1 //===-- xray-graph.cpp: XRay Function Call Graph Renderer -----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Generate a DOT file to represent the function call graph encountered in
10 // the trace.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "xray-graph.h"
15 #include "xray-registry.h"
16 #include "llvm/Support/ErrorHandling.h"
17 #include "llvm/XRay/InstrumentationMap.h"
18 #include "llvm/XRay/Trace.h"
19 
20 using namespace llvm;
21 using namespace llvm::xray;
22 
23 // Setup llvm-xray graph subcommand and its options.
24 static cl::SubCommand GraphC("graph", "Generate function-call graph");
25 static cl::opt<std::string> GraphInput(cl::Positional,
26                                        cl::desc("<xray log file>"),
27                                        cl::Required, cl::sub(GraphC));
28 
29 static cl::opt<bool>
30     GraphKeepGoing("keep-going", cl::desc("Keep going on errors encountered"),
31                    cl::sub(GraphC), cl::init(false));
32 static cl::alias GraphKeepGoing2("k", cl::aliasopt(GraphKeepGoing),
33                                  cl::desc("Alias for -keep-going"));
34 
35 static cl::opt<std::string>
36     GraphOutput("output", cl::value_desc("Output file"), cl::init("-"),
37                 cl::desc("output file; use '-' for stdout"), cl::sub(GraphC));
38 static cl::alias GraphOutput2("o", cl::aliasopt(GraphOutput),
39                               cl::desc("Alias for -output"));
40 
41 static cl::opt<std::string>
42     GraphInstrMap("instr_map",
43                   cl::desc("binary with the instrumrntation map, or "
44                            "a separate instrumentation map"),
45                   cl::value_desc("binary with xray_instr_map"), cl::sub(GraphC),
46                   cl::init(""));
47 static cl::alias GraphInstrMap2("m", cl::aliasopt(GraphInstrMap),
48                                 cl::desc("alias for -instr_map"));
49 
50 static cl::opt<bool> GraphDeduceSiblingCalls(
51     "deduce-sibling-calls",
52     cl::desc("Deduce sibling calls when unrolling function call stacks"),
53     cl::sub(GraphC), cl::init(false));
54 static cl::alias
55     GraphDeduceSiblingCalls2("d", cl::aliasopt(GraphDeduceSiblingCalls),
56                              cl::desc("Alias for -deduce-sibling-calls"));
57 
58 static cl::opt<GraphRenderer::StatType>
59     GraphEdgeLabel("edge-label",
60                    cl::desc("Output graphs with edges labeled with this field"),
61                    cl::value_desc("field"), cl::sub(GraphC),
62                    cl::init(GraphRenderer::StatType::NONE),
63                    cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
64                                          "Do not label Edges"),
65                               clEnumValN(GraphRenderer::StatType::COUNT,
66                                          "count", "function call counts"),
67                               clEnumValN(GraphRenderer::StatType::MIN, "min",
68                                          "minimum function durations"),
69                               clEnumValN(GraphRenderer::StatType::MED, "med",
70                                          "median function durations"),
71                               clEnumValN(GraphRenderer::StatType::PCT90, "90p",
72                                          "90th percentile durations"),
73                               clEnumValN(GraphRenderer::StatType::PCT99, "99p",
74                                          "99th percentile durations"),
75                               clEnumValN(GraphRenderer::StatType::MAX, "max",
76                                          "maximum function durations"),
77                               clEnumValN(GraphRenderer::StatType::SUM, "sum",
78                                          "sum of call durations")));
79 static cl::alias GraphEdgeLabel2("e", cl::aliasopt(GraphEdgeLabel),
80                                  cl::desc("Alias for -edge-label"));
81 
82 static cl::opt<GraphRenderer::StatType> GraphVertexLabel(
83     "vertex-label",
84     cl::desc("Output graphs with vertices labeled with this field"),
85     cl::value_desc("field"), cl::sub(GraphC),
86     cl::init(GraphRenderer::StatType::NONE),
87     cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
88                           "Do not label Vertices"),
89                clEnumValN(GraphRenderer::StatType::COUNT, "count",
90                           "function call counts"),
91                clEnumValN(GraphRenderer::StatType::MIN, "min",
92                           "minimum function durations"),
93                clEnumValN(GraphRenderer::StatType::MED, "med",
94                           "median function durations"),
95                clEnumValN(GraphRenderer::StatType::PCT90, "90p",
96                           "90th percentile durations"),
97                clEnumValN(GraphRenderer::StatType::PCT99, "99p",
98                           "99th percentile durations"),
99                clEnumValN(GraphRenderer::StatType::MAX, "max",
100                           "maximum function durations"),
101                clEnumValN(GraphRenderer::StatType::SUM, "sum",
102                           "sum of call durations")));
103 static cl::alias GraphVertexLabel2("v", cl::aliasopt(GraphVertexLabel),
104                                    cl::desc("Alias for -edge-label"));
105 
106 static cl::opt<GraphRenderer::StatType> GraphEdgeColorType(
107     "color-edges",
108     cl::desc("Output graphs with edge colors determined by this field"),
109     cl::value_desc("field"), cl::sub(GraphC),
110     cl::init(GraphRenderer::StatType::NONE),
111     cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
112                           "Do not color Edges"),
113                clEnumValN(GraphRenderer::StatType::COUNT, "count",
114                           "function call counts"),
115                clEnumValN(GraphRenderer::StatType::MIN, "min",
116                           "minimum function durations"),
117                clEnumValN(GraphRenderer::StatType::MED, "med",
118                           "median function durations"),
119                clEnumValN(GraphRenderer::StatType::PCT90, "90p",
120                           "90th percentile durations"),
121                clEnumValN(GraphRenderer::StatType::PCT99, "99p",
122                           "99th percentile durations"),
123                clEnumValN(GraphRenderer::StatType::MAX, "max",
124                           "maximum function durations"),
125                clEnumValN(GraphRenderer::StatType::SUM, "sum",
126                           "sum of call durations")));
127 static cl::alias GraphEdgeColorType2("c", cl::aliasopt(GraphEdgeColorType),
128                                      cl::desc("Alias for -color-edges"));
129 
130 static cl::opt<GraphRenderer::StatType> GraphVertexColorType(
131     "color-vertices",
132     cl::desc("Output graphs with vertex colors determined by this field"),
133     cl::value_desc("field"), cl::sub(GraphC),
134     cl::init(GraphRenderer::StatType::NONE),
135     cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
136                           "Do not color vertices"),
137                clEnumValN(GraphRenderer::StatType::COUNT, "count",
138                           "function call counts"),
139                clEnumValN(GraphRenderer::StatType::MIN, "min",
140                           "minimum function durations"),
141                clEnumValN(GraphRenderer::StatType::MED, "med",
142                           "median function durations"),
143                clEnumValN(GraphRenderer::StatType::PCT90, "90p",
144                           "90th percentile durations"),
145                clEnumValN(GraphRenderer::StatType::PCT99, "99p",
146                           "99th percentile durations"),
147                clEnumValN(GraphRenderer::StatType::MAX, "max",
148                           "maximum function durations"),
149                clEnumValN(GraphRenderer::StatType::SUM, "sum",
150                           "sum of call durations")));
151 static cl::alias GraphVertexColorType2("b", cl::aliasopt(GraphVertexColorType),
152                                        cl::desc("Alias for -edge-label"));
153 
154 template <class T> T diff(T L, T R) { return std::max(L, R) - std::min(L, R); }
155 
156 // Updates the statistics for a GraphRenderer::TimeStat
157 static void updateStat(GraphRenderer::TimeStat &S, int64_t L) {
158   S.Count++;
159   if (S.Min > L || S.Min == 0)
160     S.Min = L;
161   if (S.Max < L)
162     S.Max = L;
163   S.Sum += L;
164 }
165 
166 // Labels in a DOT graph must be legal XML strings so it's necessary to escape
167 // certain characters.
168 static std::string escapeString(StringRef Label) {
169   std::string Str;
170   Str.reserve(Label.size());
171   for (const auto C : Label) {
172     switch (C) {
173     case '&':
174       Str.append("&amp;");
175       break;
176     case '<':
177       Str.append("&lt;");
178       break;
179     case '>':
180       Str.append("&gt;");
181       break;
182     default:
183       Str.push_back(C);
184       break;
185     }
186   }
187   return Str;
188 }
189 
190 // Evaluates an XRay record and performs accounting on it.
191 //
192 // If the record is an ENTER record it pushes the FuncID and TSC onto a
193 // structure representing the call stack for that function.
194 // If the record is an EXIT record it checks computes computes the ammount of
195 // time the function took to complete and then stores that information in an
196 // edge of the graph. If there is no matching ENTER record the function tries
197 // to recover by assuming that there were EXIT records which were missed, for
198 // example caused by tail call elimination and if the option is enabled then
199 // then tries to recover from this.
200 //
201 // This funciton will also error if the records are out of order, as the trace
202 // is expected to be sorted.
203 //
204 // The graph generated has an immaginary root for functions called by no-one at
205 // FuncId 0.
206 //
207 // FIXME: Refactor this and account subcommand to reduce code duplication.
208 Error GraphRenderer::accountRecord(const XRayRecord &Record) {
209   using std::make_error_code;
210   using std::errc;
211   if (CurrentMaxTSC == 0)
212     CurrentMaxTSC = Record.TSC;
213 
214   if (Record.TSC < CurrentMaxTSC)
215     return make_error<StringError>("Records not in order",
216                                    make_error_code(errc::invalid_argument));
217 
218   auto &ThreadStack = PerThreadFunctionStack[Record.TId];
219   switch (Record.Type) {
220   case RecordTypes::ENTER:
221   case RecordTypes::ENTER_ARG: {
222     if (Record.FuncId != 0 && G.count(Record.FuncId) == 0)
223       G[Record.FuncId].SymbolName = FuncIdHelper.SymbolOrNumber(Record.FuncId);
224     ThreadStack.push_back({Record.FuncId, Record.TSC});
225     break;
226   }
227   case RecordTypes::EXIT:
228   case RecordTypes::TAIL_EXIT: {
229     // FIXME: Refactor this and the account subcommand to reduce code
230     // duplication
231     if (ThreadStack.size() == 0 || ThreadStack.back().FuncId != Record.FuncId) {
232       if (!DeduceSiblingCalls)
233         return make_error<StringError>("No matching ENTRY record",
234                                        make_error_code(errc::invalid_argument));
235       auto Parent = std::find_if(
236           ThreadStack.rbegin(), ThreadStack.rend(),
237           [&](const FunctionAttr &A) { return A.FuncId == Record.FuncId; });
238       if (Parent == ThreadStack.rend())
239         return make_error<StringError>(
240             "No matching Entry record in stack",
241             make_error_code(errc::invalid_argument)); // There is no matching
242                                                       // Function for this exit.
243       while (ThreadStack.back().FuncId != Record.FuncId) {
244         TimestampT D = diff(ThreadStack.back().TSC, Record.TSC);
245         VertexIdentifier TopFuncId = ThreadStack.back().FuncId;
246         ThreadStack.pop_back();
247         assert(ThreadStack.size() != 0);
248         EdgeIdentifier EI(ThreadStack.back().FuncId, TopFuncId);
249         auto &EA = G[EI];
250         EA.Timings.push_back(D);
251         updateStat(EA.S, D);
252         updateStat(G[TopFuncId].S, D);
253       }
254     }
255     uint64_t D = diff(ThreadStack.back().TSC, Record.TSC);
256     ThreadStack.pop_back();
257     VertexIdentifier VI = ThreadStack.empty() ? 0 : ThreadStack.back().FuncId;
258     EdgeIdentifier EI(VI, Record.FuncId);
259     auto &EA = G[EI];
260     EA.Timings.push_back(D);
261     updateStat(EA.S, D);
262     updateStat(G[Record.FuncId].S, D);
263     break;
264   }
265   case RecordTypes::CUSTOM_EVENT:
266   case RecordTypes::TYPED_EVENT:
267     // TODO: Support custom and typed events in the graph processing?
268     break;
269   }
270 
271   return Error::success();
272 }
273 
274 template <typename U>
275 void GraphRenderer::getStats(U begin, U end, GraphRenderer::TimeStat &S) {
276   if (begin == end) return;
277   std::ptrdiff_t MedianOff = S.Count / 2;
278   std::nth_element(begin, begin + MedianOff, end);
279   S.Median = *(begin + MedianOff);
280   std::ptrdiff_t Pct90Off = (S.Count * 9) / 10;
281   std::nth_element(begin, begin + Pct90Off, end);
282   S.Pct90 = *(begin + Pct90Off);
283   std::ptrdiff_t Pct99Off = (S.Count * 99) / 100;
284   std::nth_element(begin, begin + Pct99Off, end);
285   S.Pct99 = *(begin + Pct99Off);
286 }
287 
288 void GraphRenderer::updateMaxStats(const GraphRenderer::TimeStat &S,
289                                    GraphRenderer::TimeStat &M) {
290   M.Count = std::max(M.Count, S.Count);
291   M.Min = std::max(M.Min, S.Min);
292   M.Median = std::max(M.Median, S.Median);
293   M.Pct90 = std::max(M.Pct90, S.Pct90);
294   M.Pct99 = std::max(M.Pct99, S.Pct99);
295   M.Max = std::max(M.Max, S.Max);
296   M.Sum = std::max(M.Sum, S.Sum);
297 }
298 
299 void GraphRenderer::calculateEdgeStatistics() {
300   assert(!G.edges().empty());
301   for (auto &E : G.edges()) {
302     auto &A = E.second;
303     assert(!A.Timings.empty());
304     getStats(A.Timings.begin(), A.Timings.end(), A.S);
305     updateMaxStats(A.S, G.GraphEdgeMax);
306   }
307 }
308 
309 void GraphRenderer::calculateVertexStatistics() {
310   std::vector<uint64_t> TempTimings;
311   for (auto &V : G.vertices()) {
312     if (V.first != 0) {
313       for (auto &E : G.inEdges(V.first)) {
314         auto &A = E.second;
315         llvm::append_range(TempTimings, A.Timings);
316       }
317       getStats(TempTimings.begin(), TempTimings.end(), G[V.first].S);
318       updateMaxStats(G[V.first].S, G.GraphVertexMax);
319       TempTimings.clear();
320     }
321   }
322 }
323 
324 // A Helper function for normalizeStatistics which normalises a single
325 // TimeStat element.
326 static void normalizeTimeStat(GraphRenderer::TimeStat &S,
327                               double CycleFrequency) {
328   int64_t OldCount = S.Count;
329   S = S / CycleFrequency;
330   S.Count = OldCount;
331 }
332 
333 // Normalises the statistics in the graph for a given TSC frequency.
334 void GraphRenderer::normalizeStatistics(double CycleFrequency) {
335   for (auto &E : G.edges()) {
336     auto &S = E.second.S;
337     normalizeTimeStat(S, CycleFrequency);
338   }
339   for (auto &V : G.vertices()) {
340     auto &S = V.second.S;
341     normalizeTimeStat(S, CycleFrequency);
342   }
343 
344   normalizeTimeStat(G.GraphEdgeMax, CycleFrequency);
345   normalizeTimeStat(G.GraphVertexMax, CycleFrequency);
346 }
347 
348 // Returns a string containing the value of statistic field T
349 std::string
350 GraphRenderer::TimeStat::getString(GraphRenderer::StatType T) const {
351   std::string St;
352   raw_string_ostream S{St};
353   double TimeStat::*DoubleStatPtrs[] = {&TimeStat::Min,   &TimeStat::Median,
354                                         &TimeStat::Pct90, &TimeStat::Pct99,
355                                         &TimeStat::Max,   &TimeStat::Sum};
356   switch (T) {
357   case GraphRenderer::StatType::NONE:
358     break;
359   case GraphRenderer::StatType::COUNT:
360     S << Count;
361     break;
362   default:
363     S << (*this).*
364              DoubleStatPtrs[static_cast<int>(T) -
365                             static_cast<int>(GraphRenderer::StatType::MIN)];
366     break;
367   }
368   return S.str();
369 }
370 
371 // Returns the quotient between the property T of this and another TimeStat as
372 // a double
373 double GraphRenderer::TimeStat::getDouble(StatType T) const {
374   double retval = 0;
375   double TimeStat::*DoubleStatPtrs[] = {&TimeStat::Min,   &TimeStat::Median,
376                                         &TimeStat::Pct90, &TimeStat::Pct99,
377                                         &TimeStat::Max,   &TimeStat::Sum};
378   switch (T) {
379   case GraphRenderer::StatType::NONE:
380     retval = 0.0;
381     break;
382   case GraphRenderer::StatType::COUNT:
383     retval = static_cast<double>(Count);
384     break;
385   default:
386     retval =
387         (*this).*DoubleStatPtrs[static_cast<int>(T) -
388                                 static_cast<int>(GraphRenderer::StatType::MIN)];
389     break;
390   }
391   return retval;
392 }
393 
394 // Outputs a DOT format version of the Graph embedded in the GraphRenderer
395 // object on OS. It does this in the expected way by itterating
396 // through all edges then vertices and then outputting them and their
397 // annotations.
398 //
399 // FIXME: output more information, better presented.
400 void GraphRenderer::exportGraphAsDOT(raw_ostream &OS, StatType ET, StatType EC,
401                                      StatType VT, StatType VC) {
402   OS << "digraph xray {\n";
403 
404   if (VT != StatType::NONE)
405     OS << "node [shape=record];\n";
406 
407   for (const auto &E : G.edges()) {
408     const auto &S = E.second.S;
409     OS << "F" << E.first.first << " -> "
410        << "F" << E.first.second << " [label=\"" << S.getString(ET) << "\"";
411     if (EC != StatType::NONE)
412       OS << " color=\""
413          << CHelper.getColorString(
414                 std::sqrt(S.getDouble(EC) / G.GraphEdgeMax.getDouble(EC)))
415          << "\"";
416     OS << "];\n";
417   }
418 
419   for (const auto &V : G.vertices()) {
420     const auto &VA = V.second;
421     if (V.first == 0)
422       continue;
423     OS << "F" << V.first << " [label=\"" << (VT != StatType::NONE ? "{" : "")
424        << escapeString(VA.SymbolName.size() > 40
425                            ? VA.SymbolName.substr(0, 40) + "..."
426                            : VA.SymbolName);
427     if (VT != StatType::NONE)
428       OS << "|" << VA.S.getString(VT) << "}\"";
429     else
430       OS << "\"";
431     if (VC != StatType::NONE)
432       OS << " color=\""
433          << CHelper.getColorString(
434                 std::sqrt(VA.S.getDouble(VC) / G.GraphVertexMax.getDouble(VC)))
435          << "\"";
436     OS << "];\n";
437   }
438   OS << "}\n";
439 }
440 
441 Expected<GraphRenderer> GraphRenderer::Factory::getGraphRenderer() {
442   InstrumentationMap Map;
443   if (!GraphInstrMap.empty()) {
444     auto InstrumentationMapOrError = loadInstrumentationMap(GraphInstrMap);
445     if (!InstrumentationMapOrError)
446       return joinErrors(
447           make_error<StringError>(
448               Twine("Cannot open instrumentation map '") + GraphInstrMap + "'",
449               std::make_error_code(std::errc::invalid_argument)),
450           InstrumentationMapOrError.takeError());
451     Map = std::move(*InstrumentationMapOrError);
452   }
453 
454   const auto &FunctionAddresses = Map.getFunctionAddresses();
455 
456   symbolize::LLVMSymbolizer Symbolizer;
457   const auto &Header = Trace.getFileHeader();
458 
459   llvm::xray::FuncIdConversionHelper FuncIdHelper(InstrMap, Symbolizer,
460                                                   FunctionAddresses);
461 
462   xray::GraphRenderer GR(FuncIdHelper, DeduceSiblingCalls);
463   for (const auto &Record : Trace) {
464     auto E = GR.accountRecord(Record);
465     if (!E)
466       continue;
467 
468     for (const auto &ThreadStack : GR.getPerThreadFunctionStack()) {
469       errs() << "Thread ID: " << ThreadStack.first << "\n";
470       auto Level = ThreadStack.second.size();
471       for (const auto &Entry : llvm::reverse(ThreadStack.second))
472         errs() << "#" << Level-- << "\t"
473                << FuncIdHelper.SymbolOrNumber(Entry.FuncId) << '\n';
474     }
475 
476     if (!GraphKeepGoing)
477       return joinErrors(make_error<StringError>(
478                             "Error encountered generating the call graph.",
479                             std::make_error_code(std::errc::invalid_argument)),
480                         std::move(E));
481 
482     handleAllErrors(std::move(E),
483                     [&](const ErrorInfoBase &E) { E.log(errs()); });
484   }
485 
486   GR.G.GraphEdgeMax = {};
487   GR.G.GraphVertexMax = {};
488   GR.calculateEdgeStatistics();
489   GR.calculateVertexStatistics();
490 
491   if (Header.CycleFrequency)
492     GR.normalizeStatistics(Header.CycleFrequency);
493 
494   return GR;
495 }
496 
497 // Here we register and implement the llvm-xray graph subcommand.
498 // The bulk of this code reads in the options, opens the required files, uses
499 // those files to create a context for analysing the xray trace, then there is a
500 // short loop which actually analyses the trace, generates the graph and then
501 // outputs it as a DOT.
502 //
503 // FIXME: include additional filtering and annalysis passes to provide more
504 // specific useful information.
505 static CommandRegistration Unused(&GraphC, []() -> Error {
506   GraphRenderer::Factory F;
507 
508   F.KeepGoing = GraphKeepGoing;
509   F.DeduceSiblingCalls = GraphDeduceSiblingCalls;
510   F.InstrMap = GraphInstrMap;
511 
512   auto TraceOrErr = loadTraceFile(GraphInput, true);
513 
514   if (!TraceOrErr)
515     return make_error<StringError>(
516         Twine("Failed loading input file '") + GraphInput + "'",
517         make_error_code(llvm::errc::invalid_argument));
518 
519   F.Trace = std::move(*TraceOrErr);
520   auto GROrError = F.getGraphRenderer();
521   if (!GROrError)
522     return GROrError.takeError();
523   auto &GR = *GROrError;
524 
525   std::error_code EC;
526   raw_fd_ostream OS(GraphOutput, EC, sys::fs::OpenFlags::OF_Text);
527   if (EC)
528     return make_error<StringError>(
529         Twine("Cannot open file '") + GraphOutput + "' for writing.", EC);
530 
531   GR.exportGraphAsDOT(OS, GraphEdgeLabel, GraphEdgeColorType, GraphVertexLabel,
532                       GraphVertexColorType);
533   return Error::success();
534 });
535