Probe on function entry rather than the end of the prolog (s390x only)

[David Wilder]

Frank Ch. Eigler wrote:

>Roland McGrath <roland@redhat.com> writes:
>
>  
>
>>I don't think that flies so well.  The bugs we hit in older
>>compilers were location lists that looked fine but were incorrect
>>for the prologue regions.  There isn't any automatic way to identify
>>those location lists as bad.
>>    
>>
>
>Too bad.  OK, then let's gather some data about compiler versions and
>architectures.  If we find a reasonable and documentable dividing line
>between working and not working, then we can make systemtap assume the
>former.  (We could retain a discreet switch such as an environment
>variable to activate the prologue code for people stuck with
>non-working systems.)
>
>- FChE
>  
>
What archs did you see bugs on? I suspect any list of working and not 
working gcc versions will have to be indexed by arch.

I can try to verify that the location lists for the prolog region (on 
s390) are always correct or not.
After making my purposed change on s390x the full systemtap tests found 
no new failures. But that may not be all inclusive so I will try to 
develop a specific test.

-- 
David Wilder
IBM Linux Technology Center
Beaverton, Oregon, USA 
dwilder@us.ibm.com
(503)578-3789