Fixes PR45673
The commit 9180c14fe4 (D76206) resolved only a part of the problem
of concurrent .gcda file creation. It ensured that only one process
creates the file but did not ensure that the process locks the
file first. If not, the process which created the file may clobber
the contents written by a process which locked the file first.
This is the cause of PR45673.
This commit prevents the clobbering by revising the assumption
that a process which creates the file locks the file first.
Regardless of file creation, a process which locked the file first
uses fwrite (new_file==1) and other processes use mmap (new_file==0).
I also tried to keep the creation/first-lock process same by using
mkstemp/link/unlink but the code gets long. This commit is more
simple.
Note: You may be confused with other changes which try to resolve
concurrent file access. My understanding is (may not be correct):
D76206: Resolve race of .gcda file creation (but not lock)
This one: Resolve race of .gcda file creation and lock
D54599: Same as D76206 but abandoned?
D70910: Resolve race of multi-threaded counter flushing
D74953: Resolve counter sharing between parent/children processes
D78477: Revision of D74953
Differential Revision: https://reviews.llvm.org/D79556
Summary:
When forking in several threads, the counters were written out in using the same global static variables (see GCDAProfiling.c): that leads to crashes.
So when there is a fork, the counters are resetted in the child process and they will be dumped at exit using the interprocess file locking.
When there is an exec, the counters are written out and in case of failures they're resetted.
Reviewers: jfb, vsk, marco-c, serge-sans-paille
Reviewed By: marco-c, serge-sans-paille
Subscribers: llvm-commits, serge-sans-paille, dmajor, cfe-commits, hiraditya, dexonsmith, #sanitizers, marco-c, sylvestre.ledru
Tags: #sanitizers, #clang, #llvm
Differential Revision: https://reviews.llvm.org/D78477
The intent of the `llvm_gcda_start_file` function is that only
one process create the .gcda file and initialize it to be updated
by other processes later.
Before this change, if multiple processes are started simultaneously,
some of them may initialize the file because both the first and
second `open` calls may succeed in a race condition and `new_file`
becomes 1 in those processes. This leads incorrect coverage counter
values. This often happens in MPI (Message Passing Interface) programs.
The test program added in this change is a simple reproducer.
This change ensures only one process creates/initializes the file by
using the `O_EXCL` flag.
Differential Revision: https://reviews.llvm.org/D76206
After the format change from D69471, there can be more than one section
in an object that contains coverage function records. Look up each of
these sections and concatenate all the records together.
This re-enables the instrprof-merging.cpp test, which previously was
failing on OSes which use comdats.
Thanks to Jeremy Morse, who very kindly provided object files from the
bot I broke to help me debug.
An execution count goes missing for a constructor, this needs
investigation:
http://lab.llvm.org:8011/builders/clang-ppc64be-linux/builds/45132/
```
/home/buildbots/ppc64be-clang-test/clang-ppc64be/llvm/compiler-rt/test/profile/instrprof-merging.cpp:28:16:
error: V1: expected string not found in input
A() {} // V1: [[@LINE]]{{ *}}|{{ *}}1
<stdin>:28:32: note: possible intended match here
28| | A() {} // V1: [[@LINE]]{{ *}}|{{ *}}1
```
Summary: `.cmd` is interpreted as script in windows console.
Reviewers: davidxl, rnk
Reviewed By: davidxl
Differential Revision: https://reviews.llvm.org/D73327
This is an alternative to the continous mode that was implemented in
D68351. This mode relies on padding and the ability to mmap a file over
the existing mapping which is generally only available on POSIX systems
and isn't suitable for other platforms.
This change instead introduces the ability to relocate counters at
runtime using a level of indirection. On every counter access, we add a
bias to the counter address. This bias is stored in a symbol that's
provided by the profile runtime and is initially set to zero, meaning no
relocation. The runtime can mmap the profile into memory at abitrary
location, and set bias to the offset between the original and the new
counter location, at which point every subsequent counter access will be
to the new location, which allows updating profile directly akin to the
continous mode.
The advantage of this implementation is that doesn't require any special
OS support. The disadvantage is the extra overhead due to additional
instructions required for each counter access (overhead both in terms of
binary size and performance) plus duplication of counters (i.e. one copy
in the binary itself and another copy that's mmapped).
Differential Revision: https://reviews.llvm.org/D69740
The executable acquires an advisory record lock (`fcntl(fd, F_SETLKW, *)`) on a profile file.
Merge pool size >= 10 may be beneficial when the concurrency is large.
Also fix a small problem about snprintf. It can cause the filename to be truncated after %m.
Reviewed By: davidxl
Differential Revision: https://reviews.llvm.org/D71970
See PR43425:
https://bugs.llvm.org/show_bug.cgi?id=43425
When writing profile data on Windows we were opening profile file with
exclusive read/write access.
In case we are trying to write to the file from multiple processes
simultaneously, subsequent calls to CreateFileA would return
INVALID_HANDLE_VALUE.
To fix this, I changed to open without exclusive access and then take a
lock.
Patch by Michael Holman!
Differential revision: https://reviews.llvm.org/D70330
Make it possible to use online profile merging ("%m" mode) with
continuous sync ("%c" mode).
To implement this, the merged profile is locked in the runtime
initialization step and either a) filled out for the first time or b)
checked for compatibility. Then, the profile can simply be mmap()'d with
MAP_SHARED set. With the mmap() in place, counter updates from every
process which uses an image are mapped onto the same set of physical
pages assigned by the filesystem cache. After the mmap() is set up, the
profile is unlocked.
Differential Revision: https://reviews.llvm.org/D69586
Add support for continuously syncing profile counter updates to a file.
The motivation for this is that programs do not always exit cleanly. On
iOS, for example, programs are usually killed via a signal from the OS.
Running atexit() handlers after catching a signal is unreliable, so some
method for progressively writing out profile data is necessary.
The approach taken here is to mmap() the `__llvm_prf_cnts` section onto
a raw profile. To do this, the linker must page-align the counter and
data sections, and the runtime must ensure that counters are mapped to a
page-aligned offset within a raw profile.
Continuous mode is (for the moment) incompatible with the online merging
mode. This limitation is lifted in https://reviews.llvm.org/D69586.
Continuous mode is also (for the moment) incompatible with value
profiling, as I'm not sure whether there is interest in this and the
implementation may be tricky.
As I have not been able to test extensively on non-Darwin platforms,
only Darwin support is included for the moment. However, continuous mode
may "just work" without modification on Linux and some UNIX-likes. AIUI
the default value for the GNU linker's `--section-alignment` flag is set
to the page size on many systems. This appears to be true for LLD as
well, as its `no_nmagic` option is on by default. Continuous mode will
not "just work" on Fuchsia or Windows, as it's not possible to mmap() a
section on these platforms. There is a proposal to add a layer of
indirection to the profile instrumentation to support these platforms.
rdar://54210980
Differential Revision: https://reviews.llvm.org/D68351
When the %m filename pattern is used, the filename is unique to each
image, so the cached value is wrong.
It struck me that the full filename isn't something that's recomputed
often, so perhaps it doesn't need to be cached at all. David Li pointed
out we can go further and just hide lprofCurFilename. This may regress
workflows that depend on using the set-filename API to change filenames
across all loaded DSOs, but this is expected to be very rare.
rdar://55137071
Differential Revision: https://reviews.llvm.org/D69137
llvm-svn: 375301
This test remains flaky everywhere, I think. We should consider deleting
it and accompanying support code in GCOVProfiling: I've stopped short of
doing that now as the gcov exec* tests appear to be stable.
See the thread re: r347779.
llvm-svn: 373121
This fixes a test failure in instrprof-set-file-object-merging.c which
seems to have been caused by reuse of stale data in old raw profiles.
llvm-svn: 372041
While working on https://reviews.llvm.org/D40900 (which effectively is about enabling compiler-rt on sparc these days), I came across two failing profile testcases:
Profile-sparc :: instrprof-merge-match.test
Profile-sparc :: instrprof-merge.c
Profile-sparcv9 :: instrprof-merge-match.test
Profile-sparcv9 :: instrprof-merge.c
All of them crashed with a SIGBUS in __llvm_profile_merge_from_buffer:
Thread 2 received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1 (LWP 1)]
0x00012368 in __llvm_profile_merge_from_buffer (
ProfileData=0x2384c <main.Buffer> "\377lprofR\201", ProfileSize=360)
at /vol/llvm/src/llvm/local/projects/compiler-rt/lib/profile/InstrProfilingMerge.c:95
95 SrcDataEnd = SrcDataStart + Header->DataSize;
where Header is insufficiently aligned for a strict-alignment target like SPARC.
Fixed by forcing the alignment to uint64_t, the members of struct __llvm_profile_header,
in the callers.
Tested on sparcv9-sun-solaris2.11.
https://reviews.llvm.org/D64498
llvm-svn: 365805
These lit configuration files are really Python source code. Using the
.py file extension helps editors and tools use the correct language
mode. LLVM and Clang already use this convention for lit configuration,
this change simply applies it to all of compiler-rt.
Reviewers: vitalybuka, dberris
Differential Revision: https://reviews.llvm.org/D63658
llvm-svn: 364591
Summary:
User code can open a file on its own and pass it to the runtime, rather than
specifying a name and having the runtime open the file. This supports the use
case where a process cannot open a file on its own but can receive a file
descriptor from another process.
Relanding https://reviews.llvm.org/D62541. The original revision unlocked
the file before calling flush, this revision fixes that.
Reviewers: Dor1s, davidxl
Reviewed By: Dor1s
Subscribers: #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D63581
llvm-svn: 364231
This caused instrumented Clang to become crashy. See llvm-commits thread
for repro steps.
This also reverts follow-up r362716 which added test cases.
> Author: Sajjad Mirza
>
> Differential Revision: http://reviews.llvm.org/D62541
llvm-svn: 363134
Patch from 'troyj':
Hi, I ran into a problem with this test when the source was located in
certain directories. The mkdir(2) man page states that the set-group-ID
bit is inherited from the parent directory, but this test was written in
such a way that it assumes the bit is unset. Whether that assumption is
true depends on where the checkout lives, which leads to some people
being able to reproduce the problem whereas others cannot. I think the
correct fix is to exclude the bit from the check.
Making probinson a reviewer since they reviewed the original test.
Patch landed for troyj, thanks!
Differential Revision: D53832
llvm-svn: 357449
r355343 was landed and was reverted in r355363 due to build breakage.
This patch adds Linux/Windows support on top of r355343.
In this patch, Darwin should be working with testing case. Linux should be working,
I will enable the testing case in a follwup diff. Windows/Other should be building.
Correct implementation for Other platforms will be added.
Thanks David for reviewing the original diff, helping me with issues on Linux, and
giving suggestions for adding support for Other platforms.
llvm-svn: 355701
Summary:
I hadn't realized that instrumentation runs before inlining, so we can't
use the function as the comdat group. Doing so can create relocations
against discarded sections when references to discarded __profc_
variables are inlined into functions outside the function's comdat
group.
In the future, perhaps we should consider standardizing the comdat group
names that ELF and COFF use. It will save object file size, since
__profv_$sym won't appear in the symbol table again.
Reviewers: xur, vsk
Subscribers: eraman, hiraditya, cfe-commits, #sanitizers, llvm-commits
Tags: #clang, #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D58737
llvm-svn: 355044
Summary:
The llvm-cov tool needs to be able to find coverage names in the
executable, so the .lprfn and .lcovmap sections cannot be merged into
.rdata.
Also, the linker merges .lprfn$M into .lprfn, so llvm-cov needs to
handle that when looking up sections. It has to support running on both
relocatable object files and linked PE files.
Lastly, when loading .lprfn from a PE file, llvm-cov needs to skip the
leading zero byte added by the profile runtime.
Reviewers: vsk
Subscribers: hiraditya, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D58661
llvm-svn: 354840
Summary:
The changes in https://reviews.llvm.org/D44847 cause load time failure
due to lprofMergeValueProfData in Android libs enabled with profile generation:
"dlopen failed: cannot locate symbol "lprofMergeValueProfData" referenced by..."
Marking lprofMergeValueProfData as hidden so the correct in-module definition
is picked by the linker.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: efriedma, xur, davidxl, llvm-commits
Differential Revision: https://reviews.llvm.org/D55893
llvm-svn: 354064
Summary:
The motivating use case is eliminating duplicate profile data registered
for the same inline function in two object files. Before this change,
users would observe multiple symbol definition errors with VC link, but
links with LLD would succeed.
Users (Mozilla) have reported that PGO works well with clang-cl and LLD,
but when using LLD without this static registration, we would get into a
"relocation against a discarded section" situation. I'm not sure what
happens in that situation, but I suspect that duplicate, unused profile
information was retained. If so, this change will reduce the size of
such binaries with LLD.
Now, Windows uses static registration and is in line with all the other
platforms.
Reviewers: davidxl, wmi, inglorion, void, calixte
Subscribers: mgorny, krytarowski, eraman, fedor.sergeev, hiraditya, #sanitizers, dmajor, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D57929
llvm-svn: 353547
Summary:
Before this change, check-profile would run, but all tests would be
marked unsupported on Windows. This is the new status of 'check-profile'
after this change:
Testing Time: 6.66s
Expected Passes : 29
Expected Failures : 5
Unsupported Tests : 39
I moved many tests that exercise posix-y features like dlopen and DSOs
into the Posix subdirectory, and ran the tests on Linux to validate my
changes.
These are the remaining tests that I handled on a case by case basis:
- instrprof-path.c
Passes, Fixed some path portability issues
- instrprof-gcov-exceptions.test
Passes, the FileCheck actually succeeds on Windows, so I RUNX'd it
- instrprof-icall-promo.test
XFAILed, probably due to C++ ABI differences in vtables
- instrprof-merge-match.test
- instrprof-merge.c
- instrprof-merging.cpp
XFAILed, These seem like real bugs that need fixing
- instrprof-version-mismatch.c
XFAILed, Overriding the weak version symbol doesn't work
- instrprof-without-libc.c
UNSUPPORTED, test needs an executable symbol table, Windows has none
Reviewers: davidxl, wmi, void
Subscribers: fedor.sergeev, #sanitizers, llvm-commits
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D57853
llvm-svn: 353435
Summary:
NetBSD uses typical UNIX interfaces.
All tests pass except instrprof-dlopen-dlclose-gcov.test, as there
is not supported semantics of atexit(3) in dlopen(3)ed+dlclose(3)d
DSO.
NetBSD also ships an older version of LLVM profile (ABI v.2 predating
ABI v.4 in upstream version) inside libc. That copy has been manually
removed during the porting and testing process of the upstream version
to NetBSD. Otherwise there were conflicts between them two.
Reviewers: joerg, vitalybuka, vsk
Subscribers: srhines, fedor.sergeev, llvm-commits, mgorny, #sanitizers
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D55997
llvm-svn: 349994
Make sure that symbols needed to implement runtime support for gcov are
exported when using an export list on Darwin.
Without the clang driver exporting these symbols, the linker hides them,
resulting in tapi verification failures.
rdar://45944768
Differential Revision: https://reviews.llvm.org/D55151
llvm-svn: 348187
Alex Lorenz