[llvm-dlltool] Use EXPORTAS name type for renamed imports on ARM64EC.

Author: cjacek

llvm/lib/Object/COFFImportFile.cpp

@@ -729,7 +729,10 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
         else if (Machine == IMAGE_FILE_MACHINE_I386 &&
                  applyNameType(IMPORT_NAME_NOPREFIX, Name) == E.ImportName)
           NameType = IMPORT_NAME_NOPREFIX;
-        else if (Name == E.ImportName)
+        else if (isArm64EC(M)) {
+          NameType = IMPORT_NAME_EXPORTAS;
+          ExportName = E.ImportName;
+        } else if (Name == E.ImportName)
           NameType = IMPORT_NAME;
         else {
           Deferred D;

llvm/test/tools/llvm-dlltool/arm64ec.test

@@ -44,6 +44,19 @@ RUN: llvm-nm --print-armap test3.lib | FileCheck --check-prefix=ARMAP2 %s
 RUN: not llvm-dlltool -m arm64 -d test.def -N test2.def -l test4.lib 2>&1 | FileCheck --check-prefix=ERR %s
 ERR: native .def file is supported only on arm64ec target
 
+RUN: llvm-dlltool -m arm64ec -d test.def -l test3.lib
+RUN: llvm-readobj test3.lib | FileCheck --check-prefix=ALIAS %s
+
+ALIAS:      File: test.dll
+ALIAS-NEXT: Format: COFF-import-file-ARM64EC
+ALIAS-NEXT: Type: code
+ALIAS-NEXT: Name type: export as
+ALIAS-NEXT: Export name: func
+ALIAS-NEXT: Symbol: __imp_func
+ALIAS-NEXT: Symbol: func
+ALIAS-NEXT: Symbol: __imp_aux_func
+ALIAS-NEXT: Symbol: #func
+
 #--- test.def
 LIBRARY test.dll
 EXPORTS
@@ -53,3 +66,8 @@ EXPORTS
 LIBRARY test.dll
 EXPORTS
     otherfunc
+
+#--- test3.def
+LIBRARY test.dll
+EXPORTS
+    func == efunc