[LLD][COFF] Generate map file even if no /out flag is present

[pzheng]

Summary

Currently LLD does not generate a map file if no /out flag (e.g., /out:a.exe) is
present. This is because LLD derives the map file's name from the default output
file name is no output file name is specified explicitly on the command
line. However, in this case, the default output file name has not been set by
LLD yet when LLD tries to set the name of the map file. This patch fixes this
corner case by moving the logic handling map file flags to a place after the
default output file name is set.

[pzheng]

minor update to the commit messasge

[thakis]

lld/test/COFF/map.test

11

Please add a dedicated test instead of coopting an existing one.

[pzheng]

Add a dedicated test

[thakis]

LGTM, thanks!

[pzheng]

Thanks for reviewing!

lld/COFF/Driver.cpp

config->stdcallFixup =
       args.hasFlag(OPT_stdcall_fixup, OPT_stdcall_fixup_no, config->mingw);
   config->warnStdcallFixup = !args.hasArg(OPT_stdcall_fixup);
 
   // 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");
     config->incremental = false;
   }
 
   if (config->incremental && args.hasArg(OPT_order)) {
     warn("ignoring '/incremental' due to '/order' specification");
     config->incremental = false;
void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   }
 
   // Fail early if an output file is not writable.
   if (auto e = tryCreateFile(config->outputFile)) {
     error("cannot open output file " + config->outputFile + ": " + e.message());
     return;
   }
 
+  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 (shouldCreatePDB) {
     // Put the PDB next to the image if no /pdb flag was passed.
     if (config->pdbPath.empty()) {
       config->pdbPath = config->outputFile;
       sys::path::replace_extension(config->pdbPath, ".pdb");
     }
 
     // The embedded PDB path should be the absolute path to the PDB if no

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
+# RUN: rm -rf %t && mkdir -p %t && cd %t
+# RUN: cp %t.obj map.test.tmp.obj
+# RUN: cp %t-dll.lib map.test.tmp-dll.lib
+# RUN: lld-link /entry:main map.test.tmp.obj map.test.tmp-dll.lib /map
+# RUN: FileCheck -check-prefix=MAP -strict-whitespace %s < map.test.tmp.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