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Re: [PATCH]: Improved handling of COND_EXPR in middle-end passes
- From: Michael Matz <matz at suse dot de>
- To: Diego Novillo <dnovillo at redhat dot com>
- Cc: Roberto COSTA <roberto dot costa at st dot com>, GCC patches mailing list <gcc-patches at gcc dot gnu dot org>, Roger Sayle <roger at eyesopen dot com>, Ian Lance Taylor <ian at airs dot com>, Andrew MacLeod <amacleod at redhat dot com>, Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>
- Date: Wed, 22 Nov 2006 14:21:37 +0100 (CET)
- Subject: Re: [PATCH]: Improved handling of COND_EXPR in middle-end passes
- References: <4564206A.email@example.com> <firstname.lastname@example.org>
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.
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.