Testsuite reorganization, documentation, cleanup?

[Nathanael Nerode <neroden at doctormoo dot dyndns dot org>]

Looking at the testsuite, it's rather confusing.  Some directories are
documented in READMEs; many aren't.  There are multiple organizational
systems.  There are multiple drivers, many of which seem very similar;
one suspects redundancy.

I'd like to clean up the organization a little, or at least document it
better.  But that leads to two questions:

1. What do people think the ideal organization should be?

Here's a possible answer:

  One directory for each language's corectness tests, and one for
  anything genuinely non-language-specific (counting preprocessor as a
  language).  

  Beneath that, a subdivision by correctness, code quality, or compiler
  behavior quality.

  Beneath that, subdivision by category where appropriate (abi,
  templates, etc.)

  Beneath that, one directory for each variety (compile, execute, fail to
  compile, produce warning 'blah')

  Name tests with the date you added them plus a digit. (Eek.)

This is obviously not the best arrangement; someone with more experience
can certainly come up with better arrangements.  The point is to have one
organization which encapsulates pretty much everything.

2. What do the various existing undocumented directories represent?

For instance, why are there 'gcc.c-torture', 'gcc.dg',
and 'gcc.misc-tests'?  What are the tests in g++.dg in the subdirectories
'bprob','debug','gcov','opt',and 'tls', and why aren't they mentioned in
g++.dg/README ?  

Why are there 410 tests in gcc.dg, not sorted in any clear fashion?

I'm guessing a lot of this is historical cruft, and *can* theoretically
be simplified.

Help would, well, help. :-)

--Nathanael