Who Is Vfmaddrnd231pd?
Summary
The article investigates a purported x86 instruction, vfmaddrnd231pd, arguing that it may not exist and that documentation inconsistencies across Intel's System Programmer's Manuals (SDMs) raise questions about its status. The author demonstrates that assemblers and compilers do not recognize the instruction, tests show undefined instruction behavior on real hardware, and speculates that Intel may have removed the feature but left confusing documentation. The piece ends with a call for readers to confirm the situation.