[LLVMdev] LLVMdev Digest, Vol 76, Issue 43

[Alasdair Grant]

John Criswell writes:
> In my opinion, I think you guys are really overthinking this: volatile
> should be volatile should be volatile.  It makes the behavior of
> volatile easy to understand, it makes it easy to use, it allows LLVM to
> support the rules for the volatile keyword in C (AFAIK), and it doesn't
> require you to guess all the different, contorted ways in which
> volatile
> could be used.

Absolutely.  Another place we see volatile being used on locals is
timing loops:

  { volatile int i;
    for (i = 0; i < 10; ++i) {}
  }

Optimizing away the loop on the basis that nothing observable is
happening so it's "as if" it never happened, is counter to programmers'
intuitions about what 'volatile' means.  The savings from optimizing
volatile are negligible.  The risk of breaking working code in
difficult-to-debug ways is huge.

Al

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