On 2018-04-26 12:53 +0200, Mason wrote： > On 26/04/2018 11:26, Jack Andrews wrote: > > > This reduces it to a one-platform problem. gcc -O different to gcc > > Maybe I'm being idealistic, but why should optimization change results? > > Because, for example on x86 platforms, 'gcc -O0' will use the 80-bit > x87 stack regs, while 'gcc -O2' will use the 64-bit SSE regs. > > It is better to give up the notion that floating point computation > are exact, and accept the fact that small errors do change the > results on different implementations (and as pointed out, even on > the same implementation with different options). > > It is also worth pointing out that sometimes these small errors > accumulate into huge errors. Floating point is tricky. > > cf. https://en.wikipedia.org/wiki/Loss_of_significance > > Regards. A new PR323-like issue. cf. http://gcc.gnu.org/wiki/FAQ#PR323 -- Xi Ruoyao <ryxi@xxxxxxxxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University
