Public bug reported:
Hi,
I fiddled with BMI2 instructions and discovered that pext instructions
emulated with "qemu-x86_64 -cpu Haswell" return the wrong value. It
seemingly switches up its arguments. I suspect that the error is around the
gen_helper_pext(...) call in target-i386/translate.c. I checked helper_pext
in target-i386/int_helper.c and it works fine.
I ran my program on a CPU with BMI2 instruction set too, and it indeed
returns different values.
I didn't check pdep, it could have the same problem.
$ qemu-x86_64 --version
qemu-x86_64 version 2.6.50 (v2.6.0-2095-ge66b05e-dirty), Copyright (c)
2003-2008 Fabrice Bellard
$ uname -a
Linux lenard-hp 4.3.0-1-amd64 #1 SMP Debian 4.3.5-1 (2016-02-06) x86_64
GNU/Linux
I compiled the attached file with the command line "gcc -o main -g
-mbmi2 main.c".
$ gcc --version
gcc (Debian 5.4.0-6) 5.4.0 20160609
Best regards,
Lénárd Szolnoki
** Affects: qemu
Importance: Undecided
Status: New
** Attachment added: "main.c"
https://bugs.launchpad.net/bugs/1605123/+attachment/4704470/+files/main.c
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https://bugs.launchpad.net/bugs/1605123
Title:
PEXT returns wrong values, seemingly switches arguments
Status in QEMU:
New
Bug description:
Hi,
I fiddled with BMI2 instructions and discovered that pext instructions
emulated with "qemu-x86_64 -cpu Haswell" return the wrong value. It
seemingly switches up its arguments. I suspect that the error is around the
gen_helper_pext(...) call in target-i386/translate.c. I checked helper_pext
in target-i386/int_helper.c and it works fine.
I ran my program on a CPU with BMI2 instruction set too, and it indeed
returns different values.
I didn't check pdep, it could have the same problem.
$ qemu-x86_64 --version
qemu-x86_64 version 2.6.50 (v2.6.0-2095-ge66b05e-dirty), Copyright (c)
2003-2008 Fabrice Bellard
$ uname -a
Linux lenard-hp 4.3.0-1-amd64 #1 SMP Debian 4.3.5-1 (2016-02-06) x86_64
GNU/Linux
I compiled the attached file with the command line "gcc -o main -g
-mbmi2 main.c".
$ gcc --version
gcc (Debian 5.4.0-6) 5.4.0 20160609
Best regards,
Lénárd Szolnoki
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