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.
