[PATCH] D31410: llvm-lto2: Move the LTO::run() action behind a subcommand.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added a comment.

In https://reviews.llvm.org/D31410#723878, @zturner wrote:

> Actually perhaps better would be to make `cl::redefine` just another modifier.  Maybe call it `cl::template_opt` or something.  This way you would write:
>
>   extern cl::opt<bool> UseNewLtoPm;
>  
>   cl::opt<bool> UseNewLtoPm2(cl::template_opt(UseNewLtoPm), cl::sub(RunSubcommand));
>


The problem with that (and your other suggestion) is that it would require specifying every possible flag to be passed to this tool. There are already quite a few of them that are required for tests (basically everything in llvm/CodeGen/CommandFlags.h and a few more). Also, as this is a developer tool I may also want to pass arbitrary top-level flags to the tool (e.g. for statistics, extra dumping, etc.) which may not already be covered by tests.

So I think I'd prefer that the API look something like like this (where `cl::import_root` imports all flags from the "root" subcommand into a given subcommand):

  static cl::SubCommand RunSubcommand("run", "Run LTO", cl::import_root());

and use this hack until that is implemented.


https://reviews.llvm.org/D31410