Re: An aliasing problem

[Jason M. <ja...@mi...>]

So we don't reinvent the wheel, John Regehr maintains a set of testcases
for how compilers optimize undefined behaviors here:

https://github.com/regehr/ub-canaries

In particular see:

https://github.com/regehr/ub-canaries/tree/master/strict-aliasing

On 00:54 Tue 28 Feb     , Pascal Bourguignon wrote:
>    On 28 Feb 2017, at 00:48, Bruno Haible <[1]br...@cl...> wrote:
> 
>    Sam,
> 
>      On a second thought, this appears like a clear case for an autoconf
>      test:
>      check whether the default compiler does strict aliasing
>      optimizations
>      and, if it does, try to disable them, and if we cannot disable them,
>      fail configure.
> 
>    Yes. Excellent idea! Even with compilers that we have never heard of,
>    this will
>    do the right thing: bark at high optimization levels, and be silent
>    when not
>    optimizing.
> 
>    The thing with optimizations is that you don’t get to decide when the
>    compiler will apply them.
> 
>    So, the actual test program you will have to compile while configuring,
>    will be the actual program.  Only so, you can be sure whether the
>    compiler did the optimization.
>    --
>    __Pascal J. Bourguignon__
> 
> References
> 
>    1. mailto:br...@cl...

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