2014-09-15 19:39 GMT+04:00 Jeff Law <l...@redhat.com>: > On 09/15/14 03:51, Ilya Enkovich wrote: >>>> >>>> 2014-08-15 Ilya Enkovich <ilya.enkov...@intel.com> >>>> >>>> * ipa-split.c: Include tree-chkp.h. >>>> (find_retbnd): New. >>>> (consider_split): Do not split retbnd and retval >>>> producers. >>>> (split_function): Propagate Pointer Bounds Checker >>>> instrumentation marks and handle returned bounds. >>> >>> >>> I don't think it's sufficient to just look at the SSA_NAME_DEFSTMT and >>> verify that it's not in the header. >>> >>> You could easily have the SSA_NAME_DEF_STMT be a PHI which is in the same >>> partition as the RETURN statement. One of the PHI arguments might be fed >>> from a statement in the header, right? >>> >>> Don't you have to look at the entire set of definitions which directly >>> and >>> indirectly feed the return statement and verify that each and every one >>> is >>> in the same partition as the return statement? >> >> >> A problem I'm trying to avoid is that bounds in return statement are >> not taken into account when checking for data dependencies between >> parts. It means we may have a case when return statement with bounds >> is put into split part but bounds producer is not. If >> SSA_NAME_DEFSTMT for returned bounds is in the same partition as a >> return then I do not think I should care about the rest of definitions >> chain because regular split point checks should make sure we have >> everything required. > > Is the data dependency in the gimple IL? If so there shouldn't be anything > particularly special we need to do. If not, then how ugly would it be to > "use" the bounds at the return statement to expose the missing dependency? > > Not asking you to make that change, just want to make sure that I understand > the core issue and that if something is missing from a dependency standpoint > that we consider what it would take to expose the missing dependency.
Gimple IL has required data dependencies to handle returns properly. But split pass handles return basic block in a special way. Return basic block has to have a simple form and is not scanned using stmt walkers as it is done for all other BBs by visit_bb. It is assumed that all dependencies for return BB are PHI args and returned value. Thus returned bounds are just not taken into account. That's how I see the problem. Ilya > > jeff >
