On 15/09/2020 09:07, mx via Gcc-help wrote: > The program run in a embedded system. I turn on -flto option to > optimize the size of my program. However the program broke in > runtime. Is it normal? > You are giving very little information here, but it is certainly normal that you need to take some care if you want to use LTO in an embedded system. In particular, it's easy to end up with a system that is missing interrupt functions, non-code flash sections (vector tables, configuration options, etc.), and other code that is vital but not directly reachable from main(). Some gcc toolchains for microcontrollers come with a fair amount of this set up already, others do not. Basically, don't try using LTO unless you are happy to read the documentation for the option, read (and modify) your linker scripts, use gcc attributes, study map files, and dig into the details of what is going wrong.
