The problem starts when you have a cross-platform project where on the second platform we have a non-gcc compiler and 80-bit float calculations on non-intel hardware. That is my case where on the second platform expl calculates in the right way and after a sequence of evaluations we get a big error accumulation and the program behaviour becomes different. To my pity I can not find an example on any widespread platform to show the different behaviour of expl, so that seems to stay here for a long time. пт, 27 нояб. 2020 г. в 10:54, Stefan Ring <stefanrin@xxxxxxxxx>: > On Thu, Nov 26, 2020 at 11:46 PM Stefan Ring <stefanrin@xxxxxxxxx> wrote: > > > > On Thu, Nov 26, 2020 at 11:27 PM Alex Markin <alexanius@xxxxxxxxx> > wrote: > > > > > > memset will not help here. > > > > True, but only because it is optimized away! :D > > With -O2, the compiler pre-computes both of them at compile time, and > they are both the same (but the upper 6 bytes stay uninitialized, even > with memset). > > With -O0, the compiler pre-computes the first one and calls the > library function for the second result, which produces a different > result that differs in the last bit. > > Which is slightly surprising, but nothing that I lose sleep over... >
