Okay, let's see. The user is reporting an issue with the PEXT instruction in QEMU. They mentioned that when using the qemu-x86_64 emulator with the Haswell CPU option, the PEXT instruction returns wrong values, seemingly switching arguments. They also checked the code in translate.c and int_helper.c, and found that the helper function works fine, so the problem might be in the gen_helper_pext call. The key points here are that the bug is related to a specific CPU instruction (PEXT) from the BMI2 instruction set. The user tested it on real hardware and QEMU, and there's a discrepancy. Since PEXT is an x86 instruction, and QEMU's emulation of it is incorrect, this falls under an instruction-related bug. The problem isn't with a syscall or runtime environment but specifically with how QEMU handles the PEXT instruction. Also, the user provided evidence pointing to the instruction emulation in QEMU's code. So the category should be "instruction". instruction