[cfe-dev] [request] Improve debugging of ffast-math optimizations

Milian Wolff via cfe-dev cfe-dev at lists.llvm.org
Mon Apr 25 02:49:42 PDT 2016

On Sunday, April 24, 2016 10:51:38 AM CEST Hal Finkel via cfe-dev wrote:
> Hi!


> For optimizations, like traditional reassociation (and reduction
> vectorization), we could use the backend "remark" feature to give users
> information on where these apply. On large codes, however, such information
> would be very noisy. For this to be useful we'd need to think about how to
> filter, I suspect we'd need to combine it with profiling information, so
> they we only generated the information on actually-executed (or even hot)
> paths.

Would it be much more noisy than reports on missed auto-vectorization 
opportunities? When I used those, I always piped the output to a file and 
browsed it in an editor to find the spots I knew are hot from separate 
profiler runs. Not perfect, but certainly doable and helpful and I would 
assume much easier to implement on the clang side.

Milian Wolff
mail at milianw.de

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