Thread-safety of a profiled binary (and GCOV runtime library)

[Nathan Sidwell]

On 07/25/16 08:46, Richard Biener wrote:
> There is also the question about optimization - we go great lengths to ensure
> that for example loop store motion applies to counter updates so we get
>
>  old_ctr = values[42];
>  for (;;)
>    ...
>  values[42] = old_ctr + # iterations
>
> using atomics there might show that we have no facility to optimize atomics
> at all (given their usual semantics is to include some kind of barrier).

Hm, that suggests something along the lines of __builtin_gcov_add() and an 
associated optimization ...

nathan