[llvm-lib][llvm-dlltool][Object] Add support for EXPORTAS name types. #78772

cjacek · 2024-01-19T20:01:03Z

EXPORTAS is a new name type in import libraries. As far as I can tell, they are not documented. It's used by default on ARM64EC (this is not part of this PR, see cjacek@70946eb for a prototype of it), but MSVC allows using it on other platforms. I found the syntax from compiler-generated __declspec(dllexport) directives, which look like -export:#func,EXPORTAS,func, but MSVC also allows using it in .def files as well, which is what this PR implements. For the context, I also have a prototype of linker support: cjacek@1dbe8a6.

cc @bylaws

llvmbot · 2024-01-19T20:01:34Z

@llvm/pr-subscribers-llvm-binary-utilities

@llvm/pr-subscribers-lld

Author: Jacek Caban (cjacek)

Changes

EXPORTAS is a new name type in import libraries. As far as I can tell, they are not documented. It's used by default on ARM64EC (this is not part of this PR, see cjacek@70946eb for a prototype of it), but MSVC allows using it on other platforms. I found the syntax from compiler-generated __declspec(dllexport) directives, which look like -export:#func,EXPORTAS,func, but MSVC also allows using it in .def files as well, which is what this PR implements. For the context, I also have a prototype of linker support: cjacek@1dbe8a6.

cc @bylaws

Patch is 21.07 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/78772.diff

15 Files Affected:

(modified) lld/test/COFF/def-export-cpp.s (+1)
(modified) lld/test/COFF/def-export-stdcall.s (+13)
(modified) lld/test/COFF/dllexport.s (+4)
(modified) llvm/include/llvm/BinaryFormat/COFF.h (+4-1)
(modified) llvm/include/llvm/Object/COFFImportFile.h (+5)
(modified) llvm/lib/Object/COFFImportFile.cpp (+70-21)
(modified) llvm/lib/Object/COFFModuleDefinition.cpp (+12-1)
(modified) llvm/test/tools/llvm-dlltool/coff-decorated.def (+7)
(modified) llvm/test/tools/llvm-dlltool/coff-exports.def (+3)
(modified) llvm/test/tools/llvm-dlltool/coff-noname.def (+1)
(modified) llvm/test/tools/llvm-dlltool/no-leading-underscore.def (+2)
(modified) llvm/test/tools/llvm-lib/arm64ec-implib.test (+2)
(added) llvm/test/tools/llvm-lib/exportas.test (+94)
(modified) llvm/test/tools/llvm-readobj/COFF/file-headers.test (+1)
(modified) llvm/tools/llvm-readobj/COFFImportDumper.cpp (+6)

diff --git a/lld/test/COFF/def-export-cpp.s b/lld/test/COFF/def-export-cpp.s
index e00b35b1c5b39b..370b8ddba4104b 100644
--- a/lld/test/COFF/def-export-cpp.s
+++ b/lld/test/COFF/def-export-cpp.s
@@ -10,6 +10,7 @@
 
 # IMPLIB: File: foo.dll
 # IMPLIB: Name type: undecorate
+# IMPLIB-NEXT: Export name: GetPathOnDisk
 # IMPLIB-NEXT: Symbol: __imp_?GetPathOnDisk@@YA_NPEA_W@Z
 # IMPLIB-NEXT: Symbol: ?GetPathOnDisk@@YA_NPEA_W@Z
 
diff --git a/lld/test/COFF/def-export-stdcall.s b/lld/test/COFF/def-export-stdcall.s
index f015e205c74a33..7e4e04c77cbe7a 100644
--- a/lld/test/COFF/def-export-stdcall.s
+++ b/lld/test/COFF/def-export-stdcall.s
@@ -6,15 +6,19 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix UNDECORATED-EXPORTS %s
 
 # UNDECORATED-IMPLIB: Name type: noprefix
+# UNDECORATED-IMPLIB-NEXT: Export name: _underscored
 # UNDECORATED-IMPLIB-NEXT: __imp___underscored
 # UNDECORATED-IMPLIB-NEXT: __underscored
 # UNDECORATED-IMPLIB: Name type: undecorate
+# UNDECORATED-IMPLIB-NEXT: Export name: fastcall
 # UNDECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # UNDECORATED-IMPLIB-NEXT: fastcall@8
 # UNDECORATED-IMPLIB: Name type: undecorate
+# UNDECORATED-IMPLIB-NEXT: Export name: stdcall
 # UNDECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # UNDECORATED-IMPLIB-NEXT: _stdcall@8
 # UNDECORATED-IMPLIB: Name type: undecorate
+# UNDECORATED-IMPLIB-NEXT: Export name: vectorcall
 # UNDECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # UNDECORATED-IMPLIB-NEXT: vectorcall@@8
 
@@ -30,12 +34,15 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix DECORATED-EXPORTS %s
 
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: @fastcall@8
 # DECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-IMPLIB-NEXT: @fastcall@8
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: _stdcall@8
 # DECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: vectorcall@@8
 # DECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-IMPLIB-NEXT: vectorcall@@8
 
@@ -51,14 +58,17 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix DECORATED-MINGW-EXPORTS %s
 
 # DECORATED-MINGW-IMPLIB: Name type: name
+# DECORATED-MINGW-IMPLIB-NEXT: Export name: @fastcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: fastcall@8
 # DECORATED-MINGW-IMPLIB: Name type: noprefix
+# DECORATED-MINGW-IMPLIB-NEXT: Export name: stdcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: _stdcall@8
 # GNU tools don't support vectorcall, but this test is just to track that
 # lld's behaviour remains consistent over time.
 # DECORATED-MINGW-IMPLIB: Name type: name
+# DECORATED-MINGW-IMPLIB-NEXT: Export name: vectorcall@@8
 # DECORATED-MINGW-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-MINGW-IMPLIB-NEXT: vectorcall@@8
 
@@ -75,14 +85,17 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix MINGW-KILL-AT-EXPORTS %s
 
 # MINGW-KILL-AT-IMPLIB: Name type: noprefix
+# MINGW-KILL-AT-IMPLIB: Export name: fastcall
 # MINGW-KILL-AT-IMPLIB: __imp__fastcall
 # MINGW-KILL-AT-IMPLIB-NEXT: _fastcall
 # MINGW-KILL-AT-IMPLIB: Name type: noprefix
+# MINGW-KILL-AT-IMPLIB-NEXT: Export name: stdcall
 # MINGW-KILL-AT-IMPLIB-NEXT: __imp__stdcall
 # MINGW-KILL-AT-IMPLIB-NEXT: _stdcall
 # GNU tools don't support vectorcall, but this test is just to track that
 # lld's behaviour remains consistent over time.
 # MINGW-KILL-AT-IMPLIB: Name type: noprefix
+# MINGW-KILL-AT-IMPLIB-NEXT: Export name: vectorcall
 # MINGW-KILL-AT-IMPLIB-NEXT: __imp__vectorcall
 # MINGW-KILL-AT-IMPLIB-NEXT: _vectorcall
 
diff --git a/lld/test/COFF/dllexport.s b/lld/test/COFF/dllexport.s
index a238b70ce1b4f6..b04ebc3a33c3e2 100644
--- a/lld/test/COFF/dllexport.s
+++ b/lld/test/COFF/dllexport.s
@@ -6,15 +6,19 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix DECORATED-EXPORTS %s
 
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: @fastcall@8
 # DECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-IMPLIB-NEXT: @fastcall@8
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: _stdcall@8
 # DECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: noprefix
+# DECORATED-IMPLIB-NEXT: Export name: _underscored
 # DECORATED-IMPLIB-NEXT: __imp___underscored
 # DECORATED-IMPLIB-NEXT: __underscored
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: vectorcall@@8
 # DECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-IMPLIB-NEXT: vectorcall@@8
 
diff --git a/llvm/include/llvm/BinaryFormat/COFF.h b/llvm/include/llvm/BinaryFormat/COFF.h
index 522ee37da6e830..72461d0d9c316a 100644
--- a/llvm/include/llvm/BinaryFormat/COFF.h
+++ b/llvm/include/llvm/BinaryFormat/COFF.h
@@ -716,7 +716,10 @@ enum ImportNameType : unsigned {
   IMPORT_NAME_NOPREFIX = 2,
   /// The import name is the public symbol name, but skipping the leading ?,
   /// @, or optionally _, and truncating at the first @.
-  IMPORT_NAME_UNDECORATE = 3
+  IMPORT_NAME_UNDECORATE = 3,
+  /// The import name is specified as a separate string in the import library
+  /// object file.
+  IMPORT_NAME_EXPORTAS = 4
 };
 
 enum class GuardFlags : uint32_t {
diff --git a/llvm/include/llvm/Object/COFFImportFile.h b/llvm/include/llvm/Object/COFFImportFile.h
index edc836ff0348cb..7c5846e9c044e3 100644
--- a/llvm/include/llvm/Object/COFFImportFile.h
+++ b/llvm/include/llvm/Object/COFFImportFile.h
@@ -66,6 +66,7 @@ class COFFImportFile : public SymbolicFile {
   uint16_t getMachine() const { return getCOFFImportHeader()->Machine; }
 
   StringRef getFileFormatName() const;
+  StringRef getExportName() const;
 
 private:
   bool isData() const {
@@ -91,6 +92,10 @@ struct COFFShortExport {
   /// file, this is "baz" in "EXPORTS\nfoo = bar == baz".
   std::string AliasTarget;
 
+  /// Specifies EXPORTAS name. In a .def file, this is "bar" in
+  /// "EXPORTS\nfoo EXPORTAS bar".
+  std::string ExportAs;
+
   uint16_t Ordinal = 0;
   bool Noname = false;
   bool Data = false;
diff --git a/llvm/lib/Object/COFFImportFile.cpp b/llvm/lib/Object/COFFImportFile.cpp
index 60556c149bf735..b666ca3fd40300 100644
--- a/llvm/lib/Object/COFFImportFile.cpp
+++ b/llvm/lib/Object/COFFImportFile.cpp
@@ -52,6 +52,37 @@ StringRef COFFImportFile::getFileFormatName() const {
   }
 }
 
+StringRef COFFImportFile::getExportName() const {
+  const coff_import_header *hdr = getCOFFImportHeader();
+  StringRef name = StringRef(Data.getBufferStart() + sizeof(*hdr));
+
+  auto ltrim1 = [](StringRef s, const char *chars) {
+    return !s.empty() && strchr(chars, s[0]) ? s.substr(1) : s;
+  };
+
+  switch (hdr->getNameType()) {
+  case IMPORT_ORDINAL:
+    name = "";
+    break;
+  case IMPORT_NAME_NOPREFIX:
+    name = ltrim1(name, "?@_");
+    break;
+  case IMPORT_NAME_UNDECORATE:
+    name = ltrim1(name, "?@_");
+    name = name.substr(0, name.find('@'));
+    break;
+  case IMPORT_NAME_EXPORTAS: {
+    StringRef dllName = StringRef(name.begin() + name.size() + 1);
+    name = StringRef(dllName.begin() + dllName.size() + 1);
+    break;
+  }
+  default:
+    break;
+  }
+
+  return name;
+}
+
 static uint16_t getImgRelRelocation(MachineTypes Machine) {
   switch (Machine) {
   default:
@@ -183,6 +214,7 @@ class ObjectFactory {
   // Library Format.
   NewArchiveMember createShortImport(StringRef Sym, uint16_t Ordinal,
                                      ImportType Type, ImportNameType NameType,
+                                     StringRef ExportName,
                                      MachineTypes Machine);
 
   // Create a weak external file which is described in PE/COFF Aux Format 3.
@@ -474,12 +506,13 @@ NewArchiveMember ObjectFactory::createNullThunk(std::vector<uint8_t> &Buffer) {
   return {MemoryBufferRef{F, ImportName}};
 }
 
-NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
-                                                  uint16_t Ordinal,
-                                                  ImportType ImportType,
-                                                  ImportNameType NameType,
-                                                  MachineTypes Machine) {
+NewArchiveMember
+ObjectFactory::createShortImport(StringRef Sym, uint16_t Ordinal,
+                                 ImportType ImportType, ImportNameType NameType,
+                                 StringRef ExportName, MachineTypes Machine) {
   size_t ImpSize = ImportName.size() + Sym.size() + 2; // +2 for NULs
+  if (!ExportName.empty())
+    ImpSize += ExportName.size() + 1;
   size_t Size = sizeof(coff_import_header) + ImpSize;
   char *Buf = Alloc.Allocate<char>(Size);
   memset(Buf, 0, Size);
@@ -499,6 +532,10 @@ NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
   memcpy(P, Sym.data(), Sym.size());
   P += Sym.size() + 1;
   memcpy(P, ImportName.data(), ImportName.size());
+  if (!ExportName.empty()) {
+    P += ImportName.size() + 1;
+    memcpy(P, ExportName.data(), ExportName.size());
+  }
 
   return {MemoryBufferRef(StringRef(Buf, Size), ImportName)};
 }
@@ -615,27 +652,39 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
       ImportType = IMPORT_CONST;
 
     StringRef SymbolName = E.SymbolName.empty() ? E.Name : E.SymbolName;
-    ImportNameType NameType = E.Noname
-                                  ? IMPORT_ORDINAL
-                                  : getNameType(SymbolName, E.Name,
-                                                Machine, MinGW);
-    Expected<std::string> Name = E.ExtName.empty()
-                                     ? std::string(SymbolName)
-                                     : replace(SymbolName, E.Name, E.ExtName);
-
-    if (!Name)
-      return Name.takeError();
-
-    if (!E.AliasTarget.empty() && *Name != E.AliasTarget) {
+    std::string Name;
+
+    if (E.ExtName.empty()) {
+      Name = std::string(SymbolName);
+    } else {
+      Expected<std::string> ReplacedName =
+          replace(SymbolName, E.Name, E.ExtName);
+      if (!ReplacedName)
+        return ReplacedName.takeError();
+      Name.swap(*ReplacedName);
+    }
+
+    if (!E.AliasTarget.empty() && Name != E.AliasTarget) {
       Members.push_back(
-          OF.createWeakExternal(E.AliasTarget, *Name, false, Machine));
+          OF.createWeakExternal(E.AliasTarget, Name, false, Machine));
       Members.push_back(
-          OF.createWeakExternal(E.AliasTarget, *Name, true, Machine));
+          OF.createWeakExternal(E.AliasTarget, Name, true, Machine));
       continue;
     }
 
-    Members.push_back(
-        OF.createShortImport(*Name, E.Ordinal, ImportType, NameType, Machine));
+    ImportNameType NameType;
+    std::string ExportName;
+    if (E.Noname) {
+      NameType = IMPORT_ORDINAL;
+    } else if (!E.ExportAs.empty()) {
+      NameType = IMPORT_NAME_EXPORTAS;
+      ExportName = E.ExportAs;
+    } else {
+      NameType = getNameType(SymbolName, E.Name, Machine, MinGW);
+    }
+
+    Members.push_back(OF.createShortImport(Name, E.Ordinal, ImportType,
+                                           NameType, ExportName, Machine));
   }
 
   return writeArchive(Path, Members, SymtabWritingMode::NormalSymtab,
diff --git a/llvm/lib/Object/COFFModuleDefinition.cpp b/llvm/lib/Object/COFFModuleDefinition.cpp
index 648f01f823d007..f60dd49793685f 100644
--- a/llvm/lib/Object/COFFModuleDefinition.cpp
+++ b/llvm/lib/Object/COFFModuleDefinition.cpp
@@ -39,6 +39,7 @@ enum Kind {
   KwConstant,
   KwData,
   KwExports,
+  KwExportAs,
   KwHeapsize,
   KwLibrary,
   KwName,
@@ -118,6 +119,7 @@ class Lexer {
                    .Case("CONSTANT", KwConstant)
                    .Case("DATA", KwData)
                    .Case("EXPORTS", KwExports)
+                   .Case("EXPORTAS", KwExportAs)
                    .Case("HEAPSIZE", KwHeapsize)
                    .Case("LIBRARY", KwLibrary)
                    .Case("NAME", KwName)
@@ -286,7 +288,16 @@ class Parser {
           E.AliasTarget = std::string("_").append(E.AliasTarget);
         continue;
       }
-      unget();
+      // EXPORTAS must be at the end of export definition
+      if (Tok.K == KwExportAs) {
+        read();
+        if (Tok.K == Eof)
+          return createError(
+              "unexpected end of file, EXPORTAS identifier expected");
+        E.ExportAs = std::string(Tok.Value);
+      } else {
+        unget();
+      }
       Info.Exports.push_back(E);
       return Error::success();
     }
diff --git a/llvm/test/tools/llvm-dlltool/coff-decorated.def b/llvm/test/tools/llvm-dlltool/coff-decorated.def
index 856804686168b1..fc81f23d09d6c4 100644
--- a/llvm/test/tools/llvm-dlltool/coff-decorated.def
+++ b/llvm/test/tools/llvm-dlltool/coff-decorated.def
@@ -14,25 +14,32 @@ OtherStdcallExportName@4=CdeclInternalFunction
 CdeclExportName=StdcallInternalFunction@4
 
 ; CHECK:      Name type: noprefix
+; CHECK-NEXT: Export name: CdeclFunction
 ; CHECK-NEXT: Symbol: __imp__CdeclFunction
 ; CHECK-NEXT: Symbol: _CdeclFunction
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: StdcallFunction
 ; CHECK-NEXT: Symbol: __imp__StdcallFunction@4
 ; CHECK-NEXT: Symbol: _StdcallFunction@4
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: FastcallFunction
 ; CHECK-NEXT: Symbol: __imp_@FastcallFunction@4
 ; CHECK-NEXT: Symbol: @FastcallFunction@4
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: ??_7exception@@6B@
 ; CHECK-NEXT: Symbol: __imp_??_7exception@@6B@
 ; CHECK-NEXT: Symbol: ??_7exception@@6B@
 ; CHECK-NM: W _StdcallAlias@4
 ; CHECK-NM: U _StdcallFunction@4
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: StdcallExportName
 ; CHECK-NEXT: Symbol: __imp__StdcallExportName@4{{$}}
 ; CHECK-NEXT: Symbol: _StdcallExportName@4{{$}}
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: OtherStdcallExportName
 ; CHECK-NEXT: Symbol: __imp__OtherStdcallExportName@4{{$}}
 ; CHECK-NEXT: Symbol: _OtherStdcallExportName@4{{$}}
 ; CHECK:      Name type: noprefix
+; CHECK-NEXT: Export name: CdeclExportName
 ; CHECK-NEXT: Symbol: __imp__CdeclExportName
 ; CHECK-NEXT: Symbol: _CdeclExportName
diff --git a/llvm/test/tools/llvm-dlltool/coff-exports.def b/llvm/test/tools/llvm-dlltool/coff-exports.def
index 57c55744602156..267424db1b8c1d 100644
--- a/llvm/test/tools/llvm-dlltool/coff-exports.def
+++ b/llvm/test/tools/llvm-dlltool/coff-exports.def
@@ -17,12 +17,15 @@ AnotherFunction
 ; CHECK-ARM64: Format: COFF-import-file-ARM64
 ; CHECK: Type: code
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: TestFunction1
 ; CHECK-NEXT: Symbol: __imp_TestFunction1
 ; CHECK-NEXT: Symbol: TestFunction1
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: TestFunction2
 ; CHECK-NEXT: Symbol: __imp_TestFunction2{{$}}
 ; CHECK-NEXT: Symbol: TestFunction2{{$}}
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: TestFunction3
 ; CHECK-NEXT: Symbol: __imp_TestFunction3{{$}}
 ; CHECK-NEXT: Symbol: TestFunction3{{$}}
 
diff --git a/llvm/test/tools/llvm-dlltool/coff-noname.def b/llvm/test/tools/llvm-dlltool/coff-noname.def
index 27e60efbd2d802..7cb05846ce28a2 100644
--- a/llvm/test/tools/llvm-dlltool/coff-noname.def
+++ b/llvm/test/tools/llvm-dlltool/coff-noname.def
@@ -12,5 +12,6 @@ ByNameFunction
 ; CHECK-NEXT: Symbol: __imp__ByOrdinalFunction
 ; CHECK-NEXT: Symbol: _ByOrdinalFunction
 ; CHECK:      Name type: noprefix
+; CHECK-NEXT: Export name: ByNameFunction
 ; CHECK-NEXT: Symbol: __imp__ByNameFunction
 ; CHECK-NEXT: Symbol: _ByNameFunction
diff --git a/llvm/test/tools/llvm-dlltool/no-leading-underscore.def b/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
index 6b78e15d2b5f69..9c5e77ca29a821 100644
--- a/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
+++ b/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
@@ -9,9 +9,11 @@ alias == func
 DecoratedFunction@4
 
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: func
 ; CHECK-NEXT: Symbol: __imp_func
 ; CHECK-NEXT: Symbol: func
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: DecoratedFunction
 ; CHECK-NEXT: Symbol: __imp_DecoratedFunction@4
 ; CHECK-NEXT: Symbol: DecoratedFunction@4
 
diff --git a/llvm/test/tools/llvm-lib/arm64ec-implib.test b/llvm/test/tools/llvm-lib/arm64ec-implib.test
index 2672f8d38b7f70..4250c775daa601 100644
--- a/llvm/test/tools/llvm-lib/arm64ec-implib.test
+++ b/llvm/test/tools/llvm-lib/arm64ec-implib.test
@@ -36,6 +36,7 @@ READOBJ-NEXT: File: test.dll
 READOBJ-NEXT: Format: COFF-import-file-ARM64EC
 READOBJ-NEXT: Type: code
 READOBJ-NEXT: Name type: name
+READOBJ-NEXT: Export name: funcexp
 READOBJ-NEXT: Symbol: __imp_funcexp
 READOBJ-NEXT: Symbol: funcexp
 READOBJ-EMPTY:
@@ -43,6 +44,7 @@ READOBJ-NEXT: File: test.dll
 READOBJ-NEXT: Format: COFF-import-file-ARM64EC
 READOBJ-NEXT: Type: data
 READOBJ-NEXT: Name type: name
+READOBJ-NEXT: Export name: dataexp
 READOBJ-NEXT: Symbol: __imp_dataexp
 
 Creating a new lib containing the existing lib:
diff --git a/llvm/test/tools/llvm-lib/exportas.test b/llvm/test/tools/llvm-lib/exportas.test
new file mode 100644
index 00000000000000..f6e845ca174664
--- /dev/null
+++ b/llvm/test/tools/llvm-lib/exportas.test
@@ -0,0 +1,94 @@
+Test EXPORTAS in importlibs.
+
+RUN: split-file %s %t.dir && cd %t.dir
+RUN: llvm-lib -machine:amd64 -def:test.def -out:test.lib
+
+RUN: llvm-nm --print-armap test.lib | FileCheck --check-prefix=ARMAP %s
+
+ARMAP:      Archive map
+ARMAP-NEXT: __IMPORT_DESCRIPTOR_test in test.dll
+ARMAP-NEXT: __NULL_IMPORT_DESCRIPTOR in test.dll
+ARMAP-NEXT: __imp_func in test.dll
+ARMAP-NEXT: __imp_func2 in test.dll
+ARMAP-NEXT: __imp_func3 in test.dll
+ARMAP-NEXT: __imp_mydata in test.dll
+ARMAP-NEXT: func in test.dll
+ARMAP-NEXT: func2 in test.dll
+ARMAP-NEXT: func3 in test.dll
+ARMAP-NEXT: test_NULL_THUNK_DATA in test.dll
+
+RUN: llvm-readobj test.lib | FileCheck --check-prefix=READOBJ %s
+
+READOBJ:      File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-x86-64
+READOBJ-NEXT: Arch: x86_64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-x86-64
+READOBJ-NEXT: Arch: x86_64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-x86-64
+READOBJ-NEXT: Arch: x86_64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expfunc
+READOBJ-NEXT: Symbol: __imp_func
+READOBJ-NEXT: Symbol: func
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: data
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expdata
+READOBJ-NEXT: Symbol: __imp_mydata
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expfunc2
+READOBJ-NEXT: Symbol: __imp_func2
+READOBJ-NEXT: Symbol: func2
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expfunc3
+READOBJ-NEXT: Symbol: __imp_func3
+READOBJ-NEXT: Symbol: func3
+
+
+EXPORTAS must be at the end of entry declaration.
+RUN: not llvm-lib -machine:amd64 -def:test2.def -out:test2.lib 2>&1 \
+RUN:              | FileCheck --check-prefix=ERROR %s
+RUN: not llvm-lib -machine:amd64 -def:test3.def -out:test3.lib 2>&1 \
+RUN:              | FileCheck --check-prefix=ERROR %s
+ERROR: Invalid data was encountered while parsing the file
+
+
+#--- test.def
+LIBRARY test.dll
+EXPORTS
+        func EXPORTAS expfunc
+        mydata DATA EXPORTAS expdata
+        func2 = myfunc2 EXPORTAS expfunc2
+        func3 = otherdll.otherfunc3 EXPORTAS expfunc3
+
+#--- test2.def
+LIBRARY test.dll
+EXPORTS
+        func EXPORTAS expfunc
+        mydata EXPORTAS expdata DATA
+
+#--- test3.def
+LIBRARY test.dll
+EXPORTS
+        mydata EXPORTAS
diff --git a/llvm/test/tools/llvm-readobj/COFF/file-headers.test b/llvm/test/tools/llvm-readobj/COFF/file-headers.test
index b83a6cf5b972b3..32f39e196b0001 100644
--- a/llvm/test/tools/llvm-readobj/COFF/file-headers.test
+++ b/llvm/test/tools/llvm-reado...
[truncated]

llvmbot · 2024-01-19T20:01:34Z

@llvm/pr-subscribers-lld-coff

Author: Jacek Caban (cjacek)

Changes

EXPORTAS is a new name type in import libraries. As far as I can tell, they are not documented. It's used by default on ARM64EC (this is not part of this PR, see cjacek@70946eb for a prototype of it), but MSVC allows using it on other platforms. I found the syntax from compiler-generated __declspec(dllexport) directives, which look like -export:#func,EXPORTAS,func, but MSVC also allows using it in .def files as well, which is what this PR implements. For the context, I also have a prototype of linker support: cjacek@1dbe8a6.

cc @bylaws

Patch is 21.10 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/78772.diff

15 Files Affected:

(modified) lld/test/COFF/def-export-cpp.s (+1)
(modified) lld/test/COFF/def-export-stdcall.s (+13)
(modified) lld/test/COFF/dllexport.s (+4)
(modified) llvm/include/llvm/BinaryFormat/COFF.h (+4-1)
(modified) llvm/include/llvm/Object/COFFImportFile.h (+5)
(modified) llvm/lib/Object/COFFImportFile.cpp (+70-21)
(modified) llvm/lib/Object/COFFModuleDefinition.cpp (+12-1)
(modified) llvm/test/tools/llvm-dlltool/coff-decorated.def (+7)
(modified) llvm/test/tools/llvm-dlltool/coff-exports.def (+3)
(modified) llvm/test/tools/llvm-dlltool/coff-noname.def (+1)
(modified) llvm/test/tools/llvm-dlltool/no-leading-underscore.def (+2)
(modified) llvm/test/tools/llvm-lib/arm64ec-implib.test (+2)
(added) llvm/test/tools/llvm-lib/exportas.test (+94)
(modified) llvm/test/tools/llvm-readobj/COFF/file-headers.test (+1)
(modified) llvm/tools/llvm-readobj/COFFImportDumper.cpp (+6)

diff --git a/lld/test/COFF/def-export-cpp.s b/lld/test/COFF/def-export-cpp.s
index e00b35b1c5b39bb..370b8ddba4104b4 100644
--- a/lld/test/COFF/def-export-cpp.s
+++ b/lld/test/COFF/def-export-cpp.s
@@ -10,6 +10,7 @@
 
 # IMPLIB: File: foo.dll
 # IMPLIB: Name type: undecorate
+# IMPLIB-NEXT: Export name: GetPathOnDisk
 # IMPLIB-NEXT: Symbol: __imp_?GetPathOnDisk@@YA_NPEA_W@Z
 # IMPLIB-NEXT: Symbol: ?GetPathOnDisk@@YA_NPEA_W@Z
 
diff --git a/lld/test/COFF/def-export-stdcall.s b/lld/test/COFF/def-export-stdcall.s
index f015e205c74a33d..7e4e04c77cbe7a5 100644
--- a/lld/test/COFF/def-export-stdcall.s
+++ b/lld/test/COFF/def-export-stdcall.s
@@ -6,15 +6,19 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix UNDECORATED-EXPORTS %s
 
 # UNDECORATED-IMPLIB: Name type: noprefix
+# UNDECORATED-IMPLIB-NEXT: Export name: _underscored
 # UNDECORATED-IMPLIB-NEXT: __imp___underscored
 # UNDECORATED-IMPLIB-NEXT: __underscored
 # UNDECORATED-IMPLIB: Name type: undecorate
+# UNDECORATED-IMPLIB-NEXT: Export name: fastcall
 # UNDECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # UNDECORATED-IMPLIB-NEXT: fastcall@8
 # UNDECORATED-IMPLIB: Name type: undecorate
+# UNDECORATED-IMPLIB-NEXT: Export name: stdcall
 # UNDECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # UNDECORATED-IMPLIB-NEXT: _stdcall@8
 # UNDECORATED-IMPLIB: Name type: undecorate
+# UNDECORATED-IMPLIB-NEXT: Export name: vectorcall
 # UNDECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # UNDECORATED-IMPLIB-NEXT: vectorcall@@8
 
@@ -30,12 +34,15 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix DECORATED-EXPORTS %s
 
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: @fastcall@8
 # DECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-IMPLIB-NEXT: @fastcall@8
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: _stdcall@8
 # DECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: vectorcall@@8
 # DECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-IMPLIB-NEXT: vectorcall@@8
 
@@ -51,14 +58,17 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix DECORATED-MINGW-EXPORTS %s
 
 # DECORATED-MINGW-IMPLIB: Name type: name
+# DECORATED-MINGW-IMPLIB-NEXT: Export name: @fastcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: fastcall@8
 # DECORATED-MINGW-IMPLIB: Name type: noprefix
+# DECORATED-MINGW-IMPLIB-NEXT: Export name: stdcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-MINGW-IMPLIB-NEXT: _stdcall@8
 # GNU tools don't support vectorcall, but this test is just to track that
 # lld's behaviour remains consistent over time.
 # DECORATED-MINGW-IMPLIB: Name type: name
+# DECORATED-MINGW-IMPLIB-NEXT: Export name: vectorcall@@8
 # DECORATED-MINGW-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-MINGW-IMPLIB-NEXT: vectorcall@@8
 
@@ -75,14 +85,17 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix MINGW-KILL-AT-EXPORTS %s
 
 # MINGW-KILL-AT-IMPLIB: Name type: noprefix
+# MINGW-KILL-AT-IMPLIB: Export name: fastcall
 # MINGW-KILL-AT-IMPLIB: __imp__fastcall
 # MINGW-KILL-AT-IMPLIB-NEXT: _fastcall
 # MINGW-KILL-AT-IMPLIB: Name type: noprefix
+# MINGW-KILL-AT-IMPLIB-NEXT: Export name: stdcall
 # MINGW-KILL-AT-IMPLIB-NEXT: __imp__stdcall
 # MINGW-KILL-AT-IMPLIB-NEXT: _stdcall
 # GNU tools don't support vectorcall, but this test is just to track that
 # lld's behaviour remains consistent over time.
 # MINGW-KILL-AT-IMPLIB: Name type: noprefix
+# MINGW-KILL-AT-IMPLIB-NEXT: Export name: vectorcall
 # MINGW-KILL-AT-IMPLIB-NEXT: __imp__vectorcall
 # MINGW-KILL-AT-IMPLIB-NEXT: _vectorcall
 
diff --git a/lld/test/COFF/dllexport.s b/lld/test/COFF/dllexport.s
index a238b70ce1b4f69..b04ebc3a33c3e2d 100644
--- a/lld/test/COFF/dllexport.s
+++ b/lld/test/COFF/dllexport.s
@@ -6,15 +6,19 @@
 # RUN: llvm-readobj --coff-exports %t.dll | FileCheck -check-prefix DECORATED-EXPORTS %s
 
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: @fastcall@8
 # DECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-IMPLIB-NEXT: @fastcall@8
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: _stdcall@8
 # DECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: noprefix
+# DECORATED-IMPLIB-NEXT: Export name: _underscored
 # DECORATED-IMPLIB-NEXT: __imp___underscored
 # DECORATED-IMPLIB-NEXT: __underscored
 # DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: Export name: vectorcall@@8
 # DECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-IMPLIB-NEXT: vectorcall@@8
 
diff --git a/llvm/include/llvm/BinaryFormat/COFF.h b/llvm/include/llvm/BinaryFormat/COFF.h
index 522ee37da6e830c..72461d0d9c316a3 100644
--- a/llvm/include/llvm/BinaryFormat/COFF.h
+++ b/llvm/include/llvm/BinaryFormat/COFF.h
@@ -716,7 +716,10 @@ enum ImportNameType : unsigned {
   IMPORT_NAME_NOPREFIX = 2,
   /// The import name is the public symbol name, but skipping the leading ?,
   /// @, or optionally _, and truncating at the first @.
-  IMPORT_NAME_UNDECORATE = 3
+  IMPORT_NAME_UNDECORATE = 3,
+  /// The import name is specified as a separate string in the import library
+  /// object file.
+  IMPORT_NAME_EXPORTAS = 4
 };
 
 enum class GuardFlags : uint32_t {
diff --git a/llvm/include/llvm/Object/COFFImportFile.h b/llvm/include/llvm/Object/COFFImportFile.h
index edc836ff0348cb2..7c5846e9c044e39 100644
--- a/llvm/include/llvm/Object/COFFImportFile.h
+++ b/llvm/include/llvm/Object/COFFImportFile.h
@@ -66,6 +66,7 @@ class COFFImportFile : public SymbolicFile {
   uint16_t getMachine() const { return getCOFFImportHeader()->Machine; }
 
   StringRef getFileFormatName() const;
+  StringRef getExportName() const;
 
 private:
   bool isData() const {
@@ -91,6 +92,10 @@ struct COFFShortExport {
   /// file, this is "baz" in "EXPORTS\nfoo = bar == baz".
   std::string AliasTarget;
 
+  /// Specifies EXPORTAS name. In a .def file, this is "bar" in
+  /// "EXPORTS\nfoo EXPORTAS bar".
+  std::string ExportAs;
+
   uint16_t Ordinal = 0;
   bool Noname = false;
   bool Data = false;
diff --git a/llvm/lib/Object/COFFImportFile.cpp b/llvm/lib/Object/COFFImportFile.cpp
index 60556c149bf735b..b666ca3fd40300d 100644
--- a/llvm/lib/Object/COFFImportFile.cpp
+++ b/llvm/lib/Object/COFFImportFile.cpp
@@ -52,6 +52,37 @@ StringRef COFFImportFile::getFileFormatName() const {
   }
 }
 
+StringRef COFFImportFile::getExportName() const {
+  const coff_import_header *hdr = getCOFFImportHeader();
+  StringRef name = StringRef(Data.getBufferStart() + sizeof(*hdr));
+
+  auto ltrim1 = [](StringRef s, const char *chars) {
+    return !s.empty() && strchr(chars, s[0]) ? s.substr(1) : s;
+  };
+
+  switch (hdr->getNameType()) {
+  case IMPORT_ORDINAL:
+    name = "";
+    break;
+  case IMPORT_NAME_NOPREFIX:
+    name = ltrim1(name, "?@_");
+    break;
+  case IMPORT_NAME_UNDECORATE:
+    name = ltrim1(name, "?@_");
+    name = name.substr(0, name.find('@'));
+    break;
+  case IMPORT_NAME_EXPORTAS: {
+    StringRef dllName = StringRef(name.begin() + name.size() + 1);
+    name = StringRef(dllName.begin() + dllName.size() + 1);
+    break;
+  }
+  default:
+    break;
+  }
+
+  return name;
+}
+
 static uint16_t getImgRelRelocation(MachineTypes Machine) {
   switch (Machine) {
   default:
@@ -183,6 +214,7 @@ class ObjectFactory {
   // Library Format.
   NewArchiveMember createShortImport(StringRef Sym, uint16_t Ordinal,
                                      ImportType Type, ImportNameType NameType,
+                                     StringRef ExportName,
                                      MachineTypes Machine);
 
   // Create a weak external file which is described in PE/COFF Aux Format 3.
@@ -474,12 +506,13 @@ NewArchiveMember ObjectFactory::createNullThunk(std::vector<uint8_t> &Buffer) {
   return {MemoryBufferRef{F, ImportName}};
 }
 
-NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
-                                                  uint16_t Ordinal,
-                                                  ImportType ImportType,
-                                                  ImportNameType NameType,
-                                                  MachineTypes Machine) {
+NewArchiveMember
+ObjectFactory::createShortImport(StringRef Sym, uint16_t Ordinal,
+                                 ImportType ImportType, ImportNameType NameType,
+                                 StringRef ExportName, MachineTypes Machine) {
   size_t ImpSize = ImportName.size() + Sym.size() + 2; // +2 for NULs
+  if (!ExportName.empty())
+    ImpSize += ExportName.size() + 1;
   size_t Size = sizeof(coff_import_header) + ImpSize;
   char *Buf = Alloc.Allocate<char>(Size);
   memset(Buf, 0, Size);
@@ -499,6 +532,10 @@ NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
   memcpy(P, Sym.data(), Sym.size());
   P += Sym.size() + 1;
   memcpy(P, ImportName.data(), ImportName.size());
+  if (!ExportName.empty()) {
+    P += ImportName.size() + 1;
+    memcpy(P, ExportName.data(), ExportName.size());
+  }
 
   return {MemoryBufferRef(StringRef(Buf, Size), ImportName)};
 }
@@ -615,27 +652,39 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
       ImportType = IMPORT_CONST;
 
     StringRef SymbolName = E.SymbolName.empty() ? E.Name : E.SymbolName;
-    ImportNameType NameType = E.Noname
-                                  ? IMPORT_ORDINAL
-                                  : getNameType(SymbolName, E.Name,
-                                                Machine, MinGW);
-    Expected<std::string> Name = E.ExtName.empty()
-                                     ? std::string(SymbolName)
-                                     : replace(SymbolName, E.Name, E.ExtName);
-
-    if (!Name)
-      return Name.takeError();
-
-    if (!E.AliasTarget.empty() && *Name != E.AliasTarget) {
+    std::string Name;
+
+    if (E.ExtName.empty()) {
+      Name = std::string(SymbolName);
+    } else {
+      Expected<std::string> ReplacedName =
+          replace(SymbolName, E.Name, E.ExtName);
+      if (!ReplacedName)
+        return ReplacedName.takeError();
+      Name.swap(*ReplacedName);
+    }
+
+    if (!E.AliasTarget.empty() && Name != E.AliasTarget) {
       Members.push_back(
-          OF.createWeakExternal(E.AliasTarget, *Name, false, Machine));
+          OF.createWeakExternal(E.AliasTarget, Name, false, Machine));
       Members.push_back(
-          OF.createWeakExternal(E.AliasTarget, *Name, true, Machine));
+          OF.createWeakExternal(E.AliasTarget, Name, true, Machine));
       continue;
     }
 
-    Members.push_back(
-        OF.createShortImport(*Name, E.Ordinal, ImportType, NameType, Machine));
+    ImportNameType NameType;
+    std::string ExportName;
+    if (E.Noname) {
+      NameType = IMPORT_ORDINAL;
+    } else if (!E.ExportAs.empty()) {
+      NameType = IMPORT_NAME_EXPORTAS;
+      ExportName = E.ExportAs;
+    } else {
+      NameType = getNameType(SymbolName, E.Name, Machine, MinGW);
+    }
+
+    Members.push_back(OF.createShortImport(Name, E.Ordinal, ImportType,
+                                           NameType, ExportName, Machine));
   }
 
   return writeArchive(Path, Members, SymtabWritingMode::NormalSymtab,
diff --git a/llvm/lib/Object/COFFModuleDefinition.cpp b/llvm/lib/Object/COFFModuleDefinition.cpp
index 648f01f823d007a..f60dd49793685fa 100644
--- a/llvm/lib/Object/COFFModuleDefinition.cpp
+++ b/llvm/lib/Object/COFFModuleDefinition.cpp
@@ -39,6 +39,7 @@ enum Kind {
   KwConstant,
   KwData,
   KwExports,
+  KwExportAs,
   KwHeapsize,
   KwLibrary,
   KwName,
@@ -118,6 +119,7 @@ class Lexer {
                    .Case("CONSTANT", KwConstant)
                    .Case("DATA", KwData)
                    .Case("EXPORTS", KwExports)
+                   .Case("EXPORTAS", KwExportAs)
                    .Case("HEAPSIZE", KwHeapsize)
                    .Case("LIBRARY", KwLibrary)
                    .Case("NAME", KwName)
@@ -286,7 +288,16 @@ class Parser {
           E.AliasTarget = std::string("_").append(E.AliasTarget);
         continue;
       }
-      unget();
+      // EXPORTAS must be at the end of export definition
+      if (Tok.K == KwExportAs) {
+        read();
+        if (Tok.K == Eof)
+          return createError(
+              "unexpected end of file, EXPORTAS identifier expected");
+        E.ExportAs = std::string(Tok.Value);
+      } else {
+        unget();
+      }
       Info.Exports.push_back(E);
       return Error::success();
     }
diff --git a/llvm/test/tools/llvm-dlltool/coff-decorated.def b/llvm/test/tools/llvm-dlltool/coff-decorated.def
index 856804686168b17..fc81f23d09d6c48 100644
--- a/llvm/test/tools/llvm-dlltool/coff-decorated.def
+++ b/llvm/test/tools/llvm-dlltool/coff-decorated.def
@@ -14,25 +14,32 @@ OtherStdcallExportName@4=CdeclInternalFunction
 CdeclExportName=StdcallInternalFunction@4
 
 ; CHECK:      Name type: noprefix
+; CHECK-NEXT: Export name: CdeclFunction
 ; CHECK-NEXT: Symbol: __imp__CdeclFunction
 ; CHECK-NEXT: Symbol: _CdeclFunction
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: StdcallFunction
 ; CHECK-NEXT: Symbol: __imp__StdcallFunction@4
 ; CHECK-NEXT: Symbol: _StdcallFunction@4
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: FastcallFunction
 ; CHECK-NEXT: Symbol: __imp_@FastcallFunction@4
 ; CHECK-NEXT: Symbol: @FastcallFunction@4
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: ??_7exception@@6B@
 ; CHECK-NEXT: Symbol: __imp_??_7exception@@6B@
 ; CHECK-NEXT: Symbol: ??_7exception@@6B@
 ; CHECK-NM: W _StdcallAlias@4
 ; CHECK-NM: U _StdcallFunction@4
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: StdcallExportName
 ; CHECK-NEXT: Symbol: __imp__StdcallExportName@4{{$}}
 ; CHECK-NEXT: Symbol: _StdcallExportName@4{{$}}
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: OtherStdcallExportName
 ; CHECK-NEXT: Symbol: __imp__OtherStdcallExportName@4{{$}}
 ; CHECK-NEXT: Symbol: _OtherStdcallExportName@4{{$}}
 ; CHECK:      Name type: noprefix
+; CHECK-NEXT: Export name: CdeclExportName
 ; CHECK-NEXT: Symbol: __imp__CdeclExportName
 ; CHECK-NEXT: Symbol: _CdeclExportName
diff --git a/llvm/test/tools/llvm-dlltool/coff-exports.def b/llvm/test/tools/llvm-dlltool/coff-exports.def
index 57c557446021565..267424db1b8c1da 100644
--- a/llvm/test/tools/llvm-dlltool/coff-exports.def
+++ b/llvm/test/tools/llvm-dlltool/coff-exports.def
@@ -17,12 +17,15 @@ AnotherFunction
 ; CHECK-ARM64: Format: COFF-import-file-ARM64
 ; CHECK: Type: code
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: TestFunction1
 ; CHECK-NEXT: Symbol: __imp_TestFunction1
 ; CHECK-NEXT: Symbol: TestFunction1
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: TestFunction2
 ; CHECK-NEXT: Symbol: __imp_TestFunction2{{$}}
 ; CHECK-NEXT: Symbol: TestFunction2{{$}}
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: TestFunction3
 ; CHECK-NEXT: Symbol: __imp_TestFunction3{{$}}
 ; CHECK-NEXT: Symbol: TestFunction3{{$}}
 
diff --git a/llvm/test/tools/llvm-dlltool/coff-noname.def b/llvm/test/tools/llvm-dlltool/coff-noname.def
index 27e60efbd2d8027..7cb05846ce28a20 100644
--- a/llvm/test/tools/llvm-dlltool/coff-noname.def
+++ b/llvm/test/tools/llvm-dlltool/coff-noname.def
@@ -12,5 +12,6 @@ ByNameFunction
 ; CHECK-NEXT: Symbol: __imp__ByOrdinalFunction
 ; CHECK-NEXT: Symbol: _ByOrdinalFunction
 ; CHECK:      Name type: noprefix
+; CHECK-NEXT: Export name: ByNameFunction
 ; CHECK-NEXT: Symbol: __imp__ByNameFunction
 ; CHECK-NEXT: Symbol: _ByNameFunction
diff --git a/llvm/test/tools/llvm-dlltool/no-leading-underscore.def b/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
index 6b78e15d2b5f695..9c5e77ca29a8212 100644
--- a/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
+++ b/llvm/test/tools/llvm-dlltool/no-leading-underscore.def
@@ -9,9 +9,11 @@ alias == func
 DecoratedFunction@4
 
 ; CHECK:      Name type: name
+; CHECK-NEXT: Export name: func
 ; CHECK-NEXT: Symbol: __imp_func
 ; CHECK-NEXT: Symbol: func
 ; CHECK:      Name type: undecorate
+; CHECK-NEXT: Export name: DecoratedFunction
 ; CHECK-NEXT: Symbol: __imp_DecoratedFunction@4
 ; CHECK-NEXT: Symbol: DecoratedFunction@4
 
diff --git a/llvm/test/tools/llvm-lib/arm64ec-implib.test b/llvm/test/tools/llvm-lib/arm64ec-implib.test
index 2672f8d38b7f704..4250c775daa6012 100644
--- a/llvm/test/tools/llvm-lib/arm64ec-implib.test
+++ b/llvm/test/tools/llvm-lib/arm64ec-implib.test
@@ -36,6 +36,7 @@ READOBJ-NEXT: File: test.dll
 READOBJ-NEXT: Format: COFF-import-file-ARM64EC
 READOBJ-NEXT: Type: code
 READOBJ-NEXT: Name type: name
+READOBJ-NEXT: Export name: funcexp
 READOBJ-NEXT: Symbol: __imp_funcexp
 READOBJ-NEXT: Symbol: funcexp
 READOBJ-EMPTY:
@@ -43,6 +44,7 @@ READOBJ-NEXT: File: test.dll
 READOBJ-NEXT: Format: COFF-import-file-ARM64EC
 READOBJ-NEXT: Type: data
 READOBJ-NEXT: Name type: name
+READOBJ-NEXT: Export name: dataexp
 READOBJ-NEXT: Symbol: __imp_dataexp
 
 Creating a new lib containing the existing lib:
diff --git a/llvm/test/tools/llvm-lib/exportas.test b/llvm/test/tools/llvm-lib/exportas.test
new file mode 100644
index 000000000000000..f6e845ca174664a
--- /dev/null
+++ b/llvm/test/tools/llvm-lib/exportas.test
@@ -0,0 +1,94 @@
+Test EXPORTAS in importlibs.
+
+RUN: split-file %s %t.dir && cd %t.dir
+RUN: llvm-lib -machine:amd64 -def:test.def -out:test.lib
+
+RUN: llvm-nm --print-armap test.lib | FileCheck --check-prefix=ARMAP %s
+
+ARMAP:      Archive map
+ARMAP-NEXT: __IMPORT_DESCRIPTOR_test in test.dll
+ARMAP-NEXT: __NULL_IMPORT_DESCRIPTOR in test.dll
+ARMAP-NEXT: __imp_func in test.dll
+ARMAP-NEXT: __imp_func2 in test.dll
+ARMAP-NEXT: __imp_func3 in test.dll
+ARMAP-NEXT: __imp_mydata in test.dll
+ARMAP-NEXT: func in test.dll
+ARMAP-NEXT: func2 in test.dll
+ARMAP-NEXT: func3 in test.dll
+ARMAP-NEXT: test_NULL_THUNK_DATA in test.dll
+
+RUN: llvm-readobj test.lib | FileCheck --check-prefix=READOBJ %s
+
+READOBJ:      File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-x86-64
+READOBJ-NEXT: Arch: x86_64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-x86-64
+READOBJ-NEXT: Arch: x86_64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-x86-64
+READOBJ-NEXT: Arch: x86_64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expfunc
+READOBJ-NEXT: Symbol: __imp_func
+READOBJ-NEXT: Symbol: func
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: data
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expdata
+READOBJ-NEXT: Symbol: __imp_mydata
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expfunc2
+READOBJ-NEXT: Symbol: __imp_func2
+READOBJ-NEXT: Symbol: func2
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file-x86-64
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: export as
+READOBJ-NEXT: Export name: expfunc3
+READOBJ-NEXT: Symbol: __imp_func3
+READOBJ-NEXT: Symbol: func3
+
+
+EXPORTAS must be at the end of entry declaration.
+RUN: not llvm-lib -machine:amd64 -def:test2.def -out:test2.lib 2>&1 \
+RUN:              | FileCheck --check-prefix=ERROR %s
+RUN: not llvm-lib -machine:amd64 -def:test3.def -out:test3.lib 2>&1 \
+RUN:              | FileCheck --check-prefix=ERROR %s
+ERROR: Invalid data was encountered while parsing the file
+
+
+#--- test.def
+LIBRARY test.dll
+EXPORTS
+        func EXPORTAS expfunc
+        mydata DATA EXPORTAS expdata
+        func2 = myfunc2 EXPORTAS expfunc2
+        func3 = otherdll.otherfunc3 EXPORTAS expfunc3
+
+#--- test2.def
+LIBRARY test.dll
+EXPORTS
+        func EXPORTAS expfunc
+        mydata EXPORTAS expdata DATA
+
+#--- test3.def
+LIBRARY test.dll
+EXPORTS
+        mydata EXPORTAS
diff --git a/llvm/test/tools/llvm-readobj/COFF/file-headers.test b/llvm/test/tools/llvm-readobj/COFF/file-headers.test
index b83a6cf5b972b34..32f39e196b0001d 100644
--- a/llvm/test/tools/llvm-readobj/COFF/file-headers.test
+++ ...
[truncated]

cjacek · 2024-01-19T20:01:54Z

Depends on #78769.

cdavis5e · 2024-01-19T23:21:28Z

What's the difference between this and MinGW's == extension?

cjacek · 2024-01-20T01:18:37Z

MinGW extension adds a COFF object to import library that creates a weak external symbol. EXPORTAS is extends short import file format to store export name separate from symbol name.

cdavis5e · 2024-01-20T03:53:29Z

MinGW extension adds a COFF object to import library that creates a weak external symbol.

Really? In LLVM, maybe. I could've sworn that GNU dlltool doesn't do that; instead, it sets the imported name in the long-form import file objects it generates (.idata$6 section). A bit like what this change does, actually.

cjacek · 2024-01-22T00:48:01Z

I meant llvm-dlltool. You're right, GNU dlltool indeed uses a regular COFF object to achieve essentially the same result.

That makes EXPORTAS a potential replacement for using weak externals. I don't think we want to change that by default as it would break compatibility with linkers that don't support EXPORTAS. However, doing that for ARM64EC, which has additional auxiliary IAT symbols, seems right.

cjacek · 2024-01-25T00:33:03Z

New new version contains updated version of #78769 commit and similar string changes to getExportName.

cjacek · 2024-02-06T12:53:07Z

Rebased after #78769 landed.

dpaoliello · 2024-02-09T22:49:38Z

Feels like this depends on #81059

cjacek · 2024-02-09T23:07:16Z

My intention was for #81059 to depend on this one. Its first commit is the same as this PR, I meant it to be "stacked" PR, sorry if I made it wrong.

dpaoliello · 2024-02-09T23:15:05Z

My intention was for #81059 to depend on this one. Its first commit is the same as this PR, I meant it to be "stacked" PR, sorry if I made it wrong.

Ah, I didn't see that in the other PR, GitHub doesn't make it as explicit as phabricator did.

…llvm#78772) EXPORTAS is a new name type in import libraries. It's used by default on ARM64EC, but it's allowed on other platforms as well.

#83211) This allows handling importlibs produced by llvm-dlltool in #78772. ARM64EC import libraries use it by default, but it's supported by MSVC link.exe on other platforms too. This also avoids assuming null-terminated input, like in #78769.

…llvm#78772) EXPORTAS is a new name type in import libraries. It's used by default on ARM64EC, but it's allowed on other platforms as well.

#78772 added similar support for .def file parser and import library writer. This PR adds missing bits in LLD to propagate EXPORTAS name and allow it in `/export` parser. This is syntax is used by MSVC for ARM64EC `__declspec(dllexport)` handling.

cjacek requested review from compnerd, mstorsjo, MaskRay, jh7370 and efriedma-quic January 19, 2024 20:01

llvmbot added lld lld:COFF llvm:binary-utilities labels Jan 19, 2024

cjacek force-pushed the def-exportas branch from 5b0b654 to 4107b81 Compare January 25, 2024 00:31

cjacek force-pushed the def-exportas branch from 4107b81 to 6667573 Compare February 6, 2024 12:52

cjacek mentioned this pull request Feb 8, 2024

[llvm-lib][Object] Add support for EC importlib symbols. #81059

Merged

cjacek requested a review from dpaoliello February 9, 2024 19:57

dpaoliello approved these changes Feb 9, 2024

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[llvm-lib][llvm-dlltool][Object] Add support for EXPORTAS name types.

0311c75

cjacek force-pushed the def-exportas branch from 6667573 to 0311c75 Compare February 9, 2024 23:53

cjacek merged commit 8f23464 into llvm:main Feb 10, 2024
3 of 4 checks passed

cjacek deleted the def-exportas branch February 10, 2024 00:00

cjacek mentioned this pull request Feb 27, 2024

[LLD][COFF] Add support for IMPORT_NAME_EXPORTAS import library names. #83211

Merged

dpaoliello mentioned this pull request Mar 9, 2024

Backport fixes for ARM64EC import libraries #84590

Merged

cjacek mentioned this pull request Mar 25, 2024

[LLD][COFF] Add support for EXPORTAS import name type. #86541

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pointhex mentioned this pull request May 7, 2024

getStyleDiagHandler #91314

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aemerson mentioned this pull request May 9, 2024

release/18.x: [AArc64][GlobalISel] Fix legalizer assert for G_INSERT_VECTOR_ELT - manual merge #91672

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[llvm-lib][llvm-dlltool][Object] Add support for EXPORTAS name types. #78772

[llvm-lib][llvm-dlltool][Object] Add support for EXPORTAS name types. #78772

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[llvm-lib][llvm-dlltool][Object] Add support for EXPORTAS name types. #78772

[llvm-lib][llvm-dlltool][Object] Add support for EXPORTAS name types. #78772

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