Backport LLVM 12.0.1-4 bump to 1.7

[vchuravy]

Includes:

• [LLVM] bump to 12.0.1-4 ([LLVM] bump to 12.0.1-4 #42512)
• fix LLVM link to include new zlib dependency (fix LLVM link to include new zlib dependency #42524)
• [LLVM] actually update the branch for manual builds

[DilumAluthge]

@vchuravy Can you rebase this PR (and force-push) and see if that triggers Buildkite?

[DilumAluthge]

Thanks! Okay, it looks like Buildkite is now running on this PR.

[DilumAluthge]

Note: the Buildkite failures in the file and read test sets will be fixed once #42533 is backported to 1.7.

[vchuravy]

FreeBSD tells me that my backport was not sufficient:

ERROR: Unable to load dependent library /usr/home/julia/buildbot/w2_tester/tester_freebsd64/build/bin/../lib/julia/libjulia-internal.so.1
Message:Shared object "libz.so.1" not found, required by "libLLVM-12jl.so"

but this might also be RPATH? @vtjnash

[Sacha0]

Might I ask that we hold off with merging this backport till we are certain it will not introduce new build breakage for consumers of RC2? :)

[vchuravy]

@Sacha0 can you test whether this branch also breaks your NixOs setup?

[Sacha0]

Sure thing, I'll pull this patch onto our 1.7 testing branch and report back. Thanks again! :)

[Sacha0]

To confirm, this branch breaks our 1.7 test builds with the same failure mode that the bump on master broke our master test builds:

../../../bin/llvm-tblgen: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory
make[4]: *** [include/llvm/IR/CMakeFiles/intrinsics_gen.dir/build.make:155: include/llvm/IR/Attributes.inc] Error 127
make[3]: *** [CMakeFiles/Makefile2:8973: include/llvm/IR/CMakeFiles/intrinsics_gen.dir/all] Error 2
make[3]: *** Waiting for unfinished jobs....

[vchuravy]

@staticfloat any ideas how we can fix the RPATH issue?

@Sacha0 currently we have no CI against NixOS so this not a supported build-configuration. Could you look into adding one?

[Sacha0]

Regrets, I know little about NixOS and dearly want to avoid learning any more 😄.

[Sacha0]

Paging @rbvermaa, our Nix guru, for his thoughts :). (Also ref. JuliaPackaging/Yggdrasil#3703, #42512, #42523, #42524, and #42534 for context.)

[vchuravy]

@Sacha0 can you test this against your infrastructure?

[Sacha0]

Firing off a test of this branch and master with Rob's patch in now, will report back :).

[Sacha0]

Preliminarily it looks like both our latest-tester and 1.7-tester succeed with the addition of Rob's patch 🎉