https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106565
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2022-08-09 Known to fail| |12.1.0 Status|UNCONFIRMED |NEW Keywords| |missed-optimization Ever confirmed|0 |1 Version|unknown |10.3.0 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed also with gfortran 12. The issue is that with the combined matmul+transpose we invoke matmul with an array descriptor representing the transpose operation which results in suboptimal memory access patterns. Can you check whether ifort does the transpose separately or whether its matmul library routine simply special-cases the situation?