[RFC] Merge criteria for tree-ssa

[Bud Davis]

This comment is more about the first release of tree-ssa, which will
have gfortran as THE f77 compiler.

In the industry I work (simulation), more lines of f77 (and f66) code
will be compiled by gfortran than f90 code for another decade, at
least.  

Users are going to expect a very high level of compatability between
existing g77 code and gfortran.  

Now, on to the upcoming merge:

The criteria that makes most sense from a users viewpoint is that
tree-ssa could not be merged until gfortran was as good as g77 at
compiling f77.  Since mainline gcc has NO f95 users right now, this
criteria would keep gcc from losing existing functionality.


Of course, this is highly unrealistic !! 

Just trying to highlight some extreme viewpoints   !!! :):)


My point is g77 compatability is important.  Explicit g77 compatability
tests need to be defined and agreed upon,and these tests must pass
before tree-ssa / gfortran is released, or at least before it
transitions into maintenance mode.

Possibilities that I am aware of are NIST F77 standard compliance,
LAPACK, and the g77 testsuite.  In addition current g77 users need to be
feeding code through gfortran and submitting bug reports.


regards,
bud davis