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[Bug 1245543] Re: Wrong implementation of SSE4.1 pmovzxbw and similar in
From: |
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Subject: |
[Bug 1245543] Re: Wrong implementation of SSE4.1 pmovzxbw and similar instructions |
Date: |
Wed, 07 Oct 2020 04:17:25 -0000 |
[Expired for QEMU because there has been no activity for 60 days.]
** Changed in: qemu
Status: Incomplete => Expired
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https://bugs.launchpad.net/bugs/1245543
Title:
Wrong implementation of SSE4.1 pmovzxbw and similar instructions
Status in QEMU:
Expired
Bug description:
QEMU 1.5.0 (and git version, as far as I can tell from the source
code) has incorrect implementation of pmovzxbw and similar SSE4.1
instructions. The instruction zero-extends the first 8 8-bit elements
of a vector to 16bit vector and puts them to another vector. The
current implementation applies this operation only to the first
element and zeros out the rest.
To verify, compile the attached program for SSE4.1 (g++ -msse4.1
cvtint.cc). On real hardware, it produces the following output:
$ ./a.out
1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0
On QEMU, the output is as follows:
$ ./a.out
1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
QEMU is invoked as:
qemu-system-x86_64 \
-M pc -cpu Haswell,+sse4.1,+avx,+avx2,+fma,enforce -m 512 \
-serial stdio -no-reboot \
-kernel vmlinuz -initrd initrd.img \
-netdev user,id=user.0 -device rtl8139,netdev=user.0 -redir tcp:2222::22
\
-hda ubuntu-amd64.ext3 \
--append "rw console=tty root=/dev/sda"
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