[swift-dev] Build failure? "LLVM ERROR: Cannot represent a subtraction with a weak symbol"

Brian Gesiak modocache at gmail.com
Thu Jan 28 12:28:47 CST 2016


Thanks, Jordan!

I had thought they were, since I recall running `utils/update-checkout`
soon after encountering the error. I just tried a `git pull --rebase origin
stable` from within my `llvm` directory, though, and that pulled in 249898
"[RuntimeDyld] Fix a class of arithmetic errors introduced in r253918".
Sounds very relevant to my problem! :)

I'm building again now after pulling in the changes--if you don't hear from
me assume that everything works now. Thanks again for your help!

- Brian Gesiak


On Thu, Jan 28, 2016 at 1:09 PM, Jordan Rose <jordan_rose at apple.com> wrote:

> Hi, Brian. This required an update to LLVM as well, which Lang Hames
> should have cherry-picked to the stable branch. Are your LLVM and Clang
> fully up to date?
>
> Jordan
>
> On Jan 28, 2016, at 9:44 , Brian Gesiak via swift-dev <swift-dev at swift.org>
> wrote:
>
> Hello all!
>
> I'm encountering a build failure when compiling the stdlib, using the tip
> of master as of this morning (d44d6e). I'm running Ubuntu 15.10 on a x86_64
> machine.
>
> Here are my build logs:
> https://gist.github.com/modocache/a85851a53b570d5fca47. The logs show
> that I remove my build directory completely, before starting a clean build
> with `utils/build-script -R`.
>
> I was surprised to see a build failure, so I tried a bisect to narrow down
> what may have caused it. Here's the log from the bisect, which I made
> between master (d44d6e) and a known good commit (061c77):
> https://gist.github.com/modocache/89c347a3c50767eee7eb
>
> The bisect points to commit 638e4b, "IRGen/Runtime: Use relative addresses
> in nominal type descriptors". But I'm skeptical: that commit is weeks old,
> and was even included in swift-DEVELOPMENT-SNAPSHOT-2016-01-25-a. I very
> much doubt it introduced a build failure.
>
> I tried building swift-DEVELOPMENT-SNAPSHOT-2016-01-25-a, and even *that*
> doesn't build on my system!! I assume this snapshot has passed CI, so I
> thought there must be something wrong with my system. But William Dillion
> tells me he's experiencing the same error (
> https://twitter.com/hpux735/status/692758868670058496).
>
> William and I are both working on armv7 ports, so perhaps both of our
> build machines are similarly broken. But I'm curious if anyone has any
> ideas on what the problem might be, or if this build error reproduces for
> anyone else building on Linux. Thoughts?
>
> - Brian Gesiak
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>
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