[Swan-dev] -fno-strict-aliasing ?

Paul Wouters paul at nohats.ca
Sun Jun 5 18:44:20 UTC 2016


On Sun, 5 Jun 2016, D. Hugh Redelmeier wrote:

> We should try to follow C's aliasing rules.  But it is easy to slip.
> If you do, the compiler can cause your program to do surprising things.
> Unfortunately it is unlikely that the compiler would tell you when
> this has happened.
>
> I would think and hope that our code would survive without
> -fnon-strict-aliasing.  But to prevent surprises, it might be worth
> keeping -fno-strict-aliasing anyway.

In the past, gcc would give us warning when a strict alias rule was
broken in our code. Hence adding -fno-strict-aliasing. But as I said,
that code seems to no longer be there, as I don't see any warnings
anymore.

It's possible gcc changed and now is missing our offending code, but
not likely.

Paul


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