[llvm-lib] [Object] Use ECSYMBOLS section for ARM64EC importlib symbols. (#68328)

Author: cjacek

llvm/include/llvm/Object/COFFImportFile.h

@@ -63,6 +63,8 @@ class COFFImportFile : public SymbolicFile {
         Data.getBufferStart());
   }
 
+  uint16_t getMachine() const { return getCOFFImportHeader()->Machine; }
+
 private:
   bool isData() const {
     return getCOFFImportHeader()->getType() == COFF::IMPORT_DATA;

llvm/lib/Object/ArchiveWriter.cpp

@@ -18,6 +18,7 @@
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Object/COFF.h"
+#include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/Error.h"
 #include "llvm/Object/IRObjectFile.h"
 #include "llvm/Object/MachO.h"
@@ -659,6 +660,10 @@ static bool isECObject(object::SymbolicFile &Obj) {
     return cast<llvm::object::COFFObjectFile>(&Obj)->getMachine() !=
            COFF::IMAGE_FILE_MACHINE_ARM64;
 
+  if (Obj.isCOFFImportFile())
+    return cast<llvm::object::COFFImportFile>(&Obj)->getMachine() !=
+           COFF::IMAGE_FILE_MACHINE_ARM64;
+
   if (Obj.isIR()) {
     Expected<std::string> TripleStr =
         getBitcodeTargetTriple(Obj.getMemoryBufferRef());

llvm/lib/Object/COFFImportFile.cpp

@@ -612,7 +612,8 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
 
   return writeArchive(Path, Members, SymtabWritingMode::NormalSymtab,
                       MinGW ? object::Archive::K_GNU : object::Archive::K_COFF,
-                      /*Deterministic*/ true, /*Thin*/ false);
+                      /*Deterministic*/ true, /*Thin*/ false,
+                      /*OldArchiveBuf*/ nullptr, isArm64EC(Machine));
 }
 
 } // namespace object

llvm/test/tools/llvm-lib/arm64ec-implib.test

@@ -0,0 +1,54 @@
+Test creating ARM64EC importlib.
+
+RUN: split-file %s %t.dir && cd %t.dir
+RUN: llvm-lib -machine:arm64ec -def:test.def -out:test.lib
+
+RUN: llvm-nm --print-armap test.lib | FileCheck -check-prefix=ARMAP %s
+
+ARMAP:      Archive EC map
+ARMAP-NEXT: __IMPORT_DESCRIPTOR_test in test.dll
+ARMAP-NEXT: __NULL_IMPORT_DESCRIPTOR in test.dll
+ARMAP-NEXT: __imp_dataexp in test.dll
+ARMAP-NEXT: __imp_funcexp in test.dll
+ARMAP-NEXT: funcexp 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-ARM64EC
+READOBJ-NEXT: Arch: aarch64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-ARM64EC
+READOBJ-NEXT: Arch: aarch64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.lib(test.dll)
+READOBJ-NEXT: Format: COFF-ARM64
+READOBJ-NEXT: Arch: aarch64
+READOBJ-NEXT: AddressSize: 64bit
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file
+READOBJ-NEXT: Type: code
+READOBJ-NEXT: Name type: name
+READOBJ-NEXT: Symbol: __imp_funcexp
+READOBJ-NEXT: Symbol: funcexp
+READOBJ-EMPTY:
+READOBJ-NEXT: File: test.dll
+READOBJ-NEXT: Format: COFF-import-file
+READOBJ-NEXT: Type: data
+READOBJ-NEXT: Name type: name
+READOBJ-NEXT: Symbol: __imp_dataexp
+
+Creating a new lib containing the existing lib:
+RUN: llvm-lib -machine:arm64ec test.lib -out:test2.lib
+RUN: llvm-nm --print-armap test2.lib | FileCheck -check-prefix=ARMAP %s
+
+#--- test.def
+LIBRARY test.dll
+EXPORTS
+    funcexp
+    dataexp DATA