[flang][openmp] performance regression with 371.applu331 omp2012 benchmark when -mmlir --enable-delayed-privatization is enabled

I see around 2x performance regression when -mmlir --enable-delayed-privatization is enabled. The runtime is 90 seconds by default and when this option is disabled (-mmlir --enable-delayed-privatization=false) runtime reduces to 40 seconds.

individually, the file rhs.fppized.f90 seem to cause this performance difference.

Tried with latest sources and this issue is still there.

Reproduce the regression with the 371.applu331 omp2012 benchmark using -mmlir --enable-delayed-privatization and its false setting, then isolate the effect attributed to rhs.fppized.f90. Compare the compiler behavior and runtime results to determine where delayed privatization causes the slowdown. Done means the regression is explained and the benchmark no longer shows the reported performance gap.

Written by the indexing model from the issue text.