These peepholes replace two mfcr;mask sequences by one mfcr;mask;mask
sequence. On modern cpus, the original mfcr's were actually mfocrf,
but the new insn is an actual heavy-weight mfcr. This is very bad
for performance.
The comment says there is a three cycle delay between two consecutive
mfcr insns. This may have been true on rios, and it's true on 604,
but on 603, 750, 7400 it is just a single cycle (on 7450 it is two).
This is also a define_peephole, and we should get rid of those.
So this patch just removes the peepholes; the benefit is marginal at
best, and it so very hurts in other cases.
* config/rs6000/rs6000.md (define_peepholes for two mfcr's): Delete.
From-SVN: r237062
