to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Disable enforcing alignas() for structs that are used as thread_local
data on NetBSD. The NetBSD ld.so implementation is buggy and does
not enforce correct alignment; however, clang seems to take it for
granted and generates instructions that segv on wrongly aligned objects.
Therefore, disable those alignas() statements on NetBSD until we can
establish a better fix.
Apparently, std::aligned_storage<> does not have any real effect
at the moment, so we can leave it as-is.
Differential Revision: https://reviews.llvm.org/D56000
llvm-svn: 350029
Summary:
This change addresses an issue which shows up with the synchronised race
between threads writing into a buffer, and another thread reading the
buffer.
In a lot of cases, we cannot guarantee that threads will always see the
signal to finalise their buffers in time despite the grace periods and
state machine maintained through atomic variables. This change addresses
it by ensuring that the same instance being updated to indicate how much
of the buffer is "used" by the writing thread is the same instance being
read by the thread processing the buffer to be written out to disk or
handled through the iterators.
To do this, we ensure that all the "extents" instances live in their own
the backing store, in a different contiguous page from the
buffer-specific backing store. We also take precautions to ensure that
the atomic variables are cache-line-sized to prevent false-sharing from
unnecessarily causing cache contention on unrelated writes/reads.
It's feasible that we may in the future be able to move the storage of
the extents objects into the single backing store, slightly changing the
way to compute the size(s) of the buffers, but in the meantime we'll
settle for the isolation afforded by having a different backing store
for the extents instances.
Reviewers: mboerger
Subscribers: jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D54684
llvm-svn: 347280
Summary:
We need these fences to ensure that other threads attempting to read
bytes in the buffer will see thw writes committed before the extents are
updated. Without these, the writes can be un-committed by the time the
buffer extents counter is updated -- the fences should ensure that the
records written into the log have completed by the time we observe the
buffer extents from different threads.
Reviewers: mboerger
Subscribers: jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D54291
llvm-svn: 346474
Summary:
This change updates the version number for FDR logs to 5, and update the
trace processing to support changes in the custom event records.
In the runtime, since we're already writing down the record preamble to
handle CPU migrations and TSC wraparound, we can use the same TSC delta
encoding in the custom event and typed event records that we use in
function event records. We do the same change to typed events (which
were unsupported before this change in the trace processing) which now
show up in the trace.
Future changes should increase our testing coverage to make custom and
typed events as first class entities in the FDR mode log processing
tools.
This change is also a good example of how we end up supporting new
record types in the FDR mode implementation. This shows the places where
new record types are added and supported.
Depends on D54139.
Reviewers: mboerger
Subscribers: hiraditya, arphaman, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D54140
llvm-svn: 346293
Summary:
This change cuts across compiler-rt and llvm, to increment the FDR log
version number to 4, and include the CPU ID in the custom event records.
This is a step towards allowing us to change the `llvm::xray::Trace`
object to start representing both custom and typed events in the stream
of records. Follow-on changes will allow us to change the kinds of
records we're presenting in the stream of traces, to incorporate the
data in custom/typed events.
A follow-on change will handle the typed event case, where it may not
fit within the 15-byte buffer for metadata records.
This work is part of the larger effort to enable writing analysis and
processing tools using a common in-memory representation of the events
found in traces. The work will focus on porting existing tools in LLVM
to use the common representation and informing the design of a
library/framework for expressing trace event analysis as C++ programs.
Reviewers: mboerger, eizan
Subscribers: hiraditya, mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D53920
llvm-svn: 345798
Summary:
This change completes the refactoring of the FDR runtime to support the
following:
- Generational buffer management.
- Centralised and well-tested controller implementation.
In this change we've had to:
- Greatly simplify the code in xray_fdr_logging.cc to only implement the
glue code for calling into the controller.
- Implement the custom and typed event logging functions in the
FDRLogWriter.
- Imbue the `XRAY_NEVER_INSTRUMENT` attribute onto all functions in the
controller implementation.
Reviewers: mboerger, eizan, jfb
Subscribers: jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D53858
llvm-svn: 345568
Summary:
This change updates the buffer queue implementation to support using a
generation number to identify the lifetime of buffers. This first part
introduces the notion of the generation number, without changing the way
we handle the buffers yet.
What's missing here is the cleanup of the buffers. Ideally we'll keep
the two most recent generations. We need to ensure that before we do any
writes to the buffers, that we check the generation number(s) first.
Those changes will follow-on from this change.
Depends on D52588.
Reviewers: mboerger, eizan
Subscribers: llvm-commits, jfb
Differential Revision: https://reviews.llvm.org/D52974
llvm-svn: 344881
Summary:
This change updates the buffer queue implementation to support using a
generation number to identify the lifetime of buffers. This first part
introduces the notion of the generation number, without changing the way
we handle the buffers yet.
What's missing here is the cleanup of the buffers. Ideally we'll keep
the two most recent generations. We need to ensure that before we do any
writes to the buffers, that we check the generation number(s) first.
Those changes will follow-on from this change.
Depends on D52588.
Reviewers: mboerger, eizan
Subscribers: llvm-commits, jfb
Differential Revision: https://reviews.llvm.org/D52974
llvm-svn: 344670
This abstracts away the file descriptor related logic which makes it
easier to port XRay to platform that don't use file descriptors or
file system for writing the log data, such as Fuchsia.
Differential Revision: https://reviews.llvm.org/D52161
llvm-svn: 344578
Summary:
This is for coding standard conformance, and for fixing an ODR violation
issue: __xray::ThreadLocalData is defined twice and differently in
xray_fdr_logging.cc and xray_basic_logging.cc
Reviewers: dberris, mboerger, eizan
Reviewed By: dberris
Subscribers: delcypher, jfb, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D52639
llvm-svn: 343289
Summary:
The implementation of `internal_mmap(...)` deviates from the contract of
`mmap(...)` -- i.e. error returns are actually the equivalent of `errno`
results. We update how XRay uses `internal_mmap(...)` to better handle
these error conditions.
In the process, we change the default pointers we're using from `char*`
to `uint8_t*` to prevent potential usage of the pointers in the string
library functions that expect to operate on `char*`.
We also take the chance to "promote" sizes of individual `internal_mmap`
requests to at least page size bytes, consistent with the expectations
of calls to `mmap`.
Reviewers: cryptoad, mboerger
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D52361
llvm-svn: 342745
Summary:
This change introduces an `FDRLogWriter` type which is responsible for
serialising metadata and function records to character buffers. This is
the first step in a refactoring of the implementation of the FDR runtime
to allow for more granular testing of the individual components of the
implementation.
The main contribution of this change is a means of hiding the details of
how specific records are written to a buffer, and for managing the
extents of these buffers. We make use of C++ features (templates and
some metaprogramming) to reduce repetition in the act of writing out
specific kinds of records to the buffer.
In this process, we make a number of changes across both LLVM and
compiler-rt to allow us to use the `Trace` abstraction defined in the
LLVM project in the testing of the runtime implementation. This gives us
a closer end-to-end test which version-locks the runtime implementation
with the loading implementation in LLVM.
We also allow using gmock in compiler-rt unit tests, by adding the
requisite definitions in the `AddCompilerRT.cmake` module. We also add
the terminfo library detection along with inclusion of the appropriate
compiler flags for header include lookup.
Finally, we've gone ahead and updated the FDR logging implementation to
use the FDRLogWriter for the lowest-level record-writing details.
Following patches will isolate the state machine transitions which
manage the set-up and tear-down of the buffers we're using in multiple
threads.
Reviewers: mboerger, eizan
Subscribers: mgorny, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52220
llvm-svn: 342617
Summary:
This change introduces an `FDRLogWriter` type which is responsible for
serialising metadata and function records to character buffers. This is
the first step in a refactoring of the implementation of the FDR runtime
to allow for more granular testing of the individual components of the
implementation.
The main contribution of this change is a means of hiding the details of
how specific records are written to a buffer, and for managing the
extents of these buffers. We make use of C++ features (templates and
some metaprogramming) to reduce repetition in the act of writing out
specific kinds of records to the buffer.
In this process, we make a number of changes across both LLVM and
compiler-rt to allow us to use the `Trace` abstraction defined in the
LLVM project in the testing of the runtime implementation. This gives us
a closer end-to-end test which version-locks the runtime implementation
with the loading implementation in LLVM.
We also allow using gmock in compiler-rt unit tests, by adding the
requisite definitions in the `AddCompilerRT.cmake` module.
Finally, we've gone ahead and updated the FDR logging implementation to
use the FDRLogWriter for the lowest-level record-writing details.
Following patches will isolate the state machine transitions which
manage the set-up and tear-down of the buffers we're using in multiple
threads.
Reviewers: mboerger, eizan
Subscribers: mgorny, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52220
llvm-svn: 342518
Summary:
This change makes XRay FDR mode use a single backing store for the
buffer queue, and have indexes into that backing store instead. We also
remove the reliance on the internal allocator implementation in the FDR
mode logging implementation.
In the process of making this change we found an inconsistency with the
way we're returning buffers to the queue, and how we're setting the
extents. We take the chance to simplify the way we're managing the
extents of each buffer. It turns out we do not need the indirection for
the extents, so we co-host the atomic 64-bit int with the buffer object.
It also seems that we've not been returning the buffers for the thread
running the flush functionality when writing out the files, so we can
run into a situation where we could be missing data.
We consolidate all the allocation routines now into xray_allocator.h,
where we used to have routines defined in xray_buffer_queue.cc.
Reviewers: mboerger, eizan
Subscribers: jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52077
llvm-svn: 342356
This API has been deprecated three months ago and shouldn't be used
anymore, all clients should migrate to the new string based API.
Differential Revision: https://reviews.llvm.org/D51606
llvm-svn: 342318
Summary:
This change has a number of fixes for FDR mode in compiler-rt along with
changes to the tooling handling the traces in llvm.
In the runtime, we do the following:
- Advance the "last record" pointer appropriately when writing the
custom event data in the log.
- Add XRAY_NEVER_INSTRUMENT in the rewinding routine.
- When collecting the argument of functions appropriately marked, we
should not attempt to rewind them (and reset the counts of functions
that can be re-wound).
In the tooling, we do the following:
- Remove the state logic in BlockIndexer and instead rely on the
presence/absence of records to indicate blocks.
- Move the verifier into a loop associated with each block.
Reviewers: mboerger, eizan
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D51965
llvm-svn: 342122
When providing raw access to the FDR mode buffers, we used to not
include the extents metadata record. This oversight means that
processing the buffers in-memory will lose important information that
would have been written in files.
This change exposes the metadata record by serializing the data
similarly to how we would do it when flushing to files.
llvm-svn: 337441
Summary:
Fix a bug in FDR mode which didn't allow for re-initialising the logging
in the same process. This change ensures that:
- When we flush the FDR mode logging, that the state of the logging
implementation is `XRAY_LOG_UNINITIALIZED`.
- Fix up the thread-local initialisation to use aligned storage and
`pthread_getspecific` as well as `pthread_setspecific` for the
thread-specific data.
- Actually use the pointer provided to the thread-exit cleanup handling,
instead of assuming that the thread has thread-local data associated
with it, and reaching at thread-exit time.
In this change we also have an explicit test for two consecutive
sessions for FDR mode tracing, and ensuring both sessions succeed.
Reviewers: kpw, eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D49359
llvm-svn: 337341
Summary:
llvm-xray changes:
- account-mode - process-id {...} shows after thread-id
- convert-mode - process {...} shows after thread
- parses FDR and basic mode pid entries
- Checks version number for FDR log parsing.
Basic logging changes:
- Update header version from 2 -> 3
FDR logging changes:
- Update header version from 2 -> 3
- in writeBufferPreamble, there is an additional PID Metadata record (after thread id record and tsc record)
Test cases changes:
- fdr-mode.cc, fdr-single-thread.cc, fdr-thread-order.cc modified to catch process id output in the log.
Reviewers: dberris
Reviewed By: dberris
Subscribers: hiraditya, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D49153
llvm-svn: 336974
Summary:
This fixes http://llvm.org/PR32274.
This change adds a test to ensure that we're able to link XRay modes and
the runtime to binaries that don't need to depend on the C++ standard
library or a C++ ABI library. In particular, we ensure that this will work
with C programs compiled+linked with XRay.
To make the test pass, we need to change a few things in the XRay
runtime implementations to remove the reliance on C++ ABI features. In
particular, we change the thread-safe function-local-static
initialisation to use pthread_* instead of the C++ features that ensure
non-trivial thread-local/function-local-static initialisation.
Depends on D47696.
Reviewers: dblaikie, jfb, kpw, eizan
Reviewed By: kpw
Subscribers: echristo, eizan, kpw, mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D46998
llvm-svn: 334262
Summary:
This change extracts the recursion guard implementation from FDR Mode
and updates it to do the following:
- Do the atomic operation correctly to be signal-handler safe.
- Make it usable in both FDR and Basic Modes.
Before this change, the recursion guard relied on an unsynchronised read
and write on a volatile thread-local. A signal handler could then run in
between the read and the write, and then be able to run instrumented
code as part of the signal handling. Using an atomic exchange instead
fixes that by doing a proper mutual exclusion even in the presence of
signal handling.
Reviewers: kpw, eizan, jfb
Reviewed By: eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D47696
llvm-svn: 334064
We don't actually need to support multiple definitions of the functions
in FDR mode, but rather want to make sure that the implementation-detail
functions are marked as 'static' instead. This allows the inliner to do
its magic better for these functions too, since inline functions must
have a unique address across translation units.
llvm-svn: 334001
We planned to have FDR mode's internals unit-tested but it turns out
that we can just use end-to-end testing to verify the implementation.
We're going to move towards that approach more and more going forward,
so we're merging the implementation details of FDR mode into a single
.cc file.
We also avoid globbing in the XRay test helper macro, and instead list
down the files from the lib directory.
llvm-svn: 333986
Summary:
This change allows for handling the in-memory data associated with the
FDR mode implementation through the new `__xray_log_process_buffers`
API. With this change, we can now allow users to process the data
in-memory of the process instead of through writing files.
This for example allows users to stream the data of the FDR logging
implementation through network sockets, or through other mechanisms
instead of saving them to local files.
We introduce an FDR-specific flag, for "no_file_flush" which lets the
flushing logic skip opening/writing to files.
This option can be defaulted to `true` when building the compiler-rt
XRay runtime through the `XRAY_FDR_OPTIONS` preprocessor macro.
Reviewers: kpw, echristo, pelikan, eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D46574
llvm-svn: 332208
Summary:
In this chage we add support for the string-based configuration
mechanism for configuring FDR mode.
We deprecate most of the `xray_fdr_log_*` flags that are set with the
`XRAY_OPTIONS` environment variable. Instead we make the FDR
implementation take defaults from the `XRAY_FDR_OPTIONS` environment
variable, and use the flags defined in `xray_fdr_flags.{h,cc,inc}` for
the options we support.
This change addresses http://llvm.org/PR36790.
Depends on D46173.
Reviewers: eizan, pelikan, kpw, echristo
Subscribers: llvm-commits, mgorny
Differential Revision: https://reviews.llvm.org/D46174
llvm-svn: 331506
Summary:
Compiler-rt support first before defining the __xray_typedevent() lowering in
llvm. I'm looking for some early feedback before I touch much more code.
Reviewers: dberris
Subscribers: delcypher, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D43668
llvm-svn: 330218
Summary:
This change allows for registration of multiple logging implementations
through a central mechanism in XRay, mapping an implementation to a
"mode". Modes are strings that are used as keys to determine which
implementation to install through a single API. This mechanism allows
users to choose which implementation to install either from the
environment variable 'XRAY_OPTIONS' with the `xray_mode=` flag, or
programmatically using the `__xray_select_mode(...)` function.
Here, we introduce two API functions for the XRay logging:
__xray_log_register_mode(Mode, Impl): Associates an XRayLogImpl to a
string Mode. We can only have one implementation associated with a given
Mode.
__xray_log_select_mode(Mode): Finds the associated Impl for Mode and
installs it as if by calling `__xray_set_log_impl(...)`.
Along with these changes, we also deprecate the xray_naive_log and
xray_fdr_log flags and encourage users to instead use the xray_mode
flag.
Reviewers: kpw, dblaikie, eizan, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D40703
llvm-svn: 319759
This change is the first in a series of changes to get the XRay runtime
building on macOS. This first allows us to build the minimal parts of
XRay to get us started on supporting macOS development. These include:
- CMake changes to allow targeting x86_64 initially.
- Allowing for building the initialisation routines without
`.preinit_array` support.
- Use __sanitizer::SleepForMillis() to work around the lack of
clock_nanosleep on macOS.
- Deprecate the xray_fdr_log_grace_period_us flag, and introduce
the xray_fdr_log_grace_period_ms flag instead, to use
milliseconds across platforms.
Reviewers: kubamracek
Subscribers: llvm-commits, krytarowski, nglevin, mgorny
Differential Review: https://reviews.llvm.org/D39114
llvm-svn: 319165
Summary:
Before this change, the FDR mode implementation relied on at thread-exit
handling to return buffers back to the (global) buffer queue. This
introduces issues with the initialisation of the thread_local objects
which, even through the use of pthread_setspecific(...) may eventually
call into an allocation function. Similar to previous changes in this
line, we're finding that there is a huge potential for deadlocks when
initialising these thread-locals when the memory allocation
implementation is also xray-instrumented.
In this change, we limit the call to pthread_setspecific(...) to provide
a non-null value to associate to the key created with
pthread_key_create(...). While this doesn't completely eliminate the
potential for the deadlock(s), it does allow us to still clean up at
thread exit when we need to. The change is that we don't need to do more
work when starting and ending a thread's lifetime. We also have a test
to make sure that we actually can safely recycle the buffers in case we
end up re-using the buffer(s) available from the queue on multiple
thread entry/exits.
This change cuts across both LLVM and compiler-rt to allow us to update
both the XRay runtime implementation as well as the library support for
loading these new versions of the FDR mode logging. Version 2 of the FDR
logging implementation makes the following changes:
* Introduction of a new 'BufferExtents' metadata record that's outside
of the buffer's contents but are written before the actual buffer.
This data is associated to the Buffer handed out by the BufferQueue
rather than a record that occupies bytes in the actual buffer.
* Removal of the "end of buffer" records. This is in-line with the
changes we described above, to allow for optimistic logging without
explicit record writing at thread exit.
The optimistic logging model operates under the following assumptions:
* Threads writing to the buffers will potentially race with the thread
attempting to flush the log. To avoid this situation from occuring,
we make sure that when we've finalized the logging implementation,
that threads will see this finalization state on the next write, and
either choose to not write records the thread would have written or
write the record(s) in two phases -- first write the record(s), then
update the extents metadata.
* We change the buffer queue implementation so that once it's handed
out a buffer to a thread, that we assume that buffer is marked
"used" to be able to capture partial writes. None of this will be
safe to handle if threads are racing to write the extents records
and the reader thread is attempting to flush the log. The optimism
comes from the finalization routine being required to complete
before we attempt to flush the log.
This is a fairly significant semantics change for the FDR
implementation. This is why we've decided to update the version number
for FDR mode logs. The tools, however, still need to be able to support
older versions of the log until we finally deprecate those earlier
versions.
Reviewers: dblaikie, pelikan, kpw
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D39526
llvm-svn: 318733
Summary:
This change removes dependencies on STL types:
- std::aligned_storage -- we're using manually-aligned character
buffers instead for metadata and function records.
- std::tuple -- use a plain old struct instead.
This is an incremental step in removing all STL references from the
compiler-rt implementation of XRay (llvm.org/PR32274).
Reviewers: dblaikie, pelikan, kpw
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D39277
llvm-svn: 316816
Summary:
In FDR Mode, when we set up a new buffer for a thread that's just
overflowed, we must place the CPU identifier with the TSC record as the
first record. This is so that we can reconstruct all the function
entry/exit with deltas rooted on a TSC record for the CPU at the
beginning of the buffer.
Without doing this, the tools are rejecting the log for cases when we've
overflown and have different buffers that don't have the CPU and TSC
records as the first entry in the buffers.
Reviewers: pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38995
llvm-svn: 315987
Summary:
When the XRay user calls the API to finish writing the log, the thread
which is calling the API still hasn't finished and therefore won't get
its trace written. Add a test for only the main thread to check this.
Reviewers: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38493
llvm-svn: 314875
Summary:
Write out records about logged function call first arguments. D32840
implements the reading of this in llvm-xray.
Reviewers: dberris
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32844
llvm-svn: 314378
Summary:
Before this change, the recursion guard for the flight data recorder
(FDR) mode handlers were independent. This change makes it so that when
a handler is already in the process of running and somehow the same or
another handler starts running -- say in a signal handler, while the
XRay handler is executing -- then we can use the same thread-local
recursion guard to stop the second handler from running.
Reviewers: kpw, eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D37612
llvm-svn: 312992
Summary:
This change hides all the initialization of thread_local variables used
by the XRay FDR mode implementation behind a function call. This makes
initialization of thread-local data to be done lazily, instead of
eagerly when they're done as globals. It also gives us an isolation
mechanism if/when we want to change the TLS implementation from using
the C++ thread_local keyword, for something more ad-hoc (potentialy
using pthread directly) on some platforms or set-ups where we cannot use
the C++ thread_local variables.
Reviewers: kpw, eizan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D37248
llvm-svn: 311997
Summary:
This change attempts to remove all the dependencies we have on
std::mutex and any std::shared_ptr construction in global variables. We
instead use raw pointers to these objects, and construct them on the
heap. In cases where it's possible, we lazily initialize these pointers.
While we do not have a replacement for std::shared_ptr yet in
compiler-rt, we use this work-around to avoid having to statically
initialize the objects as globals. Subsequent changes should allow us to
completely remove our dependency on std::shared_ptr and instead have our
own implementation of the std::shared_ptr and std::weak_ptr semantics
(or completely rewrite the implementaton to not need these
standard-library provided abstractions).
Reviewers: dblaikie, kpw, pelikan
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D36078
llvm-svn: 309792
Chandler Carruth