Heads up: F21 LLVM rebase

Adam Jackson ajax at redhat.com
Mon Dec 15 15:46:24 UTC 2014


On Sat, 2014-12-13 at 01:51 +0100, Kevin Kofler wrote:

> There can be only one version of LLVM in the whole distribution at a time.

To be entirely fair this is a failing of upstream LLVM for not using
symbol versioning on Linux.  On OSX, where clearly most of LLVM's
development happens, this isn't an issue because Mach-O's two level
namespacing means every imported symbol knows which library it came
from.  If libLLVM used ELF symbol versions we'd get the same effect, and
then you could have llvm 3.5 and 3.6 in the same address space and
things would Just Work.

I'd submitted a patch for this but it didn't get merged in 3.5, at least
partly because gold doesn't support all the same command line options as
binutils' ld.  I'd make a snarky comment here about how the freedom to
choose to use a different linker is clearly a great thing that improves
users' lives, and about how mere packaging policy by definition cannot
fix implementation bugs, but at this point I feel like I'm screaming at
a wall.

I'll try again for 3.6.

- ajax



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