[Bug rtl-optimization/53176] [4.8 Regression] gcc.target/i386/movbe-2.c and gcc.dg/lower-subreg-1.c

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53176

--- Comment #3 from Uros Bizjak <ubizjak at gmail dot com> 2012-05-02 17:58:17 UTC ---
(In reply to comment #1)

> Lower-subreg is most likely a terrible transformation to do on later x86s but
> is likely to have been useful on the earlier ones.  So this regression is
> likely a good thing.

Can you please suggest, what should be added to leave decisions as they were?
We would like to fine tune the cost model in a controlled way, supported by the
data from benchmarks and applications. Forced under-the-hood changes to cost
model just don't fit this approach.