[lld] r319356 - [LLD] [COFF] Support ENTRY and SUBSYSTEM in .drectve sections

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Wed Nov 29 12:46:13 2017
New Revision: 319356

URL: http://llvm.org/viewvc/llvm-project?rev=319356&view=rev
Log:
[LLD] [COFF] Support ENTRY and SUBSYSTEM in .drectve sections

Adds support for "/ENTRY" and "/SUBSYSTEM" linker options in .drectve
sections. Some Mozilla binaries were using these directives and MSVC
link.exe appears to allow them. No attempt is made to reconcile these
with the options on the command line.

Patch by David Major!

Differential Revision: https://reviews.llvm.org/D39972

Added:
    lld/trunk/test/COFF/entry-drectve.test
    lld/trunk/test/COFF/subsystem-drectve.test
Modified:
    lld/trunk/COFF/Driver.cpp

Modified: lld/trunk/COFF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Driver.cpp?rev=319356&r1=319355&r2=319356&view=diff
==============================================================================
--- lld/trunk/COFF/Driver.cpp (original)
+++ lld/trunk/COFF/Driver.cpp Wed Nov 29 12:46:13 2017
@@ -241,6 +241,9 @@ void LinkerDriver::parseDirectives(Strin
       if (Optional<StringRef> Path = findLib(Arg->getValue()))
         enqueuePath(*Path, false);
       break;
+    case OPT_entry:
+      Config->Entry = addUndefined(mangle(Arg->getValue()));
+      break;
     case OPT_export: {
       Export E = parseExport(Arg->getValue());
       if (Config->Machine == I386 && Config->MinGW) {
@@ -268,6 +271,10 @@ void LinkerDriver::parseDirectives(Strin
     case OPT_section:
       parseSection(Arg->getValue());
       break;
+    case OPT_subsystem:
+      parseSubsystem(Arg->getValue(), &Config->Subsystem,
+                     &Config->MajorOSVersion, &Config->MinorOSVersion);
+      break;
     case OPT_editandcontinue:
     case OPT_fastfail:
     case OPT_guardsym:
@@ -1076,18 +1083,20 @@ void LinkerDriver::link(ArrayRef<const c
   // Handle /entry and /dll
   if (auto *Arg = Args.getLastArg(OPT_entry)) {
     Config->Entry = addUndefined(mangle(Arg->getValue()));
-  } else if (Args.hasArg(OPT_dll) && !Config->NoEntry) {
-    StringRef S = (Config->Machine == I386) ? "__DllMainCRTStartup at 12"
-                                            : "_DllMainCRTStartup";
-    Config->Entry = addUndefined(S);
-  } else if (!Config->NoEntry) {
-    // Windows specific -- If entry point name is not given, we need to
-    // infer that from user-defined entry name.
-    StringRef S = findDefaultEntry();
-    if (S.empty())
-      fatal("entry point must be defined");
-    Config->Entry = addUndefined(S);
-    log("Entry name inferred: " + S);
+  } else if (!Config->Entry && !Config->NoEntry) {
+    if (Args.hasArg(OPT_dll)) {
+      StringRef S = (Config->Machine == I386) ? "__DllMainCRTStartup at 12"
+                                              : "_DllMainCRTStartup";
+      Config->Entry = addUndefined(S);
+    } else {
+      // Windows specific -- If entry point name is not given, we need to
+      // infer that from user-defined entry name.
+      StringRef S = findDefaultEntry();
+      if (S.empty())
+        fatal("entry point must be defined");
+      Config->Entry = addUndefined(S);
+      log("Entry name inferred: " + S);
+    }
   }
 
   // Handle /export

Added: lld/trunk/test/COFF/entry-drectve.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/entry-drectve.test?rev=319356&view=auto
==============================================================================
--- lld/trunk/test/COFF/entry-drectve.test (added)
+++ lld/trunk/test/COFF/entry-drectve.test Wed Nov 29 12:46:13 2017
@@ -0,0 +1,24 @@
+# RUN: yaml2obj < %s > %t.obj
+# RUN: lld-link /subsystem:console /out:%t.exe %t.obj
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_I386
+  Characteristics: []
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     B800000000506800000000680000000050E80000000050E800000000
+  - Name:            .drectve
+    Characteristics: [ IMAGE_SCN_LNK_INFO, IMAGE_SCN_LNK_REMOVE ]
+    Alignment:       1
+    SectionData:     2f656e7472793a437573746f6d456e74727900 # /entry:CustomEntry
+symbols:
+  - Name:            _CustomEntry
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

Added: lld/trunk/test/COFF/subsystem-drectve.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/subsystem-drectve.test?rev=319356&view=auto
==============================================================================
--- lld/trunk/test/COFF/subsystem-drectve.test (added)
+++ lld/trunk/test/COFF/subsystem-drectve.test Wed Nov 29 12:46:13 2017
@@ -0,0 +1,21 @@
+# RUN: yaml2obj < %s > %t.obj
+# RUN: lld-link /dll /noentry /out:%t.dll %t.obj
+# RUN: llvm-readobj -file-headers %t.dll | FileCheck %s
+
+# CHECK: MajorOperatingSystemVersion: 42
+# CHECK: MinorOperatingSystemVersion: 43
+# CHECK: MajorSubsystemVersion: 42
+# CHECK: MinorSubsystemVersion: 43
+# CHECK: Subsystem: IMAGE_SUBSYSTEM_WINDOWS_CUI
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_I386
+  Characteristics: []
+sections:
+  - Name:            .drectve
+    Characteristics: [ IMAGE_SCN_LNK_INFO, IMAGE_SCN_LNK_REMOVE ]
+    Alignment:       1
+    SectionData:     2f73756273797374656d3a636f6e736f6c652c34322e343300 # /subsystem:console,42.43
+symbols:
+...