Request for reviews (S): 6810845: Performance regression in mpegaudio on x64

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6810845/webrev.00

Fixed 6810845: Performance regression in mpegaudio on x64

Problem:
Fix for 6743900 normalized blocks frequency with start block's
frequency equals 1.0. This lowed frequencies in average.
Register Allocator relay on these frequencies and in some
places it has static values against which it compares frequencies.
As result of 6743900 fix some of the code under the frequencies
checks is not triggered. In this bug case the code which is not
executed is spilling for debug info in uncommon blocks which
prevents spilling in hot paths for long LRGs.
And this causes performance regression.

Solution:
Use outer loop frequency in frequencies checks in RA
instead of static values. Also add the check for
uncommon blocks in some frequencies conditions.
Also fixed performance issue with compressed oops
to avoid converting to Bottom types of memory
operations which use a compressed oop as base.

Reviewed by:

Fix verified (y/n): y, refworkload

Other testing:
JPRT