Revert "Revert r305164/5/7."

Restore the `-gz` option to the driver with some minor tweaks to handle
the additional case for `-Wa,--compress-debug-sections`.

This intends to make the compression of the debug information
controllable from the driver.  The following is the behaviour:

  -gz           enable compression (ambiguous for format, will default to zlib-gnu)
  -gz=none      disable compression
  -gz=zlib-gnu  enable compression (deprecated GNU style zlib compression)
  -gz=zlib      enable compression (zlib based compression)

Although -Wa,-compress-debug-sections works, it should be discouraged
when using the driver to invoke the assembler.  However, we permit the
assembler to accept the GNU as style argument --compress-debug-sections
to maintain compatibility.

Note, -gz/-gz= does *NOT* imply -g.  That is, you need to additionally
specific -g for debug information to be generated.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@306115 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index bd4d521752..68b331fed2 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -1563,6 +1563,10 @@ def gdwarf_aranges : Flag<["-"], "gdwarf-aranges">, Group<g_flags_Group>;
 def gmodules : Flag <["-"], "gmodules">, Group<gN_Group>,
   HelpText<"Generate debug info with external references to clang modules"
            " or precompiled headers">;
+def gz : Flag<["-"], "gz">, Group<g_flags_Group>,
+    HelpText<"DWARF debug sections compression type">;
+def gz_EQ : Joined<["-"], "gz=">, Group<g_flags_Group>,
+    HelpText<"DWARF debug sections compression type">;
 def headerpad__max__install__names : Joined<["-"], "headerpad_max_install_names">;
 def help : Flag<["-", "--"], "help">, Flags<[CC1Option,CC1AsOption]>,
   HelpText<"Display available options">;