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[Niall Douglas <s_launchpad@xxxxxxxxxxx>]

BTW I think some history may be at work here. clang didn't support
native cpu detection back when I was the chief clang person at
BlackBerry, it may well still not. I would assume the default choice of
arm-linux-gnueabihf, judging from google searching, was mainly driven by
RaspPI enthusiasts who obviously wanted an ARMv6 clang. Now, a Cortex-A8
supports atomics just fine, but it could be that arm-linux-gnueabihf
means one thing to GCC (an ARMv6) and something rather less (an ARM7tdmi
for example, the lowest supported ARM CPU) to clang which is ARMv4 or
something.

It might be worth experimenting with a default triple for clang of armv6
-linux-gnueabihf instead. After all, Ubuntu surely does not work on
systems without atomics. I'll give this a try on Saturday and see what
happens.

BTW there is something real weird in Boost on clang armhf, exception
throw catches aren't reliable, this was causing an infinite loop of
terminate(). I'd say 1.56 is going to ship anyway, I'll see if I can
figure out the problem for 1.57, again this will be Saturday.

Niall

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to llvm-toolchain-3.4 in
Ubuntu.
https://bugs.launchpad.net/bugs/1349789

Title:
  clang armhf in trusty simply doesn't work

Status in “llvm-toolchain-3.4” package in Ubuntu:
  Confirmed

Bug description:
  I'm running Ubuntu 14.04 on armhf. clang is from the standard repo:

  root@tegra-ubuntu:~# apt-cache show clang
  Package: clang
  Priority: optional
  Section: universe/devel
  Installed-Size: 27
  Maintainer: Ubuntu Developers <ubuntu-devel-discuss@xxxxxxxxxxxxxxxx>
  Original-Maintainer: LLVM Packaging Team <pkg-llvm-team@xxxxxxxxxxxxxxxxxxxxxxx>
  Architecture: armhf
  Source: llvm-defaults (0.21ubuntu1)
  Version: 1:3.4-0ubuntu1
  Replaces: clang (<< 3.2-1~exp2)
  Depends: clang-3.4 (>= 3.4~rc3-1~)
  Filename: pool/universe/l/llvm-defaults/clang_3.4-0ubuntu1_armhf.deb
  Size: 2478
  MD5sum: eadb3f7c344e364480bdf7fdd0f698ab
  SHA1: ec4d0bfcad42bf536ee8d9257f8930dd32e1a261
  SHA256: f6d9a8fbfc06d93cd4c1a2437114454cc1eec805a635efc490a7e1e6eec2b3de
  Description-en: C, C++ and Objective-C compiler (LLVM based)
   Clang project is a C, C++, Objective C and Objective C++ front-end
   for the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler
   Collection (GCC).
   .
   Clang implements all of the ISO C++ 1998 and 2001 standards and also provides
   a partial support of C++1y.
   .
   This is a dependency package providing the default clang compiler.
  Description-md5: ea1f164ac255f39c6ec78685f71ef19b
  Bugs: https://bugs.launchpad.net/ubuntu/+filebug
  Origin: Ubuntu

  
  Anyway, it does not produce working output. Here are some examples:

  https://ci.nedprod.com/view/Boost.AFIO/job/Boost.AFIO%20Build%20POSIX_ARM_clang%203.4/9/consoleFull

  This log shows how clang has the wrong default target CPU, so it
  outputs unsupported ARM instructions (see the end after the warnings
  spew).

  If I force the target cpu to a cortex-a15 it now at least compiles and
  links and starts to run unit tests:

  https://ci.nedprod.com/view/Boost.AFIO/job/Boost.AFIO%20Test%20POSIX_ARM_clang%203.4/7/consoleFull

  ... but hangs in the first unit test, and is timed out. Before you
  think it the unit tests, here is the exact same thing for GCC 4.8:

  https://ci.nedprod.com/view/Boost.AFIO/job/Boost.AFIO%20Test%20POSIX_ARM_GCC%204.8/7/console

  The unit tests all run and pass as expected. Everything also works
  fine on x86 and x64 with clang 3.4 on Ubuntu 14.04, this appears to be
  an armhf misconfiguration.

  Niall

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