https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110530
--- Comment #2 from Haiqing Zhao <haiqingzhao at microsoft dot com> --- (In reply to Andrew Pinski from comment #1) > This code is undefined for 2 reasons. > > First is unsigned int and unsigned long are 2 different sizes on LP64 > targets (x86_64-linux-gnu is one of those, while windows is not). > Second is if they are the same size, then there is an aliasing violation in > that you cannot do a store as an `unsigned long` and then do a load from > that same location as an `unsigned int` as C says those 2 types don't alias. > > > -fsanitize=address will catch the first reason. Dear Andrew, Thanks a lot for your prompt explanation. I tested on a 32-bit platform and the issue shall be due to the neglect of strict aliasing. With the experiment which addes -fno-strict-alising when compiling, the code can also execute normally. Again thanks for your information. Sincere Regards, Haiqing
