[llvm-dev] [cfe-dev] [RFC] Embedding Bitcode in Object Files

Rafael EspĂ­ndola via llvm-dev llvm-dev at lists.llvm.org
Thu Feb 4 14:00:35 PST 2016

On 3 February 2016 at 14:01, Steven Wu via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Hi Peter
> It is not currently related because we started the implementation before Thin-LTO
> gets proposed in the community but our "__LLVM, __bitcode" section is pretty much
> the same as ".llvmbc" section. Note ".llvmbc" doesn't really follow the section
> naming convention for MachO objects. I am hoping to unify them during the upstream
> of the implementation.

That would be my main request. Seems like a nice feature, but we
should have one implementation of it :-)

BTW, can you explain a bit why you need things like "-O0" recorded? In
case you want to go from bitcode back to object file one file at a
time (no LTO)? Is that orthogonal? That is, should the command line be
included in .bc files too? What is the command line option that is
included, the -cc1 or the driver one?

There was some discussion on the past about which options get run in
clang if given -flto. For example, it seems likely that a more
conservative inlining pass would be a good thing to not remove
opportunities for the link time inlining. What would happen with
"-flto -fembed-bitcode"? Would the bitcode be the same as with just
-flto and the object file less optimized?


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