Hi, On Wed, 17 Nov 2004, Dave Korn wrote: > Excuse me for butting in, but I don't understand what makes anyone > think this code _ought_ to produce the same results at different -O > levels[*]. While it's true that with signed arithmetic we are allowed to simply break, such behaviour can (and in this case indeed does) point out a real problem in the optimizers, so its often a bit too hasty to ignore a problem just because the source code is not totally conformant. With unsigned int a similar thing happens, namely that the second call to H(B,C) is deleted. The SuSE compiler has unit-at-a-time, hence determines that H is in fact a const function. Somehow it misses that C is modified between the two calls, ergo it thinks that both calls give the same results, and deletes the latter. Ciao, Michael.
