CFG review needed for fix of "PowerPC shrink-wrap support 3 of 3"

[David Miller]

From: Bernd Schmidt <bernds@codesourcery.com>
Date: Tue, 15 Nov 2011 01:54:34 +0100

> On 11/15/11 01:43, Richard Henderson wrote:
>> On 11/14/2011 11:56 AM, Alan Modra wrote:
>>> 	* function.c (thread_prologue_and_epilogue_insns): Guard
>>> 	emitting return with single_succ_p test.
>> 
>> Hmm.  This looks plausible too.  
>> 
>> Bernd's patch made sure that cfglayout didn't do something impossible.
>> Of course, it's possible that his patch should merely be an assert,
>> and the correct fix goes here.
> 
> I haven't really looked at Alan's patch; I'm thinking there were
> probably two bugs - the one I found being latent before. Note that the
> problematic CFG exists way before thread_prologue_and_epilogue even
> runs, so an assert would still trigger.

I suspect that Alan's fix here will take care of the sparc ada bootstrap
regression reported, and regardless if it's correct it should be installed.