bdiff: don't check border condition in loop This is pretty much a copy of d500ddae7494, just to a different loop. The condition `p == plast` (`plast == a + len - 1`) was only true on the final iteration of the loop. So it was wasteful to check for it on every iteration. We decrease the iteration count by 1 and add an explicit check for `p == plast` after the loop. Again, we see modest wins. From the mozilla-unified repository: $ perfbdiff -m 3041e4d59df2 ! wall 0.035502 comb 0.040000 user 0.040000 sys 0.000000 (best of 100) ! wall 0.030480 comb 0.030000 user 0.030000 sys 0.000000 (best of 100) $ perfbdiff 0e9928989e9c --alldata --count 100 ! wall 4.097394 comb 4.100000 user 4.100000 sys 0.000000 (best of 3) ! wall 3.597798 comb 3.600000 user 3.600000 sys 0.000000 (best of 3) The 2nd example throws a total of ~3.3GB of data at bdiff. This change increases the throughput from ~811 MB/s to ~924 MB/s.

     1

https://bz.mercurial-scm.org/612

     2

     3

  $ hg init

     4

  $ mkdir src

     5

  $ echo a > src/a.c

     6

  $ hg ci -Ama

     7

  adding src/a.c

     8

     9

  $ hg mv src source

    10

  moving src/a.c to source/a.c (glob)

    11

    12

  $ hg ci -Ammove

    13

    14

  $ hg co -C 0

    15

  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

    16

    17

  $ echo new > src/a.c

    18

  $ echo compiled > src/a.o

    19

  $ hg ci -mupdate

    20

  created new head

    21

    22

  $ hg status

    23

  ? src/a.o

    24

    25

  $ hg merge

    26

  merging src/a.c and source/a.c to source/a.c

    27

  0 files updated, 1 files merged, 0 files removed, 0 files unresolved

    28

  (branch merge, don't forget to commit)

    29

    30

  $ hg status

    31

  M source/a.c

    32

  R src/a.c

    33

  ? src/a.o

    34