tree b39a56147a2c740ca883872be65455fb99cbe770
parent 824dfca301dd0449a189f01e32e25448e503f7df
author Philipp Wagner <phw@lowrisc.org> 1621280790 +0100
committer Philipp Wagner <mail@philipp-wagner.com> 1621435481 +0100

[otbnsim] Collect statistics about basic blocks

Calculate the length of basic blocks and extended basic blocks and
present the findings as histogram when asked to dump statistics about
the execution.

Also include unit tests to check the counting behavior on small
examples.

Example:

```
$ hw/ip/otbn/dv/otbnsim/standalone.py build-out/sw/otbn/rsa_1024_enc_test.elf --dump-stats=-
[some output omitted]

Basic block statistics
----------------------

Number of instructions within a basic block

  # of instr.    frequency
-------------  -----------
            1         3250
            2         2367
            3         6274
            4           40
            5         6720
            6         1381
            7         1362
            8            3
            9           84
           10         2049
           12            1
           13          255
           17          757

Number of instructions within an extended basic block

  # of instr.    frequency
-------------  -----------
            1           67
            2         1090
            3         6150
            4            5
            5         6150
            6         1374
            7            2
            8         1028
            9           18
           10            1
           11            1
           12         2048
           14            1
           15           84
           19            1
           48          168
          122            3
          124           60
          125           20
          127            1
         3354            1
```

Signed-off-by: Philipp Wagner <phw@lowrisc.org>