[Bug 780551] Re: incorrect interface in avxintrin.h

[Matthias Kretz]

I can understand your standpoint. But I'm sure you can understand that I
find this highly unsatisfactory.

But what I would really like to discuss is what measures you're taking
that this is not going to happen again? Are you looking into a macro
that can identify the distribution (I'd be happy to support you in
getting such a feature integrated upstream)?

What is required, from my view as library developer, is really a bug-by-
bug compatibility between compilers with the same version. Everything
else is a nightmare to support.

And yes, other distris are also patching their GCCs. So I'd be happy to
get this discussion going for all distributions...

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to gcc-4.5 in Ubuntu.
https://bugs.launchpad.net/bugs/780551

Title:
  incorrect interface in avxintrin.h

Status in Linaro GCC:
  New
Status in “gcc-4.5” package in Ubuntu:
  Won't Fix

Bug description:
  Binary package hint: gcc-4.5

  The following code compiles with vanilla GCC:
  __m128 m, x;
  float *mem;
  #if defined(__GNUC__) && __GNUC__ == 4 && (__GNUC_MINOR__ < 5 || (__GNUC_MINOR__ == 5 && __GNUC_PATCHLEVEL__ <= 2))
  _mm_maskstore_ps(mem, m, x);
  #else
  _mm_maskstore_ps(mem, _mm_castps_si128(m), x);
  #endif

  It fails to compile on Ubuntu because the interface of _mm_maskstore_ps was changed to the interface of GCC 4.5.3, but the version number was kept at 4.5.2.
  Which macro does Ubuntu GCC provide to check for this?

  For what it's worth, I believe this patch should be reverted in the
  GCC package, though it's probably too late already. I'd hope the
  updates to the gcc package would be good enough, though. Or consider
  to upgrade to 4.5.3 completely.

  Also, just to add a bit of perspective: I do nightly builds of a
  software project where GCC snapshots between even patch levels often
  exhibit miscompilations. I don't see how a distribution could sensibly
  take any patches from GCC between releases and release that as a given
  GCC package. A distribution has the means to ensure that its own
  packages compile, but that it executes correctly...? In this case you
  broke source compatibility without any means to distinguish the
  interface version. Since it only affects development for AVX it is no
  wonder that you don't notice. That hopefully doesn't imply that you
  don't care...

  ProblemType: Bug
  DistroRelease: Ubuntu 11.04
  Package: gcc 4:4.5.2-1ubuntu3
  ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
  Uname: Linux 2.6.38-8-generic x86_64
  NonfreeKernelModules: nvidia
  Architecture: amd64
  Date: Tue May 10 16:13:13 2011
  InstallationMedia: Kubuntu 11.04 "Natty Narwhal" - Release amd64 (20110426.3)
  ProcEnviron:
   LANGUAGE=en_US:en
   PATH=(custom, user)
   LANG=en_US.UTF-8
   SHELL=/bin/zsh
  SourcePackage: gcc-defaults
  UpgradeStatus: No upgrade log present (probably fresh install)