New Issue: + reduction on records: just use '+=' if available

Notifications Issues
1

20535, "vasslitvinov", "+ reduction on records: just use '+=' if available", "2022-08-26T21:31:54Z"

Consider the standard plus reduction over a user-defined record:

record R { }  var r: R; forall ... with (+ reduce r) {...} writeln(r);

Our plus reduction implementation, i.e., class SumReduceScanOp in ChapelReduce.chpl, uses:

  • operator + to determine the accumulation type of the reduction
  • operator += to actually perform accumulation

This issue proposes to ignore the operator +, even allow its absence, if operator +=(R,R) is defined. If so, the accumulation type would be R and only += would be invoked at run time.

To implement this proposal, I suggest simply augmenting chpl_sumTypeIsSame() in ChapelReduce.chpl to check availability of +=(R,R) and return true if it is available.