[llvm-objcopy] Make -S an alias for --strip-all

[jakehehrlich]

Summary

-S should be an alias for --strip-all not an alias for --strip-all-gnu which at best has imaginary use cases. llvm-objcopy's --strip-all has proven to be compatible with the uses of --strip-all in GNU objcopy in huge code bases with no complaints. llvm-objcopy's --strip-all makes binaries smaller and has a more principled definition.

[alexander-shaposhnikov]

@jakehehrlich Jake, would you mind committing this ?

[jakehehrlich]

Hey, sorry. I've been gone for 2 weeks between ICFP/Strange Loop and being in Seattle. Commit this now.

llvm/test/tools/llvm-objcopy/strip-all-gnu.test

 # RUN: yaml2obj %s > %t
 # RUN: cp %t %t1
 # RUN: llvm-objcopy --strip-all-gnu %t %t2
 # RUN: llvm-readobj -file-headers -sections %t2 | FileCheck %s
-# RUN: llvm-objcopy -S %t1 %t3
-# RUN: cmp %t2 %t3
 
 !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
   Type:            ET_REL
   Machine:         EM_X86_64
 Sections:

llvm/test/tools/llvm-objcopy/strip-all.test

 # RUN: cp %t %t7
 # RUN: llvm-strip -strip-all %t7
 # RUN: cmp %t2 %t7
 
 # RUN: cp %t %t8
 # RUN: llvm-strip --strip-all %t8
 # RUN: cmp %t2 %t8
 
+# RUN: cp %t %t9
+# RUN: llvm-objcopy -S %t9 %t9
+# RUN: cmp %t2 %t9
+
 # Verify that a non-existent symbol table (after first call to llvm-strip)
 # can be handled correctly.
 # RUN: cp %t %t9
 # RUN: llvm-strip --strip-all -keep=unavailable_symbol %t9
 # RUN: llvm-strip --strip-all -keep=unavailable_symbol %t9
 # RUN: cmp %t2 %t9
 
 !ELF

llvm/tools/llvm-objcopy/ObjcopyOpts.td

defm only_keep : Eq<"only-keep">,
                  HelpText<"Remove all but <section>">;
 def j : JoinedOrSeparate<["-"], "j">,
                       Alias<only_keep>;
 defm add_section : Eq<"add-section">,
                    MetaVarName<"section=file">,
                    HelpText<"Make a section named <section> with the contents of <file>.">;
 def strip_all : Flag<["-", "--"], "strip-all">,
                 HelpText<"Remove non-allocated sections other than .gnu.warning* sections">;
+def S : Flag<["-"], "S">,
+        Alias<strip_all>;
 def strip_all_gnu : Flag<["-", "--"], "strip-all-gnu">,
                     HelpText<"Compaitable with GNU objcopy's --strip-all">;
-def S : Flag<["-"], "S">,
-        Alias<strip_all_gnu>;
 def strip_debug : Flag<["-", "--"], "strip-debug">,
                   HelpText<"Remove all debug information">;
 def strip_dwo : Flag<["-", "--"], "strip-dwo">,
                 HelpText<"Remove all DWARF .dwo sections from file">;
 def strip_sections : Flag<["-", "--"], "strip-sections">,
                      HelpText<"Remove all section headers">;
 def strip_non_alloc : Flag<["-", "--"], "strip-non-alloc">,
                       HelpText<"Remove all non-allocated sections">;