Richard Guenther wrote: > On Tue, Jan 27, 2009 at 11:35 AM, Paolo Bonzini <bonz...@gnu.org> wrote: >>>>> Not for PTA though ;) >>>> Care to expand? >>> PTA tracks points-to-NULL as pointing to "nothing". >>> This probably should be conditional on -fdelete-null-pointer-checks. >>> Otherwise *NULL and *anything won't alias. >> Yes, you're right. I'll see if I can construct a testcase and a patch. > > Thanks.
It is now PR38984. Andrew's point about -fnon-call-exceptions is also worth pondering (and that's an understatement). >> BTW, I was thinking of not doing the optimization anyway on volatile >> pointers. What do you think? > > It should be taken care of automatically by loading it from memory > before each dereference, no? In this case, I meant more specifically the NULL test optimization that the OP stumbled in. That would be a GCC extension, not taking advantage for volatile pointers of the undefinedness that the standard guarantees. Paolo
