4 ms·

The downside of reordering being performance? Or something else?

• 10x-dev 5y ago
  Performance is usually the upside. The downside is subtle bugs that can happen due to side effects of the statements being reordered between sequence points.
  • WithinReason 5y ago
    AFAIK compilers don't reorder if it would change the result.
    • Thiez 5y ago
      Compilers not allowed to violate the language spec when optimizing. But the spec may be fairly generous in its allowed interpretations, which may not match what a programmer may naively expect. C, with its many undefined behaviors and implementation defined behaviors, is especially dangerous.