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Fortran array slices and -frepack-arrays
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Cc: nd <nd at arm dot com>
- Date: Fri, 13 Apr 2018 14:32:29 +0000
- Subject: Fortran array slices and -frepack-arrays
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I looked at a few performance anomalies between gfortran and Flang - it appears array slices
are treated differently. Using -frepack-arrays fixed a performance issue in gfortran and didn't
cause any regressions. Making input array slices contiguous helps both locality and enables
So I wonder whether it should be made the default (-O3 or just -Ofast)? Alternatively would
it be feasible in Fortran to version functions or loops if all arguments are contiguous slices?