[Bug 1883784] [NEW] [ppc64le] qemu behavior differs from ppc64le hardware

[Evan Nemerson]

Public bug reported:

I have some code which passes my test suite on PPC64LE hardware when
compiled with GCC 10, but the saem binary fails with both qemu-ppc64le
4.2 (on Fedora 32) and qemu-ppc64le-static 5.0.0 (Debian testing).

I'm not getting any errors about illegal instructions or anything, like
that; the results are just silently different on qemu.

I've generated a reduced test case, which is attached along with the
binaries (both are the same code, one is just statically linked).  They
should execute successufully on PPC64LE hardware, but on qemu they hit a
__builtin_abort (because the computed value doesn't match the expected
value).

Without being familiar with PPC assembly I'm not sure what else I can
do, but if there is anything please let me know.

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: ppc64le

** Attachment added: "test case"
   
https://bugs.launchpad.net/bugs/1883784/+attachment/5384531/+files/mm_cvtpd_ps.tar.bz2

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https://bugs.launchpad.net/bugs/1883784

Title:
  [ppc64le] qemu behavior differs from ppc64le hardware

Status in QEMU:
  New

Bug description:
  I have some code which passes my test suite on PPC64LE hardware when
  compiled with GCC 10, but the saem binary fails with both qemu-ppc64le
  4.2 (on Fedora 32) and qemu-ppc64le-static 5.0.0 (Debian testing).

  I'm not getting any errors about illegal instructions or anything,
  like that; the results are just silently different on qemu.

  I've generated a reduced test case, which is attached along with the
  binaries (both are the same code, one is just statically linked).
  They should execute successufully on PPC64LE hardware, but on qemu
  they hit a __builtin_abort (because the computed value doesn't match
  the expected value).

  Without being familiar with PPC assembly I'm not sure what else I can
  do, but if there is anything please let me know.

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