Re: [rs6000] Fix PR 50906, eh_frame and other woes

[Olivier Hainque <hainque at adacore dot com>]

On Nov 9, 2011, at 18:15 , Olivier Hainque wrote:
> I'm not convinced that the potential gain is worth the extra
> complexity and potential risk of running into another subtle
> subcase, with hard to track sporadic runtime failures for
> starters. I don't have numbers though.
> 
> That's a port maintainer call, I guess ?

 David, opinion on this point ?

 My understanding is that we have two options

 1) try to preserve the current attempt at maximizing
    optimization opportunities with precise stack/frame
    tie insns, 

 2) simplify for a slightly more brutal option, with
    a strong (mem:blk scratch) barrier instead

 My feeling is that 2 would be a sensible option.
 
 Trying to get the precise insns right has caused multiple
 issues (several PRs about hard to track silent wrong code
 generated, trickier implementation), and I'm not convinced
 that the legitimate code efficiency gains are worth the 
 trouble.

 As I wrote, I don't have numbers to backup the latter point
 though.

 Thanks for your feedback,

 Olivier