[llvm-dlltool] Fix renamed imports without a separate regular import entry

lld/test/COFF/lib.test

@@ -1,6 +1,14 @@
 # RUN: lld-link /machine:x64 /def:%S/Inputs/library.def /out:%t.lib
 # RUN: llvm-nm %t.lib | FileCheck %s
 
+CHECK: 00000000 R __imp_constant
+CHECK: 00000000 R constant
+
+CHECK: 00000000 D __imp_data
+
+CHECK: 00000000 T __imp_function
+CHECK: 00000000 T function
+
 CHECK: 00000000 a @comp.id
 CHECK: 00000000 a @feat.00
 CHECK: 00000000 W alias
@@ -11,11 +19,3 @@ CHECK: 00000000 a @feat.00
 CHECK: 00000000 W __imp_alias
 CHECK:          U __imp_function
 
-CHECK: 00000000 R __imp_constant
-CHECK: 00000000 R constant
-
-CHECK: 00000000 D __imp_data
-
-CHECK: 00000000 T __imp_function
-CHECK: 00000000 T function
-

llvm/include/llvm/Object/COFFImportFile.h

@@ -135,11 +135,10 @@ struct COFFShortExport {
 /// linking both ARM64EC and pure ARM64 objects, and the linker will pick only
 /// the exports relevant to the target platform. For non-hybrid targets,
 /// the NativeExports parameter should not be used.
-Error writeImportLibrary(StringRef ImportName, StringRef Path,
-                         ArrayRef<COFFShortExport> Exports,
-                         COFF::MachineTypes Machine, bool MinGW,
-                         ArrayRef<COFFShortExport> NativeExports = std::nullopt,
-                         bool AddUnderscores = true);
+Error writeImportLibrary(
+    StringRef ImportName, StringRef Path, ArrayRef<COFFShortExport> Exports,
+    COFF::MachineTypes Machine, bool MinGW,
+    ArrayRef<COFFShortExport> NativeExports = std::nullopt);
 
 } // namespace object
 } // namespace llvm

llvm/lib/Object/COFFImportFile.cpp

@@ -12,6 +12,8 @@
 
 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/ArchiveWriter.h"
@@ -657,8 +659,7 @@ NewArchiveMember ObjectFactory::createWeakExternal(StringRef Sym,
 Error writeImportLibrary(StringRef ImportName, StringRef Path,
                          ArrayRef<COFFShortExport> Exports,
                          MachineTypes Machine, bool MinGW,
-                         ArrayRef<COFFShortExport> NativeExports,
-                         bool AddUnderscores) {
+                         ArrayRef<COFFShortExport> NativeExports) {
 
   MachineTypes NativeMachine = Machine;
   if (isArm64EC(Machine)) {
@@ -680,6 +681,13 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
 
   auto addExports = [&](ArrayRef<COFFShortExport> Exp,
                         MachineTypes M) -> Error {
+    StringMap<std::string> RegularImports;
+    struct Deferred {
+      std::string Name;
+      ImportType ImpType;
+      const COFFShortExport *Export;
+    };
+    SmallVector<Deferred, 0> Renames;
     for (const COFFShortExport &E : Exp) {
       if (E.Private)
         continue;
@@ -724,15 +732,11 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
         else if (Name == E.ImportName)
           NameType = IMPORT_NAME;
         else {
-          StringRef Prefix = "";
-          if (Machine == IMAGE_FILE_MACHINE_I386 && AddUnderscores)
-            Prefix = "_";
-
-          if (ImportType == IMPORT_CODE)
-            Members.push_back(OF.createWeakExternal(
-                (Prefix + E.ImportName).str(), Name, false, M));
-          Members.push_back(OF.createWeakExternal((Prefix + E.ImportName).str(),
-                                                  Name, true, M));
+          Deferred D;
+          D.Name = Name;
+          D.ImpType = ImportType;
+          D.Export = &E;
+          Renames.push_back(D);
           continue;
         }
       } else {
@@ -754,9 +758,25 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
         }
       }
 
+      RegularImports[applyNameType(NameType, Name)] = Name;
       Members.push_back(OF.createShortImport(Name, E.Ordinal, ImportType,
                                              NameType, ExportName, M));
     }
+    for (const auto &D : Renames) {
+      auto It = RegularImports.find(D.Export->ImportName);
+      if (It != RegularImports.end()) {
+        // We have a regular import entry for a symbol with the name we
+        // want to reference; produce an alias pointing at that.
+        StringRef Symbol = It->second;
+        if (D.ImpType == IMPORT_CODE)
+          Members.push_back(OF.createWeakExternal(Symbol, D.Name, false, M));
+        Members.push_back(OF.createWeakExternal(Symbol, D.Name, true, M));
+      } else {
+        Members.push_back(OF.createShortImport(D.Name, D.Export->Ordinal,
+                                               D.ImpType, IMPORT_NAME_EXPORTAS,
+                                               D.Export->ImportName, M));
+      }
+    }
     return Error::success();
   };
 

llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp

@@ -243,9 +243,8 @@ int llvm::dlltoolDriverMain(llvm::ArrayRef<const char *> ArgsArr) {
   }
 
   std::string Path = std::string(Args.getLastArgValue(OPT_l));
-  if (!Path.empty() &&
-      writeImportLibrary(OutputFile, Path, Exports, Machine,
-                         /*MinGW=*/true, NativeExports, AddUnderscores))
+  if (!Path.empty() && writeImportLibrary(OutputFile, Path, Exports, Machine,
+                                          /*MinGW=*/true, NativeExports))
     return 1;
   return 0;
 }

llvm/test/tools/llvm-dlltool/coff-decorated.def

@@ -7,7 +7,7 @@ EXPORTS
 CdeclFunction
 StdcallFunction@4
 @FastcallFunction@4
-StdcallAlias@4==StdcallFunction@4
+StdcallAlias@4==StdcallFunction
 ??_7exception@@6B@
 StdcallExportName@4=StdcallInternalFunction@4
 OtherStdcallExportName@4=CdeclInternalFunction

llvm/test/tools/llvm-dlltool/coff-weak-exports.def

@@ -5,6 +5,9 @@
 
 LIBRARY test.dll
 EXPORTS
+AltTestFunction
+AltTestFunction2
+AltTestData
 TestFunction==AltTestFunction
 TestData DATA == AltTestData
 ; When creating an import library, the DLL internal function name of
@@ -17,21 +20,25 @@ ImpLibName2 = Implementation2 == AltTestFunction2
 ; matter for the import library
 ImpLibName3 = kernel32.Sleep
 
+; CHECK:      T AltTestFunction
+; CHECK-NEXT: T __imp_AltTestFunction
+; CHECK:      T AltTestFunction2
+; CHECK-NEXT: T __imp_AltTestFunction2
+; CHECK:      T ImpLibName
+; CHECK-NEXT: T __imp_ImpLibName
+; CHECK:      T ImpLibName3
+; CHECK-NEXT: T __imp_ImpLibName3
 ; CHECK:      U AltTestFunction
 ; CHECK-NEXT: W TestFunction
 ; CHECK:      U __imp_AltTestFunction
 ; CHECK-NEXT: W __imp_TestFunction
 ; CHECK-NOT:  W TestData
 ; CHECK:      U __imp_AltTestData
 ; CHECK-NEXT: W __imp_TestData
-; CHECK:      T ImpLibName
-; CHECK-NEXT: T __imp_ImpLibName
 ; CHECK:      U AltTestFunction2
 ; CHECK-NEXT: W ImpLibName2
 ; CHECK:      U __imp_AltTestFunction2
 ; CHECK-NEXT: W __imp_ImpLibName2
-; CHECK:      T ImpLibName3
-; CHECK-NEXT: T __imp_ImpLibName3
 
 ; ARCH-NOT: unknown arch
 

llvm/test/tools/llvm-dlltool/renaming.def

@@ -0,0 +1,39 @@
+; RUN: llvm-dlltool -k -m i386 --input-def %s --output-lib %t.a
+; RUN: llvm-readobj %t.a | FileCheck %s
+; RUN: llvm-nm %t.a | FileCheck %s -check-prefix=CHECK-NM
+
+LIBRARY test.dll
+EXPORTS
+
+symbolname == actualimport
+
+dataname DATA == actualdata
+
+_wcstok == wcstok
+wcstok == wcstok_s
+
+; CHECK-NM-NOT: actualimport
+; CHECK-NM-NOT: actualdata
+
+; CHECK:      Type: code
+; CHECK-NEXT: Name type: export as
+; CHECK-NEXT: Export name: actualimport
+; CHECK-NEXT: Symbol: __imp__symbolname
+; CHECK-NEXT: Symbol: _symbolname
+
+; CHECK:      Type: data
+; CHECK-NEXT: Name type: export as
+; CHECK-NEXT: Export name: actualdata
+; CHECK-NEXT: Symbol: __imp__dataname
+
+; CHECK:      Type: code
+; CHECK-NEXT: Name type: export as
+; CHECK-NEXT: Export name: wcstok
+; CHECK-NEXT: Symbol: __imp___wcstok
+; CHECK-NEXT: Symbol: __wcstok
+
+; CHECK:      Type: code
+; CHECK-NEXT: Name type: export as
+; CHECK-NEXT: Export name: wcstok_s
+; CHECK-NEXT: Symbol: __imp__wcstok
+; CHECK-NEXT: Symbol: _wcstok