Revert [llvm-objcopy][NFC] Refactor output target parsing

This reverts r364254 (git commit 545f001d1b9a7b58a68d75e70bfc36c841de8999)

This change causes some llvm-obcopy tests to fail with valgrind.

Following is the output for basic-keep.test
Command Output (stderr):
--

==107406== Conditional jump or move depends on uninitialised value(s)
==107406==    at 0x1A30DD: executeObjcopy(llvm::objcopy::CopyConfig const&) (llvm-objcopy.cpp:235)
==107406==    by 0x1A3935: main (llvm-objcopy.cpp:294)

llvm-svn: 364379

1 files changed, 6 insertions, 8 deletions

diff --git a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
index b366c6e5598..b6af729afe8 100644
--- a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -154,14 +154,12 @@ static std::unique_ptr<Writer> createELFWriter(const CopyConfig &Config,
 static std::unique_ptr<Writer> createWriter(const CopyConfig &Config,
                                             Object &Obj, Buffer &Buf,
                                             ElfType OutputElfType) {
-  switch (Config.OutputFormat) {
-  case FileFormat::Binary:
-    return llvm::make_unique<BinaryWriter>(Obj, Buf);
-  case FileFormat::IHex:
-    return llvm::make_unique<IHexWriter>(Obj, Buf);
-  default:
-    return createELFWriter(Config, Obj, Buf, OutputElfType);
-  }
+  using Functor = std::function<std::unique_ptr<Writer>()>;
+  return StringSwitch<Functor>(Config.OutputFormat)
+      .Case("binary", [&] { return llvm::make_unique<BinaryWriter>(Obj, Buf); })
+      .Case("ihex", [&] { return llvm::make_unique<IHexWriter>(Obj, Buf); })
+      .Default(
+          [&] { return createELFWriter(Config, Obj, Buf, OutputElfType); })();
 }
 
 template <class ELFT>