[Bug 1815057] Please test proposed package

[Łukasz Zemczak]

Hello bugproxy, or anyone else affected,

Accepted gcc-7 into cosmic-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/gcc-7/7.4.0-1ubuntu1~18.10 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-cosmic to verification-done-cosmic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-cosmic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

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https://bugs.launchpad.net/bugs/1815057

Title:
  [UBUNTU] GCC Wrong code generate for floating point workloads Ubuntu
  18.04

Status in Ubuntu on IBM z Systems:
  In Progress
Status in gcc-7 package in Ubuntu:
  Fix Released
Status in gcc-8 package in Ubuntu:
  Fix Released
Status in gcc-7 source package in Bionic:
  New
Status in gcc-8 source package in Bionic:
  New
Status in gcc-7 source package in Cosmic:
  Fix Committed
Status in gcc-8 source package in Cosmic:
  New

Bug description:
  An IBM Z GCC backend problem leads to wrong code being generated for
  some floating point workloads.

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88856

  A patch has been committed to the GCC 7 and 8 upstream branch and
  needs to be picked up for the Ubuntu 18.04 compiler.

  https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=268551

  This change might require rebuilding floating point related packages.
  Although the actual problem is hard to trigger. I could only reproduce
  it in case if conversion introduces load on condition instructions in
  the ce2 pass. The testcase I've looked into came from the python scipy
  package which builds with -funroll-loops. The load on condition
  opportunity in that case was introduced with the RTL loop unrolling.
  This made the split1 pass to use the problematic splitter generating
  wrong code in the end.

  According to https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=915738

  The patch has been picked up for gcc-8 8.2.0-18 already

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