On 07/03/14 15:39, Henrik Juul Pedersen wrote: > Hi, I'm not sure if this is the correct forum, but I'm not sure > whether this is a bug, or a feature. gcc-help can be appropriate, but if your question is very specific to the avr port then avr-gcc-list@xxxxxxxxxx might be better. > > Im working on a program for an AVR microcontroller using avr-gcc for > the compilation. > > > I have gotten an issue with a single function variable not being > checked after optimization. Do you mean a variable local to the function (as distinct from a function pointer variable)? > My question is: shouldn't I be able to assume that function variables > are treated as being volatile, unless optimized away completely? No, you should assume the compiler will do all sorts of wonderful optimisations with local variables. It is usually a bit more limited with local static variables, but "normal" local variables (what used to be called "auto" variables before C++11 usurped that keyword) can be heavily optimised. > Marking the function variable volatile solves the issue. > > The code is compiled with -O2 -ffreestanding -Wall -Wextra and > produces no warnings. > > I have not been able to create a simple test-case, but I can supply > the entire source upon request. > It is usually not useful to have a large source file - a small test case is best. It is quite common that in the process of finding a small test case that shows the problem, people find the issue themselves. mvh., David
