semantic: 0.983
instruction: 0.964
boot: 0.678
other: 0.609
mistranslation: 0.606

x86 BLSI and BLSR semantic bug
Description of problem
The result of instruction BLSI and BLSR is different from the CPU. The value of CF is different.

Steps to reproduce

Compile this code


void main() {
    asm("blsi rax, rbx");
}



Execute and compare the result with the CPU. The value of CF is exactly the opposite. This problem happens with BLSR, too.


Additional information
This bug is discovered by research conducted by KAIST SoftSec.