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From: Thomas Huth <1828867@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1828867] Re: QEmu translation is incorrect when using REX in combination with LAHF/SAHF
Date: Tue, 04 May 2021 15:46:13 -0000	[thread overview]
Message-ID: <162014317342.514.15063643059808175449.malone@chaenomeles.canonical.com> (raw)
In-Reply-To: 155776862725.26593.3375928624162381326.malonedeb@soybean.canonical.com

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/130


** Changed in: qemu
       Status: New => Expired

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #130
   https://gitlab.com/qemu-project/qemu/-/issues/130

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https://bugs.launchpad.net/bugs/1828867

Title:
  QEmu translation is incorrect when using REX in combination with
  LAHF/SAHF

Status in QEMU:
  Expired

Bug description:
  When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
  These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
  On hardware the REX prefix doesn't effect behaviour of these instructions at all.
  QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.

  I've attached a patch that is super terrible just so I can work around
  the issue locally and to sort of show off how it is to be "fixed"

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      parent reply	other threads:[~2021-05-04 15:57 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
2019-05-13 17:31 ` [Qemu-devel] [Bug 1828867] " Sonicadvance1
2019-05-13 20:24 ` Alex Bennée
2021-04-22  6:15 ` Thomas Huth
2021-04-22  6:46 ` Ryan Houdek
2021-05-04 15:46 ` Thomas Huth [this message]

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