[PATCH] D64458: add -fthinlto-index= option to clang-cl

[Reid Kleckner via Phabricator via cfe-commits]

rnk added a comment.

In D64458#1577435 <https://reviews.llvm.org/D64458#1577435>, @pcc wrote:

> Do we really need to support clang-cl syntax here? Can't the user of -fthinlto-index= use the regular clang driver?


I think it depends on how many compiler flags we have to pass to backend compilation actions. I don't have a good sense of how many of those actually matter. Some flags affect the object file and are not encoded in bitcode, like -ffunction-sections. It's potentially onerous for a build system to have to work out for itself that `cl -O2` implicitly enables `-Gy`, which is the MSVC spelling of `-ffunction-sections`, so therefore we need this other set of backend action flags. It seems nicer to for the build system to just take the first stage command line and re-run it with a new input and this new flag.

If we want to make the behavior consistent, I would say we should port this new -x ir behavior over to clang so it's the same as clang-cl.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D64458/new/

https://reviews.llvm.org/D64458