Revise the coverage mapping format to reduce binary size by:
1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.
This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).
Rationale for changes to the format:
- With the current format, most coverage function records are discarded.
E.g., more than 97% of the records in llc are *duplicate* placeholders
for functions visible-but-not-used in TUs. Placeholders *are* used to
show under-covered functions, but duplicate placeholders waste space.
- We reached general consensus about giving (1) a try at the 2017 code
coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
duplicates is simpler than alternatives like teaching build systems
about a coverage-aware database/module/etc on the side.
- Revising the format is expensive due to the backwards compatibility
requirement, so we might as well compress filenames while we're at it.
This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).
See CoverageMappingFormat.rst for the details on what exactly has
changed.
Fixes PR34533 [2], hopefully.
[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533
Differential Revision: https://reviews.llvm.org/D69471
Emit a gap region beginning where the switch body begins. This sets line
execution counts in the areas between non-overlapping cases to 0.
This also removes some special handling of the first case in a switch:
these are now treated like any other case.
This does not resolve an outstanding issue with case statement regions
that do not end when a region is terminated. But it should address
llvm.org/PR44011.
Differential Revision: https://reviews.llvm.org/D70571
This reverts commit 9d4806a387.
There seem to be bugs in llvm-cov --path-equivalence that are causing
Chromium problems. Revert this until they are understood or fixed.
This reverts r374324 (git commit 62808631ac)
I changed the test to not rely on finding the sequence "clang, test,
CoverageMapping" in the CWD used to run the test. Instead it makes its
own internal directory hierarchy of foo/bar/baz and looks for that.
llvm-svn: 374403
This reverts commit f6777964bd.
Because the absolute path check relies on temporary path containing
"clang", "test" and "CoverageMapping" as a subsequence, which is not
necessarily true on all systems(breaks internal integrates). Wanted to
fix it by checking for a leading "/" instead, but then noticed that it
would break windows tests, so leaving it to the author instead.
llvm-svn: 374324
Summary:
The cache recorded the wrong expansion location for all but the first
stringization. It seems uncommon to stringize the same macro argument
multiple times, so this cache doesn't seem that important.
Fixes PR39942
Reviewers: vsk, rsmith
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D65428
llvm-svn: 367337
There is no reason to emit coverage mappings for artificial statements
contained within defaulted methods, as these statements are not visible
to users.
Only emit a mapping for the body of the defaulted method (clang treats
the text of the "default" keyword as the body when reporting locations).
This allows users to see how often the default method is called, but
trims down the coverage mapping by skipping visitation of the children
of the method.
The immediate motivation for this change is that the lexer's
getPreciseTokenLocEnd API cannot return the correct location when given
an artificial statement (with a somewhat made-up location) as an input.
Test by Orivej Desh!
Fixes llvm.org/PR39822.
llvm-svn: 347803
popRegions used to assume that the start location of a region can't be
nested deeper than the end location, which is not always true.
Patch by Orivej Desh!
Differential Revision: https://reviews.llvm.org/D53244
llvm-svn: 347262
A deferred region should end before the start of a label, and should not
extend to the start of the label sub-statement.
Fixes llvm.org/PR35867.
llvm-svn: 333715
Discard the last uncompleted deferred region in a decl, if one exists.
This prevents lines at the end of a function containing only whitespace
or closing braces from being marked as uncovered, if they follow a
region terminator (return/break/etc).
The previous behavior was to heuristically complete deferred regions at
the end of a decl. In practice this ended up being too brittle for too
little gain. Users would complain that there was no way to reach full
code coverage because whitespace at the end of a function would be
marked uncovered.
rdar://40238228
Differential Revision: https://reviews.llvm.org/D46918
llvm-svn: 333609
When parsing C++ type construction expressions with list initialization,
forward the locations of the braces to Sema.
Without these locations, the code coverage pass crashes on the given test
case, because the pass relies on getLocEnd() returning a valid location.
Here is what this patch does in more detail:
- Forwards init-list brace locations to Sema (ParseExprCXX),
- Builds an InitializationKind with these locations (SemaExprCXX), and
- Uses these locations for constructor initialization (SemaInit).
The remaining changes fall out of introducing a new overload for
creating direct-list InitializationKinds.
Testing: check-clang, and a stage2 coverage-enabled build of clang with
asserts enabled.
Differential Revision: https://reviews.llvm.org/D41921
llvm-svn: 322729
Emit a gap area starting after the r-paren location and ending at the
start of the body for the braces-optional statements (for, for-each,
while, etc). The count for the gap area equal to the body's count. This
extends the fix in r317758.
Fixes PR35387, rdar://35570345
Testing: stage2 coverage-enabled build of clang, check-clang
llvm-svn: 319373
There are some limitations with emitting regions in macro expansions
because we don't gather file IDs within the expansions. Fix the check
that prevents us from emitting deferred regions in expansions to make an
exception for headers, which is something we can handle.
rdar://35373009
llvm-svn: 317760
The area immediately after a terminated region in the function top-level
should have the same count as the label it precedes.
This solves another problem with wrapped segments. Consider:
1| a:
2| return 0;
3| b:
4| return 1;
Without a gap area starting after the first return, the wrapped segment
from line 2 would make it look like line 3 is executed, when it's not.
rdar://35373009
llvm-svn: 317759
The area immediately after the closing right-paren of an if condition
should have a count equal to the 'then' block's count. Use a gap region
to set this count, so that region highlighting for the 'then' block
remains precise.
This solves a problem we have with wrapped segments. Consider:
1| if (false)
2| foo();
Without a gap area starting after the condition, the wrapped segment
from line 1 would make it look like line 2 is executed, when it's not.
rdar://35373009
llvm-svn: 317758
A trailing deferred region isn't necessary in a function that ends with
this pattern:
...
else {
...
return;
}
Special-case this pattern so that the closing curly brace of the
function isn't marked as uncovered. This issue came up in PR34962.
llvm-svn: 315982
This makes it possible to view sub-line region counts for the l.h.s of
&& and || expressions in coverage reports.
It also fixes PR33465, which shows an example of incorrect coverage
output for an assignment statement containing '||'.
llvm-svn: 315979
Add an option to emit limited coverage info for unused decls. It's just a
cl::opt for now to allow us to experiment quickly.
When building llc, this results in an 84% size reduction in the llvm_covmap
section, and a similar size reduction in the llvm_prf_names section. In
practice I expect the size reduction to be roughly quadratic with the size of
the program.
The downside is that coverage for headers will no longer be complete. This will
make the line/function/region coverage metrics incorrect, since they will be
artificially high. One mitigation would be to somehow disable those metrics
when using limited-coverage=true.
This is related to: llvm.org/PR34533 (make SourceBasedCodeCoverage scale)
Differential Revision: https://reviews.llvm.org/D38107
llvm-svn: 314002
As a special case, throw away deferred regions for trailing returns.
This allows the closing curly brace to have a count, and is less
distracting.
llvm-svn: 313603
This patch teaches the preprocessor to report more precise source ranges for
code that is skipped due to conditional directives.
The new behavior includes the '#' from the opening directive and the full text
of the line containing the closing directive in the skipped area. This matches
up clang's behavior (we don't IRGen the code between the closing "endif" and
the end of a line).
This also affects the code coverage implementation. See llvm.org/PR34166 (this
also happens to be rdar://problem/23224058).
The old behavior (report the end of the skipped range as the end
location of the 'endif' token) is preserved for indexing clients.
Differential Revision: https://reviews.llvm.org/D36642
llvm-svn: 312947
The current coverage implementation doesn't handle region termination
very precisely. Take for example an `if' statement with a `return':
void f() {
if (true) {
return; // The `if' body's region is terminated here.
}
// This line gets the same coverage as the `if' condition.
}
If the function `f' is called, the line containing the comment will be
marked as having executed once, which is not correct.
The solution here is to create a deferred region after terminating a
region. The deferred region is completed once the start location of the
next statement is known, and is then pushed onto the region stack.
In the cases where it's not possible to complete a deferred region, it
can safely be dropped.
Testing: lit test updates, a stage2 coverage-enabled build of clang
This is a reapplication but there are no changes from the original commit.
With D36813, the segment builder in llvm will be able to handle deferred
regions correctly.
llvm-svn: 312818
The %T lit expansion expands to a common directory shared between all the tests in the same directory, which is unexpected and unintuitive, and more importantly, it's been a source of subtle race conditions and flaky tests. In https://reviews.llvm.org/D35396, it was agreed that it would be best to simply ban %T and only keep %t, which is unique to each test. When a test needs a temporary directory, it can just create one using mkdir %t.
This patch removes %T in clang.
Differential Revision: https://reviews.llvm.org/D36437
llvm-svn: 310950
The code after a noreturn call doesn't execute.
The pattern in the testcase is pretty common in LLVM (a switch with
a default case that calls llvm_unreachable).
The original version of this patch was reverted in r309995 due to a
crash. This version includes a fix for that crash (testcase in
test/CoverageMapping/md.cpp).
Differential Revision: https://reviews.llvm.org/D36250
llvm-svn: 310406
This reverts commit r310010. I don't think there's anything wrong with
this commit, but it's causing clang to generate output that llvm-cov
doesn't do a good job with and the fix isn't immediately clear.
See Eli's comment in D36250 for more context.
I'm reverting the clang change so the coverage bot can revert back to
producing sensible output, and to give myself some time to investigate
what went wrong in llvm.
llvm-svn: 310154
The current coverage implementation doesn't handle region termination
very precisely. Take for example an `if' statement with a `return':
void f() {
if (true) {
return; // The `if' body's region is terminated here.
}
// This line gets the same coverage as the `if' condition.
}
If the function `f' is called, the line containing the comment will be
marked as having executed once, which is not correct.
The solution here is to create a deferred region after terminating a
region. The deferred region is completed once the start location of the
next statement is known, and is then pushed onto the region stack.
In the cases where it's not possible to complete a deferred region, it
can safely be dropped.
Testing: lit test updates, a stage2 coverage-enabled build of clang
llvm-svn: 310010
The code after a noreturn call doesn't execute.
The pattern in the testcase is pretty common in LLVM (a switch with
a default case that calls llvm_unreachable).
Differential Revision: https://reviews.llvm.org/D36250
llvm-svn: 309995
We never overwrite the end location of a region, so we would end up with
an overly large region when we reused the switch's region.
It's possible this code will be substantially rewritten in the near
future to deal with fallthrough more accurately, but this seems like
an improvement on its own for now.
Differential Revision: https://reviews.llvm.org/D34801
llvm-svn: 309901
The coverage implementation marks functions which won't be emitted as
'deferred', so that it can emit empty coverage regions for them later
(once their linkages are known).
Functions in dependent contexts are an exception: if there isn't a full
instantiation of a function, it shouldn't be marked 'deferred'. We've
been breaking that rule without much consequence because we just ended
up with useless, extra, empty coverage mappings. With PR32679, this
behavior finally caused a crash, because clang marked a partial template
specialization as 'deferred', causing the MS mangler to choke in its
delayed-template-parsing mode:
error: cannot mangle this template type parameter type yet
(http://bugs.llvm.org/show_bug.cgi?id=32679)
Fix this by checking if a decl's context is a dependent context before
marking it 'deferred'.
Based on a patch by Adam Folwarczny!
Differential Revision: https://reviews.llvm.org/D32144
llvm-svn: 300723
This is a re-try of r295085: fix up some test cases that assume that
profile name variables are preserved by the instrprof pass.
This catches one additional case in test/CoverageMapping/unused_names.c.
llvm-svn: 295101
This patch fixes a regression introduced in r262697 that changed the way the
coverage regions for switches are constructed. The PGO instrumentation counter
for a switch statement refers to the counter at the exit of the switch.
Therefore, the coverage region for the switch statement should cover the code
that comes after the switch, and not the switch statement itself.
rdar://28480997
Differential Revision: https://reviews.llvm.org/D24981
llvm-svn: 282554
In most cases these code regions are just redundant, but sometimes they
could be assigned to the counter of the parent code region instead of
the counter of the nested block.
Differential Revision: https://reviews.llvm.org/D23987
llvm-svn: 280199
If there were several nested statements arranged in a way that all of them
end up with the same macro, then the expansion of this macro was assigned
with all the corresponding counters of these statements.
As a result, the wrong counter value was shown for the macro in llvm-cov.
This patch fixes the issue by preventing adding a counter for an expanded
source range if it already has an assigned counter, which is expected
to come from the most specific statement.
Differential Revision: https://reviews.llvm.org/D23160
llvm-svn: 279962
After r275121, we stopped mapping regions from system headers. Lambdas
declared in regions belonging to system headers started producing empty
coverage mappings, since the files corresponding to their spelling locs
were being ignored.
The coverage reader doesn't know what to do with these empty mappings.
This commit makes sure that we don't produce them and adds a test. I'll
make the reader stricter in a follow-up commit.
llvm-svn: 276716
The builder prints out the following IR:
\5CCoverageMapping\5COutput\5Ctest\5Cf1.c
The updated test in r276367 expects path separators to be either '/' or
'\\', so it chokes on the unexpected "5C" stuff. I'm not sure what that
is, but I included a kludge that should work around it.
Failing bot:
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast/builds/8718
llvm-svn: 276370
We should be able to use `mkdir` without turning on `REQUIRES: shell`.
Moreover, this test should check for a path separator which precedes the
relative filename to make sure that absolute paths are being used.
llvm-svn: 276367
Vedant Kumar