From: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
To: qemu-devel@nongnu.org
Subject: [Bug 1841990] Re: instruction 'denbcdq' misbehaving
Date: Thu, 26 Sep 2019 05:47:04 -0000 [thread overview]
Message-ID: <156947682494.27303.3220440229032560299.malone@soybean.canonical.com> (raw)
In-Reply-To: 156711057074.6835.13599471410604217618.malonedeb@soybean.canonical.com
That's looking much better :) And finally, how many failures do you get
running the same test under QEMU 3.1? If that gives you zero failures
then I'll need to look a lot closer at the changes to try and figure out
what is going on.
As a matter of interest, which tests are the ones that are failing?
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https://bugs.launchpad.net/bugs/1841990
Title:
instruction 'denbcdq' misbehaving
Status in QEMU:
New
Bug description:
Instruction 'denbcdq' appears to have no effect. Test case attached.
On ppc64le native:
--
gcc -g -O -mcpu=power9 bcdcfsq.c test-denbcdq.c -o test-denbcdq
$ ./test-denbcdq
0x00000000000000000000000000000000
0x0000000000000000000000000000000c
0x22080000000000000000000000000000
$ ./test-denbcdq 1
0x00000000000000000000000000000001
0x0000000000000000000000000000001c
0x22080000000000000000000000000001
$ ./test-denbcdq $(seq 0 99)
0x00000000000000000000000000000064
0x0000000000000000000000000000100c
0x22080000000000000000000000000080
--
With "qemu-ppc64le -cpu power9"
--
$ qemu-ppc64le -cpu power9 -L [...] ./test-denbcdq
0x00000000000000000000000000000000
0x0000000000000000000000000000000c
0x0000000000000000000000000000000c
$ qemu-ppc64le -cpu power9 -L [...] ./test-denbcdq 1
0x00000000000000000000000000000001
0x0000000000000000000000000000001c
0x0000000000000000000000000000001c
$ qemu-ppc64le -cpu power9 -L [...] ./test-denbcdq $(seq 100)
0x00000000000000000000000000000064
0x0000000000000000000000000000100c
0x0000000000000000000000000000100c
--
I started looking at the code, but I got confused rather quickly.
Could be related to endianness? I think denbcdq arrived on the scene
before little-endian was a big deal. Maybe something to do with
utilizing implicit floating-point register pairs... I don't think the
right data is getting to helper_denbcdq, which would point back to the
gen_fprp_ptr uses in dfp-impl.inc.c (GEN_DFP_T_FPR_I32_Rc). (Maybe?)
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next prev parent reply other threads:[~2019-09-26 5:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
2019-08-30 6:29 ` [Qemu-devel] [Bug 1841990] " Alex Bennée
2019-08-30 7:32 ` Philippe Mathieu-Daudé
2019-08-30 8:12 ` Philippe Mathieu-Daudé
2019-08-30 13:14 ` Paul Clarke
2019-08-30 17:40 ` Philippe Mathieu-Daudé
2019-08-31 17:52 ` Mark Cave-Ayland
2019-08-31 21:16 ` Paul Clarke
2019-09-24 15:54 ` Mark Cave-Ayland
2019-09-25 17:51 ` Paul Clarke
2019-09-25 19:09 ` Mark Cave-Ayland
2019-09-25 21:21 ` Paul Clarke
2019-09-26 5:47 ` Mark Cave-Ayland [this message]
2019-09-26 14:08 ` Paul Clarke
2019-09-26 16:00 ` Mark Cave-Ayland
2019-09-26 16:26 ` Paul Clarke
2019-09-26 16:43 ` Paul Clarke
2019-09-26 16:59 ` Mark Cave-Ayland
2019-09-26 17:31 ` Paul Clarke
2019-09-26 17:57 ` Mark Cave-Ayland
2021-05-02 18:09 ` Thomas Huth
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