eliminating them as dead code.
Both volatile and "memory" are used because of some concern that the compiler
may still cache values across the asm block without it, and because this was
such a painful debugging session that I wanted to ensure that it's never
repeated.
if (n <= 0) return 0;
- asm (
+ asm volatile (
" subq %0,%0 \n" /* clear carry */
" jmp 1f \n"
".p2align 4 \n"
" sbbq %0,%0 \n"
: "=&r"(ret),"+c"(n),"+r"(i)
: "r"(rp),"r"(ap),"r"(bp)
- : "cc"
+ : "cc", "memory"
);
return ret&1;
if (n <= 0) return 0;
- asm (
+ asm volatile (
" subq %0,%0 \n" /* clear borrow */
" jmp 1f \n"
".p2align 4 \n"
" sbbq %0,%0 \n"
: "=&r"(ret),"+c"(n),"+r"(i)
: "r"(rp),"r"(ap),"r"(bp)
- : "cc"
+ : "cc", "memory"
);
return ret&1;