llvm/tools/llvm-xray/xray-converter.cc
Keith Wyss ed2657e43a [XRay] Minimal tool to convert xray traces to Chrome's Trace Event Format.
Minimal tool to convert xray traces to Chrome's Trace Event Format.

Summary:
Make use of Chrome Trace Event format's Duration events and stack frame dict to
produce Json files that chrome://tracing can visualize from xray function call
traces. Trace Event format is more robust and has several features like
argument logging, function categorization, multi process traces, etc. that we
can add as needed. Duration events cover an important base case.

Part of this change is rearranging the code so that the TrieNode data structure
can be used from multiple tools and can carry parameterized baggage on the
nodes. I put the actual behavior changes in llvm-xray convert exclusively.

Exploring the trace of instrumented llc was pretty nifty if overwhelming.
I can envision this being very useful for analyzing contention scenarios or
tuning parameters like batch sizes in a producer consumer queue. For more
targeted traces likemthis, let's talk about how we want to approach trace
pruning.

Reviewers: dberris, pelikan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D39362

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317531 91177308-0d34-0410-b5e6-96231b3b80d8
2017-11-07 00:28:28 +00:00

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//===- xray-converter.cc - XRay Trace Conversion --------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Implements the trace conversion functions.
//
//===----------------------------------------------------------------------===//
#include "xray-converter.h"
#include "trie-node.h"
#include "xray-registry.h"
#include "llvm/DebugInfo/Symbolize/Symbolize.h"
#include "llvm/Support/EndianStream.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/ScopedPrinter.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/XRay/InstrumentationMap.h"
#include "llvm/XRay/Trace.h"
#include "llvm/XRay/YAMLXRayRecord.h"
using namespace llvm;
using namespace xray;
// llvm-xray convert
// ----------------------------------------------------------------------------
static cl::SubCommand Convert("convert", "Trace Format Conversion");
static cl::opt<std::string> ConvertInput(cl::Positional,
cl::desc("<xray log file>"),
cl::Required, cl::sub(Convert));
enum class ConvertFormats { BINARY, YAML, CHROME_TRACE_EVENT };
static cl::opt<ConvertFormats> ConvertOutputFormat(
"output-format", cl::desc("output format"),
cl::values(clEnumValN(ConvertFormats::BINARY, "raw", "output in binary"),
clEnumValN(ConvertFormats::YAML, "yaml", "output in yaml"),
clEnumValN(ConvertFormats::CHROME_TRACE_EVENT, "trace_event",
"Output in chrome's trace event format. "
"May be visualized with the Catapult trace viewer.")),
cl::sub(Convert));
static cl::alias ConvertOutputFormat2("f", cl::aliasopt(ConvertOutputFormat),
cl::desc("Alias for -output-format"),
cl::sub(Convert));
static cl::opt<std::string>
ConvertOutput("output", cl::value_desc("output file"), cl::init("-"),
cl::desc("output file; use '-' for stdout"),
cl::sub(Convert));
static cl::alias ConvertOutput2("o", cl::aliasopt(ConvertOutput),
cl::desc("Alias for -output"),
cl::sub(Convert));
static cl::opt<bool>
ConvertSymbolize("symbolize",
cl::desc("symbolize function ids from the input log"),
cl::init(false), cl::sub(Convert));
static cl::alias ConvertSymbolize2("y", cl::aliasopt(ConvertSymbolize),
cl::desc("Alias for -symbolize"),
cl::sub(Convert));
static cl::opt<std::string>
ConvertInstrMap("instr_map",
cl::desc("binary with the instrumentation map, or "
"a separate instrumentation map"),
cl::value_desc("binary with xray_instr_map"),
cl::sub(Convert), cl::init(""));
static cl::alias ConvertInstrMap2("m", cl::aliasopt(ConvertInstrMap),
cl::desc("Alias for -instr_map"),
cl::sub(Convert));
static cl::opt<bool> ConvertSortInput(
"sort",
cl::desc("determines whether to sort input log records by timestamp"),
cl::sub(Convert), cl::init(true));
static cl::alias ConvertSortInput2("s", cl::aliasopt(ConvertSortInput),
cl::desc("Alias for -sort"),
cl::sub(Convert));
using llvm::yaml::Output;
void TraceConverter::exportAsYAML(const Trace &Records, raw_ostream &OS) {
YAMLXRayTrace Trace;
const auto &FH = Records.getFileHeader();
Trace.Header = {FH.Version, FH.Type, FH.ConstantTSC, FH.NonstopTSC,
FH.CycleFrequency};
Trace.Records.reserve(Records.size());
for (const auto &R : Records) {
Trace.Records.push_back({R.RecordType, R.CPU, R.Type, R.FuncId,
Symbolize ? FuncIdHelper.SymbolOrNumber(R.FuncId)
: llvm::to_string(R.FuncId),
R.TSC, R.TId, R.CallArgs});
}
Output Out(OS, nullptr, 0);
Out << Trace;
}
void TraceConverter::exportAsRAWv1(const Trace &Records, raw_ostream &OS) {
// First write out the file header, in the correct endian-appropriate format
// (XRay assumes currently little endian).
support::endian::Writer<support::endianness::little> Writer(OS);
const auto &FH = Records.getFileHeader();
Writer.write(FH.Version);
Writer.write(FH.Type);
uint32_t Bitfield{0};
if (FH.ConstantTSC)
Bitfield |= 1uL;
if (FH.NonstopTSC)
Bitfield |= 1uL << 1;
Writer.write(Bitfield);
Writer.write(FH.CycleFrequency);
// There's 16 bytes of padding at the end of the file header.
static constexpr uint32_t Padding4B = 0;
Writer.write(Padding4B);
Writer.write(Padding4B);
Writer.write(Padding4B);
Writer.write(Padding4B);
// Then write out the rest of the records, still in an endian-appropriate
// format.
for (const auto &R : Records) {
Writer.write(R.RecordType);
// The on disk naive raw format uses 8 bit CPUs, but the record has 16.
// There's no choice but truncation.
Writer.write(static_cast<uint8_t>(R.CPU));
switch (R.Type) {
case RecordTypes::ENTER:
case RecordTypes::ENTER_ARG:
Writer.write(uint8_t{0});
break;
case RecordTypes::EXIT:
Writer.write(uint8_t{1});
break;
case RecordTypes::TAIL_EXIT:
Writer.write(uint8_t{2});
break;
}
Writer.write(R.FuncId);
Writer.write(R.TSC);
Writer.write(R.TId);
Writer.write(Padding4B);
Writer.write(Padding4B);
Writer.write(Padding4B);
}
}
namespace {
// A structure that allows building a dictionary of stack ids for the Chrome
// trace event format.
struct StackIdData {
// Each Stack of function calls has a unique ID.
unsigned id;
// Bookkeeping so that IDs can be maintained uniquely across threads.
// Traversal keeps sibling pointers to other threads stacks. This is helpful
// to determine when a thread encounters a new stack and should assign a new
// unique ID.
SmallVector<TrieNode<StackIdData> *, 4> siblings;
};
using StackTrieNode = TrieNode<StackIdData>;
// A helper function to find the sibling nodes for an encountered function in a
// thread of execution. Relies on the invariant that each time a new node is
// traversed in a thread, sibling bidirectional pointers are maintained.
SmallVector<StackTrieNode *, 4>
findSiblings(StackTrieNode *parent, int32_t FnId, uint32_t TId,
const DenseMap<uint32_t, SmallVector<StackTrieNode *, 4>>
&StackRootsByThreadId) {
SmallVector<StackTrieNode *, 4> Siblings{};
if (parent == nullptr) {
for (auto map_iter : StackRootsByThreadId) {
// Only look for siblings in other threads.
if (map_iter.first != TId)
for (auto node_iter : map_iter.second) {
if (node_iter->FuncId == FnId)
Siblings.push_back(node_iter);
}
}
return Siblings;
}
for (auto *ParentSibling : parent->ExtraData.siblings)
for (auto node_iter : ParentSibling->Callees)
if (node_iter->FuncId == FnId)
Siblings.push_back(node_iter);
return Siblings;
}
// Given a function being invoked in a thread with id TId, finds and returns the
// StackTrie representing the function call stack. If no node exists, creates
// the node. Assigns unique IDs to stacks newly encountered among all threads
// and keeps sibling links up to when creating new nodes.
StackTrieNode *findOrCreateStackNode(
StackTrieNode *Parent, int32_t FuncId, uint32_t TId,
DenseMap<uint32_t, SmallVector<StackTrieNode *, 4>> &StackRootsByThreadId,
DenseMap<unsigned, StackTrieNode *> &StacksByStackId, unsigned *id_counter,
std::forward_list<StackTrieNode> &NodeStore) {
SmallVector<StackTrieNode *, 4> &ParentCallees =
Parent == nullptr ? StackRootsByThreadId[TId] : Parent->Callees;
auto match = find_if(ParentCallees, [FuncId](StackTrieNode *ParentCallee) {
return FuncId == ParentCallee->FuncId;
});
if (match != ParentCallees.end())
return *match;
SmallVector<StackTrieNode *, 4> siblings =
findSiblings(Parent, FuncId, TId, StackRootsByThreadId);
if (siblings.empty()) {
NodeStore.push_front({FuncId, Parent, {}, {(*id_counter)++, {}}});
StackTrieNode *CurrentStack = &NodeStore.front();
StacksByStackId[*id_counter - 1] = CurrentStack;
ParentCallees.push_back(CurrentStack);
return CurrentStack;
}
unsigned stack_id = siblings[0]->ExtraData.id;
NodeStore.push_front({FuncId, Parent, {}, {stack_id, std::move(siblings)}});
StackTrieNode *CurrentStack = &NodeStore.front();
for (auto *sibling : CurrentStack->ExtraData.siblings)
sibling->ExtraData.siblings.push_back(CurrentStack);
ParentCallees.push_back(CurrentStack);
return CurrentStack;
}
void writeTraceViewerRecord(raw_ostream &OS, int32_t FuncId, uint32_t TId,
bool Symbolize,
const FuncIdConversionHelper &FuncIdHelper,
double EventTimestampUs,
const StackTrieNode &StackCursor,
StringRef FunctionPhenotype) {
OS << " ";
OS << llvm::formatv(
R"({ "name" : "{0}", "ph" : "{1}", "tid" : "{2}", "pid" : "1", )"
R"("ts" : "{3:f3}", "sf" : "{4}" })",
(Symbolize ? FuncIdHelper.SymbolOrNumber(FuncId)
: llvm::to_string(FuncId)),
FunctionPhenotype, TId, EventTimestampUs, StackCursor.ExtraData.id);
}
} // namespace
void TraceConverter::exportAsChromeTraceEventFormat(const Trace &Records,
raw_ostream &OS) {
const auto &FH = Records.getFileHeader();
auto CycleFreq = FH.CycleFrequency;
unsigned id_counter = 0;
OS << "{\n \"traceEvents\": [";
DenseMap<uint32_t, StackTrieNode *> StackCursorByThreadId{};
DenseMap<uint32_t, SmallVector<StackTrieNode *, 4>> StackRootsByThreadId{};
DenseMap<unsigned, StackTrieNode *> StacksByStackId{};
std::forward_list<StackTrieNode> NodeStore{};
int loop_count = 0;
for (const auto &R : Records) {
if (loop_count++ == 0)
OS << "\n";
else
OS << ",\n";
// Chrome trace event format always wants data in micros.
// CyclesPerMicro = CycleHertz / 10^6
// TSC / CyclesPerMicro == TSC * 10^6 / CycleHertz == MicroTimestamp
// Could lose some precision here by converting the TSC to a double to
// multiply by the period in micros. 52 bit mantissa is a good start though.
// TODO: Make feature request to Chrome Trace viewer to accept ticks and a
// frequency or do some more involved calculation to avoid dangers of
// conversion.
double EventTimestampUs = double(1000000) / CycleFreq * double(R.TSC);
StackTrieNode *&StackCursor = StackCursorByThreadId[R.TId];
switch (R.Type) {
case RecordTypes::ENTER:
case RecordTypes::ENTER_ARG:
StackCursor = findOrCreateStackNode(StackCursor, R.FuncId, R.TId,
StackRootsByThreadId, StacksByStackId,
&id_counter, NodeStore);
// Each record is represented as a json dictionary with function name,
// type of B for begin or E for end, thread id, process id (faked),
// timestamp in microseconds, and a stack frame id. The ids are logged
// in an id dictionary after the events.
writeTraceViewerRecord(OS, R.FuncId, R.TId, Symbolize, FuncIdHelper,
EventTimestampUs, *StackCursor, "B");
break;
case RecordTypes::EXIT:
case RecordTypes::TAIL_EXIT:
// No entries to record end for.
if (StackCursor == nullptr)
break;
// Should we emit an END record anyway or account this condition?
// (And/Or in loop termination below)
StackTrieNode *PreviousCursor = nullptr;
do {
writeTraceViewerRecord(OS, StackCursor->FuncId, R.TId, Symbolize,
FuncIdHelper, EventTimestampUs, *StackCursor,
"E");
PreviousCursor = StackCursor;
StackCursor = StackCursor->Parent;
} while (PreviousCursor->FuncId != R.FuncId && StackCursor != nullptr);
break;
}
}
OS << "\n ],\n"; // Close the Trace Events array.
OS << " "
<< "\"displayTimeUnit\": \"ns\",\n";
// The stackFrames dictionary substantially reduces size of the output file by
// avoiding repeating the entire call stack of function names for each entry.
OS << R"( "stackFrames": {)";
int stack_frame_count = 0;
for (auto map_iter : StacksByStackId) {
if (stack_frame_count++ == 0)
OS << "\n";
else
OS << ",\n";
OS << " ";
OS << llvm::formatv(
R"("{0}" : { "name" : "{1}")", map_iter.first,
(Symbolize ? FuncIdHelper.SymbolOrNumber(map_iter.second->FuncId)
: llvm::to_string(map_iter.second->FuncId)));
if (map_iter.second->Parent != nullptr)
OS << llvm::formatv(R"(, "parent": "{0}")",
map_iter.second->Parent->ExtraData.id);
OS << " }";
}
OS << "\n }\n"; // Close the stack frames map.
OS << "}\n"; // Close the JSON entry.
}
namespace llvm {
namespace xray {
static CommandRegistration Unused(&Convert, []() -> Error {
// FIXME: Support conversion to BINARY when upgrading XRay trace versions.
InstrumentationMap Map;
if (!ConvertInstrMap.empty()) {
auto InstrumentationMapOrError = loadInstrumentationMap(ConvertInstrMap);
if (!InstrumentationMapOrError)
return joinErrors(make_error<StringError>(
Twine("Cannot open instrumentation map '") +
ConvertInstrMap + "'",
std::make_error_code(std::errc::invalid_argument)),
InstrumentationMapOrError.takeError());
Map = std::move(*InstrumentationMapOrError);
}
const auto &FunctionAddresses = Map.getFunctionAddresses();
symbolize::LLVMSymbolizer::Options Opts(
symbolize::FunctionNameKind::LinkageName, true, true, false, "");
symbolize::LLVMSymbolizer Symbolizer(Opts);
llvm::xray::FuncIdConversionHelper FuncIdHelper(ConvertInstrMap, Symbolizer,
FunctionAddresses);
llvm::xray::TraceConverter TC(FuncIdHelper, ConvertSymbolize);
std::error_code EC;
raw_fd_ostream OS(ConvertOutput, EC,
ConvertOutputFormat == ConvertFormats::BINARY
? sys::fs::OpenFlags::F_None
: sys::fs::OpenFlags::F_Text);
if (EC)
return make_error<StringError>(
Twine("Cannot open file '") + ConvertOutput + "' for writing.", EC);
auto TraceOrErr = loadTraceFile(ConvertInput, ConvertSortInput);
if (!TraceOrErr)
return joinErrors(
make_error<StringError>(
Twine("Failed loading input file '") + ConvertInput + "'.",
std::make_error_code(std::errc::executable_format_error)),
TraceOrErr.takeError());
auto &T = *TraceOrErr;
switch (ConvertOutputFormat) {
case ConvertFormats::YAML:
TC.exportAsYAML(T, OS);
break;
case ConvertFormats::BINARY:
TC.exportAsRAWv1(T, OS);
break;
case ConvertFormats::CHROME_TRACE_EVENT:
TC.exportAsChromeTraceEventFormat(T, OS);
break;
}
return Error::success();
});
} // namespace xray
} // namespace llvm