[LLVMdev] LLVMdev Digest, Vol 76, Issue 43

[Duncan Sands]

Hi Kenneth,

> Well...strictly as LLVM IR I find externally visible incorrect behavior
> unlikely, it's just a "different definition".  For C and C++, I'd be
> looking at more complicated variations of
>
> int main()
> {
>      volatile int i = 1;
>      return 0;
> }
>
> It's clear that the LLVM IR representation of i cannot be simply
> IR-volatile qualified, as that load gets optimized out while C and C++
> won't optimize it out.  I'd *hope* that DragonEgg and llvm-gcc both
> leave the load of i in, when in --pedantic mode.  [That is, I expect it
> to take something more intricate than this elementary test case to
> trigger any bugs here.]

both dragonegg and llvm-gcc remove the volatile.  I don't see why they
shouldn't, since the program behaves exactly the same (as far as anyone
external can tell) as if it had been left there.

Ciao,

Duncan.