[Bug target/30282] Optimization flag -O1 -fschedule-insns2 cause red zone to be used when there is none

[amodra at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30282

--- Comment #16 from Alan Modra <amodra at gmail dot com> 2011-08-05 16:29:02 UTC ---
Created attachment 24923
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24923
minimal rs6000.c fix

This fix just ensures we have a stack tie at the ABI_V4 stack reset.  Note that
only for ABI_V4 do we currently have frame_reg_rtx != sp_reg_rtx in
rs6000_emit_stack_reset.