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Re: Integer Overflow/Wrap and GCC Optimizations
On 1/24/2013 10:02 AM, Jeffrey Walton wrote:
What I am not clear about is when an operation is deemed "undefined"
or "implementation defined".
The compiler is free to assume that no arithmetic operation
on signed integers results in overflow. It is allowed to
take advantage of such assumptions in generating code (and
it does so).
You have no right to assume *anything* about the semantics
of code that has an integer overflow (let alone make
asssumptions about the generated code).
This is truly undefined, not implementation defined, and
if your program has such an overflow, you cannot assume
ANYTHING about the generated code.