[Compiler-sig] merging branches

[Neil Schemenauer]

[Note: compiler-sig added to Cc list]

On Wed, Oct 19, 2005 at 01:00:08PM -0600, Neil Schemenauer wrote:
> On Wed, Oct 19, 2005 at 11:28:06AM -0400, Jeremy Hylton wrote:
> > test_02_arigo (__main__.TraceTestCase) ... FAIL
> 
> This one fails because the new compiler does dead code elimination
> for "while 0" but not for "if 0".  I've added optimization for "if
> 0" and disabled the "while 0" optimization for now.

Oops, the "if 0" optimization is tricker than I thought.  The new
compiler needs something like look_for_offending_return() to detect
illegal "return" statements inside generator functions.  It's harder
to do in the new compiler because nodes cannot be treated
generically (the look_for_offending_return() is pretty simple and
just self recurses).

This check needs to be done after the symtable does its pass
(symtable_visit_expr and friends).   I wonder if it would be a good
idea to add another general pass that runs between the symtable
building and the code generation.  Initially it would only check for
illegal return statements but if we wanted to add pychecker type
stuff in the future then that would seem to be the place to do it.

Am I making this more complicated then it needs to be?  Maybe I'm
missing some easy way to write a look_for_offending_return()
equivalent.

  Neil