[llvm-strip] Add missing aliases for --strip-debug

[alexander-shaposhnikov]

Summary

Add missing aliases for --strip-debug: -g, -S, -d.
https://sourceware.org/binutils/docs/binutils/strip.html
Test plan: make check-all

[paulsemel]

LGTM :)

[jhenderson]

LGTM. I do question the idea that -g removes debug information, since everywhere else it adds it, but since that's what the GNU tool does, we should probably follow it.

llvm/trunk/test/tools/llvm-objcopy/strip-debug.test

 # RUN: yaml2obj %s > %t
+# RUN: cp %t %t3
 # RUN: llvm-objcopy -strip-debug %t %t2
 # RUN: llvm-readobj -file-headers -sections -symbols %t2 | FileCheck %s
 
-# We run yaml2obj again rather than copy %t to avoid interfering 
-# with llvm-objcopy's test (which potentially could have corrupted/updated the binary).
+# Verify that the previous run of llvm-objcopy has not modified the input.
+# RUN: cmp %t %t3
 
-# RUN: yaml2obj %s > %t3
 # RUN: llvm-strip -strip-debug %t3
-# RUN: llvm-readobj -file-headers -sections -symbols %t3 | FileCheck %s
 # RUN: cmp %t2 %t3
 
+# RUN: cp %t %t4
+# RUN: llvm-strip -d %t4
+# RUN: cmp %t2 %t4
+
+# RUN: cp %t %t5
+# RUN: llvm-strip -g %t5
+# RUN: cmp %t2 %t5
+
+# RUN: cp %t %t6
+# RUN: llvm-strip -S %t6
+# RUN: cmp %t2 %t6
+
 !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
   Type:            ET_REL
   Machine:         EM_X86_64
 Sections:
   - Name:            .debugfoo

llvm/trunk/tools/llvm-objcopy/StripOpts.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 output : Eq<"o">,
               MetaVarName<"output">,
               HelpText<"Write output to <file>">;
 
 def strip_debug : Flag<["-", "--"], "strip-debug">,
                   HelpText<"Remove debugging symbols only">;
 
+def d : Flag<["-"], "d">,
+        Alias<strip_debug>;
+
+def g : Flag<["-"], "g">,
+        Alias<strip_debug>;
+
+def S : Flag<["-"], "S">,
+        Alias<strip_debug>;
+
 defm remove_section : Eq<"remove-section">,
                       MetaVarName<"section">,
                       HelpText<"Remove <section>">;
 
 def R : JoinedOrSeparate<["-"], "R">,
         Alias<remove_section>;
 
 defm keep_symbol : Eq<"keep-symbol">,
                    MetaVarName<"symbol">,
                    HelpText<"Do not remove symbol <symbol>">;
 
 def K : JoinedOrSeparate<["-"], "K">,
         Alias<keep_symbol>;