No, unconditionally safe. The C standard exactly defines unsigned overflow while specifically leaving signed overflow undefined.
(Pedantically timing is always a crapshoot in C, a compiler only need produce the same results as the abstract machine. It could freely take all your secret data and modulate it into the timing and be conforming. -- but considering that intel/amd won't make timing promises about the instructions themselves...)
No, unconditionally safe. The C standard exactly defines unsigned overflow while specifically leaving signed overflow undefined.
(Pedantically timing is always a crapshoot in C, a compiler only need produce the same results as the abstract machine. It could freely take all your secret data and modulate it into the timing and be conforming. -- but considering that intel/amd won't make timing promises about the instructions themselves...)