On 27/11/2016 19:56, Florian Weimer wrote: > Julien Teisseire wrote: > >> Could you give me some help / doc / information / example on how >> -ftree-pta works, what kind of source code it's optimizing ... >> I am currently unable to detect in my code where the bug is ! > > Do you use casts a lot? Do you access objects with a different type > from that they were originally created with? For the record, the description given in the manual for -ftree-pta is... Perform function-local points-to analysis on trees. This flag is enabled by default at -O and higher. (-O means -O1 in gcc) Florian, you suspect an aliasing issue? The OP might try -fno-strict-aliasing as used for the Linux kernel. Regards.