Peter Dimov wrote: [...]
I don't need the value, but it doesn't matter; it's just as fast. Or just as slow. x86 isn't very predictable (I don't know how familiar you are with it); some instructions look better on paper but are (or were) actually
1996 or 1997 was the last time I wrote something in x86 asm. On "Blue Lightning 486."
slower (on 586 and above) than an equivalent RISC-style read/modify/write sequence, inc included. And of course the rules change with every generation (in some cases, sub-generation) of CPUs.
Basically, the only way to know which is faster is to measure it.
Nah. For the sake of killing C/C++ volatiles rather sooner than later, I strongly suggest that you hide that load in asm. Just add load+cmp followed by ZF branch prior to "lock dec" which also sets ZF, IIRC.
Eh, __asm__ is no better than a volatile. Both are non-portable.
Except that volatile has defined semantics (both must die too in favor of threads and exceptions) that has really nothing to do with multiple threads and msync. I mean "decoration function" for sig_atomic_t statics and setjmp/longjmp()-sensitive locals in C and POSIX (C++ aside for a moment). "Promotion" of volatile mess is much worse than use of good asm, I think. regards, alexander.