On Sat, 2005-04-23 at 12:42 +0000, linux@horizon.com wrote: > - You don't need to decrement %r1 before saving registers. > The PPC calling convention defines a "red zone" below the > current stack pointer that is guaranteed never to be touched > by signal handlers or the like. This is specifically for > leaf procedure optimization, and is at least 224 bytes. On ELF ppc32 ABI ? Hrm... the SysV ABI document says "The only permitted references with negative offsets from the stack pointer are those described here for establishing a stack frame." I know MacOS had a red zone, but do we ? > - Is that many stw/lwz instructions faster than stmw/lmw? > The latter is at least more cahce-friendly. More cache friendly ? Hrm.. I wouldn't be sure. Also, I remember readind a while ago that those store/load multiple instructions aren't that recommended. They aren't very good on some CPU models. I would expect the bus/cache bandwidth to be the limiting factor here anyway, and as you point out below, the they don't deal with unaligned access very well in all cases. - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.htmlReceived on Sun Apr 24 12:45:24 2005
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