Missed optimization in simple_cst_equal() and has_cleanups()?

[grahams@rcp.co.uk]

Hi

There are a couple of routines in tree.c (simple_cst_equal, has_cleanups)   
which try
to answer a couple of simple questions. These routine return either a   
definative
yes/no or a "don't know". They return a "don't know" if they encounter a   
language
specific tree code.

If instead of returning "don't know" the question was passed onto the   
language specific
code to supply the answer then this might open up possibilities for   
optimizations which
at present are missed (ie the language specific code might have been able   
to give
a definitive yes/no answer).

Obviously the language specific code could just return "I don't know" if   
there is no quick
and easy answer.

My question is are there any language specific tree nodes where the   
language specific code
could provide a quick and easy answer to either of these questions with a   
definitive yes/no?

Does anybody have any comments.

Graham