On Friday, 14 October 2016 at 11:51:32 UTC, Johan Engelen wrote:
On Friday, 14 October 2016 at 11:17:55 UTC, Andrei Alexandrescu wrote:
On 10/14/2016 05:24 AM, Johan Engelen wrote:
I like "hints".


How many other hints are out there? -- Andrei

Things that come to mind:
- this value is probably X  (bool, int, pointer)
- this type is probably Y
- this function is likely hot/cold (UDA)
- this data is likely to be accessed soon (_could_ lead to a prefetch) - this member field is hot/cold (iirc, Class members may be re-ordered) (UDA)

- this pointer is aligned to N bytes
- this pointer doesn't alias with this pointer

There are also loop hints:

- this loop has no loop dependency, go wild auto-vectorizer!
- this loop is better unrolled by N

These hints are all dangerous. Manual prefetching, manual branch hints, forced unrolling count: I've seen those 3 hints reduce performance by being worse than the processor/compiler.

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