The main comparison functions we provide for comparing
object ids are hashcmp() and oidcmp(). These are more
flexible than a strict equality check, since they also
express ordering. That makes them useful for sorting and
binary searching. However, it also makes them potentially
slower than a strict equality check. Consider this C code,
which is traditionally what our hashcmp has looked like:
#include <string.h>
int hashcmp(const unsigned char *a, const unsigned char *b)
{
return memcmp(a, b, 20);
}
Compiling with "gcc -O2 -S -fverbose-asm", the generated
assembly shows that we actually call memcmp(). But if we
change this to a strict equality check:
return !memcmp(a, b, 20);
we get a faster inline version:
movq (%rdi), %rax # MEM[(void *)a_4(D)], MEM[(void *)a_4(D)]
movq 8(%rdi), %rdx # MEM[(void *)a_4(D)], tmp101
xorq (%rsi), %rax # MEM[(void *)b_5(D)], tmp94
xorq 8(%rsi), %rdx # MEM[(void *)b_5(D)], tmp93
orq %rax, %rdx # tmp94, tmp93
jne .L2 #,
movl 16(%rsi), %eax # MEM[(void *)b_5(D)], tmp104
cmpl %eax, 16(%rdi) # tmp104, MEM[(void *)a_4(D)]
je .L5 #,
Obviously our hashcmp() doesn't include the "!". But because
it's an inline function, optimizing compilers are able to
see "!hashcmp(a,b)" in calling code and take advantage of
this case. So there has been no value thus far in
introducing a more restricted interface for doing strict
equality checks.
But as Git learns about more values for the_hash_algo, our
hashcmp() will grow more complicated and may even delegate
at runtime to functions optimized specifically for that hash
size. That breaks the inline connection we have, and the
compiler will have to assume that the caller really cares
about the sign and magnitude of the memcmp() result, even
though the vast majority don't.
We can solve that by introducing a hasheq() function (and
matching oideq() wrapper), which callers can use to make it
clear that they only care about equality. For now, the
implementation will literally be "!hashcmp()", but it frees
us up later to introduce code optimized specifically for the
equality check.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Sometimes we want to suppress a coccinelle transformation
inside a particular function. For example, in finding
conversions of hashcmp() to oidcmp(), we should not convert
the call in oidcmp() itself, since that would cause infinite
recursion. We write that like this:
@@
identifier f != oidcmp;
expression E1, E2;
@@
f(...) {...
- hashcmp(E1->hash, E2->hash)
+ oidcmp(E1, E2)
...}
to match the interior of any function _except_ oidcmp().
Unfortunately, this doesn't catch all cases (e.g., the one
in sequencer.c that this patch fixes). The problem, as
explained by one of the Coccinelle developers in [1], is:
For transformation, A ... B requires that B occur on every
execution path starting with A, unless that execution path
ends up in error handling code. (eg, if (...) { ...
return; }). Here your A is the start of the function. So
you need a call to hashcmp on every path through the
function, which fails when you add ifs.
[...]
Another issue with A ... B is that by default A and B
should not appear in the matched region. So your original
rule matches only the case where every execution path
contains exactly one call to hashcmp, not more than one.
One way to solve this is to put the pattern inside an
angle-bracket pattern like "<... P ...>", which allows zero
or more matches of P. That works (and is what this patch
does), but it has one drawback: it matches more than we care
about, and Coccinelle uses extra CPU. Here are timings for
"make coccicheck" before and after this patch:
[before]
real 1m27.122s
user 7m34.451s
sys 0m37.330s
[after]
real 2m18.040s
user 10m58.310s
sys 0m41.549s
That's not ideal, but it's more important for this to be
correct than to be fast. And coccicheck is already fairly
slow (and people don't run it for every single patch). So
it's an acceptable tradeoff.
There _is_ a better way to do it, which is to record the
position at which we find hashcmp(), and then check it
against the forbidden function list. Like:
@@
position p : script:python() { p[0].current_element != "oidcmp" };
expression E1,E2;
@@
- hashcmp@p(E1->hash, E2->hash)
+ oidcmp(E1, E2)
This is only a little slower than the current code, and does
the right thing in all cases. Unfortunately, not all builds
of Coccinelle include python support (including the ones in
Debian). Requiring it may mean that fewer people can easily
run the tool, which is worse than it simply being a little
slower.
We may want to revisit this decision in the future if:
- builds with python become more common
- we find more uses for python support that tip the
cost-benefit analysis
But for now this patch sticks with the angle-bracket
solution, and converts all existing cocci patches. This
fixes only one missed case in the current code, though it
makes a much better difference for some new rules I'm adding
(converting "!hashcmp()" to "hasheq()" misses over half the
possible conversions using the old form).
[1] https://public-inbox.org/git/alpine.DEB.2.21.1808240652370.2344@hadrien/
Helped-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Partially revert the support for multiple hash functions to regain
hash comparison performance; we'd think of a way to do this better
in the next cycle.
* jk/hashcmp-optim-for-2.19:
hashcmp: assert constant hash size
Test fixes.
* sg/test-must-be-empty:
tests: use 'test_must_be_empty' instead of 'test_cmp <empty> <out>'
tests: use 'test_must_be_empty' instead of 'test_cmp /dev/null <out>'
tests: use 'test_must_be_empty' instead of 'test ! -s'
tests: use 'test_must_be_empty' instead of '! test -s'
"git cmd -h" updates.
* rs/opt-updates:
parseopt: group literal string alternatives in argument help
remote: improve argument help for add --mirror
checkout-index: improve argument help for --stage
"git help --config" (which is used in command line completion)
missed the configuration variables not described in the main
config.txt file but are described in another file that is included
by it, which has been corrected.
* nd/complete-config-vars:
generate-cmdlist.sh: collect config from all config.txt files
"git branch --list" learned to take the default sort order from the
'branch.sort' configuration variable, just like "git tag --list"
pays attention to 'tag.sort'.
* sm/branch-sort-config:
branch: support configuring --sort via .gitconfig
The meaning of the possible values the "core.checkStat"
configuration variable can take were not adequately documented,
which has been fixed.
* nd/config-core-checkstat-doc:
config.txt: clarify core.checkStat
275267937b (range-diff: make dual-color the default mode, 2018-08-13)
replaced --dual-color with --no-dual-color but left the option's
summary untouched. Rewrite the summary to describe --no-dual-color
rather than dual-color.
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Kyle Meyer <kyle@kyleam.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix typos and convert a question which does not expect to be replied
to a simple advice.
Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The core.commitGraph config setting was accidentally removed from
the config documentation. In that same patch, the config setting
that writes a commit-graph during garbage collection was incorrectly
written to the doc as "gc.commitGraph" instead of "gc.writeCommitGraph".
Reported-by: Szeder Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The verbose output of the test 'reword without issues functions as
intended' in 't3423-rebase-reword.sh', added in a9279c6785 (sequencer:
do not squash 'reword' commits when we hit conflicts, 2018-06-19),
contains the following error output:
sed: -e expression #1, char 2: extra characters after command
This error comes from within the 'fake-editor.sh' script created by
'lib-rebase.sh's set_fake_editor() function, and the root cause is the
FAKE_LINES="pick 1 reword 2" variable in the test in question, in
particular the "pick" word. 'fake-editor.sh' assumes 'pick' to be the
default rebase command and doesn't support an explicit 'pick' command
in FAKE_LINES. As a result, 'pick' will be used instead of a line
number when assembling the following 'sed' script:
sed -n picks/^pick/pick/p
which triggers the aforementioned error.
Luckily, this didn't affect the test's correctness: the erroring 'sed'
command doesn't write anything to the todo script, and processing the
rest of FAKE_LINES generates the desired todo script, as if that
'pick' command were not there at all.
The minimal fix would be to remove the 'pick' word from FAKE_LINES,
but that would leave us susceptible to similar issues in the future.
Instead, teach the fake-editor script to recognize an explicit 'pick'
command, which is still a fairly trivial change.
In the future we might want to consider reinforcing this fake editor
script with an &&-chain and stricter parsing of the FAKE_LINES
variable (e.g. to error out when encountering unknown rebase commands
or commands and line numbers in the wrong order).
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Prior to 509f6f62a4 (cache: update object ID functions for
the_hash_algo, 2018-07-16), hashcmp() called memcmp() with a
constant size of 20 bytes. Some compilers were able to turn
that into a few quad-word comparisons, which is faster than
actually calling memcmp().
In 509f6f62a4, we started using the_hash_algo->rawsz
instead. Even though this will always be 20, the compiler
doesn't know that while inlining hashcmp() and ends up just
generating a call to memcmp().
Eventually we'll have to deal with multiple hash sizes, but
for the upcoming v2.19, we can restore some of the original
performance by asserting on the size. That gives the
compiler enough information to know that the memcmp will
always be called with a length of 20, and it performs the
same optimization.
Here are numbers for p0001.2 run against linux.git on a few
versions. This is using -O2 with gcc 8.2.0.
Test v2.18.0 v2.19.0-rc0 HEAD
------------------------------------------------------------------------------
0001.2: 34.24(33.81+0.43) 34.83(34.42+0.40) +1.7% 33.90(33.47+0.42) -1.0%
You can see that v2.19 is a little slower than v2.18. This
commit ended up slightly faster than v2.18, but there's a
fair bit of run-to-run noise (the generated code in the two
cases is basically the same). This patch does seem to be
consistently 1-2% faster than v2.19.
I tried changing hashcpy(), which was also touched by
509f6f62a4, in the same way, but couldn't measure any
speedup. Which makes sense, at least for this workload. A
traversal of the whole commit graph requires looking up
every entry of every tree via lookup_object(). That's many
multiples of the numbers of objects in the repository (most
of the lookups just return "yes, we already saw that
object").
[jn: verified using "make object.s" that the memcmp call goes away.]
Reported-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Jeff King <peff@peff.net
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Several tests in 't3420-rebase-autostash.sh' start various rebase
processes that are expected to fail because of merge conflicts. These
tests then run '! grep' to ensure that the autostash feature did its
job, and the dirty contents of a file is gone. However, due to the
test repo's history and the choice of upstream branch that file
shouldn't exist in the conflicted state at all. Consequently, this
'grep' doesn't fail as expected, because it can't find the dirty
content, but it fails because it can't open the file.
Tighten this check by using 'test_path_is_missing' instead, thereby
avoiding unexpected errors from 'grep' as well.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test 'store updates stash ref and reflog' in 't3903-stash.sh'
creates a stash from a new file, runs 'git reset --hard' to throw away
any modifications to the work tree, and then runs '! grep' to ensure
that the staged contents are gone. Since the file didn't exist
before, it shouldn't exist after 'git reset' either. Consequently,
this 'grep' doesn't fail as expected, because it can't find the staged
content, but it fails because it can't open the file.
Tighten this check by using 'test_path_is_missing' instead, thereby
avoiding an unexpected error from 'grep' as well.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In a recent update in 2.18 era, "git pack-objects" started
producing a larger than necessary packfiles by missing
opportunities to use large deltas.
* nd/pack-deltify-regression-fix:
pack-objects: fix performance issues on packing large deltas
Prior to d3c6751b18 (tests: make use of the test_must_be_empty
function, 2018-07-27), in the test 'rev-list should succeed with empty
output on empty stdin' in 't6018-rev-list-glob' the empty 'expect'
file served dual purpose: besides specifying the expected output, as
usual, it also served as empty input for 'git rev-list --stdin'.
Then d3c6751b18 came along, and, as part of the conversion to
'test_must_be_empty', removed this empty 'expect' file, not realizing
its secondary purpose. Redirecting stdin from the now non-existing
file failed the test, but since this test expects failure in the first
place, this issue went unnoticed.
Redirect 'git rev-list's stdin explicitly from /dev/null to provide
empty input. (Strictly speaking we don't need this redirection,
because the test script's stdin is already redirected from /dev/null
anyway, but I think it's better to be explicit about it.)
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test ' context does not include preceding empty lines' in the
block of tests 'change with long common tail and no context' in
't4051-diff-function-context.sh' tries to read the file
'long_common_tail.diff.diff', but that file doesn't exist as its name
contains one more '.diff' suffixes than necessary.
Despite this error the test still succeeded without checking what it's
supposed to, because this erroneous read is done on the line:
test "$(first_context_line <long_common_tail.diff.diff)" != " "
which means that:
- the command substitution hides the error, so it won't fail the
test, and
- the result of the command substitution is the empty string, which
is, of course, not equal to a single space character, so the
condition is fulfilled, and the test succeeds.
As a minimal fix, fix the name of the file to be read.
In the future we might want to reorganize this test script (1) to use
'test_cmp' instead of 'test's and command substitutions to catch
failing commands and to provide helpful error messages, and (2) to
specify what the expected result actually _is_ instead of what it
isn't.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the test 'checkout with autocrlf=input' in 't0020-crlf.sh', one of
the 'has_cr' checks looks at the non-existing file 'two' instead of
'dir/two'. The test still succeeds, without actually checking what it
was supposed to, because this check is expected to fail anyway.
As a minimal fix, fix the name of the file to be checked.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test '--dry-run with conflicts fixed from a merge' in
't7501-commit.sh', added in 8dc874b2ee (wt-status.c: set commitable
bit if there is a meaningful merge., 2016-02-15), runs the following
unnecessary and downright bogus command substitution:
! $(git merge --no-commit commit-1) &&
I.e. after 'git merge ...' is executed and expectedly fails, the test
attempts to execute its output:
Merging:
80f2ea2 commit 2
virtual commit-1
found 1 common ancestor:
e60d113 Initial commit
Auto-merging test-file
CONFLICT (content): Merge conflict in test-file
Automatic merge failed; fix conflicts and then commit the result.
as a command, which most likely fails, because there is no such
command as "Merging:". Then '!' negates the failed exit status, the
test continues, and eventually succeeds.
Remove this command substitution and use 'test_must_fail' to ensure
that 'git merge' fails.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The author_date_slab is used to store the author date of a commit
when walking with the --author-date flag in rev-list or log. This
was added as an 'unsigned long' in
81c6b38b "log: --author-date-order"
Since 'unsigned long' is ambiguous in its bit-ness across platforms
(64-bit in Linux, 32-bit in Windows, for example), most references
to the author dates in commit.c were converted to timestamp_t in
dddbad72 "timestamp_t: a new data type for timestamps"
However, the slab definition was missed, leading to a mismatch in
the data types in Windows. This would not reveal itself as a bug
unless someone authors a commit after February 2106, but commits
can store anything as their author date.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test-tool programs include "test-tool.h" as their first
include, which breaks our CodingGuideline of "the first
include must be git-compat-util.h or an equivalent".
Rather than change them all, let's instead make test-tool.h
one of those equivalents, just like we do for builtin.h
(which many of the actual git builtins include first).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Using 'test_must_be_empty' is shorter and more idiomatic than
>empty &&
test_cmp empty out
as it saves the creation of an empty file. Furthermore, sometimes the
expected empty file doesn't have such a descriptive name like 'empty',
and its creation is far away from the place where it's finally used
for comparison (e.g. in 't7600-merge.sh', where two expected empty
files are created in the 'setup' test, but are used only about 500
lines later).
These cases were found by instrumenting 'test_cmp' to error out the
test script when it's used to compare empty files, and then converted
manually.
Note that even after this patch there still remain a lot of cases
where we use 'test_cmp' to check empty files:
- Sometimes the expected output is not hard-coded in the test, but
'test_cmp' is used to ensure that two similar git commands produce
the same output, and that output happens to be empty, e.g. the
test 'submodule update --merge - ignores --merge for new
submodules' in 't7406-submodule-update.sh'.
- Repetitive common tasks, including preparing the expected results
and running 'test_cmp', are often extracted into a helper
function, and some of this helper's callsites expect no output.
- For the same reason as above, the whole 'test_expect_success'
block is within a helper function, e.g. in 't3070-wildmatch.sh'.
- Or 'test_cmp' is invoked in a loop, e.g. the test 'cvs update
(-p)' in 't9400-git-cvsserver-server.sh'.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Using 'test_must_be_empty' is more idiomatic than 'test_cmp /dev/null
out', and its message on error is perhaps a bit more to the point.
This patch was basically created by running:
sed -i -e 's%test_cmp /dev/null%test_must_be_empty%' t[0-9]*.sh
with the exception of the change in 'should not fail in an empty repo'
in 't7401-submodule-summary.sh', where it was 'test_cmp output
/dev/null'.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Using 'test_must_be_empty' is preferable to 'test ! -s', because it
gives a helpful error message if the given file is unexpectedly no
empty, while the latter remains completely silent. Furthermore, it
also catches cases when the given file unexpectedly does not exist at
all.
This patch was created by:
sed -i -e 's/test ! -s/test_must_be_empty/' t[0-9]*.sh
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Using 'test_must_be_empty' is preferable to '! test -s', because it
gives a helpful error message if the given file is unexpectedly not
empty, while the latter remains completely silent. Furthermore, it
also catches cases when the given file unexpectedly does not exist at
all.
This patch was basically created by:
sed -i -e 's/! test -s/test_must_be_empty/' t[0-9]*.sh
with the following notable exceptions:
- The '! test -s' check in '.gitmodules ignore=dirty suppresses
submodules with untracked content' in 't7508-status.sh' is left
as-is, because it's bogus and, therefore, it's subject of a
dedicated patch.
- The '! test -s' checks in 't9131-git-svn-empty-symlink.sh' and
't9135-git-svn-moved-branch-empty-file.sh' are immediately
preceeded by a 'test -f' to ensure that the files exist in the
first place. 'test_must_be_empty' ensures that as well, so those
'test -f' commands are removed as well.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This formally clarifies that the "--option=" part is the same for all
alternatives.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Group the possible values using a pair of parentheses and don't mark
them for translation, as they are literal strings that have to be used
as-is in any locale.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Spell out all alternatives and avoid using a numerical range operator,
as it is not mentioned in CodingGuidelines and the resulting string is
still concise. Wrap them in parentheses to document clearly that the
"--stage=" part is common among them.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This script uses Documentation/config.txt as input for "git help
--config" and "git config" completion but it misses the fact that
config.txt includes other txt files. Include all *config.txt as input
when scanning for config keys. This could produce false positives, but
as long as we stick to the blah-config.txt naming convention, we
should be ok.
While at there, move diff.* from config.txt to diff-config.txt where
all other diff config keys are.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The sideband code learned to optionally paint selected keywords at
the beginning of incoming lines on the receiving end.
* hn/highlight-sideband-keywords:
sideband: do not read beyond the end of input
sideband: highlight keywords in remote sideband output
"git cherry-pick --quit" failed to remove CHERRY_PICK_HEAD even
though we won't be in a cherry-pick session after it returns, which
has been corrected.
* nd/cherry-pick-quit-fix:
cherry-pick: fix --quit not deleting CHERRY_PICK_HEAD
Jeff King