LLVM 6.0 RC2 Released, Retpoline Support Still Settling

Written by Michael Larabel in LLVM on 7 February 2018 at 05:22 PM EST. 1 Comment
The second release candidate of LLVM 6.0 has been tagged.

Hans Wennborg announced the availability of LLVM 6.0 RC2 a short time ago. He noted in the brief release announcement, "There's been a lot of merges since rc1, and hopefully the tests are in a better state now."

LLVM 6.0 as well as the Clang 6.0 C/C++ compiler front-end are carrying a lot of new features and changes. LLVM 6.0 is still anticipated for release around 21 February.

Meanwhile, LLVM's code for Retpoline support for mitigating Spectre is still in flux. From this commit earlier today, "Make the external thunk names exactly match the names that happened to end up in GCC. This is really unfortunate, as the names don't have much rhyme or reason to them. Originally in the discussions it seemed fine to rely on aliases to map different names to whatever external thunk code developers wished to use but there are practical problems with that in the kernel it turns out. And since we're discovering this practical problems late and since GCC has already shipped a release with one set of names, we are forced, yet again, to blindly match what is there. Somewhat rushing this patch out for the Linux kernel folks to test and so we can get it patched into our releases."

The firmed up Retpoline support will be in LLVM 6.0 but they will also be issuing an LLVM 5.0 point release as soon as the backported support is ready for shipping.
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