perf diff: Support hot streams comparison

perf diff: Support hot streams comparison

This patch enables perf-diff with "--stream" option.

"--stream": Enable hot streams comparison

Now let's see example.

perf record -b ...      Generate perf.data.old with branch data
perf record -b ...      Generate perf.data with branch data
perf diff --stream

[ Matched hot streams ]

hot chain pair 1:
            cycles: 1, hits: 27.77%                  cycles: 1, hits: 9.24%
        ---------------------------              --------------------------
                      main div.c:39                           main div.c:39
                      main div.c:44                           main div.c:44

hot chain pair 2:
           cycles: 34, hits: 20.06%                cycles: 27, hits: 16.98%
        ---------------------------              --------------------------
          __random_r random_r.c:360               __random_r random_r.c:360
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:380               __random_r random_r.c:380
          __random_r random_r.c:357               __random_r random_r.c:357
              __random random.c:293                   __random random.c:293
              __random random.c:293                   __random random.c:293
              __random random.c:291                   __random random.c:291
              __random random.c:291                   __random random.c:291
              __random random.c:291                   __random random.c:291
              __random random.c:288                   __random random.c:288
                     rand rand.c:27                          rand rand.c:27
                     rand rand.c:26                          rand rand.c:26
                           rand@plt                                rand@plt
                           rand@plt                                rand@plt
              compute_flag div.c:25                   compute_flag div.c:25
              compute_flag div.c:22                   compute_flag div.c:22
                      main div.c:40                           main div.c:40
                      main div.c:40                           main div.c:40
                      main div.c:39                           main div.c:39

hot chain pair 3:
             cycles: 9, hits: 4.48%                  cycles: 6, hits: 4.51%
        ---------------------------              --------------------------
          __random_r random_r.c:360               __random_r random_r.c:360
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:388               __random_r random_r.c:388
          __random_r random_r.c:380               __random_r random_r.c:380

[ Hot streams in old perf data only ]

hot chain 1:
            cycles: 18, hits: 6.75%
         --------------------------
          __random_r random_r.c:360
          __random_r random_r.c:388
          __random_r random_r.c:388
          __random_r random_r.c:380
          __random_r random_r.c:357
              __random random.c:293
              __random random.c:293
              __random random.c:291
              __random random.c:291
              __random random.c:291
              __random random.c:288
                     rand rand.c:27
                     rand rand.c:26
                           rand@plt
                           rand@plt
              compute_flag div.c:25
              compute_flag div.c:22
                      main div.c:40

hot chain 2:
            cycles: 29, hits: 2.78%
         --------------------------
              compute_flag div.c:22
                      main div.c:40
                      main div.c:40
                      main div.c:39

[ Hot streams in new perf data only ]

hot chain 1:
                                                     cycles: 4, hits: 4.54%
                                                 --------------------------
                                                              main div.c:42
                                                      compute_flag div.c:28

hot chain 2:
                                                     cycles: 5, hits: 3.51%
                                                 --------------------------
                                                              main div.c:39
                                                              main div.c:44
                                                              main div.c:42
                                                      compute_flag div.c:28

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20201009022845.13141-8-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>