[tree-ssa] Enhance statement checking & fix minor buglets

[Daniel Berlin]

On Apr 5, 2004, at 6:42 PM, Richard Henderson wrote:

> On Mon, Apr 05, 2004 at 02:12:46PM -0400, Diego Novillo wrote:
>> Well, one thing that occurred to me would be to re-associate these
>> expressions to be PLUS_EXPR<SSA_NAME,MINUS_EXPR>.  That would be a 
>> valid
>> gimple expression if MINUS_EXPR is_gimple_min_invariant.  Though that
>> strikes me as somewhat hackish.

> True, but it might be good enough.  I'm working on it.
>
This would then be the only binary expression that allowed a binary 
expression as one of it's operands, which would seriously defeat the 
purpose of GIMPLE.
>