[PATCH]: Improved handling of COND_EXPR in middle-end passes

Michael Matz matz@suse.de
Wed Nov 22 13:29:00 GMT 2006


On Wed, 22 Nov 2006, Diego Novillo wrote:

> I'm starting to wonder if it wouldn't be better to disallow
> 	lval = COND_EXPR
> in GIMPLE.  Passes that benefit from this (if-conversion for the vectorizer)
> could temporarily break this rule to get extended BBs.
> But I'm not convinced either way.  Not allowing COND_EXPRs on the RHS of an
> assignment would certainly make life more difficult for these passes.
> Thoughts?

Actually we were pondering about the possibility to extend gimple to even 
allow conditional statements (i.e. on the LHS!), perhaps in very 
restrictive form to not have to fiddle with PHI nodes.  Probably that's 
not necessary, though.  But if-conversion on tree-level might also be 
usefull in not just the vectorizer, so if it's not too much hassle I think 
it would be nicer to continue supporting COND_EXPR at least in the RHS.


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