Indirect branch profiling:

1. what is the frequency of 1-target indirect branches in benchmarks?

1-target indirect branch
there is only one target of this indirect branch instruction during execution.
therefore when we say n-target indirect branch, we mean indirect branches that has n targets during execution.

frequency 
Assume there are 100 guest indirect branches executed (dynamic count) during execution, and there are 8 1-target indirect branches executed. The frequency is 8/100 = 8%.

N-Target Indirect Branches Frequency Distribution of 400.perlbench with diffmail.pl test input:

seems not very useful information

2. what is the hit ratio of last-target prediction of indirect branches?

last-target prediction:
Predict next target of one indirect branch with its last target.

400.perlbench with ref. input diffmail.pl:

Overall 73.63%
RET 93.99%
INDIRECT_CALL 20.45%
UNCOND_INDIRECT_JMP 48.98%

gcc with ref. input 166.i:

Overall 64.77%

RET 61.08%

INDIRECT_CALL 97.93%

UNCOND_INDIRECT_JMP 66.35%

gcc with ref. input scilab.i

Overall 58.93%

RET 61.54%

INDIRECT_CALL 92.98%

UNCOND_INDIRECT_JMP 44.43%

445.gobmk with ref. test  input nngs.tst :

Overall 56.17%

RET 56.01%

INDIRECT_CALL 78.30%

UNCOND_INDIRECT_JMP 67.25%

mini cache prediction is not helpful, it degrades performance about 4%.