* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
@ 2019-08-30 6:29 ` Alex Bennée
2019-08-30 7:32 ` Philippe Mathieu-Daudé
` (18 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Alex Bennée @ 2019-08-30 6:29 UTC (permalink / raw)
To: qemu-devel
** Tags added: ppc64 testcase
--
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
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
` (17 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Philippe Mathieu-Daudé @ 2019-08-30 7:32 UTC (permalink / raw)
To: qemu-devel
I tried to compile your test program with 2 different GCC versions but
it keeps failing, do you need a special/recent version? Meanwhile can
you attach a statically linked binary?
$ gcc -v
gcc version 6.3.0 20170516 (Debian 6.3.0-18)
$ gcc -g -O -mcpu=power9 test-denbcdq.c -o test-denbcdq
test-denbcdq.c: In function 'bcdcfsq':
test-denbcdq.c:7:2: error: impossible register constraint in 'asm'
asm volatile ( "bcdcfsq. %0,%1,0" : "=v" (r) : "v" (i128) );
^~~
--
$ gcc version 8.1.1 20180626 (Red Hat Cross 8.1.1-3) (GCC)
$ gcc -g -O -mcpu=power9 test-denbcdq.c -o test-denbcdq
test-denbcdq.c: In function ‘main’:
test-denbcdq.c:15:3: error: decimal floating point not supported for this target
_Decimal128 d128;
^~~~~~~~~~~
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
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
` (16 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Philippe Mathieu-Daudé @ 2019-08-30 8:12 UTC (permalink / raw)
To: qemu-devel
FWIW I could compile the attached test with:
$ gcc -v
gcc version 8.3.1 20190507 (Red Hat 8.3.1-4) (GCC)
--
You received this bug notification because you are a member of qemu-
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (2 preceding siblings ...)
2019-08-30 8:12 ` Philippe Mathieu-Daudé
@ 2019-08-30 13:14 ` Paul Clarke
2019-08-30 17:40 ` Philippe Mathieu-Daudé
` (15 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-08-30 13:14 UTC (permalink / raw)
To: qemu-devel
@Philippe, thank you for spending the time to find a compiler that works with the testcase. I've been operating on RHEL 8 primarily:
gcc version 8.2.1 20180905 (Red Hat 8.2.1-3) (GCC)
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (3 preceding siblings ...)
2019-08-30 13:14 ` Paul Clarke
@ 2019-08-30 17:40 ` Philippe Mathieu-Daudé
2019-08-31 17:52 ` Mark Cave-Ayland
` (14 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Philippe Mathieu-Daudé @ 2019-08-30 17:40 UTC (permalink / raw)
To: qemu-devel
This seems related to this change:
commit ef96e3ae9698d6726a8113f448c82985a9f31ff5
Author: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Date: Wed Jan 2 09:14:22 2019 +0000
target/ppc: move FP and VMX registers into aligned vsr register array
The VSX register array is a block of 64 128-bit registers where the first 32
registers consist of the existing 64-bit FP registers extended to 128-bit
using new VSR registers, and the last 32 registers are the VMX 128-bit
registers as show below:
64-bit 64-bit
+--------------------+--------------------+
| FP0 | | VSR0
+--------------------+--------------------+
| FP1 | | VSR1
+--------------------+--------------------+
| ... | ... | ...
+--------------------+--------------------+
| FP30 | | VSR30
+--------------------+--------------------+
| FP31 | | VSR31
+--------------------+--------------------+
| VMX0 | VSR32
+-----------------------------------------+
| VMX1 | VSR33
+-----------------------------------------+
| ... | ...
+-----------------------------------------+
| VMX30 | VSR62
+-----------------------------------------+
| VMX31 | VSR63
+-----------------------------------------+
In order to allow for future conversion of VSX instructions to use TCG vector
operations, recreate the same layout using an aligned version of the existing
vsr register array.
Since the old fpr and avr register arrays are removed, the existing callers
must also be updated to use the correct offset in the vsr register array. This
also includes switching the relevant VMState fields over to using subarrays
to make sure that migration is preserved.
@@ -1055,11 +1053,10 @@ struct CPUPPCState {
- /* VSX registers */
- uint64_t vsr[32];
+ /* VSX registers (including FP and AVR) */
+ ppc_vsr_t vsr[64] QEMU_ALIGNED(16);
The denbcdq helper is:
#define DFP_HELPER_ENBCD(op, size) \
void helper_##op(CPUPPCState *env, uint64_t *t, uint64_t *b, uint32_t s) \
{ \
[...]
if ((size) == 64) { \
t[0] = dfp.t64[0]; \
} else if ((size) == 128) { \
t[0] = dfp.t64[HI_IDX]; \
t[1] = dfp.t64[LO_IDX]; \
} \
}
t[1] doesn't point to the proper vsr register anymore.
--
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (4 preceding siblings ...)
2019-08-30 17:40 ` Philippe Mathieu-Daudé
@ 2019-08-31 17:52 ` Mark Cave-Ayland
2019-08-31 21:16 ` Paul Clarke
` (13 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-08-31 17:52 UTC (permalink / raw)
To: qemu-devel
Thanks for the report Paul (and also the investigation work Philippe).
So yes it seems the DFP code is another fallout from the conversion of
the floating point registers over to host-endian/VSR format. I've had a
quick look at this and it seems that the simple fix to compensate for
the FP registers not being contiguous anymore still won't work on
ppc64le.
In order to fix this properly I think the best solution is to use an
approach similar to that used in my last set of VSX patches, i.e. using
macros to avoid having separate code paths for big and little endian
hosts.
I can certainly come up with some patches for this, however I don't have
any ppc64le hardware to test it myself. If I were to do a trial
conversion of denbcdq would you be able to test it for me?
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Qemu-devel] [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (5 preceding siblings ...)
2019-08-31 17:52 ` Mark Cave-Ayland
@ 2019-08-31 21:16 ` Paul Clarke
2019-09-24 15:54 ` Mark Cave-Ayland
` (12 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-08-31 21:16 UTC (permalink / raw)
To: qemu-devel
I have access to lots of Power hardware, and happy to test and help
however I can! Thanks, Mark!
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (6 preceding siblings ...)
2019-08-31 21:16 ` Paul Clarke
@ 2019-09-24 15:54 ` Mark Cave-Ayland
2019-09-25 17:51 ` Paul Clarke
` (11 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-09-24 15:54 UTC (permalink / raw)
To: qemu-devel
Sorry I didn't get a chance to look at this before I went away on
holiday, however I've just posted a patchset at
https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg05577.html
which should resolve the issue for you.
With the above patchset applied I now see the following results with
your test program:
LE host:
$ ../qemu-ppc64le -L /usr/powerpc64le-linux-gnu -cpu power9 test-denbcdqle
0x00000000000000000000000000000000
0x0000000000000000000000000000000c
0x22080000000000000000000000000000
$ ../qemu-ppc64le -L /usr/powerpc64le-linux-gnu -cpu power9 test-denbcdqle 1
0x00000000000000000000000000000001
0x0000000000000000000000000000001c
0x22080000000000000000000000000001
$ ../qemu-ppc64le -L /usr/powerpc64le-linux-gnu -cpu power9 test-denbcdqle $(seq 0 99)
0x00000000000000000000000000000064
0x0000000000000000000000000000100c
0x22080000000000000000000000000080
BE host:
$ ../qemu-ppc64 -L /usr/powerpc64-linux-gnu -cpu power9 test-denbcdq
0x00000000000000000000000000000000
0x000000000000000c0000000000000000
0x00000000000000002208000000000000
$ ../qemu-ppc64 -L /usr/powerpc64-linux-gnu -cpu power9 test-denbcdq 1
0x00000000000000010000000000000000
0x000000000000001c0000000000000000
0x00000000000000012208000000000000
$ ../qemu-ppc64 -L /usr/powerpc64-linux-gnu -cpu power9 test-denbcdq $(seq 0 99)
0x00000000000000640000000000000000
0x000000000000100c0000000000000000
0x00000000000000802208000000000000
If you could confirm that the BE host results above match those on real
hardware then that would be great as I've switched over to use macros
that should do the right thing regardless of host endian.
Finally if you have access to a more comprehensive test suite then that
would be helpful to test more of the 64-bit DFP number paths and some of
more esoteric DFP instructions.
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (7 preceding siblings ...)
2019-09-24 15:54 ` Mark Cave-Ayland
@ 2019-09-25 17:51 ` Paul Clarke
2019-09-25 19:09 ` Mark Cave-Ayland
` (10 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-09-25 17:51 UTC (permalink / raw)
To: qemu-devel
I'm still trying to track down a BE system. Everything I have which is
newer than POWER7 is LE, and POWER7 is not sufficient to run the test.
The test suite that produced the problem is from https://github.com
/open-power-sdk/pveclib. The good news is that with your (v1) changes,
275 tests no longer fail. 22 tests still fail, but I bet it is
different issue(s).
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (8 preceding siblings ...)
2019-09-25 17:51 ` Paul Clarke
@ 2019-09-25 19:09 ` Mark Cave-Ayland
2019-09-25 21:21 ` Paul Clarke
` (9 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-09-25 19:09 UTC (permalink / raw)
To: qemu-devel
That certainly sounds like progress. Did you see the follow up email
indicating the typo that I found in patch 6? It can be fixed by applying
the following diff on top:
diff --git a/target/ppc/dfp_helper.c b/target/ppc/dfp_helper.c
index c2d335e928..b801acbedc 100644
--- a/target/ppc/dfp_helper.c
+++ b/target/ppc/dfp_helper.c
@@ -1054,7 +1054,7 @@ static inline void dfp_set_sign_64(ppc_vsr_t *t, uint8_t sgn)
static inline void dfp_set_sign_128(ppc_vsr_t *t, uint8_t sgn)
{
t->VsrD(0) <<= 4;
- t->VsrD(0) |= (t->VsrD(0) >> 60);
+ t->VsrD(0) |= (t->VsrD(1) >> 60);
t->VsrD(1) <<= 4;
t->VsrD(1) |= (sgn & 0xF);
}
Does that help any more tests to pass? Also the changes to the FP
register layout were made in QEMU 4.0 and so it seems to me that even if
some tests fail, if the results between QEMU 3.1 and QEMU git master
with the patchset applied are equivalent then we can assume that the
patchset functionality is correct.
--
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply related [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (9 preceding siblings ...)
2019-09-25 19:09 ` Mark Cave-Ayland
@ 2019-09-25 21:21 ` Paul Clarke
2019-09-26 5:47 ` Mark Cave-Ayland
` (8 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-09-25 21:21 UTC (permalink / raw)
To: qemu-devel
> Did you see the follow up email indicating the typo that I found in
patch 6?
I did, then forgot to include it in my build. I've included that change
now...
> Does that help any more tests to pass?
I'm down from 22 failures to 8.
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (10 preceding siblings ...)
2019-09-25 21:21 ` Paul Clarke
@ 2019-09-26 5:47 ` Mark Cave-Ayland
2019-09-26 14:08 ` Paul Clarke
` (7 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-09-26 5:47 UTC (permalink / raw)
To: qemu-devel
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?
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (11 preceding siblings ...)
2019-09-26 5:47 ` Mark Cave-Ayland
@ 2019-09-26 14:08 ` Paul Clarke
2019-09-26 16:00 ` Mark Cave-Ayland
` (6 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-09-26 14:08 UTC (permalink / raw)
To: qemu-devel
I haven't tried QEMU 3.1 yet. Adding to to-do list.
I am narrowing down the remaining failures. Within the pveclib test suite, there are two tests, one is failing, "pveclib_test". It contains numerous subtests. The failing subtests are:
- test_setb_bcdsq
- test_setb_bcdinv
- test_bcdsr
- test_bcdsrrqi
Investigating the first two so far, it looks like "bcdadd." and
"bcdsub." are not operating correctly. gdb sessions showing the
difference in behavior between QEMU 4.2+patches and hardware (in that
order):
QEMU 4.2+patches:
(gdb) x/i $pc
=> 0x10000698 <vec_setbool_bcdsq+60>: bcdsub. v0,v0,v1,0
(gdb) p $vr0.uint128
$3 = 0x9999999999999999999999999999999d
(gdb) p $vr1.uint128
$4 = 0x1d
(gdb) stepi
(gdb) p $vr1.uint128
$5 = 0x1d
hardware:
1: x/i $pc
=> 0x10000698 <vec_setbool_bcdsq+60>: bcdsub. v0,v0,v1,0
(gdb) p $vr0.uint128
$2 = 0x9999999999999999999999999999999d
(gdb) p $vr1.uint128
$3 = 0x1d
(gdb) nexti
(gdb) p $vr0.uint128
$4 = 0x9999999999999999999999999999998d
--
QEMU 4.2+patches:
=> 0x10000740 <vec_setbool_bcdinv+60>: bcdadd. v0,v0,v1,0
(gdb) p $vr0.uint128
$1 = 0xa999999999999999000000000000000c
(gdb) p $vr1.uint128
$2 = 0xc
(gdb) p $cr
$4 = 0x24000242
(gdb) nexti
(gdb) p $vr0.uint128
$5 = 0xffffffffffffffffffffffffffffffff
(gdb) p $cr
$6 = 0x24000212
hardware:
=> 0x10000740 <vec_setbool_bcdinv+60>: bcdadd. v0,v0,v1,0
(gdb) p $vr0.uint128
$2 = 0xa999999999999999000000000000000c
(gdb) p $vr1.uint128
$3 = 0xc
(gdb) p $cr
$4 = 0x24000442
(gdb) nexti
(gdb) p $vr0.uint128
$5 = 0x999999999999999000000000000000c
(gdb) p $cr
$6 = 0x24000412
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (12 preceding siblings ...)
2019-09-26 14:08 ` Paul Clarke
@ 2019-09-26 16:00 ` Mark Cave-Ayland
2019-09-26 16:26 ` Paul Clarke
` (5 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-09-26 16:00 UTC (permalink / raw)
To: qemu-devel
Right so this looks like a different bug: if you look at helper_bcdadd()
and helper_bcdsub() in target/ppc/int_helper.c then you can see the
problem straight away: the code is accessing the elements of ppc_avr_t
without directly without using the VsrX() macros which correct for host
endian.
Fortunately the fix is really easy - replace the direct access with the
relevant VsrX() macro from target/ppc/cpu.h instead. It does look as if
there are several places in the BCD code that need fixing up though.
The first thing to fix is the #define BCD_DIG_BYTE around line 2055: the
VsrX() macro offsets are in "big-endian" format to match the ISA
specification so VsrD(0) is the MSB and VsrD(1) is the LSB, which means
that during the conversion you generally want the index from within the
#if defined(HOST_WORDS_BIGENDIAN) ... #endif section.
Given that the VsrX() macros invert the array index according to host
endian then you can completely remove everything between #if
defined(HOST_WORDS_BIGENDIAN) ... #endif and replace it with simply:
#define BCD_DIG_BYTE(n) (15 - ((n) / 2))
Then as an example in the bcd_get_sgn() function below you can change
the switch from:
switch (bcd->u8[BCD_DIG_BYTE(0)] & 0xF)
to:
switch (bcd->VsrB(BCD_DIG_BYTE(0)) & 0xF)
etc. and repeat for the remaining bcd helpers down to helper_vsbox()
around line 2766. Note it seems the last few bcd helpers have a #if
defined(HOST_WORDS_BIGENDIAN) ... #endif section towards the start that
might a bit of thought, however once they are written in terms of the
VsrX() macros then everything will "just work" regardless of host
endian.
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (13 preceding siblings ...)
2019-09-26 16:00 ` Mark Cave-Ayland
@ 2019-09-26 16:26 ` Paul Clarke
2019-09-26 16:43 ` Paul Clarke
` (4 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-09-26 16:26 UTC (permalink / raw)
To: qemu-devel
`vsl` appears to be acting incorrectly as well, per the test
'vec_bcdsr':
=> 0x100006e0 <vec_slq+132>: vsl v0,v0,v1
(gdb) p $vr0.uint128
$21 = 0x10111213141516172021222324252650
(gdb) p $vr1.uint128
$22 = 0x0
(gdb) stepi
0x00000000100006e4 in vec_slq ()
1: x/i $pc each byte
=> 0x100006e4 <vec_slq+136>: xxlor vs0,vs32,vs32
(gdb) p $vr0.uint128
$23 = 0x10111213141516572021222324252650
=> 0x100006e0 <vec_slq+132>: vsl v0,v0,v1
(gdb) p $vr0.uint128
$21 = 0x10111213141516172021222324252650
(gdb) p $vr1.uint128
$22 = 0x0
(gdb) stepi
0x00000000100006e4 in vec_slq ()
1: x/i $pc
=> 0x100006e4 <vec_slq+136>: xxlor vs0,vs32,vs32
(gdb) p $vr0.uint128
$23 = 0x10111213141516172021222324252650
Note in the final result differs in the first nybble of the 8th MSB
('57' vs '17').
--
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (14 preceding siblings ...)
2019-09-26 16:26 ` Paul Clarke
@ 2019-09-26 16:43 ` Paul Clarke
2019-09-26 16:59 ` Mark Cave-Ayland
` (3 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-09-26 16:43 UTC (permalink / raw)
To: qemu-devel
The final failure is 'vsr' acting incorrectly, with basically the same
issue as 'vsl'.
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (15 preceding siblings ...)
2019-09-26 16:43 ` Paul Clarke
@ 2019-09-26 16:59 ` Mark Cave-Ayland
2019-09-26 17:31 ` Paul Clarke
` (2 subsequent siblings)
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-09-26 16:59 UTC (permalink / raw)
To: qemu-devel
Ahhh in that case I suspect that you may be seeing a bug in this commit:
commit 4e6d0920e7547e6af4bbac5ffe9adfe6ea621822
Author: Stefan Brankovic <stefan.brankovic@rt-rk.com>
Date: Mon Jul 15 16:22:48 2019 +0200
target/ppc: Optimize emulation of vsl and vsr instructions
Optimization of altivec instructions vsl and vsr(Vector Shift Left/Rigt).
Perform shift operation (left and right respectively) on 128 bit value of
register vA by value specified in bits 125-127 of register vB. Lowest 3
bits in each byte element of register vB must be identical or result is
undefined.
For vsl instruction, the first step is bits 125-127 of register vB have
to be saved in variable sh. Then, the highest sh bits of the lower
doubleword element of register vA are saved in variable shifted,
in order not to lose those bits when shift operation is performed on
the lower doubleword element of register vA, which is the next
step. After shifting the lower doubleword element shift operation
is performed on higher doubleword element of vA, with replacement of
the lowest sh bits(that are now 0) with bits saved in shifted.
For vsr instruction, firstly, the bits 125-127 of register vB have
to be saved in variable sh. Then, the lowest sh bits of the higher
doubleword element of register vA are saved in variable shifted,
in odred not to lose those bits when the shift operation is
performed on the higher doubleword element of register vA, which is
the next step. After shifting higher doubleword element, shift operation
is performed on lower doubleword element of vA, with replacement of
highest sh bits(that are now 0) with bits saved in shifted.
Signed-off-by: Stefan Brankovic <stefan.brankovic@rt-rk.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1563200574-11098-3-git-send-email-stefan.brankovic@rt-rk.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
In fact, looking at that commit I think you should just be able to
revert it for a quick test - does that enable your regression tests to
pass?
--
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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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (16 preceding siblings ...)
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
19 siblings, 0 replies; 21+ messages in thread
From: Paul Clarke @ 2019-09-26 17:31 UTC (permalink / raw)
To: qemu-devel
Reverted 4e6d0920e7547e6af4bbac5ffe9adfe6ea621822, and those 'vsl/vsr'
tests now succeed.
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (17 preceding siblings ...)
2019-09-26 17:31 ` Paul Clarke
@ 2019-09-26 17:57 ` Mark Cave-Ayland
2021-05-02 18:09 ` Thomas Huth
19 siblings, 0 replies; 21+ messages in thread
From: Mark Cave-Ayland @ 2019-09-26 17:57 UTC (permalink / raw)
To: qemu-devel
Great! It looks as if I can't add Stefan to the bug report in launchpad
since he isn't registered there, so I'll send a quick email to qemu-
devel and add him as CC.
In the meantime whilst your test setup is working and everything is
fresh, I'll have a quick go at switching the BCD_DIG_BYTE bits over to
use the VsrX() macros to abstract out more host endian behaviour...
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread* [Bug 1841990] Re: instruction 'denbcdq' misbehaving
2019-08-29 20:29 [Qemu-devel] [Bug 1841990] [NEW] instruction 'denbcdq' misbehaving Paul Clarke
` (18 preceding siblings ...)
2019-09-26 17:57 ` Mark Cave-Ayland
@ 2021-05-02 18:09 ` Thomas Huth
19 siblings, 0 replies; 21+ messages in thread
From: Thomas Huth @ 2021-05-02 18:09 UTC (permalink / raw)
To: qemu-devel
If I got that right, this has been fixed by this commit here:
https://gitlab.com/qemu-project/qemu/-/commit/8d745875c28528a3015
... so I'm closing this now. If you disagree, feel free to open it again.
** Changed in: qemu
Status: New => Fix Released
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1841990
Title:
instruction 'denbcdq' misbehaving
Status in QEMU:
Fix Released
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?)
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1841990/+subscriptions
^ permalink raw reply [flat|nested] 21+ messages in thread