[Bug 1987266] Comment bridged from LTC Bugzilla

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------- Comment From MAHESH.BODAPATI at ibm.com 2023-10-12 09:46 EDT-------
Machine : ltcden12-lp6
GCC : 11.4
I didn't see the issue with above system.
root at ltcden12-lp6:~/glibc_check/Build# ./elf/ld.so --library-path .:math ./math/test-ibm128-llround
testing long double (without inline functions)

Test suite completed:
1156 test cases plus 656 tests for exception flags and
656 tests for errno executed.
All tests passed successfully.

------- Comment From MAHESH.BODAPATI at ibm.com 2023-10-13 04:14 EDT-------
This is not reproducible with glibc master.
Machine : ltcd97-lp3
ppc64le and gcc 12.2
[maheshbodapati at ltcd97-lp3 Build]$ ./elf/ld.so --library-path .:math ./math/test-ibm128-llround
testing long double (without inline functions)

Test suite completed:
1156 test cases plus 656 tests for exception flags and
656 tests for errno executed.
All tests passed successfully.
[maheshbodapati at ltcd97-lp3 Build]$ gcc --version
gcc (GCC) 12.2.1 20221121 (Red Hat 12.2.1-4)

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https://bugs.launchpad.net/bugs/1987266

Title:
  test-ibm128-llround fails on ppc64el when built with gcc-12 and -O2 or
  higher

Status in GLibC:
  Fix Released
Status in The Ubuntu-power-systems project:
  Fix Released
Status in glibc package in Ubuntu:
  Fix Released

Bug description:
  root at kinetic:~/build# ./elf/ld.so --library-path .:math ./math/test-ibm128-llround
  testing long double (without inline functions)
  Failure: llround (0x7fffffffffffffff.8p0): Exception "Invalid operation" not set
  Failure: llround_downward (0x7fffffffffffffff.8p0): Exception "Invalid operation" not set
  Failure: llround_towardzero (0x7fffffffffffffff.8p0): Exception "Invalid operation" not set
  Failure: llround_upward (0x7fffffffffffffff.8p0): Exception "Invalid operation" not set

  Test suite completed:
    1156 test cases plus 656 tests for exception flags and
      656 tests for errno executed.
    4 errors occurred.

  Recompiling math/s_llroundl.os with gcc-11 or with gcc-12 -O1 is
  enough to fix this. Looking at the disassembly though I'm completely
  confused, feraiseexcept (FE_INVALID); is still getting called in the
  failing case and the code that runs after that looks the same (I've
  spent far too long trying to debug this). I've uploaded the .o files
  to https://people.canonical.com/~mwh/good.o and
  https://people.canonical.com/~mwh/bad.o -- good luck to the next
  person!

  A potential fix is here:
  https://sourceware.org/pipermail/libc-alpha/2022-August/141547.html

  For more details and discussions have a look at the attached upstream
  bug.

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