[llvm-objcopy] Add -F|--target compatibility

[rupprecht]

Summary

This change adds support for the GNU --target flag, which sets both --input-target and --output-target.

GNU objcopy doesn't do any checking for whether both --target and --{input,output}-target are used, and so it allows both, e.g. "--target A --output-target B" is equivalent to "--input-target A --output-target B" since the later command line flag would override earlier ones. This may be error prone, so I chose to implement it as an error if both are used. I'm not sure if anyone is actually using both.

[jakehehrlich]

I think this is probably fine. I think having the error is better than not having it. I'm just concerned someone somewhere is using GNU objcopy in the way mentioned in the error. I'm fine treating this as an error and only switching behavior if and when someone hits an issue.

So LGTM. I'd wait on one more person to cast their vote on this situation.

[rupprecht]

Rebase past rL344307

[alexander-shaposhnikov]

thanks, sorry for causing you to rebase

[jhenderson]

llvm/trunk/test/tools/llvm-objcopy/input-output-target.test

14 ↗

(On Diff #169344)

What's this TODO about?

[rupprecht]

llvm/trunk/test/tools/llvm-objcopy/input-output-target.test

14 ↗

(On Diff #169344)

D'oh, forgot to remove the TODO after I implemented the test case
Will remove this in a separate commit, thanks for noticing this!

test/tools/llvm-objcopy/input-output-target.test

+# RUN: echo abcd > %t.txt
+
+# Preserve input to verify it is not modified
+# RUN: cp %t.txt %t-copy.txt
+
+# -F <target> is equivalent to -I <target> -O <target>
+# RUN: llvm-objcopy -F binary -B i386:x86-64 %t.txt %t.2.txt
+# RUN: cmp %t-copy.txt %t.2.txt
+
+# --target <target> is equivalent to --input-target <target> --output-target <target>
+# RUN: llvm-objcopy --target binary -B i386:x86-64 %t.txt %t.3.txt
+# RUN: cmp %t-copy.txt %t.3.txt
+
+# TODO: check --target and --input-target/--output-target are incompatible
+# RUN: not llvm-objcopy --target binary --input-target binary -B i386:x86-64 \
+# RUN:     %t.txt %t.4.txt 2>&1 \
+# RUN:     | FileCheck %s --check-prefix=BAD-FLAG
+# RUN: not llvm-objcopy --target binary --output-target binary -B i386:x86-64 \
+# RUN:     %t.txt %t.4.txt 2>&1 \
+# RUN:     | FileCheck %s --check-prefix=BAD-FLAG
+
+# BAD-FLAG: --target cannot be used with --input-target or --output-target.

tools/llvm-objcopy/ObjcopyOpts.td

 include "llvm/Option/OptParser.td"
 
 multiclass Eq<string name> {
   def NAME: Separate<["--", "-"], name>;
   def NAME # _eq: Joined<["--", "-"], name # "=">, Alias<!cast<Separate>(NAME)>;
 }
 
 def help : Flag<["-", "--"], "help">;
 defm binary_architecture : Eq<"binary-architecture">,
                            HelpText<"Used when transforming an architecture-less format (such as binary) to another format">;
 def B : JoinedOrSeparate<["-"], "B">,
         Alias<binary_architecture>;
+defm target : Eq<"target">,
+              HelpText<"Format of the input and output file">,
+              Values<"binary">;
+def F : JoinedOrSeparate<[ "-" ], "F">, Alias<target>;
 defm input_target : Eq<"input-target">,
                     HelpText<"Format of the input file">,
                     Values<"binary">;
 def I : JoinedOrSeparate<[ "-" ], "I">, Alias<input_target>;
 defm output_target : Eq<"output-target">,
                      HelpText<"Format of the output file">,
                      Values<"binary">;
 def compress_debug_sections : Flag<["--", "-"], "compress-debug-sections">;

tools/llvm-objcopy/llvm-objcopy.cpp

if (Positional.empty())
     error("No input file specified");
 
   if (Positional.size() > 2)
     error("Too many positional arguments");
 
   CopyConfig Config;
   Config.InputFilename = Positional[0];
   Config.OutputFilename = Positional[Positional.size() == 1 ? 0 : 1];
+  if (InputArgs.hasArg(OBJCOPY_target) &&
+      (InputArgs.hasArg(OBJCOPY_input_target) ||
+       InputArgs.hasArg(OBJCOPY_output_target)))
+    error("--target cannot be used with --input-target or --output-target");
+
+  if (InputArgs.hasArg(OBJCOPY_target)) {
+    Config.InputFormat = InputArgs.getLastArgValue(OBJCOPY_target);
+    Config.OutputFormat = InputArgs.getLastArgValue(OBJCOPY_target);
+  } else {
     Config.InputFormat = InputArgs.getLastArgValue(OBJCOPY_input_target);
     Config.OutputFormat = InputArgs.getLastArgValue(OBJCOPY_output_target);
+  }
   if (Config.InputFormat == "binary") {
     auto BinaryArch = InputArgs.getLastArgValue(OBJCOPY_binary_architecture);
     if (BinaryArch.empty())
       error("Specified binary input without specifiying an architecture");
     Config.BinaryArch = getMachineInfo(BinaryArch);
   }
 
   if (auto Arg = InputArgs.getLastArg(OBJCOPY_compress_debug_sections,