/Inputs/map.yaml -o %t.obj
 # RUN: lld-link /out:%t.exe /entry:main %t.obj %t-dll.lib /map:%T/foo.map  /lldmap
 # RUN: FileCheck -check-prefix=MAP -strict-whitespace %s < %T/foo.map
 # RUN: FileCheck -check-prefix=LLDMAP -strict-whitespace %s < %t.map
 # RUN: lld-link /out:%t.exe /entry:main %t.obj %t-dll.lib /map /lldmap:%T/foo-lld.map
 # RUN: FileCheck -check-prefix=MAP -strict-whitespace %s < %t.map
 # RUN: FileCheck -check-prefix=LLDMAP -strict-whitespace %s < %T/foo-lld.map
+# RUN: lld-link /out:%t.dll /dll %t-dll.obj /export:exportfn1 \
+# RUN:   /export:foo=exportfn2 /map /mapinfo:exports
+# RUN: FileCheck -check-prefix=MAPINFO -strict-whitespace %s < %t.map
 
 # MAP: {{.*}}
 # MAP-EMPTY:
 # MAP-NEXT: Timestamp is {{.*}}
 # MAP-EMPTY:
 # MAP-NEXT: Preferred load address is 0000000140000000
 # MAP-EMPTY:
 # MAP-NEXT: Start         Length     Name                   Class

 # MAP-EMPTY:
 # MAP-NEXT: 0001:00000043       staticdef                  0000000140001043     map.test.tmp.obj
 
 
 # LLDMAP:      Address  Size     Align Out     In      Symbol
 # LLDMAP-NEXT: 00001000 00000026  4096 .text
 # LLDMAP-NEXT: 00001000 00000008     4         {{.*}}map.test.tmp.obj:(.text)
 # LLDMAP-NEXT: 00001000 00000000     0                 main
+
+# MAPINFO: Exports
+# MAPINFO-EMPTY:
+# MAPINFO-NEXT:  ordinal    name
+# MAPINFO-EMPTY:
+# MAPINFO-NEXT:        1    exportfn1
+# MAPINFO-NEXT:        2    exportfn3
+# MAPINFO-NEXT:        3    exportfn2
+# MAPINFO-NEXT:               exported name: foo