ART: Profile all branches for on-stack replacement
Change the switch, goto and mterp interpreters to profile
not-taken as well as taken branches. This allows for on-stack
replacement when the cfg has been rearranged such that the loop
header was originally the fallthrough of a Dalvik byte-code branch.
Note that this increases the already-heavy cost of branch profiling.
Measuring on a Nexus 6 using a very branchy benchmark (logic subtest
from Caffeinemark), we see:
No profiling Taken only Taken & not-taken
mterp 9728 3434 2384
C++ goto 3914 2422 2037
C++ switch 2986 2411 2112
As measured, the cost of branch profiling is dominating execution
time. This will be addressed in follow-up CLs.
8 files changed