Re: [PATCH] S/390 port modernization 4/4

[Jim Blandy <jimb@redhat.com>]

Ulrich Weigand <weigand@i1.informatik.uni-erlangen.de> writes:
> this is patch 4/4 to update the s390 backend.
> 
> The focus of this patch is frame handling; it completely removes
> all old-style frame routines and switches the backend to use the
> new frame handling using frame_unwind and frame_base.
> 
> This is still using prologue analysis; in fact the analyser is
> made somewhat more generic: it now understands the new long
> displacement instructions introduced with z990, and it is also
> more flexible in that it can handle unknown instructions 
> intermixed with the prologue due to instruction scheduling.
> Also, literal pool constants are now accepted in 64-bit mode
> as well (not just 31-bit mode).
> 
> This patch removes the last (to my knowledge) use of deprecated
> features in the s390 backend.
> 
> 
> Tested on s390-ibm-linux and s390x-ibm-linux with no new regressions.
> Fixes (about) 23 unexpected and 4 known failures on s390;
> fixes (about) 26 unexpected and 1 known failures on s390x.

This looks great.

For another target, I made the same optimistic assumption you did
about unrecognized instructions, and it worked well.  I did run into
some problems with the analysis going too far, but those were all
exposed by the test suite, so you've probably found everything I did.