Le 04/06/2018 à 08:50, Henri Sivonen a écrit :
> On Wed, May 30, 2018 at 5:16 PM, Mike Hommey wrote:
>> On Wed, May 30, 2018 at 02:40:01PM +0300, Henri Sivonen wrote:
>>> The Linux distro case is
>>> trickier than Mozilla's compiler choice. For CPUs that are tier-3 for
>>> Mozilla, we already tolerate less great performance attributes in
>>> order to enable availability, so distros keeping using GCC for tier-3
>>> probably isn't a problem. x86_64 could be a problem, though. If
>>> Firefox's performance becomes significantly dependent on having
>>> cross-language inlining, and I expect it will, having a substantial
>>> portion of the user base run without it while thinking they have a
>>> top-tier build could be bad. I hope we can get x86_64 Linux distros to
>>> track our compiler configuration closely.
>> That part might end up more difficult than one could expect.
>> Cross-language inlining is going to require rustc and clang having a
>> compatible llvm ir, and that's pretty much guaranteed to be a problem,
>> even for Mozilla.
> I thought the rustc codebase supported building with unpatched LLVM in
> order to let distros maintain one copy of LLVM source (if not .so). Is
> that not the case?
It is indeed the case. Debian/Ubuntu remove LLVM sources in a repackaging
phase and use the libraries provided by the distribution.
We (Mozilla) are also already applying patches on our local clang
builds. Example:
https://dxr.mozilla.org/mozilla-central/source/build/build-clang/clang-6-pre-linux64.json?q=clang-6-pre-linux64.json_type=direct#17
S
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