[clang-offload-bundler] Reuse original file extension for device archive member

This patch changes clang-offload-bundler to use the original file extension for
the device archive member when unbundling archives instead of printing a warning
and defaulting to ".o".

Differential Revision: https://reviews.llvm.org/D114776

Author: sndmitriev

clang/test/Driver/fat-archive-unbundle-ext.c

@@ -0,0 +1,21 @@
+// REQUIRES: x86-registered-target
+// UNSUPPORTED: windows, darwin, aix
+
+// Generate dummy fat object
+// RUN: %clang -O0 -target %itanium_abi_triple %s -c -o %t.host.o
+// RUN: echo 'Content of device file' > %t.tgt.o
+// RUN: clang-offload-bundler -type=o -targets=host-%itanium_abi_triple,openmp-%itanium_abi_triple -inputs=%t.host.o,%t.tgt.o -outputs=%t.fat.obj
+
+// Then create a static archive with that object
+// RUN: rm -f %t.fat.a
+// RUN: llvm-ar cr %t.fat.a %t.fat.obj
+
+// Unbundle device part from the archive. Check that bundler does not print warnings.
+// RUN: clang-offload-bundler -unbundle -type=a -targets=openmp-%itanium_abi_triple -inputs=%t.fat.a -outputs=%t.tgt.a 2>&1 | FileCheck --allow-empty --check-prefix=CHECK-WARNING %s
+// CHECK-WARNING-NOT: warning
+
+// Check that device archive member inherited file extension from the original file.
+// RUN: llvm-ar t %t.tgt.a | FileCheck --check-prefix=CHECK-ARCHIVE %s
+// CHECK-ARCHIVE: {{\.obj$}}
+
+void foo(void) {}

clang/tools/clang-offload-bundler/ClangOffloadBundler.cpp

@@ -180,21 +180,19 @@ struct OffloadTargetInfo {
   }
 };
 
-static StringRef getDeviceFileExtension(StringRef Device) {
+static StringRef getDeviceFileExtension(StringRef Device,
+                                        StringRef BundleFileName) {
   if (Device.contains("gfx"))
     return ".bc";
   if (Device.contains("sm_"))
     return ".cubin";
-
-  WithColor::warning() << "Could not determine extension for archive"
-                          "members, using \".o\"\n";
-  return ".o";
+  return sys::path::extension(BundleFileName);
 }
 
 static std::string getDeviceLibraryFileName(StringRef BundleFileName,
                                             StringRef Device) {
   StringRef LibName = sys::path::stem(BundleFileName);
-  StringRef Extension = getDeviceFileExtension(Device);
+  StringRef Extension = getDeviceFileExtension(Device, BundleFileName);
 
   std::string Result;
   Result += LibName;