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[XRay] Use FDR Records+Visitors for Trace Loading

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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
This commit is contained in:
Dean Michael Berris 2018-09-11 06:45:59 +00:00
parent d2c50408d4
commit 985c2b9226
6 changed files with 231 additions and 547 deletions
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3
llvm/include/llvm/XRay/BlockIndexer.h
View File

@ -29,6 +29,7 @@ public:
struct Block {
uint64_t ProcessID;
int32_t ThreadID;
WallclockRecord *WallclockTime;
std::vector<Record *> Records;
};
@ -41,7 +42,7 @@ private:
enum class State : unsigned { SeekExtents, ExtentsFound, ThreadIDFound };
State CurrentState = State::SeekExtents;
Block CurrentBlock{0, 0, {}};
Block CurrentBlock{0, 0, nullptr, {}};
public:
explicit BlockIndexer(Index &I) : RecordVisitor(), Indices(I) {}

61
llvm/include/llvm/XRay/FDRTraceExpander.h Normal file
View File

@ -0,0 +1,61 @@
//===- FDRTraceExpander.h - XRay FDR Mode Log Expander --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// We define an FDR record visitor which can re-constitute XRayRecord instances
// from a sequence of FDR mode records in arrival order into a collection.
//
//===----------------------------------------------------------------------===//
#ifndef INCLUDE_LLVM_XRAY_FDRTRACEEXPANDER_H_
#define INCLUDE_LLVM_XRAY_FDRTRACEEXPANDER_H_
#include "llvm/ADT/STLExtras.h"
#include "llvm/XRay/FDRRecords.h"
#include "llvm/XRay/XRayRecord.h"
namespace llvm {
namespace xray {
class TraceExpander : public RecordVisitor {
// Type-erased callback for handling individual XRayRecord instances.
function_ref<void(const XRayRecord &)> C;
int32_t PID = 0;
int32_t TID = 0;
uint64_t BaseTSC = 0;
XRayRecord CurrentRecord{};
uint16_t CPUId = 0;
uint16_t LogVersion = 0;
bool BuildingFunction = false;
bool IgnoringRecords = false;
void resetCurrentRecord();
public:
explicit TraceExpander(function_ref<void(const XRayRecord &)> F, uint16_t L)
: RecordVisitor(), C(std::move(F)), LogVersion(L) {}
Error visit(BufferExtents &) override;
Error visit(WallclockRecord &) override;
Error visit(NewCPUIDRecord &) override;
Error visit(TSCWrapRecord &) override;
Error visit(CustomEventRecord &) override;
Error visit(CallArgRecord &) override;
Error visit(PIDRecord &) override;
Error visit(NewBufferRecord &) override;
Error visit(EndBufferRecord &) override;
Error visit(FunctionRecord &) override;
// Must be called after all the records have been processed, to handle the
// most recent record generated.
Error flush();
};
} // namespace xray
} // namespace llvm
#endif // INCLUDE_LLVM_XRAY_FDRTRACEEXPANDER_H_

4
llvm/lib/XRay/BlockIndexer.cpp
View File

@ -22,9 +22,11 @@ Error BlockIndexer::visit(BufferExtents &) {
std::tie(It, std::ignore) =
Indices.insert({{CurrentBlock.ProcessID, CurrentBlock.ThreadID}, {}});
It->second.push_back({CurrentBlock.ProcessID, CurrentBlock.ThreadID,
CurrentBlock.WallclockTime,
std::move(CurrentBlock.Records)});
CurrentBlock.ProcessID = 0;
CurrentBlock.ThreadID = 0;
CurrentBlock.WallclockTime = nullptr;
CurrentBlock.Records = {};
}
CurrentState = State::ExtentsFound;
@ -33,6 +35,7 @@ Error BlockIndexer::visit(BufferExtents &) {
Error BlockIndexer::visit(WallclockRecord &R) {
CurrentBlock.Records.push_back(&R);
CurrentBlock.WallclockTime = &R;
return Error::success();
}
@ -86,6 +89,7 @@ Error BlockIndexer::flush() {
std::tie(It, std::ignore) =
Indices.insert({{CurrentBlock.ProcessID, CurrentBlock.ThreadID}, {}});
It->second.push_back({CurrentBlock.ProcessID, CurrentBlock.ThreadID,
CurrentBlock.WallclockTime,
std::move(CurrentBlock.Records)});
CurrentBlock.ProcessID = 0;
CurrentBlock.ThreadID = 0;

1
llvm/lib/XRay/CMakeLists.txt
View File

@ -4,6 +4,7 @@ add_llvm_library(LLVMXRay
BlockVerifier.cpp
FDRRecordProducer.cpp
FDRRecords.cpp
FDRTraceExpander.cpp
FDRTraceWriter.cpp
FileHeaderReader.cpp
InstrumentationMap.cpp

92
llvm/lib/XRay/FDRTraceExpander.cpp Normal file
View File

@ -0,0 +1,92 @@
//===- FDRTraceExpander.cpp -----------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/XRay/FDRTraceExpander.h"
namespace llvm {
namespace xray {
void TraceExpander::resetCurrentRecord() {
if (BuildingFunction)
C(CurrentRecord);
BuildingFunction = false;
CurrentRecord.CallArgs.clear();
}
Error TraceExpander::visit(BufferExtents &) {
resetCurrentRecord();
return Error::success();
}
Error TraceExpander::visit(WallclockRecord &) { return Error::success(); }
Error TraceExpander::visit(NewCPUIDRecord &R) {
CPUId = R.cpuid();
BaseTSC = R.tsc();
return Error::success();
}
Error TraceExpander::visit(TSCWrapRecord &R) {
BaseTSC = R.tsc();
return Error::success();
}
Error TraceExpander::visit(CustomEventRecord &) {
// TODO: Support custom event records in the future.
resetCurrentRecord();
return Error::success();
}
Error TraceExpander::visit(CallArgRecord &R) {
CurrentRecord.CallArgs.push_back(R.arg());
CurrentRecord.Type = RecordTypes::ENTER_ARG;
return Error::success();
}
Error TraceExpander::visit(PIDRecord &R) {
PID = R.pid();
return Error::success();
}
Error TraceExpander::visit(NewBufferRecord &R) {
if (IgnoringRecords)
IgnoringRecords = false;
TID = R.tid();
if (LogVersion == 2)
PID = R.tid();
return Error::success();
}
Error TraceExpander::visit(EndBufferRecord &) {
IgnoringRecords = true;
resetCurrentRecord();
return Error::success();
}
Error TraceExpander::visit(FunctionRecord &R) {
resetCurrentRecord();
if (!IgnoringRecords) {
BaseTSC += R.delta();
CurrentRecord.Type = R.recordType();
CurrentRecord.FuncId = R.functionId();
CurrentRecord.TSC = BaseTSC;
CurrentRecord.PId = PID;
CurrentRecord.TId = TID;
CurrentRecord.CPU = CPUId;
BuildingFunction = true;
}
return Error::success();
}
Error TraceExpander::flush() {
resetCurrentRecord();
return Error::success();
}
} // namespace xray
} // namespace llvm

617
llvm/lib/XRay/Trace.cpp
View File

@ -15,8 +15,16 @@
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/XRay/BlockIndexer.h"
#include "llvm/XRay/BlockVerifier.h"
#include "llvm/XRay/FDRRecordConsumer.h"
#include "llvm/XRay/FDRRecordProducer.h"
#include "llvm/XRay/FDRRecords.h"
#include "llvm/XRay/FDRTraceExpander.h"
#include "llvm/XRay/FileHeaderReader.h"
#include "llvm/XRay/YAMLXRayRecord.h"
#include <memory>
#include <vector>
using namespace llvm;
using namespace llvm::xray;
@ -26,11 +34,6 @@ namespace {
using XRayRecordStorage =
std::aligned_storage<sizeof(XRayRecord), alignof(XRayRecord)>::type;
// This is the number of bytes in the "body" of a MetadataRecord in FDR Mode.
// This already excludes the first byte, which indicates the type of metadata
// record it is.
constexpr auto kFDRMetadataBodySize = 15;
Error loadNaiveFormatLog(StringRef Data, bool IsLittleEndian,
XRayFileHeader &FileHeader,
std::vector<XRayRecord> &Records) {
@ -201,467 +204,6 @@ Error loadNaiveFormatLog(StringRef Data, bool IsLittleEndian,
return Error::success();
}
/// When reading from a Flight Data Recorder mode log, metadata records are
/// sparse compared to packed function records, so we must maintain state as we
/// read through the sequence of entries. This allows the reader to denormalize
/// the CPUId and Thread Id onto each Function Record and transform delta
/// encoded TSC values into absolute encodings on each record.
struct FDRState {
uint16_t CPUId;
int32_t ThreadId;
int32_t ProcessId;
uint64_t BaseTSC;
/// Encode some of the state transitions for the FDR log reader as explicit
/// checks. These are expectations for the next Record in the stream.
enum class Token {
NEW_BUFFER_RECORD_OR_EOF,
WALLCLOCK_RECORD,
NEW_CPU_ID_RECORD,
FUNCTION_SEQUENCE,
SCAN_TO_END_OF_THREAD_BUF,
CUSTOM_EVENT_DATA,
CALL_ARGUMENT,
BUFFER_EXTENTS,
PID_RECORD,
};
Token Expects;
// Each threads buffer may have trailing garbage to scan over, so we track our
// progress.
uint64_t CurrentBufferSize;
uint64_t CurrentBufferConsumed;
};
const char *fdrStateToTwine(const FDRState::Token &state) {
switch (state) {
case FDRState::Token::NEW_BUFFER_RECORD_OR_EOF:
return "NEW_BUFFER_RECORD_OR_EOF";
case FDRState::Token::WALLCLOCK_RECORD:
return "WALLCLOCK_RECORD";
case FDRState::Token::NEW_CPU_ID_RECORD:
return "NEW_CPU_ID_RECORD";
case FDRState::Token::FUNCTION_SEQUENCE:
return "FUNCTION_SEQUENCE";
case FDRState::Token::SCAN_TO_END_OF_THREAD_BUF:
return "SCAN_TO_END_OF_THREAD_BUF";
case FDRState::Token::CUSTOM_EVENT_DATA:
return "CUSTOM_EVENT_DATA";
case FDRState::Token::CALL_ARGUMENT:
return "CALL_ARGUMENT";
case FDRState::Token::BUFFER_EXTENTS:
return "BUFFER_EXTENTS";
case FDRState::Token::PID_RECORD:
return "PID_RECORD";
}
return "UNKNOWN";
}
/// State transition when a NewBufferRecord is encountered.
Error processFDRNewBufferRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::NEW_BUFFER_RECORD_OR_EOF)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Malformed log: Read New Buffer record kind out of sequence; expected: "
"%s at offset %d.",
fdrStateToTwine(State.Expects), OffsetPtr);
auto PreReadOffset = OffsetPtr;
State.ThreadId = RecordExtractor.getSigned(&OffsetPtr, 4);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the thread id at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::WALLCLOCK_RECORD;
// Advance the offset pointer by enough bytes representing the remaining
// padding in a metadata record.
OffsetPtr += kFDRMetadataBodySize - 4;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when an EndOfBufferRecord is encountered.
Error processFDREndOfBufferRecord(FDRState &State, uint32_t &OffsetPtr) {
if (State.Expects == FDRState::Token::NEW_BUFFER_RECORD_OR_EOF)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Malformed log: Received EOB message without current buffer; expected: "
"%s at offset %d.",
fdrStateToTwine(State.Expects), OffsetPtr);
State.Expects = FDRState::Token::SCAN_TO_END_OF_THREAD_BUF;
// Advance the offset pointer by enough bytes representing the remaining
// padding in a metadata record.
OffsetPtr += kFDRMetadataBodySize;
return Error::success();
}
/// State transition when a NewCPUIdRecord is encountered.
Error processFDRNewCPUIdRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::FUNCTION_SEQUENCE &&
State.Expects != FDRState::Token::NEW_CPU_ID_RECORD)
return make_error<StringError>(
Twine("Malformed log. Read NewCPUId record kind out of sequence; "
"expected: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto BeginOffset = OffsetPtr;
auto PreReadOffset = OffsetPtr;
State.CPUId = RecordExtractor.getU16(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the CPU field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
State.BaseTSC = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the base TSC field at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::FUNCTION_SEQUENCE;
// Advance the offset pointer by a few bytes, to account for the padding in
// CPU ID metadata records that we've already advanced through.
OffsetPtr += kFDRMetadataBodySize - (OffsetPtr - BeginOffset);
assert(OffsetPtr - BeginOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a TSCWrapRecord (overflow detection) is encountered.
Error processFDRTSCWrapRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::FUNCTION_SEQUENCE)
return make_error<StringError>(
Twine("Malformed log. Read TSCWrap record kind out of sequence; "
"expecting: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
State.BaseTSC = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the base TSC field at offset %d.", OffsetPtr);
// Advance the offset pointer by a few more bytes, accounting for the padding
// in the metadata record after reading the base TSC.
OffsetPtr += kFDRMetadataBodySize - 8;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a WallTimeMarkerRecord is encountered.
Error processFDRWallTimeRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::WALLCLOCK_RECORD)
return make_error<StringError>(
Twine("Malformed log. Read Wallclock record kind out of sequence; "
"expecting: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
// Read in the data from the walltime record.
auto PreReadOffset = OffsetPtr;
auto WallTime = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the walltime record at offset %d.", OffsetPtr);
// TODO: Someday, reconcile the TSC ticks to wall clock time for presentation
// purposes. For now, we're ignoring these records.
(void)WallTime;
State.Expects = FDRState::Token::NEW_CPU_ID_RECORD;
// Advance the offset pointer by a few more bytes, accounting for the padding
// in the metadata record after reading in the walltime data.
OffsetPtr += kFDRMetadataBodySize - 8;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a PidRecord is encountered.
Error processFDRPidRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::PID_RECORD)
return make_error<StringError>(
Twine("Malformed log. Read Pid record kind out of sequence; "
"expected: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
State.ProcessId = RecordExtractor.getSigned(&OffsetPtr, 4);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the process ID at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::NEW_CPU_ID_RECORD;
// Advance the offset pointer by a few more bytes, accounting for the padding
// in the metadata record after reading in the PID.
OffsetPtr += kFDRMetadataBodySize - 4;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a CustomEventMarker is encountered.
Error processCustomEventMarker(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
// We can encounter a CustomEventMarker anywhere in the log, so we can handle
// it regardless of the expectation. However, we do set the expectation to
// read a set number of fixed bytes, as described in the metadata.
auto BeginOffset = OffsetPtr;
auto PreReadOffset = OffsetPtr;
uint32_t DataSize = RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading a custom event marker at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
uint64_t TSC = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the TSC at offset %d.", OffsetPtr);
// FIXME: Actually represent the record through the API. For now we only
// skip through the data.
(void)TSC;
// Advance the offset ptr by the size of the data associated with the custom
// event, as well as the padding associated with the remainder of the metadata
// record.
OffsetPtr += (kFDRMetadataBodySize - (OffsetPtr - BeginOffset)) + DataSize;
if (!RecordExtractor.isValidOffset(OffsetPtr))
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Reading custom event data moves past addressable trace data (starting "
"at offset %d, advancing to offset %d).",
BeginOffset, OffsetPtr);
return Error::success();
}
/// State transition when an BufferExtents record is encountered.
Error processBufferExtents(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::BUFFER_EXTENTS)
return make_error<StringError>(
Twine("Malformed log. Buffer Extents unexpected; expected: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
State.CurrentBufferSize = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed to read current buffer size at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::NEW_BUFFER_RECORD_OR_EOF;
// Advance the offset pointer by enough bytes accounting for the padding in a
// metadata record, after we read in the buffer extents.
OffsetPtr += kFDRMetadataBodySize - 8;
return Error::success();
}
/// State transition when a CallArgumentRecord is encountered.
Error processFDRCallArgumentRecord(FDRState &State,
DataExtractor &RecordExtractor,
std::vector<XRayRecord> &Records,
uint32_t &OffsetPtr) {
auto &Enter = Records.back();
if (Enter.Type != RecordTypes::ENTER && Enter.Type != RecordTypes::ENTER_ARG)
return make_error<StringError>(
"CallArgument needs to be right after a function entry",
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
auto Arg = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed to read argument record at offset %d.", OffsetPtr);
Enter.Type = RecordTypes::ENTER_ARG;
Enter.CallArgs.emplace_back(Arg);
// Advance the offset pointer by enough bytes accounting for the padding in a
// metadata record, after reading the payload.
OffsetPtr += kFDRMetadataBodySize - 8;
return Error::success();
}
/// Advances the state machine for reading the FDR record type by reading one
/// Metadata Record and updating the State appropriately based on the kind of
/// record encountered. The RecordKind is encoded in the first byte of the
/// Record, which the caller should pass in because they have already read it
/// to determine that this is a metadata record as opposed to a function record.
///
/// Beginning with Version 2 of the FDR log, we do not depend on the size of the
/// buffer, but rather use the extents to determine how far to read in the log
/// for this particular buffer.
///
/// In Version 3, FDR log now includes a pid metadata record after
/// WallTimeMarker
Error processFDRMetadataRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr,
std::vector<XRayRecord> &Records,
uint16_t Version, uint8_t FirstByte) {
// The remaining 7 bits of the first byte are the RecordKind enum for each
// Metadata Record.
switch (FirstByte >> 1) {
case 0: // NewBuffer
if (auto E = processFDRNewBufferRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
case 1: // EndOfBuffer
if (Version >= 2)
return make_error<StringError>(
"Since Version 2 of FDR logging, we no longer support EOB records.",
std::make_error_code(std::errc::executable_format_error));
if (auto E = processFDREndOfBufferRecord(State, OffsetPtr))
return E;
break;
case 2: // NewCPUId
if (auto E = processFDRNewCPUIdRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
case 3: // TSCWrap
if (auto E = processFDRTSCWrapRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
case 4: // WallTimeMarker
if (auto E = processFDRWallTimeRecord(State, RecordExtractor, OffsetPtr))
return E;
// In Version 3 and and above, a PidRecord is expected after WallTimeRecord
if (Version >= 3)
State.Expects = FDRState::Token::PID_RECORD;
break;
case 5: // CustomEventMarker
if (auto E = processCustomEventMarker(State, RecordExtractor, OffsetPtr))
return E;
break;
case 6: // CallArgument
if (auto E = processFDRCallArgumentRecord(State, RecordExtractor, Records,
OffsetPtr))
return E;
break;
case 7: // BufferExtents
if (auto E = processBufferExtents(State, RecordExtractor, OffsetPtr))
return E;
break;
case 9: // Pid
if (auto E = processFDRPidRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Illegal metadata record type: '%d' at offset %d.", FirstByte >> 1,
OffsetPtr);
}
return Error::success();
}
/// Reads a function record from an FDR format log, appending a new XRayRecord
/// to the vector being populated and updating the State with a new value
/// reference value to interpret TSC deltas.
///
/// The XRayRecord constructed includes information from the function record
/// processed here as well as Thread ID and CPU ID formerly extracted into
/// State.
Error processFDRFunctionRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr, uint8_t FirstByte,
std::vector<XRayRecord> &Records) {
switch (State.Expects) {
case FDRState::Token::NEW_BUFFER_RECORD_OR_EOF:
return make_error<StringError>(
"Malformed log. Received Function Record before new buffer setup.",
std::make_error_code(std::errc::executable_format_error));
case FDRState::Token::WALLCLOCK_RECORD:
return make_error<StringError>(
"Malformed log. Received Function Record when expecting wallclock.",
std::make_error_code(std::errc::executable_format_error));
case FDRState::Token::PID_RECORD:
return make_error<StringError>(
"Malformed log. Received Function Record when expecting pid.",
std::make_error_code(std::errc::executable_format_error));
case FDRState::Token::NEW_CPU_ID_RECORD:
return make_error<StringError>(
"Malformed log. Received Function Record before first CPU record.",
std::make_error_code(std::errc::executable_format_error));
default:
Records.emplace_back();
auto &Record = Records.back();
Record.RecordType = 0; // Record is type NORMAL.
// Back up one byte to re-read the first byte, which is important for
// computing the function id for a record.
--OffsetPtr;
auto PreReadOffset = OffsetPtr;
uint32_t FuncIdBitField = RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading truncated function id field at offset %d.",
OffsetPtr);
FirstByte = FuncIdBitField & 0xffu;
// Strip off record type bit and use the next three bits.
auto T = (FirstByte >> 1) & 0x07;
switch (T) {
case static_cast<decltype(T)>(RecordTypes::ENTER):
Record.Type = RecordTypes::ENTER;
break;
case static_cast<decltype(T)>(RecordTypes::EXIT):
Record.Type = RecordTypes::EXIT;
break;
case static_cast<decltype(T)>(RecordTypes::TAIL_EXIT):
Record.Type = RecordTypes::TAIL_EXIT;
break;
case static_cast<decltype(T)>(RecordTypes::ENTER_ARG):
Record.Type = RecordTypes::ENTER_ARG;
State.Expects = FDRState::Token::CALL_ARGUMENT;
break;
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Illegal function record type '%d' at offset %d.", T, OffsetPtr);
}
Record.CPU = State.CPUId;
Record.TId = State.ThreadId;
Record.PId = State.ProcessId;
// Despite function Id being a signed int on XRayRecord,
// when it is written to an FDR format, the top bits are truncated,
// so it is effectively an unsigned value. When we shift off the
// top four bits, we want the shift to be logical, so we read as
// uint32_t.
Record.FuncId = FuncIdBitField >> 4;
// FunctionRecords have a 32 bit delta from the previous absolute TSC
// or TSC delta. If this would overflow, we should read a TSCWrap record
// with an absolute TSC reading.
PreReadOffset = OffsetPtr;
uint64_t NewTSC = State.BaseTSC + RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading TSC delta at offset %d.", OffsetPtr);
State.BaseTSC = NewTSC;
Record.TSC = NewTSC;
}
return Error::success();
}
/// Reads a log in FDR mode for version 1 of this binary format. FDR mode is
/// defined as part of the compiler-rt project in xray_fdr_logging.h, and such
/// a log consists of the familiar 32 bit XRayHeader, followed by sequences of
@ -709,100 +251,83 @@ Error loadFDRLog(StringRef Data, bool IsLittleEndian,
XRayFileHeader &FileHeader, std::vector<XRayRecord> &Records) {
if (Data.size() < 32)
return make_error<StringError>(
"Not enough bytes for an XRay log.",
std::make_error_code(std::errc::invalid_argument));
return createStringError(std::make_error_code(std::errc::invalid_argument),
"Not enough bytes for an XRay FDR log.");
DataExtractor DE(Data, IsLittleEndian, 8);
DataExtractor Reader(Data, IsLittleEndian, 8);
uint32_t OffsetPtr = 0;
auto FileHeaderOrError = readBinaryFormatHeader(Reader, OffsetPtr);
auto FileHeaderOrError = readBinaryFormatHeader(DE, OffsetPtr);
if (!FileHeaderOrError)
return FileHeaderOrError.takeError();
FileHeader = std::move(FileHeaderOrError.get());
uint64_t BufferSize = 0;
// First we load the records into memory.
std::vector<std::unique_ptr<Record>> FDRRecords;
{
StringRef ExtraDataRef(FileHeader.FreeFormData, 16);
DataExtractor ExtraDataExtractor(ExtraDataRef, IsLittleEndian, 8);
uint32_t ExtraDataOffset = 0;
BufferSize = ExtraDataExtractor.getU64(&ExtraDataOffset);
}
FDRState::Token InitialExpectation;
switch (FileHeader.Version) {
case 1:
InitialExpectation = FDRState::Token::NEW_BUFFER_RECORD_OR_EOF;
break;
case 2:
case 3:
InitialExpectation = FDRState::Token::BUFFER_EXTENTS;
break;
default:
return make_error<StringError>(
Twine("Unsupported version '") + Twine(FileHeader.Version) + "'",
std::make_error_code(std::errc::executable_format_error));
}
FDRState State{0, 0, 0, 0, InitialExpectation, BufferSize, 0};
// RecordSize will tell the loop how far to seek ahead based on the record
// type that we have just read.
while (Reader.isValidOffset(OffsetPtr)) {
auto BeginOffset = OffsetPtr;
if (State.Expects == FDRState::Token::SCAN_TO_END_OF_THREAD_BUF) {
OffsetPtr += State.CurrentBufferSize - State.CurrentBufferConsumed;
State.CurrentBufferConsumed = 0;
State.Expects = FDRState::Token::NEW_BUFFER_RECORD_OR_EOF;
continue;
}
auto PreReadOffset = OffsetPtr;
uint8_t BitField = Reader.getU8(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading first byte of record at offset %d.", OffsetPtr);
bool isMetadataRecord = BitField & 0x01uL;
bool isBufferExtents =
(BitField >> 1) == 7; // BufferExtents record kind == 7
if (isMetadataRecord) {
if (auto E = processFDRMetadataRecord(State, Reader, OffsetPtr, Records,
FileHeader.Version, BitField))
return E;
} else { // Process Function Record
if (auto E = processFDRFunctionRecord(State, Reader, OffsetPtr, BitField,
Records))
FileBasedRecordProducer P(FileHeader, DE, OffsetPtr);
LogBuilderConsumer C(FDRRecords);
while (DE.isValidOffsetForDataOfSize(OffsetPtr, 1)) {
auto R = P.produce();
if (!R)
return R.takeError();
if (auto E = C.consume(std::move(R.get())))
return E;
}
}
// The BufferExtents record is technically not part of the buffer, so we
// don't count the size of that record against the buffer's actual size.
if (!isBufferExtents)
State.CurrentBufferConsumed += OffsetPtr - BeginOffset;
// Next we index the records into blocks.
BlockIndexer::Index Index;
{
BlockIndexer Indexer(Index);
for (auto &R : FDRRecords)
if (auto E = R->apply(Indexer))
return E;
if (auto E = Indexer.flush())
return E;
}
assert(State.CurrentBufferConsumed <= State.CurrentBufferSize);
if ((FileHeader.Version == 2 || FileHeader.Version == 3) &&
State.CurrentBufferSize == State.CurrentBufferConsumed) {
// In Version 2 of the log, we don't need to scan to the end of the thread
// buffer if we've already consumed all the bytes we need to.
State.Expects = FDRState::Token::BUFFER_EXTENTS;
State.CurrentBufferSize = BufferSize;
State.CurrentBufferConsumed = 0;
// Then we verify the consistency of the blocks.
{
BlockVerifier Verifier;
for (auto &PTB : Index) {
auto &Blocks = PTB.second;
for (auto &B : Blocks) {
for (auto *R : B.Records)
if (auto E = R->apply(Verifier))
return E;
if (auto E = Verifier.verify())
return E;
Verifier.reset();
}
}
}
// Having iterated over everything we've been given, we've either consumed
// everything and ended up in the end state, or were told to skip the rest.
bool Finished = State.Expects == FDRState::Token::SCAN_TO_END_OF_THREAD_BUF &&
State.CurrentBufferSize == State.CurrentBufferConsumed;
if ((State.Expects != FDRState::Token::NEW_BUFFER_RECORD_OR_EOF &&
State.Expects != FDRState::Token::BUFFER_EXTENTS) &&
!Finished)
return make_error<StringError>(
Twine("Encountered EOF with unexpected state expectation ") +
fdrStateToTwine(State.Expects) +
". Remaining expected bytes in thread buffer total " +
Twine(State.CurrentBufferSize - State.CurrentBufferConsumed),
std::make_error_code(std::errc::executable_format_error));
// This is now the meat of the algorithm. Here we sort the blocks according to
// the Walltime record in each of the blocks for the same thread. This allows
// us to more consistently recreate the execution trace in temporal order.
// After the sort, we then reconstitute `Trace` records using a stateful
// visitor associated with a single process+thread pair.
{
for (auto &PTB : Index) {
auto &Blocks = PTB.second;
llvm::sort(
Blocks.begin(), Blocks.end(),
[](const BlockIndexer::Block &L, const BlockIndexer::Block &R) {
return (L.WallclockTime->seconds() < R.WallclockTime->seconds() &&
L.WallclockTime->nanos() < R.WallclockTime->nanos());
});
TraceExpander Expander([&](const XRayRecord &R) { Records.push_back(R); },
FileHeader.Version);
for (auto &B : Blocks) {
for (auto *R : B.Records)
if (auto E = R->apply(Expander))
return E;
}
if (auto E = Expander.flush())
return E;
}
}
return Error::success();
}