On Mon, Aug 11, 2008 at 3:55 PM, Andrey Belevantsev <[EMAIL PROTECTED]> wrote: > 1. Make the required fixes inside the cfglayout hooks so that both the new > behavior and the old behavior is supported and the user can choose one of > them. As we still need to see the created jumps, we need to make > try_redirect_by_replacing_jump and force_nonfallthru functions either to > call user-defined hooks on the new jumps or to record the new jumps in a > vector to which the user can get access. > > 2. Factor out the hooks and helpers from cfg*.c into smaller functions and > create the alternative implementations of hooks inside the scheduler, which > will see the new jumps. The old behavior will be retained as we'll not > change the original hooks. > > 3. Modify try_redirect_by_replacing_jump and force_nonfallthru as in #1, but > do this in cfgrtl mode. No changes to the cfglayout mode will be needed > then, and it will not be used at all.
I prefer a mix of #2 and #1. I think much of the code in cfglayout.c:fixup_reorder_chain() could itself be made to work in cfglayout mode. You could modify the code to insert jumps where necessary before actually joining the basic blocks/headers/footers to a chain again. And you could create predicates that say yes/no on the question "do I need to end this basic block (in cfglayout mode) with a jump or not?" Gr. Steven
