Re:What is C in practice?
by kazinator on Monday June 29, 2015 @03:08PM
(#9800208)
> If the compiler was able to determine that there is a code path whereby j might be undefined, should it be allowed to remove the body of the loop, even in those cases where the programmer knows by other means that "j >= 1"?
No; rather, the correct logic is that compiler must preserve the body of the loop if there exists the possibility that it can be reached by a valid code path without any undefined behavior (j is defined, and so forth). Only if the compiler can prove that no well-defined execution path can reach the body can it remove it.
(A bad idea to do without any warning, though. If undefined behavior is confirmed, it should be diagnosed.)
No; rather, the correct logic is that compiler must preserve the body of the loop if there exists the possibility that it can be reached by a valid code path without any undefined behavior (j is defined, and so forth). Only if the compiler can prove that no well-defined execution path can reach the body can it remove it.
(A bad idea to do without any warning, though. If undefined behavior is confirmed, it should be diagnosed.)