phosek added inline comments.
================
Comment at: clang/cmake/caches/Fuchsia-stage2.cmake:124
set(RUNTIMES_${target}_LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
- set(RUNTIMES_${target}_LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
set(RUNTIMES_${target}_LIBCXX_ABI_VERSION 2 CACHE STRING "")
----------------
ldionne wrote:
> ldionne wrote:
> > phosek wrote:
> > > ldionne wrote:
> > > > phosek wrote:
> > > > > ldionne wrote:
> > > > > > Note that I am removing these options here because I don't think
> > > > > > they are required -- since we specify
> > > > > > `LIBCXXABI_ENABLE_SHARED=OFF`, there is no shared libc++abi to link
> > > > > > against, so we should already be linking against `libc++abi.a`
> > > > > > regardless of this change.
> > > > > This option was set to merge `libc++abi.a` into `libc++.a` so to
> > > > > achieve the same effect, presumably we would need to set
> > > > > `-DLIBCXX_CXX_ABI=libcxxabi-objects`?
> > > > I agree this is suspicious, but why is there no
> > > > `LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY` specified here then? I
> > > > can add `-DLIBCXX_CXX_ABI=libcxxabi-objects`, I just want to make sure
> > > > we both understand what's going on.
> > > This is intentional. We are merging `libc++abi.a` into `libc++.a` but we
> > > ship `libc++abi.so` and `libc++.so` as separate (and use the generated
> > > linker script to pull in `libc++abi.so` when you pass `-lc++` to linker).
> > > I'd be fine merging `libc++abi.so` into `libc++.so` as well, but we'll
> > > need to figure out a transition plan since there are several places in
> > > our build right now that expect `libc++abi.so` to exist. We cannot land
> > > this change as is because that would break the `-static-libstdc++` use
> > > case, since Clang driver only passes `-lc++` to the linker and not
> > > `-lc++abi` and there's nothing that would pull `libc++abi.a` in.
> > I see, so to summarize, basically you want to use `libcxxabi-objects` for
> > the static `libc++.a`, but `libcxxabi` for the dynamic `libc++.so`. This
> > change as currently laid out does not permit that to happen, since
> > `libcxxabi-objects` implies that the objects are merged both in the static
> > and in the shared library. I guess we could introduce a new
> > `libcxxabi-objects-static` option, however that would be kind of strange.
> > We can either do that, or wait for you to stop relying on `libc++abi.so`
> > existing and switch to `libcxxabi-objects` wholesale for Fuchsia. WDYT?
> Gentle ping. It would be nice to land this in one form or another. If you
> don't think Fuchsia can stop relying on `libc++abi.so` being there, I could
> add yet another `libcxxabi-objects-static` -- I still feel like that's better
> than the status quo.
We discussed this on our team and we don't have any issues switching towards
combined `libc++.so`, we just need to figure out a transition plan. Let me test
this change locally to see if landing this as is will break anything.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D125683/new/
https://reviews.llvm.org/D125683
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