[Obviously non-SPARC recipients dropped, but I probably missed some.] >> __ffs on the available architectures: > SPARC: sparc64: YES, sparc32: NO > Patch needs to be updated to refelct this. I didn't see the sparc64 implementation, but on looking again, I have to say that no, it doesn't. arch/sparc/lib/ffs.S is a custom implementation of __ffs, but it's a function call and 33 instructions/18 cycles long. There are several similar custom implementations that I also considered "NO". "fast" in this context means a handful of inline instructions, usually one of: 1. A direct count_trailing_zeros instruction, 2. count_leading_zeros(x ^ (x-1)), or 3. count_leading_zeros(bit_reverse(x)), or 4. popcount(~x & (x-1)). The question is whether __ffs plus a variable shift is faster than three instructions plus an unpredictable branch. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
