rustbuild: allow dynamically linking LLVM #37822
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The makefiles and `mklldeps.py` called `llvm-config --shared-mode` to find out if LLVM defaulted to shared or static libraries, and just went with that. But under rustbuild, `librustc_llvm/build.rs` was assuming that LLVM should be static, and even forcing `--link-static` for 3.9+. Now that build script also uses `--shared-mode` to learn the default, which should work better for pre-3.9 configured for dynamic linking, as it wasn't possible back then to choose differently via `llvm-config`. Further, the configure script now has a new `--enable-llvm-link-shared` option, which allows one to manually override `--link-shared` on 3.9+ instead of forcing static.
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r? @eddyb (rust_highfive has picked a reviewer for you, use r? to override) |
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Looks good to me! It appears though that |
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Ah, I hadn't noticed that |
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Ah ok, either's fine by me! |
There are now four static/shared scenarios that can happen for the supported LLVM versions: - 3.9+: By default use `llvm-config --link-static` - 3.9+ and `--enable-llvm-link-shared`: Use `--link-shared` instead. - 3.8: Use `llvm-config --shared-mode` and go with its answer. - 3.7: Just assume static, maintaining the status quo.
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OK, that push will hopefully help 3.7, and I updated the PR summary with the four linking scenarios. |
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Hmm, those latest travis jobs don't look like they actually tried anything... |
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@bors: r+ Thanks! |
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📌 Commit f324037 has been approved by |
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⌛ Testing commit f324037 with merge b1da18f... |
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rustbuild: allow dynamically linking LLVM The makefiles and `mklldeps.py` called `llvm-config --shared-mode` to find out if LLVM defaulted to shared or static libraries, and just went with that. But under rustbuild, `librustc_llvm/build.rs` was assuming that LLVM should be static, and even forcing `--link-static` for 3.9+. Now that build script also uses `--shared-mode` to learn the default, which should work better for pre-3.9 configured for dynamic linking, as it wasn't possible back then to choose differently via `llvm-config`. Further, the configure script now has a new `--enable-llvm-link-shared` option, which allows one to manually override `--link-shared` on 3.9+ instead of forcing static. Update: There are now four static/shared scenarios that can happen for the supported LLVM versions: - 3.9+: By default use `llvm-config --link-static` - 3.9+ and `--enable-llvm-link-shared`: Use `--link-shared` instead. - 3.8: Use `llvm-config --shared-mode` and go with its answer. - 3.7: Just assume static, maintaining the status quo.
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The makefiles and
mklldeps.pycalledllvm-config --shared-modetofind out if LLVM defaulted to shared or static libraries, and just went
with that. But under rustbuild,
librustc_llvm/build.rswas assumingthat LLVM should be static, and even forcing
--link-staticfor 3.9+.Now that build script also uses
--shared-modeto learn the default,which should work better for pre-3.9 configured for dynamic linking, as
it wasn't possible back then to choose differently via
llvm-config.Further, the configure script now has a new
--enable-llvm-link-sharedoption, which allows one to manually override
--link-sharedon 3.9+instead of forcing static.
Update: There are now four static/shared scenarios that can happen
for the supported LLVM versions:
llvm-config --link-static--enable-llvm-link-shared: Use--link-sharedinstead.llvm-config --shared-modeand go with its answer.