INSN_SCOPE changes break mips-elf

[Jan Hubicka]

> 
> mips-elf has had regressions ever since the INSN_SCOPE changes were installed
> into the tree.  While the number of regressions has gone down since the
> introduction of the INSN_SCOPE changes one regression still remains.
> 
> The remaining regression is gcc.dg/debug/debug-6 where we manage to lose
> all debug information for "xyzzy".  I believe the fundamental problem is your
> code in scope_to_insns_initialize does not properly handle SEQUENCEs as
> generated by the delay slot filling pass.

I noticed that, I already have patch to do the trick around sequences.
I guess I can't insert the notes into the sequences, or can I?
> 
> While we do expect some lossage of debugging information when optimizing, this
> case seems excessive and I think you should fix it.  It's probably also wise
> to pay more attention to the regression tester after invasive changes such
> as the INSN_SCOPE work.

It is still in my TODO list, scheduled for today.  I already did some
changes yesterday night, but it is bit dificult for some other targets
I've tested (like m68k, where the last instruction in the scope is
elliminated by combine and thus I believe it makes sense to omit the
block).  I explained it in the
other mail.

Honza
> 
> [ I made a naive attempt to fix this, but it generated more problems than it
>   solved. ]
> 
> 
> Jeff
> 
> 
> 
>