Re: [PATCH] C undefined behavior fix

dewar
2002-01-09T10:42:40Z

<<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,