On Wed, 8 Jan 2014, Jakub Jelinek wrote: > On Wed, Jan 08, 2014 at 11:45:28AM +0100, Richard Biener wrote: > > I prefer to always do this, not do the fancy insertion-before. That > > would do repeated folding for > > > > fold_stmt (gsi); > > fold_stmt (gsi); > > fold_stmt (gsi); > > > > where the last two should be a no-op. > > I don't see how is that possible, at least for the __builtin_unreachable > case, because by just setting the fndecl to __builtin_unreachable and > keeping the incompatible fntype and bogus arguments for it all the > predicates whether it is a valid/suitable builtin call will fail and we > don't have a __builtin_unreachable function you could call.
Well, that just means we need two sets of predicates to check for a builtin call. The __builtin_unreachable code wants to know what the callee is, not if that's a "valid" call to it. But yeah - this starts to get confusing :/ > So at least for builtin we want to make sure it has the right parameters. > If the lhs is something we can just initialize to zero, we can replace the > call with zeroing the lhs, but that is no the case always. I start to think this is a too complex transform for stmt folding ... > For __cxa_pure_virtual we could just keep the code as is (just with the > !inplace addition and spelling fix?), but would need to fix up whatever ICEs > during checking on it to honor fntype rather than decl's type. Yes. So a patch just keeping the targets.length () == 1 case in folding with just replacing the fndecl of the call is ok. Thanks, Richard.
