is it safe to use xmm registers to save the general-purpose ones?

问题

        pushf       //couldnt store this in other registers 
        movd xmm0,eax//storing in xmm registers instead of   pushing
        movd xmm1,ebx//
        movd xmm2,ecx//
        movd xmm3,edx//
        movd xmm4,edi//end of push backups
        .
        .//doing work
        .
        movd edi,xmm4//pop edi
        movd edx,xmm3//pop edx
        movd ecx,xmm2//pop ecx
        movd ebx,xmm1//pop ebx
        movd eax,xmm0//pop eax
        popf

is %50 faster than push eax version in my computer. Is this safe?

回答1:

Yes, as long as you (or some code you're calling) doesn't use XMM regs for anything else in the meantime. In fact, this trick is commonly used in BIOS code before RAM init.

来源：https://stackoverflow.com/questions/11630571/is-it-safe-to-use-xmm-registers-to-save-the-general-purpose-ones