Revert "PowerPC shrink-wrap support 3 of 3"

[Hans-Peter Nilsson]

> From: Hans-Peter Nilsson <hp@axis.com>
> Date: Wed, 9 Nov 2011 09:55:59 +0100

> > From: Alan Modra <amodra@gmail.com>
> > Date: Tue, 1 Nov 2011 16:33:40 +0100
> 
> > On Tue, Nov 01, 2011 at 12:57:22AM +1030, Alan Modra wrote:
> 
> >         * function.c (bb_active_p): Delete.
> >         (dup_block_and_redirect, active_insn_between): New functions.
> >         (convert_jumps_to_returns, emit_return_for_exit): New functions,
> >         split out from..
> >         (thread_prologue_and_epilogue_insns): ..here.  Delete
> >         shadowing variables.  Don't do prologue register clobber tests
> >         when shrink wrapping already failed.  Delete all last_bb_active
> >         code.  Instead compute tail block candidates for duplicating
> >         exit path.  Remove these from antic set.  Duplicate tails when
> >         reached from both blocks needing a prologue/epilogue and
> >         blocks not needing such.
> >         * ifcvt.c (dead_or_predicable): Test both flag_shrink_wrap and
> >         HAVE_simple_return.
> >         * bb-reorder.c (get_uncond_jump_length): Make global.
> >         * bb-reorder.h (get_uncond_jump_length): Declare.
> >         * cfgrtl.c (rtl_create_basic_block): Comment typo fix.
> >         (rtl_split_edge): Likewise.  Warning fix.
> >         (rtl_duplicate_bb): New function.
> >         (rtl_cfg_hooks): Enable can_duplicate_block_p and duplicate_block.
> 
> This (a revision in the range 181187:181189) broke build for
> cris-elf like so:
> See PR51051.

Given that this also broke arm-linux-gnueabi, a primary
platform, and Alan being absent until the 15th according to a
message on IRC, I move to revert r181188.

I think I need someone with appropriate write privileges to
agree with that, and to also give 48h for someone to fix the
problem.  Sorry for not forthcoming on the second point.

brgds, H-P
PS. where is the policy written down, besides the mailing list archives?