On 02/02/18 23:03, jacob navia wrote: > Le 02/02/2018 à 22:11, Florian Weimer a écrit : >> * jacob navia: >> >>> I have in my small C compiler introduced the following construct: >>> >>> #pragma optimize(on/off,push/pop) >> Not sure what you are after. GCC has something quite similar: >> >> <https://gcc.gnu.org/onlinedocs/gcc/Function-Specific-Option-Pragmas.html> >> > > Great! > > I had never seen it, and the docs in my machine weren't very explicit > about that. > > I apologize for the noise and thank you for pointing me to that doc. > > jacob > >
You will find gcc manuals for many versions of the tools at <https://gcc.gnu.org/onlinedocs/>. In your debugging, I find the most common causes of "it works when optimisation is disabled" to be aliasing problems, integer overflow issues, or missing volatiles (that is more common in my world of embedded programming, rather than PC software). So rather than just: #pragma GCC optimize("-O2") and #pragma GCC optimize("-O0") I'd recommend testing with #pragma GCC optimize("-fno-strict-aliasing") and #pragma GCC optimize("-fwrapv") to see if that helps you isolate your problems quickly. And if you have a reasonably modern gcc, try out the -fsanitize options - they can be a great help in spotting bugs at run-time.
