Messages in this thread | | | From | dewar@gnat ... | Subject | Re: [PATCH] C undefined behavior fix | Date | Wed, 9 Jan 2002 05:42:20 -0500 (EST) |
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<<Especially if there are cases were this optimization yields a slower =
access (or even worse indirect bugs). E.g. if the referenced "volatile short" is a hardware register and the access is multiplexed over a slow 8 bit bus. There are embedded systems around where this is the case and the (cross-)compiler has no way to know this (except it can be told by the programmer). >>
Well that of course is a situation where the compiler is being deliberately misinformed as to the relative costs of various machine instructions, and that is definitely a problem. One can even imagine hardware (not such a hard feat, one of our customers had such hardware) where a word access works, but a byte access fails due to hardware shortcuts, - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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