[readtapi] Cleanup printing command line options (llvm#75106)

Also, add a version option.

(cherry picked from commit 142e567)

Author: cyndyishida

llvm/test/tools/llvm-readtapi/command-line.test

@@ -4,12 +4,17 @@
 ; RUN: not llvm-readtapi -merge -compare -compact %t/tmp.tbd %t/tmp2.tbd 2>&1 | FileCheck %s --check-prefix MULTI_ACTION
 // Check unsupported file output format.
 ; RUN: not llvm-readtapi -merge -compact %t/tmp.tbd %t/tmp2.tbd --filetype=tbd-v2 2>&1 | FileCheck %s --check-prefix FILE_FORMAT 
+// Check version printing.
+; RUN: llvm-readtapi -v 2>&1 | FileCheck %s --check-prefix VERSION
+; RUN: llvm-readtapi --version 2>&1 | FileCheck %s --check-prefix VERSION
 
-CHECK: OVERVIEW: LLVM TAPI file reader and manipulator
-CHECK: USAGE: llvm-readtapi [options] [-arch <arch>]* <inputs> [-o <output>]*
-CHECK: OPTIONS:
-CHECK:   -help    display this help
+; CHECK: OVERVIEW: LLVM TAPI file reader and transformer 
+; CHECK: USAGE: llvm-readtapi <command> [-arch <architecture> <options>]* <inputs> [-o <output>]*
+; CHECK: COMMANDS:
+; CHECK: OPTIONS:
+; CHECK:   -help    display this help
 
-MULTI_ACTION: error: only one of the following actions can be specified: -merge -compare
-FILE_FORMAT: error: deprecated filetype 'tbd-v2' is not supported to write
+; MULTI_ACTION: error: only one of the following actions can be specified: -merge -compare
+; FILE_FORMAT: error: deprecated filetype 'tbd-v2' is not supported to write
 
+; VERSION: {{ version }}

llvm/tools/llvm-readtapi/TapiOpts.td

@@ -10,17 +10,19 @@ multiclass JS<string name, string help, string var = ""> {
 //
 // Top level operations 
 //
-def action_group : OptionGroup<"action group">;
+def action_group : OptionGroup<"action group">, HelpText<"COMMANDS">;
 def compare : FF<"compare", "compare tapi files for library differences">, Group<action_group>;
 def merge : FF<"merge", "merge the input files that represent the same library">, Group<action_group>;
-def extract: FF<"extract", "extract architecture from input file">, Group<action_group>;
-def remove: FF<"remove", "remove architecture from input file">, Group<action_group>;
+def extract: FF<"extract", "extract <architecture> from input file">, Group<action_group>;
+def remove: FF<"remove", "remove <architecture> from input file">, Group<action_group>;
 
 //
 // General Driver options 
 //
 def help : FF<"help", "display this help">;
+def version: FF<"version", "print the llvm-readtapi version">;
+def v: FF<"v", "alias for --version">, Alias<version>;
 defm output: JS<"o", "write output to <file>","<file>">;
 def compact: FF<"compact", "write compact tapi output file">;
 defm filetype: JS<"filetype", "specify the output file type (tbd-v3, tbd-v4 or tbd-v5)","<value>">;
-defm arch: JS<"arch", "specify the architecture", "<architecture>">;
+defm arch: JS<"arch", "specify the <architecture>", "<architecture>">;

llvm/tools/llvm-readtapi/llvm-readtapi.cpp

@@ -1,4 +1,4 @@
-//===-- llvm-readtapi.cpp - tapi file reader and manipulator -----*- C++-*-===//
+//===-- llvm-readtapi.cpp - tapi file reader and transformer -----*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -171,9 +171,15 @@ int main(int Argc, char **Argv) {
       Argc, Argv, OPT_UNKNOWN, Saver, [&](StringRef Msg) { reportError(Msg); });
   if (Args.hasArg(OPT_help)) {
     Tbl.printHelp(outs(),
-                  "USAGE: llvm-readtapi [options] [-arch <arch>]* <inputs> [-o "
+                  "USAGE: llvm-readtapi <command> [-arch <architecture> "
+                  "<options>]* <inputs> [-o "
                   "<output>]*",
-                  "LLVM TAPI file reader and manipulator");
+                  "LLVM TAPI file reader and transformer");
+    return EXIT_SUCCESS;
+  }
+
+  if (Args.hasArg(OPT_version)) {
+    cl::PrintVersionMessage();
     return EXIT_SUCCESS;
   }