[Bug rtl-optimization/15521] New: sched1 extends life of hard registers on SMALL_REGISTER_CLASSES targets when exceptions are enabled

[amylaar at gcc dot gnu dot org]

The current mailine fails to build libstdc++-v3 for sh-elf.  We get
a reload failure compiling locale-inst.cc for -m4-single-only .
The first scheduling pass moves the instruction that moves the call
value from a hard to a pseudo register away from the call, which extends
the lifetime of r0 across an instruction with indexed addressing.
The problem is that the call is in a different scheduling region, as
exception handling causes it to end a basic block.
Thus, sched_analyze doesn't see the CALL_INSN during the current region
scheduling, in_post_call_group_p does not get set, and thus the return
value copy instruction doesn't get the SCHED_GROUP_P bit set.

A patch is here:
http://gcc.gnu.org/ml/gcc-patches/2004-05/msg00857.html

-- 
           Summary: sched1 extends life of hard registers on
                    SMALL_REGISTER_CLASSES targets when exceptions are
                    enabled
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code, build, patch, EH
          Severity: critical
          Priority: P2
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amylaar at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: any
  GCC host triplet: any
GCC target triplet: sh-elf and other SMALL_REGISTER_CLASSES targets


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15521