[LLD] [MinGW] Simplify handling of os/subsystem version

[mstorsjo]

Summary

As they can be set independently after D88802, we can get rid of a bit of extra code - simplifying the logic here before adding more complication to it later.

[mati865]

Nit: according to https://docs.microsoft.com/en-us/cpp/build/reference/subsystem-specify-subsystem?view=vs-2019 the minimal and the default subsystem for ARM should be 6.02.

The diff itself LGTM.

[mstorsjo]

In D88803#2311479, @mati865 wrote:

Nit: according to https://docs.microsoft.com/en-us/cpp/build/reference/subsystem-specify-subsystem?view=vs-2019 the minimal and the default subsystem for ARM should be 6.02.

Thanks for pointing that out - apparently this isn't something that has been enforced or that has caused issues so far though.

lld/COFF/Config.h

struct Configuration {
   uint64_t imageBase = -1;
   uint64_t fileAlign = 512;
   uint64_t stackReserve = 1024 * 1024;
   uint64_t stackCommit = 4096;
   uint64_t heapReserve = 1024 * 1024;
   uint64_t heapCommit = 4096;
   uint32_t majorImageVersion = 0;
   uint32_t minorImageVersion = 0;
+  // If changing the default os/subsys version here, update the default in
+  // the MinGW driver accordingly.
   uint32_t majorOSVersion = 6;
   uint32_t minorOSVersion = 0;
   uint32_t majorSubsystemVersion = 6;
   uint32_t minorSubsystemVersion = 0;
   uint32_t timestamp = 0;
   uint32_t functionPadMin = 0;
   bool dynamicBase = true;
   bool allowBind = true;

lld/MinGW/Driver.cpp

if (auto *a = args.getLastArg(OPT_entry)) {
     if (args.getLastArgValue(OPT_m) == "i386pe" && s.startswith("_"))
       add("-entry:" + s.substr(1));
     else
       add("-entry:" + s);
   }
 
   if (args.hasArg(OPT_major_os_version, OPT_minor_os_version,
                   OPT_major_subsystem_version, OPT_minor_subsystem_version)) {
-    auto *majOSVer = args.getLastArg(OPT_major_os_version);
-    auto *minOSVer = args.getLastArg(OPT_minor_os_version);
-    auto *majSubSysVer = args.getLastArg(OPT_major_subsystem_version);
-    auto *minSubSysVer = args.getLastArg(OPT_minor_subsystem_version);
-    if (majOSVer && majSubSysVer &&
-        StringRef(majOSVer->getValue()) != StringRef(majSubSysVer->getValue()))
-      warn("--major-os-version and --major-subsystem-version set to differing "
-           "versions, not supported");
-    if (minOSVer && minSubSysVer &&
-        StringRef(minOSVer->getValue()) != StringRef(minSubSysVer->getValue()))
-      warn("--minor-os-version and --minor-subsystem-version set to differing "
-           "versions, not supported");
+    StringRef majOSVer = args.getLastArgValue(OPT_major_os_version, "6");
+    StringRef minOSVer = args.getLastArgValue(OPT_minor_os_version, "0");
+    StringRef majSubSysVer = args.getLastArgValue(OPT_major_subsystem_version, "6");
+    StringRef minSubSysVer = args.getLastArgValue(OPT_minor_subsystem_version, "0");
     StringRef subSys = args.getLastArgValue(OPT_subs, "default");
-    StringRef major = majOSVer ? majOSVer->getValue()
-                               : majSubSysVer ? majSubSysVer->getValue() : "6";
-    StringRef minor = minOSVer ? minOSVer->getValue()
-                               : minSubSysVer ? minSubSysVer->getValue() : "";
-    StringRef sep = minor.empty() ? "" : ".";
-    add("-subsystem:" + subSys + "," + major + sep + minor);
+    add("-osversion:" + majOSVer + "." + minOSVer);
+    add("-subsystem:" + subSys + "," + majSubSysVer + "." + minSubSysVer);
   } else if (auto *a = args.getLastArg(OPT_subs)) {
     add("-subsystem:" + StringRef(a->getValue()));
   }
 
   if (auto *a = args.getLastArg(OPT_out_implib))
     add("-implib:" + StringRef(a->getValue()));
   if (auto *a = args.getLastArg(OPT_stack))
     add("-stack:" + StringRef(a->getValue()));

lld/test/MinGW/driver.test

 MLLVM: -mllvm:bar -mllvm:baz
 
 RUN: ld.lld -### foo.o -m i386pep -subsystem console | FileCheck -check-prefix=SUBSYSTEM %s
 RUN: ld.lld -### foo.o -m i386pep --subsystem console | FileCheck -check-prefix=SUBSYSTEM %s
 RUN: ld.lld -### foo.o -m i386pep -subsystem=console | FileCheck -check-prefix=SUBSYSTEM %s
 RUN: ld.lld -### foo.o -m i386pep --subsystem=console | FileCheck -check-prefix=SUBSYSTEM %s
 SUBSYSTEM: -subsystem:console
 
-RUN: ld.lld -### foo.o -m i386pep --major-os-version 7 --minor-os-version 8 | FileCheck -check-prefix=SUBSYSTEM_VERSION %s
+RUN: ld.lld -### foo.o -m i386pep --major-os-version 7 --minor-os-version 8 | FileCheck -check-prefix=OS_VERSION %s
+RUN: ld.lld -### foo.o -m i386pep --major-os-version=7 --minor-os-version=8 | FileCheck -check-prefix=OS_VERSION %s
+OS_VERSION: -osversion:7.8 -subsystem:default,6.0
+
 RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version 7 --minor-subsystem-version 8 | FileCheck -check-prefix=SUBSYSTEM_VERSION %s
-RUN: ld.lld -### foo.o -m i386pep --major-os-version=7 --minor-os-version=8 --major-subsystem-version=7 --minor-subsystem-version=8 | FileCheck -check-prefix=SUBSYSTEM_VERSION %s
-SUBSYSTEM_VERSION: -subsystem:default,7.8
+RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version=7 --minor-subsystem-version=8 | FileCheck -check-prefix=SUBSYSTEM_VERSION %s
+SUBSYSTEM_VERSION: -osversion:6.0 -subsystem:default,7.8
 
 RUN: ld.lld -### foo.o -m i386pep --minor-subsystem-version 8 | FileCheck -check-prefix=SUBSYSTEM_DEFAULT_MAJOR %s
 SUBSYSTEM_DEFAULT_MAJOR: -subsystem:default,6.8
 
 RUN: ld.lld -### foo.o -m i386pep --major-subsystem-version 7 | FileCheck -check-prefix=SUBSYSTEM_DEFAULT_MINOR %s
-SUBSYSTEM_DEFAULT_MINOR: -subsystem:default,7
+SUBSYSTEM_DEFAULT_MINOR: -subsystem:default,7.0
 
-RUN: ld.lld -### foo.o -m i386pep --subsystem windows --major-os-version 7 --minor-os-version 8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
+RUN: ld.lld -### foo.o -m i386pep --subsystem windows --major-subsystem-version 7 --minor-subsystem-version 8 | FileCheck -check-prefix=SUBSYSTEM_WINDOWS %s
 SUBSYSTEM_WINDOWS: -subsystem:windows,7.8
 
 RUN: ld.lld -### foo.o -m i386pep -stack 4194304,8192 | FileCheck -check-prefix=STACK %s
 RUN: ld.lld -### foo.o -m i386pep --stack 4194304,8192 | FileCheck -check-prefix=STACK %s
 STACK: -stack:4194304,8192
 
 RUN: ld.lld -### foo.o -m i386pep -verbose | FileCheck -check-prefix=VERBOSE %s
 RUN: ld.lld -### foo.o -m i386pep --verbose | FileCheck -check-prefix=VERBOSE %s