There's a nearly identical issue in LLVM [1]. So neither are currently able to handle ADCX/ADOX in their IR and can only support it through inline assembly. I

There's a nearly identical issue in LLVM [1]. So neither are currently able to handle ADCX/ADOX in their IR and can only support it through inline assembly. I was hoping LLVM could maybe bypass this IR limitation for the iXYZ types and generate the optimal instruction sequence, but from your assembly it looks like that doesn't happen either. [1] https://bugs.llvm.org/show_bug.cgi?id=41546#c1 https://bugs.llvm.org/show_bug.cgi?id=41546#c1