[Bug 1856682] Re: GCC Miscompilation in vectorized code

Dimitri John Ledkov launchpad at surgut.co.uk
Wed Jan 29 22:14:20 UTC 2020


* Update to SVN 20200104 (r279880) from the gcc-9-branch.
      ...
      PR target/92950 (S390),

In focal, for gcc-9.

** Changed in: gcc-9 (Ubuntu)
       Status: New => Fix Released

** Bug watch added: GCC Bugzilla #92950
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92950

** Also affects: gcc via
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92950
   Importance: Unknown
       Status: Unknown

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https://bugs.launchpad.net/bugs/1856682

Title:
  GCC Miscompilation in vectorized code

Status in gcc:
  Unknown
Status in Ubuntu on IBM z Systems:
  Triaged
Status in gcc-5 package in Ubuntu:
  New
Status in gcc-6 package in Ubuntu:
  New
Status in gcc-7 package in Ubuntu:
  New
Status in gcc-8 package in Ubuntu:
  New
Status in gcc-9 package in Ubuntu:
  Fix Released

Bug description:
  Miscompilation in autovectorized code.
   
  ---Steps to Reproduce---
   See GCC BZ: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92950

  The following testcase abort when being compiled with -O3 -march=z13
  on IBM Z:

  struct a {
    int b;
    char c;
  };
  struct a d = {1, 16};
  struct a *e = &d;

  int f = 0;

  int main() {
    struct a g = {0, 0 };
    f = 0;

    for (; f <= 1; f++) {
      g = d;
      *e = g;
    }

    if (d.c != 16)
      __builtin_abort();
  }

  The movv1qi pattern emits halfword load instructions instead of character
  loads.

  All GCC versions since GCC 5 are affected.
  Patches for GCC 8, 9, and 10 have been committed to the gcc.gnu.org branches.
   
  Userspace tool common name: gcc  
  The userspace tool has the following bit modes: 64 
  Userspace rpm: various Ubuntu gcc packages

  
  Package need to updated within LP

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