aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm14/tools/llvm-exegesis/llvm-exegesis.cpp
blob: aecae5c949e54d3685f7ee83768f69fd1e126dd3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
//===-- llvm-exegesis.cpp ---------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Measures execution properties (latencies/uops) of an instruction.
///
//===----------------------------------------------------------------------===//

#include "lib/Analysis.h"
#include "lib/BenchmarkResult.h"
#include "lib/BenchmarkRunner.h"
#include "lib/Clustering.h"
#include "lib/Error.h"
#include "lib/LlvmState.h"
#include "lib/PerfHelper.h"
#include "lib/SnippetFile.h"
#include "lib/SnippetRepetitor.h"
#include "lib/Target.h"
#include "lib/TargetSelect.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCInstBuilder.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetSelect.h"
#include <algorithm>
#include <string>

namespace llvm {
namespace exegesis {

static cl::OptionCategory Options("llvm-exegesis options");
static cl::OptionCategory BenchmarkOptions("llvm-exegesis benchmark options");
static cl::OptionCategory AnalysisOptions("llvm-exegesis analysis options");

static cl::opt<int> OpcodeIndex(
    "opcode-index",
    cl::desc("opcode to measure, by index, or -1 to measure all opcodes"),
    cl::cat(BenchmarkOptions), cl::init(0));

static cl::opt<std::string>
    OpcodeNames("opcode-name",
                cl::desc("comma-separated list of opcodes to measure, by name"),
                cl::cat(BenchmarkOptions), cl::init(""));

static cl::opt<std::string> SnippetsFile("snippets-file",
                                         cl::desc("code snippets to measure"),
                                         cl::cat(BenchmarkOptions),
                                         cl::init(""));

static cl::opt<std::string>
    BenchmarkFile("benchmarks-file",
                  cl::desc("File to read (analysis mode) or write "
                           "(latency/uops/inverse_throughput modes) benchmark "
                           "results. “-” uses stdin/stdout."),
                  cl::cat(Options), cl::init(""));

static cl::opt<exegesis::InstructionBenchmark::ModeE> BenchmarkMode(
    "mode", cl::desc("the mode to run"), cl::cat(Options),
    cl::values(clEnumValN(exegesis::InstructionBenchmark::Latency, "latency",
                          "Instruction Latency"),
               clEnumValN(exegesis::InstructionBenchmark::InverseThroughput,
                          "inverse_throughput",
                          "Instruction Inverse Throughput"),
               clEnumValN(exegesis::InstructionBenchmark::Uops, "uops",
                          "Uop Decomposition"),
               // When not asking for a specific benchmark mode,
               // we'll analyse the results.
               clEnumValN(exegesis::InstructionBenchmark::Unknown, "analysis",
                          "Analysis")));

static cl::opt<exegesis::InstructionBenchmark::ResultAggregationModeE>
    ResultAggMode(
        "result-aggregation-mode",
        cl::desc("How to aggregate multi-values result"), cl::cat(Options),
        cl::values(clEnumValN(exegesis::InstructionBenchmark::Min, "min",
                              "Keep min reading"),
                   clEnumValN(exegesis::InstructionBenchmark::Max, "max",
                              "Keep max reading"),
                   clEnumValN(exegesis::InstructionBenchmark::Mean, "mean",
                              "Compute mean of all readings"),
                   clEnumValN(exegesis::InstructionBenchmark::MinVariance,
                              "min-variance",
                              "Keep readings set with min-variance")),
        cl::init(exegesis::InstructionBenchmark::Min));

static cl::opt<exegesis::InstructionBenchmark::RepetitionModeE> RepetitionMode(
    "repetition-mode", cl::desc("how to repeat the instruction snippet"),
    cl::cat(BenchmarkOptions),
    cl::values(
        clEnumValN(exegesis::InstructionBenchmark::Duplicate, "duplicate",
                   "Duplicate the snippet"),
        clEnumValN(exegesis::InstructionBenchmark::Loop, "loop",
                   "Loop over the snippet"),
        clEnumValN(exegesis::InstructionBenchmark::AggregateMin, "min",
                   "All of the above and take the minimum of measurements")),
    cl::init(exegesis::InstructionBenchmark::Duplicate));

static cl::opt<unsigned>
    NumRepetitions("num-repetitions",
                   cl::desc("number of time to repeat the asm snippet"),
                   cl::cat(BenchmarkOptions), cl::init(10000));

static cl::opt<unsigned>
    LoopBodySize("loop-body-size",
                 cl::desc("when repeating the instruction snippet by looping "
                          "over it, duplicate the snippet until the loop body "
                          "contains at least this many instruction"),
                 cl::cat(BenchmarkOptions), cl::init(0));

static cl::opt<unsigned> MaxConfigsPerOpcode(
    "max-configs-per-opcode",
    cl::desc(
        "allow to snippet generator to generate at most that many configs"),
    cl::cat(BenchmarkOptions), cl::init(1));

static cl::opt<bool> IgnoreInvalidSchedClass(
    "ignore-invalid-sched-class",
    cl::desc("ignore instructions that do not define a sched class"),
    cl::cat(BenchmarkOptions), cl::init(false));

static cl::opt<exegesis::InstructionBenchmarkClustering::ModeE>
    AnalysisClusteringAlgorithm(
        "analysis-clustering", cl::desc("the clustering algorithm to use"),
        cl::cat(AnalysisOptions),
        cl::values(clEnumValN(exegesis::InstructionBenchmarkClustering::Dbscan,
                              "dbscan", "use DBSCAN/OPTICS algorithm"),
                   clEnumValN(exegesis::InstructionBenchmarkClustering::Naive,
                              "naive", "one cluster per opcode")),
        cl::init(exegesis::InstructionBenchmarkClustering::Dbscan));

static cl::opt<unsigned> AnalysisDbscanNumPoints(
    "analysis-numpoints",
    cl::desc("minimum number of points in an analysis cluster (dbscan only)"),
    cl::cat(AnalysisOptions), cl::init(3));

static cl::opt<float> AnalysisClusteringEpsilon(
    "analysis-clustering-epsilon",
    cl::desc("epsilon for benchmark point clustering"),
    cl::cat(AnalysisOptions), cl::init(0.1));

static cl::opt<float> AnalysisInconsistencyEpsilon(
    "analysis-inconsistency-epsilon",
    cl::desc("epsilon for detection of when the cluster is different from the "
             "LLVM schedule profile values"),
    cl::cat(AnalysisOptions), cl::init(0.1));

static cl::opt<std::string>
    AnalysisClustersOutputFile("analysis-clusters-output-file", cl::desc(""),
                               cl::cat(AnalysisOptions), cl::init(""));
static cl::opt<std::string>
    AnalysisInconsistenciesOutputFile("analysis-inconsistencies-output-file",
                                      cl::desc(""), cl::cat(AnalysisOptions),
                                      cl::init(""));

static cl::opt<bool> AnalysisDisplayUnstableOpcodes(
    "analysis-display-unstable-clusters",
    cl::desc("if there is more than one benchmark for an opcode, said "
             "benchmarks may end up not being clustered into the same cluster "
             "if the measured performance characteristics are different. by "
             "default all such opcodes are filtered out. this flag will "
             "instead show only such unstable opcodes"),
    cl::cat(AnalysisOptions), cl::init(false));

static cl::opt<std::string> CpuName(
    "mcpu",
    cl::desc("cpu name to use for pfm counters, leave empty to autodetect"),
    cl::cat(Options), cl::init(""));

static cl::opt<bool>
    DumpObjectToDisk("dump-object-to-disk",
                     cl::desc("dumps the generated benchmark object to disk "
                              "and prints a message to access it"),
                     cl::cat(BenchmarkOptions), cl::init(true));

static ExitOnError ExitOnErr("llvm-exegesis error: ");

// Helper function that logs the error(s) and exits.
template <typename... ArgTs> static void ExitWithError(ArgTs &&... Args) {
  ExitOnErr(make_error<Failure>(std::forward<ArgTs>(Args)...));
}

// Check Err. If it's in a failure state log the file error(s) and exit.
static void ExitOnFileError(const Twine &FileName, Error Err) {
  if (Err) {
    ExitOnErr(createFileError(FileName, std::move(Err)));
  }
}

// Check E. If it's in a success state then return the contained value.
// If it's in a failure state log the file error(s) and exit.
template <typename T>
T ExitOnFileError(const Twine &FileName, Expected<T> &&E) {
  ExitOnFileError(FileName, E.takeError());
  return std::move(*E);
}

// Checks that only one of OpcodeNames, OpcodeIndex or SnippetsFile is provided,
// and returns the opcode indices or {} if snippets should be read from
// `SnippetsFile`.
static std::vector<unsigned> getOpcodesOrDie(const MCInstrInfo &MCInstrInfo) {
  const size_t NumSetFlags = (OpcodeNames.empty() ? 0 : 1) +
                             (OpcodeIndex == 0 ? 0 : 1) +
                             (SnippetsFile.empty() ? 0 : 1);
  if (NumSetFlags != 1) {
    ExitOnErr.setBanner("llvm-exegesis: ");
    ExitWithError("please provide one and only one of 'opcode-index', "
                  "'opcode-name' or 'snippets-file'");
  }
  if (!SnippetsFile.empty())
    return {};
  if (OpcodeIndex > 0)
    return {static_cast<unsigned>(OpcodeIndex)};
  if (OpcodeIndex < 0) {
    std::vector<unsigned> Result;
    for (unsigned I = 1, E = MCInstrInfo.getNumOpcodes(); I < E; ++I)
      Result.push_back(I);
    return Result;
  }
  // Resolve opcode name -> opcode.
  const auto ResolveName = [&MCInstrInfo](StringRef OpcodeName) -> unsigned {
    for (unsigned I = 1, E = MCInstrInfo.getNumOpcodes(); I < E; ++I)
      if (MCInstrInfo.getName(I) == OpcodeName)
        return I;
    return 0u;
  };
  SmallVector<StringRef, 2> Pieces;
  StringRef(OpcodeNames.getValue())
      .split(Pieces, ",", /* MaxSplit */ -1, /* KeepEmpty */ false);
  std::vector<unsigned> Result;
  for (const StringRef &OpcodeName : Pieces) {
    if (unsigned Opcode = ResolveName(OpcodeName))
      Result.push_back(Opcode);
    else
      ExitWithError(Twine("unknown opcode ").concat(OpcodeName));
  }
  return Result;
}

// Generates code snippets for opcode `Opcode`.
static Expected<std::vector<BenchmarkCode>>
generateSnippets(const LLVMState &State, unsigned Opcode,
                 const BitVector &ForbiddenRegs) {
  const Instruction &Instr = State.getIC().getInstr(Opcode);
  const MCInstrDesc &InstrDesc = Instr.Description;
  // Ignore instructions that we cannot run.
  if (InstrDesc.isPseudo() || InstrDesc.usesCustomInsertionHook())
    return make_error<Failure>(
        "Unsupported opcode: isPseudo/usesCustomInserter");
  if (InstrDesc.isBranch() || InstrDesc.isIndirectBranch())
    return make_error<Failure>("Unsupported opcode: isBranch/isIndirectBranch");
  if (InstrDesc.isCall() || InstrDesc.isReturn())
    return make_error<Failure>("Unsupported opcode: isCall/isReturn");

  const std::vector<InstructionTemplate> InstructionVariants =
      State.getExegesisTarget().generateInstructionVariants(
          Instr, MaxConfigsPerOpcode);

  SnippetGenerator::Options SnippetOptions;
  SnippetOptions.MaxConfigsPerOpcode = MaxConfigsPerOpcode;
  const std::unique_ptr<SnippetGenerator> Generator =
      State.getExegesisTarget().createSnippetGenerator(BenchmarkMode, State,
                                                       SnippetOptions);
  if (!Generator)
    ExitWithError("cannot create snippet generator");

  std::vector<BenchmarkCode> Benchmarks;
  for (const InstructionTemplate &Variant : InstructionVariants) {
    if (Benchmarks.size() >= MaxConfigsPerOpcode)
      break;
    if (auto Err = Generator->generateConfigurations(Variant, Benchmarks,
                                                     ForbiddenRegs))
      return std::move(Err);
  }
  return Benchmarks;
}

void benchmarkMain() {
#ifndef HAVE_LIBPFM
  ExitWithError("benchmarking unavailable, LLVM was built without libpfm.");
#endif

  if (exegesis::pfm::pfmInitialize())
    ExitWithError("cannot initialize libpfm");

  InitializeNativeTarget();
  InitializeNativeTargetAsmPrinter();
  InitializeNativeTargetAsmParser();
  InitializeNativeExegesisTarget();

  const LLVMState State(CpuName);

  // Preliminary check to ensure features needed for requested
  // benchmark mode are present on target CPU and/or OS.
  ExitOnErr(State.getExegesisTarget().checkFeatureSupport());

  const std::unique_ptr<BenchmarkRunner> Runner =
      ExitOnErr(State.getExegesisTarget().createBenchmarkRunner(
          BenchmarkMode, State, ResultAggMode));
  if (!Runner) {
    ExitWithError("cannot create benchmark runner");
  }

  const auto Opcodes = getOpcodesOrDie(State.getInstrInfo());

  SmallVector<std::unique_ptr<const SnippetRepetitor>, 2> Repetitors;
  if (RepetitionMode != InstructionBenchmark::RepetitionModeE::AggregateMin)
    Repetitors.emplace_back(SnippetRepetitor::Create(RepetitionMode, State));
  else {
    for (InstructionBenchmark::RepetitionModeE RepMode :
         {InstructionBenchmark::RepetitionModeE::Duplicate,
          InstructionBenchmark::RepetitionModeE::Loop})
      Repetitors.emplace_back(SnippetRepetitor::Create(RepMode, State));
  }

  BitVector AllReservedRegs;
  llvm::for_each(Repetitors,
                 [&AllReservedRegs](
                     const std::unique_ptr<const SnippetRepetitor> &Repetitor) {
                   AllReservedRegs |= Repetitor->getReservedRegs();
                 });

  std::vector<BenchmarkCode> Configurations;
  if (!Opcodes.empty()) {
    for (const unsigned Opcode : Opcodes) {
      // Ignore instructions without a sched class if
      // -ignore-invalid-sched-class is passed.
      if (IgnoreInvalidSchedClass &&
          State.getInstrInfo().get(Opcode).getSchedClass() == 0) {
        errs() << State.getInstrInfo().getName(Opcode)
               << ": ignoring instruction without sched class\n";
        continue;
      }

      auto ConfigsForInstr = generateSnippets(State, Opcode, AllReservedRegs);
      if (!ConfigsForInstr) {
        logAllUnhandledErrors(
            ConfigsForInstr.takeError(), errs(),
            Twine(State.getInstrInfo().getName(Opcode)).concat(": "));
        continue;
      }
      std::move(ConfigsForInstr->begin(), ConfigsForInstr->end(),
                std::back_inserter(Configurations));
    }
  } else {
    Configurations = ExitOnErr(readSnippets(State, SnippetsFile));
  }

  if (NumRepetitions == 0) {
    ExitOnErr.setBanner("llvm-exegesis: ");
    ExitWithError("--num-repetitions must be greater than zero");
  }

  // Write to standard output if file is not set.
  if (BenchmarkFile.empty())
    BenchmarkFile = "-";

  for (const BenchmarkCode &Conf : Configurations) {
    InstructionBenchmark Result = ExitOnErr(Runner->runConfiguration(
        Conf, NumRepetitions, LoopBodySize, Repetitors, DumpObjectToDisk));
    ExitOnFileError(BenchmarkFile, Result.writeYaml(State, BenchmarkFile));
  }
  exegesis::pfm::pfmTerminate();
}

// Prints the results of running analysis pass `Pass` to file `OutputFilename`
// if OutputFilename is non-empty.
template <typename Pass>
static void maybeRunAnalysis(const Analysis &Analyzer, const std::string &Name,
                             const std::string &OutputFilename) {
  if (OutputFilename.empty())
    return;
  if (OutputFilename != "-") {
    errs() << "Printing " << Name << " results to file '" << OutputFilename
           << "'\n";
  }
  std::error_code ErrorCode;
  raw_fd_ostream ClustersOS(OutputFilename, ErrorCode,
                            sys::fs::FA_Read | sys::fs::FA_Write);
  if (ErrorCode)
    ExitOnFileError(OutputFilename, errorCodeToError(ErrorCode));
  if (auto Err = Analyzer.run<Pass>(ClustersOS))
    ExitOnFileError(OutputFilename, std::move(Err));
}

static void analysisMain() {
  ExitOnErr.setBanner("llvm-exegesis: ");
  if (BenchmarkFile.empty())
    ExitWithError("--benchmarks-file must be set");

  if (AnalysisClustersOutputFile.empty() &&
      AnalysisInconsistenciesOutputFile.empty()) {
    ExitWithError(
        "for --mode=analysis: At least one of --analysis-clusters-output-file "
        "and --analysis-inconsistencies-output-file must be specified");
  }

  InitializeNativeTarget();
  InitializeNativeTargetAsmPrinter();
  InitializeNativeTargetDisassembler();

  // Read benchmarks.
  const LLVMState State("");
  const std::vector<InstructionBenchmark> Points = ExitOnFileError(
      BenchmarkFile, InstructionBenchmark::readYamls(State, BenchmarkFile));

  outs() << "Parsed " << Points.size() << " benchmark points\n";
  if (Points.empty()) {
    errs() << "no benchmarks to analyze\n";
    return;
  }
  // FIXME: Check that all points have the same triple/cpu.
  // FIXME: Merge points from several runs (latency and uops).

  std::string Error;
  const auto *TheTarget =
      TargetRegistry::lookupTarget(Points[0].LLVMTriple, Error);
  if (!TheTarget) {
    errs() << "unknown target '" << Points[0].LLVMTriple << "'\n";
    return;
  }

  std::unique_ptr<MCSubtargetInfo> SubtargetInfo(
      TheTarget->createMCSubtargetInfo(Points[0].LLVMTriple, CpuName, ""));

  std::unique_ptr<MCInstrInfo> InstrInfo(TheTarget->createMCInstrInfo());
  assert(InstrInfo && "Unable to create instruction info!");

  const auto Clustering = ExitOnErr(InstructionBenchmarkClustering::create(
      Points, AnalysisClusteringAlgorithm, AnalysisDbscanNumPoints,
      AnalysisClusteringEpsilon, SubtargetInfo.get(), InstrInfo.get()));

  const Analysis Analyzer(
      *TheTarget, std::move(SubtargetInfo), std::move(InstrInfo), Clustering,
      AnalysisInconsistencyEpsilon, AnalysisDisplayUnstableOpcodes, CpuName);

  maybeRunAnalysis<Analysis::PrintClusters>(Analyzer, "analysis clusters",
                                            AnalysisClustersOutputFile);
  maybeRunAnalysis<Analysis::PrintSchedClassInconsistencies>(
      Analyzer, "sched class consistency analysis",
      AnalysisInconsistenciesOutputFile);
}

} // namespace exegesis
} // namespace llvm

int main(int Argc, char **Argv) {
  using namespace llvm;
  cl::ParseCommandLineOptions(Argc, Argv, "");

  exegesis::ExitOnErr.setExitCodeMapper([](const Error &Err) {
    if (Err.isA<exegesis::ClusteringError>())
      return EXIT_SUCCESS;
    return EXIT_FAILURE;
  });

  if (exegesis::BenchmarkMode == exegesis::InstructionBenchmark::Unknown) {
    exegesis::analysisMain();
  } else {
    exegesis::benchmarkMain();
  }
  return EXIT_SUCCESS;
}