[flang-commits] [flang] [flang][Lower] Always generate namelist group locally (PR #109303)

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jeanPerier wrote:

> I agree that creating a very large namelist could be a performance hit. Do those programs declare all variables inside of the namelist inside of a common block (i.e. is this an optimization that users expect)?. If some of the variables are local then this optimization could not be performed anyway.

I lack expertise about old code to judge here. I went ahead and ran an instrumented compiler through some of our regression tests. Out of about 400 tests using namelists, 150 fell into cases where the namelist data structure could be made global (37%). I am not sure however that this is an optimization that user expect given gfortran and ifort do not seem to be doing it, but nvfortran and classic flang are doing it I think.

https://github.com/llvm/llvm-project/pull/109303