ref: fcdc5b4a8db42f064830bb5fa25f6f020fa121c6 dir: /builtins_plan9.c/
#include "platform.h" int __builtin_clz(unsigned int x) { unsigned int r; if(x == 0) return 32; for(r = 0; (x & (1UL<<31)) == 0; x <<= 1, r++); return r; }