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.
#require svn svn-bindings
$ cat >> $HGRCPATH <<EOF
> [extensions]
> convert =
> EOF
$ convert()
> {
> startrev=$1
> repopath=A-r$startrev-hg
> hg convert --config convert.svn.startrev=$startrev \
> --config convert.svn.trunk=branches/branch1 \
> --config convert.svn.branches=" " \
> --config convert.svn.tags= \
> --datesort svn-repo $repopath
> hg -R $repopath log -G \
> --template '{rev} {desc|firstline} files: {files}\n'
> echo
> }
$ svnadmin create svn-repo
$ svnadmin load -q svn-repo < "$TESTDIR/svn/startrev.svndump"
Convert before branching point
$ convert 3
initializing destination A-r3-hg repository
scanning source...
sorting...
converting...
3 removeb
2 changeaa
1 branch, changeaaa
0 addc,changeaaaa
o 3 addc,changeaaaa files: a c
|
o 2 branch, changeaaa files: a
|
o 1 changeaa files: a
|
o 0 removeb files: a
Convert before branching point
$ convert 4
initializing destination A-r4-hg repository
scanning source...
sorting...
converting...
2 changeaa
1 branch, changeaaa
0 addc,changeaaaa
o 2 addc,changeaaaa files: a c
|
o 1 branch, changeaaa files: a
|
o 0 changeaa files: a
Convert at branching point
$ convert 5
initializing destination A-r5-hg repository
scanning source...
sorting...
converting...
1 branch, changeaaa
0 addc,changeaaaa
o 1 addc,changeaaaa files: a c
|
o 0 branch, changeaaa files: a
Convert last revision only
$ convert 6
initializing destination A-r6-hg repository
scanning source...
sorting...
converting...
0 addc,changeaaaa
o 0 addc,changeaaaa files: a c