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> It's actually an interesting example where undefined behavior allowed compiler optimization That is literally reason why any behavior is considered undefined

> It's actually an interesting example where undefined behavior allowed compiler optimization That is literally reason why any behavior is considered undefined. So that the compiler can skip checks to produce better optimized code.

secondcoming 5y ago
And so you get an optimal, but broken, program. This helps nobody.
- ehvatum 5y ago
  It helps everyone whose input does not cause undefined behavior.
- leetcrew 5y ago
  in most cases a program that invokes undefined behavior is already broken; it's just a question of how catastrophic the failure will be.
saagarjha 5y ago
Actually, many instances of undefined behavior are born out of a desire for portability. Some processors will fault on both of those and the standard wants to be inclusive of those behaviors. Compilers happen to be able to use the definition of undefined behavior to also optimize code, but the concept is born out of practicality.