How to disable sibcall optimization?

[Jan Hubicka <hubicka at atrey dot karlin dot mff dot cuni dot cz>]

Hi
While doing the usual benchmarking for new snapshot, I found that there are
important performance regresions in number of benchmarks (the overall results
are again comparable with 2.95).  While looking for the purpose I believe most
of those problems are caused by the sibcall code, that optimize flowgraph too
much and makes loop optimizer fail on even more loops than it does currently.
Now the loop fails in most cases on multiple entry points error.

It looks like there is no way to disable sibcalls easilly. Why? I think we
ought to have disabling flag for every such non-trivial transformation
for debugging purposes.

How far is the work on turning loop.c to use the new loop infrastructure?

Honza