[petsc-dev] What is this? "Optimize VecNorm_MPI. Use BLASdot_ instead of BLASnrm2_"

[Jed Brown]

http://petsc.cs.iit.edu/petsc/petsc-dev/rev/a8a483b98169

This baffles me. I can think of no good reason for this, which gives me the
impression that we are optimizing for an implementation quirk. If you have
evidence that the performance of BLAS dot() is better than nrm2() across
platforms and implementations, then we are witnessing a major
implementation failure and people need to be shamed.

Aliasing is also *explicitly disallowed* by Fortran, so the result of

BLASdot_(&bn,xx,&one,xx,&one);

is not defined.
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