Summary:
This change covers a number of things spanning LLVM and compiler-rt,
which are related in a non-trivial way.
In LLVM, we have a library that handles the FDR mode even log loading,
which uses C++'s runtime polymorphism feature to better faithfully
represent the events that are written down by the FDR mode runtime. We
do this by interpreting a trace that's serliased in a common format
agreed upon by both the trace loading library and the FDR mode runtime.
This library is under active development, which consists of features
allowing us to reconstitute a higher-level event log.
This event log is used by the conversion and visualisation tools we have
for interpreting XRay traces.
One of the tools we have is a diagnostic tool in llvm-xray called
`fdr-dump` which we've been using to debug our expectations of what the
FDR runtime should be writing and what the logical FDR event log
structures are. We use this fairly extensively to reason about why some
non-trivial traces we're generating with FDR mode runtimes fail to
convert or fail to parse correctly.
One of these failures we've found in manual debugging of some of the
traces we've seen involve an inconsistency between the buffer extents (a
record indicating how many bytes to follow are part of a logical
thread's event log) and the record of the bytes written into the log --
sometimes it turns out the data could be garbage, due to buffers being
recycled, but sometimes we're seeing the buffer extent indicating a log
is "shorter" than the actual records associated with the buffer. This
case happens particularly with function entry records with a call
argument.
This change for now updates the FDR mode runtime to write the bytes for
the function call and arg record before updating the buffer extents
atomically, allowing multiple threads to see a consistent view of the
data in the buffer using the atomic counter associated with a buffer.
What we're trying to prevent here is partial updates where we see the
intermediary updates to the buffer extents (function record size then
call argument record size) becoming observable from another thread, for
instance, one doing the serialization/flushing.
To do both diagnose this issue properly, we need to be able to honour
the extents being set in the `BufferExtents` records marking the
beginning of the logical buffers when reading an FDR trace. Since LLVM
doesn't use C++'s RTTI mechanism, we instead follow the advice in the
documentation for LLVM Style RTTI
(https://llvm.org/docs/HowToSetUpLLVMStyleRTTI.html). We then rely on
this RTTI feature to ensure that our file-based record producer (our
streaming "deserializer") can honour the extents of individual buffers
as we interpret traces.
This also sets us up to be able to eventually do smart
skipping/continuation of FDR logs, seeking instead to find BufferExtents
records in cases where we find potentially recoverable errors. In the
meantime, we make this change to operate in a strict mode when reading
logical buffers with extent records.
Reviewers: mboerger
Subscribers: hiraditya, llvm-commits, jfb
Differential Revision: https://reviews.llvm.org/D54201
llvm-svn: 346473
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 LLVM and compiler-rt to add support for
rendering custom events in the XRayRecord type, to allow for including
user-provided annotations in the output YAML (as raw bytes).
This work enables us to add custom event and typed event records into
the `llvm::xray::Trace` type for user-provided events. This can then be
programmatically handled through the C++ API and can be included in some
of the tooling as well. For now we support printing the raw data we
encounter in the custom events in the converted output.
Future work will allow us to start interpreting these custom and typed
events through a yet-to-be-defined API for extending the trace analysis
library.
Reviewers: mboerger
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D54139
llvm-svn: 346214
Summary:
Fix some issues discovered from mostly manual inspection of outputs from
the `llvm-xray fdr-dump` tool.
It turns out we haven't been writing the deltas properly, and have been
writing down zeros for deltas of some records. This change fixes this
oversight born by the recent refactoring.
Reviewers: mboerger
Subscribers: llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D54022
llvm-svn: 345954
Summary:
This is a follow-on change to D53858 which turns out to have had a TSC
accounting bug when writing out function exit records in FDR mode.
This change adds a number of tests to ensure that:
- We are handling the delta between the exit TSC and the last TSC we've
seen.
- We are writing the custom event and typed event records as a single
update to the buffer extents.
- We are able to catch boundary conditions when loading FDR logs.
We introduce a TSC matcher to the test helpers, which we use in the
testing/verification of the TSC accounting change.
Reviewers: mboerger
Subscribers: mgorny, hiraditya, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D53967
llvm-svn: 345905
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
There are a few leftovers in rL343163 which span two lines. This commit
changes these llvm::sort(C.begin(), C.end, ...) to llvm::sort(C, ...)
llvm-svn: 343426
Summary:
This change spans both LLVM and compiler-rt, where we do the following:
- Add XRay to the LLVMBuild system, to allow for distributing the XRay
trace loading library along with the LLVM distributions.
- Use `llvm-config` better in the compiler-rt XRay implementation, to
depend on the potentially already-distributed LLVM XRay library.
While this is tested with the standalone compiler-rt build, it does
require that the LLVMXRay library (and LLVMSupport as well) are
available during the build. In case the static libraries are available,
the unit tests will build and work fine. We're still having issues with
attempting to use a shared library version of the LLVMXRay library since
the shared library might not be accessible from the standard shared
library lookup paths.
The larger change here is the inclusion of the LLVMXRay library in the
distribution, which allows for building tools around the XRay traces and
profiles that the XRay runtime already generates.
Reviewers: echristo, beanz
Subscribers: mgorny, hiraditya, mboerger, llvm-commits
Differential Revision: https://reviews.llvm.org/D52349
llvm-svn: 342859
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
Summary:
In this change, we overhaul the implementation for loading
`llvm::xray::Trace` objects from files by using the combination of
specific FDR Record types and visitors breaking up the logic to
reconstitute an execution trace from flight-data recorder mode traces.
This change allows us to handle out-of-temporal order blocks as written
in files, and more consistently recreate an execution trace spanning
multiple blocks and threads. To do this, we use the `WallclockRecord`
associated with each block to maintain temporal order of blocks, before
attempting to recreate an execution trace.
The new addition in this change is the `TraceExpander` type which can be
thought of as a decompression/decoding routine. This allows us to
maintain the state of an execution environment (thread+process) and
create `XRayRecord` instances that fit nicely into the `Trace`
container. We don't have a specific unit test for the TraceExpander
type, since the end-to-end tests for the `llvm-xray convert` tools
already cover precisely this codepath.
This change completes the refactoring started with D50441.
Depends on D51911.
Reviewers: mboerger, eizan
Subscribers: mgorny, hiraditya, mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D51912
llvm-svn: 341906
Summary:
This more correctly reflects the data written by the FDR mode runtime.
This is a continuation of the work in D50441.
Reviewers: mboerger, eizan
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51911
llvm-svn: 341905
Summary:
In this change, we implement a `BlockPrinter` which orders records in a
Block that's been indexed by the `BlockIndexer`. This is used in the
`llvm-xray fdr-dump` tool which ties together the various types and
utilities we've been working on, to allow for inspection of XRay FDR
mode traces both with and without verification.
This change is the final step of the refactoring of D50441.
Reviewers: mboerger, eizan
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51846
llvm-svn: 341887
Summary:
This patch implements a `BlockVerifier` type which enforces the
invariants of the log structure of FDR mode logs on a per-block basis.
This ensures that the data we encounter from an FDR mode log
semantically correct (i.e. that records follow the documented "grammar"
for FDR mode log records).
This is another part of the refactoring of D50441.
This is a slightly modified version of rL341628, avoiding the
`std::tuple<...>` constructor that is not constexpr in C++11.
Reviewers: mboerger, eizan
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51723
llvm-svn: 341769
Summary:
This patch implements a `BlockVerifier` type which enforces the
invariants of the log structure of FDR mode logs on a per-block basis.
This ensures that the data we encounter from an FDR mode log
semantically correct (i.e. that records follow the documented "grammar"
for FDR mode log records).
This is another part of the refactoring of D50441.
Reviewers: mboerger, eizan
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51723
llvm-svn: 341628
Summary:
This change adds a `BlockIndexer` type which maintains pointers to
records that belong to the same process+thread pairs. The indexing
happens with order of appearance of records as they are visited.
This version of the indexer currently only supports FDR version 3 logs,
which contain `BufferExtent` records. We will add support for v2 and v1
logs in follow-up patches.
This is another part of D50441.
Reviewers: eizan, kpw, mboerger
Reviewed By: mboerger
Subscribers: mboerger, mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51673
llvm-svn: 341518
Summary:
This change adds a `RecordPrinter` type which does some basic text
serialization of the FDR record instances. This is one component of the
tool we're building to dump the records from an FDR mode log as-is.
This is a small part of D50441.
Reviewers: eizan, kpw
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51672
llvm-svn: 341447
Since we changed the storage for the PID in PIDRecord instances, we need
to also update the way we load the data from a DataExtractor through the
RecordInitializer.
llvm-svn: 341243
Previously we've been reading and writing the wrong types which only
worked in little endian implementations. This time we're writing the
same typed values the runtime is using, and reading them appropriately
as well.
llvm-svn: 341241
This change allows us to let the compiler do the right thing for when
handling big-endian and little-endian records for FDR mode function
records.
Previously, we assumed that the encoding was little-endian that reading
the first byte to look for the function id and function record types was
ordered in a little-endian manner. This change allows us to better
handle function records where the first four bytes may actually be
encoded in big-endian thus giving us the wrong bytes where we're seeking
the function information from.
This is a follow-up to D51210 and D51289.
llvm-svn: 341236
This change makes the writer implementation more consistent with the way
fields are written down to avoid assumptions on bitfield order and
padding. We also fix an inconsistency between the type returned by the
`delta()` accessor to match the data member it's returning.
This is a follow-up to D51289 and D51210.
llvm-svn: 341230
This change makes the XRay Trace loading functions first use a
little-endian data extractor, then on failures try a big-endian data
extractor. Without this change, the trace loading facility will not work
with data written from a big-endian machine.
Follow-up to D51210 and D51289.
llvm-svn: 341226
Before this patch, the FDRTraceWriter would not take endianness into
account when writing data into the output stream.
This is a follow-up to D51289 and D51210.
llvm-svn: 341223
This simplifies the implementation of the metadata lookup by using
scoped enums, rather than using enum classes. This way we can get the
number-name mapping without having to resort to comments.
Follow-up to D51289.
llvm-svn: 341205
Summary:
This patch defines two new base types called `RecordProducer` and
`RecordConsumer` which have default implementations for convenience
(particularly for testing).
A `RecordProducer` implementation has one member function called
`produce()` which serves as a factory constructor for `Record`
instances. This code exercises the `RecordInitializer` code path in the
implementation for `FileBasedRecordProducer`.
A `RecordConsumer` has a single member function called `consume(...)`
which, as the name implies, consumes instances of
`std::unique_ptr<Record>`. We have two implementations, one of which is
used in the test to generate a vector of `std::unique_ptr<Record>`
similar to how the `LogBuilder` implementation works.
We introduce a test in `FDRProducerConsumerTest` which ensures that
records we write through the `FDRTraceWriter` can be loaded by the
`FileBasedRecordProducer`. The record(s) loaded this way are written
again through the `FDRTraceWriter` into a separate string, which we then
compare. This ensures that the read-in bytes to create the `Record`
instances in memory can be replicated when written out through the
`FDRTraceWriter`.
This change depends on D51210 and is part of the refactoring of D50441
into smaller, more focused changes.
Reviewers: eizan, kpw
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51289
llvm-svn: 341180
Summary:
This is the first step in the larger refactoring and reduction of
D50441.
This step in the process does the following:
- Introduces more granular types of `Record`s representing the many
kinds of records written/read by the Flight Data Recorder (FDR) mode
`Trace` loading function(s).
- Introduces an abstract `RecordVisitor` type meant to handle the
processing of the various `Record` derived types. This `RecordVisitor`
has two implementations in this patch: `RecordInitializer` and
`FDRTraceWriter`.
- We also introduce a convenience interface for building a collection of
`Record` instances called a `LogBuilder`. This allows us to generate
sequences of `Record` instances manually (used in unit tests but
useful otherwise).
- The`FDRTraceWriter` class implements the `RecordVisitor` interface and
handles the writing of metadata records to a `raw_ostream`. We
demonstrate that in the unit test, we can generate in-memory FDR mode
traces using the specific `Record` derived types, which we load
through the `loadTrace(...)` function yielding valid `Trace` objects.
This patch introduces the required types and concepts for us to start
replacing the logic implemented in the `loadFDRLog` function to use the
more granular types. In subsequent patches, we will introduce more
visitor implementations which isolate the verification, printing,
indexing, production/consumption, and finally the conversion of the FDR
mode logs.
The overarching goal of these changes is to make handling FDR mode logs
better tested, more understandable, more extensible, and more
systematic. This will also allow us to better represent the execution
trace, as we improve the fidelity of the events we represent in an XRay
`Trace` object, which we intend to do after FDR mode log processing is
in better shape.
Reviewers: eizan
Reviewed By: eizan
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51210
llvm-svn: 341029
Summary:
This change implements the profile loading functionality in LLVM to
support XRay's profiling mode in compiler-rt.
We introduce a type named `llvm::xray::Profile` which allows building a
profile representation. We can load an XRay profile from a file to build
Profile instances, or do it manually through the Profile type's API.
The intent is to get the `llvm-xray` tool to generate `Profile`
instances and use that as the common abstraction through which all
conversion and analysis can be done. In the future we can generate
`Profile` instances from `Trace` instances as well, through conversion
functions.
Some of the key operations supported by the `Profile` API are:
- Path interning (`Profile::internPath(...)`) which returns a unique path
identifier.
- Block appending (`Profile::addBlock(...)`) to add thread-associated
profile information.
- Path ID to Path lookup (`Profile::expandPath(...)`) to look up a
PathID and return the original interned path.
- Block iteration.
A 'Path' in this context represents the function call stack in
leaf-to-root order. This is represented as a path in an internally
managed prefix tree in the `Profile` instance. Having a handle (PathID)
to identify the unique Paths we encounter for a particular Profile
allows us to reduce the amount of memory required to associate profile
data to a particular Path.
This is the first of a series of patches to migrate the `llvm-stacks`
tool towards using a single profile representation.
Depends on D48653.
Reviewers: kpw, eizan
Reviewed By: kpw
Subscribers: kpw, thakis, mgorny, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D48370
llvm-svn: 341012
This patch splits the file trace loading function into two versions, one
that takes a filename and one that takes a `DataExtractor`.
This change is a precursor to larger changes to increase test coverage
for the trace loading implementation.
llvm-svn: 340603
Summary:
This patch moves out the definition of the XRay log file header from
binary logs into its own header and implementation file.
This is one part of the refactoring being done in D50441.
Reviewers: eizan
Subscribers: mgorny, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D51086
llvm-svn: 340389
Summary:
This change uses a single offset pointer used throughout the
implementation of the individual record parsers. This allows us to
report where in a trace file parsing failed.
We're still in an intermediate step here as we prepare to refactor this
further into a set of types and use object-oriented design principles
for a cleaner implementation. The next steps will be to allow us to
parse/dump files in a streaming fashion and incrementally build up the
structures in memory instead of the current all-or-nothing approach.
Reviewers: kpw, eizan
Reviewed By: kpw
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D50169
llvm-svn: 339092
Summary:
This change implements the profile loading functionality in LLVM to
support XRay's profiling mode in compiler-rt.
We introduce a type named `llvm::xray::Profile` which allows building a
profile representation. We can load an XRay profile from a file to build
Profile instances, or do it manually through the Profile type's API.
The intent is to get the `llvm-xray` tool to generate `Profile`
instances and use that as the common abstraction through which all
conversion and analysis can be done. In the future we can generate
`Profile` instances from `Trace` instances as well, through conversion
functions.
Some of the key operations supported by the `Profile` API are:
- Path interning (`Profile::internPath(...)`) which returns a unique path
identifier.
- Block appending (`Profile::addBlock(...)`) to add thread-associated
profile information.
- Path ID to Path lookup (`Profile::expandPath(...)`) to look up a
PathID and return the original interned path.
- Block iteration.
A 'Path' in this context represents the function call stack in
leaf-to-root order. This is represented as a path in an internally
managed prefix tree in the `Profile` instance. Having a handle (PathID)
to identify the unique Paths we encounter for a particular Profile
allows us to reduce the amount of memory required to associate profile
data to a particular Path.
This is the first of a series of patches to migrate the `llvm-stacks`
tool towards using a single profile representation.
Depends on D48653.
Reviewers: kpw, eizan
Reviewed By: kpw
Subscribers: mgorny, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D48370
llvm-svn: 338825
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
Dean Michael Berris