[Beowulf] Re: f77 in f90

Dave Love d.love at liverpool.ac.uk
Sun Jun 28 04:37:50 PDT 2009

Prentice Bisbal <prentice at ias.edu> writes:

>> Will there be any performance loss (or gain) in compiling the fortran77
>> code with mpif90 (where the code will be containing some fortran90
>> constructs as well)? Any opinion?
> I doubt it. Most modern Fortran compilers do F77 and F90 (ifort and
> gfortran for example), so the same optimization logic is being used.

I've used one fairly recently where the f77 and f90 front ends were
different, but I can't remember which.

I'm not sure if it's what the OP means, but in principle you win with
f90 constructs, like array operations, because the compiler has more
scope with greater abstraction.  However, you may actually do better
with explicit loops, for instance, depending on the particular code and
compiler.  There were benchmark data on that from some ago, but
doubtless things have improved since.

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