1//===- GCOVProfiling.cpp - Insert edge counters for gcov profiling --------===//
2//
3//                      The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This pass implements GCOV-style profiling. When this pass is run it emits
11// "gcno" files next to the existing source, and instruments the code that runs
12// to records the edges between blocks that run and emit a complementary "gcda"
13// file on exit.
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/Transforms/Instrumentation.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/Hashing.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/Statistic.h"
22#include "llvm/ADT/StringExtras.h"
23#include "llvm/ADT/StringMap.h"
24#include "llvm/ADT/UniqueVector.h"
25#include "llvm/IR/DebugInfo.h"
26#include "llvm/IR/DebugLoc.h"
27#include "llvm/IR/IRBuilder.h"
28#include "llvm/IR/InstIterator.h"
29#include "llvm/IR/Instructions.h"
30#include "llvm/IR/IntrinsicInst.h"
31#include "llvm/IR/Module.h"
32#include "llvm/Pass.h"
33#include "llvm/Support/CommandLine.h"
34#include "llvm/Support/Debug.h"
35#include "llvm/Support/FileSystem.h"
36#include "llvm/Support/Path.h"
37#include "llvm/Support/raw_ostream.h"
38#include "llvm/Transforms/Utils/ModuleUtils.h"
39#include <algorithm>
40#include <memory>
41#include <string>
42#include <utility>
43using namespace llvm;
44
45#define DEBUG_TYPE "insert-gcov-profiling"
46
47static cl::opt<std::string>
48DefaultGCOVVersion("default-gcov-version", cl::init("402*"), cl::Hidden,
49                   cl::ValueRequired);
50static cl::opt<bool> DefaultExitBlockBeforeBody("gcov-exit-block-before-body",
51                                                cl::init(false), cl::Hidden);
52
53GCOVOptions GCOVOptions::getDefault() {
54  GCOVOptions Options;
55  Options.EmitNotes = true;
56  Options.EmitData = true;
57  Options.UseCfgChecksum = false;
58  Options.NoRedZone = false;
59  Options.FunctionNamesInData = true;
60  Options.ExitBlockBeforeBody = DefaultExitBlockBeforeBody;
61
62  if (DefaultGCOVVersion.size() != 4) {
63    llvm::report_fatal_error(std::string("Invalid -default-gcov-version: ") +
64                             DefaultGCOVVersion);
65  }
66  memcpy(Options.Version, DefaultGCOVVersion.c_str(), 4);
67  return Options;
68}
69
70namespace {
71  class GCOVFunction;
72
73  class GCOVProfiler : public ModulePass {
74  public:
75    static char ID;
76    GCOVProfiler() : GCOVProfiler(GCOVOptions::getDefault()) {}
77    GCOVProfiler(const GCOVOptions &Opts) : ModulePass(ID), Options(Opts) {
78      assert((Options.EmitNotes || Options.EmitData) &&
79             "GCOVProfiler asked to do nothing?");
80      ReversedVersion[0] = Options.Version[3];
81      ReversedVersion[1] = Options.Version[2];
82      ReversedVersion[2] = Options.Version[1];
83      ReversedVersion[3] = Options.Version[0];
84      ReversedVersion[4] = '\0';
85      initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
86    }
87    const char *getPassName() const override {
88      return "GCOV Profiler";
89    }
90
91  private:
92    bool runOnModule(Module &M) override;
93
94    // Create the .gcno files for the Module based on DebugInfo.
95    void emitProfileNotes();
96
97    // Modify the program to track transitions along edges and call into the
98    // profiling runtime to emit .gcda files when run.
99    bool emitProfileArcs();
100
101    // Get pointers to the functions in the runtime library.
102    Constant *getStartFileFunc();
103    Constant *getIncrementIndirectCounterFunc();
104    Constant *getEmitFunctionFunc();
105    Constant *getEmitArcsFunc();
106    Constant *getSummaryInfoFunc();
107    Constant *getDeleteWriteoutFunctionListFunc();
108    Constant *getDeleteFlushFunctionListFunc();
109    Constant *getEndFileFunc();
110
111    // Create or retrieve an i32 state value that is used to represent the
112    // pred block number for certain non-trivial edges.
113    GlobalVariable *getEdgeStateValue();
114
115    // Produce a table of pointers to counters, by predecessor and successor
116    // block number.
117    GlobalVariable *buildEdgeLookupTable(Function *F,
118                                         GlobalVariable *Counter,
119                                         const UniqueVector<BasicBlock *>&Preds,
120                                         const UniqueVector<BasicBlock*>&Succs);
121
122    // Add the function to write out all our counters to the global destructor
123    // list.
124    Function *insertCounterWriteout(ArrayRef<std::pair<GlobalVariable*,
125                                                       MDNode*> >);
126    Function *insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> >);
127    void insertIndirectCounterIncrement();
128
129    std::string mangleName(DICompileUnit CU, const char *NewStem);
130
131    GCOVOptions Options;
132
133    // Reversed, NUL-terminated copy of Options.Version.
134    char ReversedVersion[5];
135    // Checksum, produced by hash of EdgeDestinations
136    SmallVector<uint32_t, 4> FileChecksums;
137
138    Module *M;
139    LLVMContext *Ctx;
140    SmallVector<std::unique_ptr<GCOVFunction>, 16> Funcs;
141  };
142}
143
144char GCOVProfiler::ID = 0;
145INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling",
146                "Insert instrumentation for GCOV profiling", false, false)
147
148ModulePass *llvm::createGCOVProfilerPass(const GCOVOptions &Options) {
149  return new GCOVProfiler(Options);
150}
151
152static StringRef getFunctionName(MDSubprogram *SP) {
153  if (!SP->getLinkageName().empty())
154    return SP->getLinkageName();
155  return SP->getName();
156}
157
158namespace {
159  class GCOVRecord {
160   protected:
161    static const char *const LinesTag;
162    static const char *const FunctionTag;
163    static const char *const BlockTag;
164    static const char *const EdgeTag;
165
166    GCOVRecord() = default;
167
168    void writeBytes(const char *Bytes, int Size) {
169      os->write(Bytes, Size);
170    }
171
172    void write(uint32_t i) {
173      writeBytes(reinterpret_cast<char*>(&i), 4);
174    }
175
176    // Returns the length measured in 4-byte blocks that will be used to
177    // represent this string in a GCOV file
178    static unsigned lengthOfGCOVString(StringRef s) {
179      // A GCOV string is a length, followed by a NUL, then between 0 and 3 NULs
180      // padding out to the next 4-byte word. The length is measured in 4-byte
181      // words including padding, not bytes of actual string.
182      return (s.size() / 4) + 1;
183    }
184
185    void writeGCOVString(StringRef s) {
186      uint32_t Len = lengthOfGCOVString(s);
187      write(Len);
188      writeBytes(s.data(), s.size());
189
190      // Write 1 to 4 bytes of NUL padding.
191      assert((unsigned)(4 - (s.size() % 4)) > 0);
192      assert((unsigned)(4 - (s.size() % 4)) <= 4);
193      writeBytes("\0\0\0\0", 4 - (s.size() % 4));
194    }
195
196    raw_ostream *os;
197  };
198  const char *const GCOVRecord::LinesTag = "\0\0\x45\x01";
199  const char *const GCOVRecord::FunctionTag = "\0\0\0\1";
200  const char *const GCOVRecord::BlockTag = "\0\0\x41\x01";
201  const char *const GCOVRecord::EdgeTag = "\0\0\x43\x01";
202
203  class GCOVFunction;
204  class GCOVBlock;
205
206  // Constructed only by requesting it from a GCOVBlock, this object stores a
207  // list of line numbers and a single filename, representing lines that belong
208  // to the block.
209  class GCOVLines : public GCOVRecord {
210   public:
211    void addLine(uint32_t Line) {
212      assert(Line != 0 && "Line zero is not a valid real line number.");
213      Lines.push_back(Line);
214    }
215
216    uint32_t length() const {
217      // Here 2 = 1 for string length + 1 for '0' id#.
218      return lengthOfGCOVString(Filename) + 2 + Lines.size();
219    }
220
221    void writeOut() {
222      write(0);
223      writeGCOVString(Filename);
224      for (int i = 0, e = Lines.size(); i != e; ++i)
225        write(Lines[i]);
226    }
227
228    GCOVLines(StringRef F, raw_ostream *os)
229      : Filename(F) {
230      this->os = os;
231    }
232
233   private:
234    StringRef Filename;
235    SmallVector<uint32_t, 32> Lines;
236  };
237
238
239  // Represent a basic block in GCOV. Each block has a unique number in the
240  // function, number of lines belonging to each block, and a set of edges to
241  // other blocks.
242  class GCOVBlock : public GCOVRecord {
243   public:
244    GCOVLines &getFile(StringRef Filename) {
245      GCOVLines *&Lines = LinesByFile[Filename];
246      if (!Lines) {
247        Lines = new GCOVLines(Filename, os);
248      }
249      return *Lines;
250    }
251
252    void addEdge(GCOVBlock &Successor) {
253      OutEdges.push_back(&Successor);
254    }
255
256    void writeOut() {
257      uint32_t Len = 3;
258      SmallVector<StringMapEntry<GCOVLines *> *, 32> SortedLinesByFile;
259      for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
260               E = LinesByFile.end(); I != E; ++I) {
261        Len += I->second->length();
262        SortedLinesByFile.push_back(&*I);
263      }
264
265      writeBytes(LinesTag, 4);
266      write(Len);
267      write(Number);
268
269      std::sort(SortedLinesByFile.begin(), SortedLinesByFile.end(),
270                [](StringMapEntry<GCOVLines *> *LHS,
271                   StringMapEntry<GCOVLines *> *RHS) {
272        return LHS->getKey() < RHS->getKey();
273      });
274      for (SmallVectorImpl<StringMapEntry<GCOVLines *> *>::iterator
275               I = SortedLinesByFile.begin(), E = SortedLinesByFile.end();
276           I != E; ++I)
277        (*I)->getValue()->writeOut();
278      write(0);
279      write(0);
280    }
281
282    ~GCOVBlock() {
283      DeleteContainerSeconds(LinesByFile);
284    }
285
286    GCOVBlock(const GCOVBlock &RHS) : GCOVRecord(RHS), Number(RHS.Number) {
287      // Only allow copy before edges and lines have been added. After that,
288      // there are inter-block pointers (eg: edges) that won't take kindly to
289      // blocks being copied or moved around.
290      assert(LinesByFile.empty());
291      assert(OutEdges.empty());
292    }
293
294   private:
295    friend class GCOVFunction;
296
297    GCOVBlock(uint32_t Number, raw_ostream *os)
298        : Number(Number) {
299      this->os = os;
300    }
301
302    uint32_t Number;
303    StringMap<GCOVLines *> LinesByFile;
304    SmallVector<GCOVBlock *, 4> OutEdges;
305  };
306
307  // A function has a unique identifier, a checksum (we leave as zero) and a
308  // set of blocks and a map of edges between blocks. This is the only GCOV
309  // object users can construct, the blocks and lines will be rooted here.
310  class GCOVFunction : public GCOVRecord {
311   public:
312     GCOVFunction(DISubprogram SP, raw_ostream *os, uint32_t Ident,
313                  bool UseCfgChecksum, bool ExitBlockBeforeBody)
314         : SP(SP), Ident(Ident), UseCfgChecksum(UseCfgChecksum), CfgChecksum(0),
315           ReturnBlock(1, os) {
316      this->os = os;
317
318      Function *F = SP->getFunction();
319      DEBUG(dbgs() << "Function: " << getFunctionName(SP) << "\n");
320
321      uint32_t i = 0;
322      for (auto &BB : *F) {
323        // Skip index 1 if it's assigned to the ReturnBlock.
324        if (i == 1 && ExitBlockBeforeBody)
325          ++i;
326        Blocks.insert(std::make_pair(&BB, GCOVBlock(i++, os)));
327      }
328      if (!ExitBlockBeforeBody)
329        ReturnBlock.Number = i;
330
331      std::string FunctionNameAndLine;
332      raw_string_ostream FNLOS(FunctionNameAndLine);
333      FNLOS << getFunctionName(SP) << SP->getLine();
334      FNLOS.flush();
335      FuncChecksum = hash_value(FunctionNameAndLine);
336    }
337
338    GCOVBlock &getBlock(BasicBlock *BB) {
339      return Blocks.find(BB)->second;
340    }
341
342    GCOVBlock &getReturnBlock() {
343      return ReturnBlock;
344    }
345
346    std::string getEdgeDestinations() {
347      std::string EdgeDestinations;
348      raw_string_ostream EDOS(EdgeDestinations);
349      Function *F = Blocks.begin()->first->getParent();
350      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
351        GCOVBlock &Block = getBlock(I);
352        for (int i = 0, e = Block.OutEdges.size(); i != e; ++i)
353          EDOS << Block.OutEdges[i]->Number;
354      }
355      return EdgeDestinations;
356    }
357
358    uint32_t getFuncChecksum() {
359      return FuncChecksum;
360    }
361
362    void setCfgChecksum(uint32_t Checksum) {
363      CfgChecksum = Checksum;
364    }
365
366    void writeOut() {
367      writeBytes(FunctionTag, 4);
368      uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
369                          1 + lengthOfGCOVString(SP->getFilename()) + 1;
370      if (UseCfgChecksum)
371        ++BlockLen;
372      write(BlockLen);
373      write(Ident);
374      write(FuncChecksum);
375      if (UseCfgChecksum)
376        write(CfgChecksum);
377      writeGCOVString(getFunctionName(SP));
378      writeGCOVString(SP->getFilename());
379      write(SP->getLine());
380
381      // Emit count of blocks.
382      writeBytes(BlockTag, 4);
383      write(Blocks.size() + 1);
384      for (int i = 0, e = Blocks.size() + 1; i != e; ++i) {
385        write(0);  // No flags on our blocks.
386      }
387      DEBUG(dbgs() << Blocks.size() << " blocks.\n");
388
389      // Emit edges between blocks.
390      if (Blocks.empty()) return;
391      Function *F = Blocks.begin()->first->getParent();
392      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
393        GCOVBlock &Block = getBlock(I);
394        if (Block.OutEdges.empty()) continue;
395
396        writeBytes(EdgeTag, 4);
397        write(Block.OutEdges.size() * 2 + 1);
398        write(Block.Number);
399        for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
400          DEBUG(dbgs() << Block.Number << " -> " << Block.OutEdges[i]->Number
401                       << "\n");
402          write(Block.OutEdges[i]->Number);
403          write(0);  // no flags
404        }
405      }
406
407      // Emit lines for each block.
408      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
409        getBlock(I).writeOut();
410      }
411    }
412
413   private:
414    DISubprogram SP;
415    uint32_t Ident;
416    uint32_t FuncChecksum;
417    bool UseCfgChecksum;
418    uint32_t CfgChecksum;
419    DenseMap<BasicBlock *, GCOVBlock> Blocks;
420    GCOVBlock ReturnBlock;
421  };
422}
423
424std::string GCOVProfiler::mangleName(DICompileUnit CU, const char *NewStem) {
425  if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
426    for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
427      MDNode *N = GCov->getOperand(i);
428      if (N->getNumOperands() != 2) continue;
429      MDString *GCovFile = dyn_cast<MDString>(N->getOperand(0));
430      MDNode *CompileUnit = dyn_cast<MDNode>(N->getOperand(1));
431      if (!GCovFile || !CompileUnit) continue;
432      if (CompileUnit == CU) {
433        SmallString<128> Filename = GCovFile->getString();
434        sys::path::replace_extension(Filename, NewStem);
435        return Filename.str();
436      }
437    }
438  }
439
440  SmallString<128> Filename = CU->getFilename();
441  sys::path::replace_extension(Filename, NewStem);
442  StringRef FName = sys::path::filename(Filename);
443  SmallString<128> CurPath;
444  if (sys::fs::current_path(CurPath)) return FName;
445  sys::path::append(CurPath, FName);
446  return CurPath.str();
447}
448
449bool GCOVProfiler::runOnModule(Module &M) {
450  this->M = &M;
451  Ctx = &M.getContext();
452
453  if (Options.EmitNotes) emitProfileNotes();
454  if (Options.EmitData) return emitProfileArcs();
455  return false;
456}
457
458static bool functionHasLines(Function *F) {
459  // Check whether this function actually has any source lines. Not only
460  // do these waste space, they also can crash gcov.
461  for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
462    for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
463         I != IE; ++I) {
464      // Debug intrinsic locations correspond to the location of the
465      // declaration, not necessarily any statements or expressions.
466      if (isa<DbgInfoIntrinsic>(I)) continue;
467
468      const DebugLoc &Loc = I->getDebugLoc();
469      if (!Loc)
470        continue;
471
472      // Artificial lines such as calls to the global constructors.
473      if (Loc.getLine() == 0) continue;
474
475      return true;
476    }
477  }
478  return false;
479}
480
481void GCOVProfiler::emitProfileNotes() {
482  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
483  if (!CU_Nodes) return;
484
485  for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
486    // Each compile unit gets its own .gcno file. This means that whether we run
487    // this pass over the original .o's as they're produced, or run it after
488    // LTO, we'll generate the same .gcno files.
489
490    DICompileUnit CU = cast<MDCompileUnit>(CU_Nodes->getOperand(i));
491    std::error_code EC;
492    raw_fd_ostream out(mangleName(CU, "gcno"), EC, sys::fs::F_None);
493    std::string EdgeDestinations;
494
495    unsigned FunctionIdent = 0;
496    for (auto *SP : CU->getSubprograms()) {
497      Function *F = SP->getFunction();
498      if (!F) continue;
499      if (!functionHasLines(F)) continue;
500
501      // gcov expects every function to start with an entry block that has a
502      // single successor, so split the entry block to make sure of that.
503      BasicBlock &EntryBlock = F->getEntryBlock();
504      BasicBlock::iterator It = EntryBlock.begin();
505      while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
506        ++It;
507      EntryBlock.splitBasicBlock(It);
508
509      Funcs.push_back(make_unique<GCOVFunction>(SP, &out, FunctionIdent++,
510                                                Options.UseCfgChecksum,
511                                                Options.ExitBlockBeforeBody));
512      GCOVFunction &Func = *Funcs.back();
513
514      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
515        GCOVBlock &Block = Func.getBlock(BB);
516        TerminatorInst *TI = BB->getTerminator();
517        if (int successors = TI->getNumSuccessors()) {
518          for (int i = 0; i != successors; ++i) {
519            Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
520          }
521        } else if (isa<ReturnInst>(TI)) {
522          Block.addEdge(Func.getReturnBlock());
523        }
524
525        uint32_t Line = 0;
526        for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
527             I != IE; ++I) {
528          // Debug intrinsic locations correspond to the location of the
529          // declaration, not necessarily any statements or expressions.
530          if (isa<DbgInfoIntrinsic>(I)) continue;
531
532          const DebugLoc &Loc = I->getDebugLoc();
533          if (!Loc)
534            continue;
535
536          // Artificial lines such as calls to the global constructors.
537          if (Loc.getLine() == 0) continue;
538
539          if (Line == Loc.getLine()) continue;
540          Line = Loc.getLine();
541          if (SP != getDISubprogram(Loc.getScope()))
542            continue;
543
544          GCOVLines &Lines = Block.getFile(SP->getFilename());
545          Lines.addLine(Loc.getLine());
546        }
547      }
548      EdgeDestinations += Func.getEdgeDestinations();
549    }
550
551    FileChecksums.push_back(hash_value(EdgeDestinations));
552    out.write("oncg", 4);
553    out.write(ReversedVersion, 4);
554    out.write(reinterpret_cast<char*>(&FileChecksums.back()), 4);
555
556    for (auto &Func : Funcs) {
557      Func->setCfgChecksum(FileChecksums.back());
558      Func->writeOut();
559    }
560
561    out.write("\0\0\0\0\0\0\0\0", 8);  // EOF
562    out.close();
563  }
564}
565
566bool GCOVProfiler::emitProfileArcs() {
567  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
568  if (!CU_Nodes) return false;
569
570  bool Result = false;
571  bool InsertIndCounterIncrCode = false;
572  for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
573    DICompileUnit CU = cast<MDCompileUnit>(CU_Nodes->getOperand(i));
574    SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
575    for (auto *SP : CU->getSubprograms()) {
576      Function *F = SP->getFunction();
577      if (!F) continue;
578      if (!functionHasLines(F)) continue;
579      if (!Result) Result = true;
580      unsigned Edges = 0;
581      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
582        TerminatorInst *TI = BB->getTerminator();
583        if (isa<ReturnInst>(TI))
584          ++Edges;
585        else
586          Edges += TI->getNumSuccessors();
587      }
588
589      ArrayType *CounterTy =
590        ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
591      GlobalVariable *Counters =
592        new GlobalVariable(*M, CounterTy, false,
593                           GlobalValue::InternalLinkage,
594                           Constant::getNullValue(CounterTy),
595                           "__llvm_gcov_ctr");
596      CountersBySP.push_back(std::make_pair(Counters, SP));
597
598      UniqueVector<BasicBlock *> ComplexEdgePreds;
599      UniqueVector<BasicBlock *> ComplexEdgeSuccs;
600
601      unsigned Edge = 0;
602      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
603        TerminatorInst *TI = BB->getTerminator();
604        int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
605        if (Successors) {
606          if (Successors == 1) {
607            IRBuilder<> Builder(BB->getFirstInsertionPt());
608            Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
609                                                                Edge);
610            Value *Count = Builder.CreateLoad(Counter);
611            Count = Builder.CreateAdd(Count, Builder.getInt64(1));
612            Builder.CreateStore(Count, Counter);
613          } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
614            IRBuilder<> Builder(BI);
615            Value *Sel = Builder.CreateSelect(BI->getCondition(),
616                                              Builder.getInt64(Edge),
617                                              Builder.getInt64(Edge + 1));
618            SmallVector<Value *, 2> Idx;
619            Idx.push_back(Builder.getInt64(0));
620            Idx.push_back(Sel);
621            Value *Counter = Builder.CreateInBoundsGEP(Counters->getValueType(),
622                                                       Counters, Idx);
623            Value *Count = Builder.CreateLoad(Counter);
624            Count = Builder.CreateAdd(Count, Builder.getInt64(1));
625            Builder.CreateStore(Count, Counter);
626          } else {
627            ComplexEdgePreds.insert(BB);
628            for (int i = 0; i != Successors; ++i)
629              ComplexEdgeSuccs.insert(TI->getSuccessor(i));
630          }
631
632          Edge += Successors;
633        }
634      }
635
636      if (!ComplexEdgePreds.empty()) {
637        GlobalVariable *EdgeTable =
638          buildEdgeLookupTable(F, Counters,
639                               ComplexEdgePreds, ComplexEdgeSuccs);
640        GlobalVariable *EdgeState = getEdgeStateValue();
641
642        for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
643          IRBuilder<> Builder(ComplexEdgePreds[i + 1]->getFirstInsertionPt());
644          Builder.CreateStore(Builder.getInt32(i), EdgeState);
645        }
646
647        for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
648          // Call runtime to perform increment.
649          IRBuilder<> Builder(ComplexEdgeSuccs[i+1]->getFirstInsertionPt());
650          Value *CounterPtrArray =
651            Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
652                                               i * ComplexEdgePreds.size());
653
654          // Build code to increment the counter.
655          InsertIndCounterIncrCode = true;
656          Builder.CreateCall2(getIncrementIndirectCounterFunc(),
657                              EdgeState, CounterPtrArray);
658        }
659      }
660    }
661
662    Function *WriteoutF = insertCounterWriteout(CountersBySP);
663    Function *FlushF = insertFlush(CountersBySP);
664
665    // Create a small bit of code that registers the "__llvm_gcov_writeout" to
666    // be executed at exit and the "__llvm_gcov_flush" function to be executed
667    // when "__gcov_flush" is called.
668    FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
669    Function *F = Function::Create(FTy, GlobalValue::InternalLinkage,
670                                   "__llvm_gcov_init", M);
671    F->setUnnamedAddr(true);
672    F->setLinkage(GlobalValue::InternalLinkage);
673    F->addFnAttr(Attribute::NoInline);
674    if (Options.NoRedZone)
675      F->addFnAttr(Attribute::NoRedZone);
676
677    BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
678    IRBuilder<> Builder(BB);
679
680    FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
681    Type *Params[] = {
682      PointerType::get(FTy, 0),
683      PointerType::get(FTy, 0)
684    };
685    FTy = FunctionType::get(Builder.getVoidTy(), Params, false);
686
687    // Initialize the environment and register the local writeout and flush
688    // functions.
689    Constant *GCOVInit = M->getOrInsertFunction("llvm_gcov_init", FTy);
690    Builder.CreateCall2(GCOVInit, WriteoutF, FlushF);
691    Builder.CreateRetVoid();
692
693    appendToGlobalCtors(*M, F, 0);
694  }
695
696  if (InsertIndCounterIncrCode)
697    insertIndirectCounterIncrement();
698
699  return Result;
700}
701
702// All edges with successors that aren't branches are "complex", because it
703// requires complex logic to pick which counter to update.
704GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
705    Function *F,
706    GlobalVariable *Counters,
707    const UniqueVector<BasicBlock *> &Preds,
708    const UniqueVector<BasicBlock *> &Succs) {
709  // TODO: support invoke, threads. We rely on the fact that nothing can modify
710  // the whole-Module pred edge# between the time we set it and the time we next
711  // read it. Threads and invoke make this untrue.
712
713  // emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
714  size_t TableSize = Succs.size() * Preds.size();
715  Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
716  ArrayType *EdgeTableTy = ArrayType::get(Int64PtrTy, TableSize);
717
718  std::unique_ptr<Constant * []> EdgeTable(new Constant *[TableSize]);
719  Constant *NullValue = Constant::getNullValue(Int64PtrTy);
720  for (size_t i = 0; i != TableSize; ++i)
721    EdgeTable[i] = NullValue;
722
723  unsigned Edge = 0;
724  for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
725    TerminatorInst *TI = BB->getTerminator();
726    int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
727    if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
728      for (int i = 0; i != Successors; ++i) {
729        BasicBlock *Succ = TI->getSuccessor(i);
730        IRBuilder<> Builder(Succ);
731        Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
732                                                            Edge + i);
733        EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
734                  (Preds.idFor(BB)-1)] = cast<Constant>(Counter);
735      }
736    }
737    Edge += Successors;
738  }
739
740  GlobalVariable *EdgeTableGV =
741      new GlobalVariable(
742          *M, EdgeTableTy, true, GlobalValue::InternalLinkage,
743          ConstantArray::get(EdgeTableTy,
744                             makeArrayRef(&EdgeTable[0],TableSize)),
745          "__llvm_gcda_edge_table");
746  EdgeTableGV->setUnnamedAddr(true);
747  return EdgeTableGV;
748}
749
750Constant *GCOVProfiler::getStartFileFunc() {
751  Type *Args[] = {
752    Type::getInt8PtrTy(*Ctx),  // const char *orig_filename
753    Type::getInt8PtrTy(*Ctx),  // const char version[4]
754    Type::getInt32Ty(*Ctx),    // uint32_t checksum
755  };
756  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
757  return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
758}
759
760Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
761  Type *Int32Ty = Type::getInt32Ty(*Ctx);
762  Type *Int64Ty = Type::getInt64Ty(*Ctx);
763  Type *Args[] = {
764    Int32Ty->getPointerTo(),                // uint32_t *predecessor
765    Int64Ty->getPointerTo()->getPointerTo() // uint64_t **counters
766  };
767  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
768  return M->getOrInsertFunction("__llvm_gcov_indirect_counter_increment", FTy);
769}
770
771Constant *GCOVProfiler::getEmitFunctionFunc() {
772  Type *Args[] = {
773    Type::getInt32Ty(*Ctx),    // uint32_t ident
774    Type::getInt8PtrTy(*Ctx),  // const char *function_name
775    Type::getInt32Ty(*Ctx),    // uint32_t func_checksum
776    Type::getInt8Ty(*Ctx),     // uint8_t use_extra_checksum
777    Type::getInt32Ty(*Ctx),    // uint32_t cfg_checksum
778  };
779  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
780  return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
781}
782
783Constant *GCOVProfiler::getEmitArcsFunc() {
784  Type *Args[] = {
785    Type::getInt32Ty(*Ctx),     // uint32_t num_counters
786    Type::getInt64PtrTy(*Ctx),  // uint64_t *counters
787  };
788  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
789  return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
790}
791
792Constant *GCOVProfiler::getSummaryInfoFunc() {
793  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
794  return M->getOrInsertFunction("llvm_gcda_summary_info", FTy);
795}
796
797Constant *GCOVProfiler::getDeleteWriteoutFunctionListFunc() {
798  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
799  return M->getOrInsertFunction("llvm_delete_writeout_function_list", FTy);
800}
801
802Constant *GCOVProfiler::getDeleteFlushFunctionListFunc() {
803  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
804  return M->getOrInsertFunction("llvm_delete_flush_function_list", FTy);
805}
806
807Constant *GCOVProfiler::getEndFileFunc() {
808  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
809  return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
810}
811
812GlobalVariable *GCOVProfiler::getEdgeStateValue() {
813  GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
814  if (!GV) {
815    GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
816                            GlobalValue::InternalLinkage,
817                            ConstantInt::get(Type::getInt32Ty(*Ctx),
818                                             0xffffffff),
819                            "__llvm_gcov_global_state_pred");
820    GV->setUnnamedAddr(true);
821  }
822  return GV;
823}
824
825Function *GCOVProfiler::insertCounterWriteout(
826    ArrayRef<std::pair<GlobalVariable *, MDNode *> > CountersBySP) {
827  FunctionType *WriteoutFTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
828  Function *WriteoutF = M->getFunction("__llvm_gcov_writeout");
829  if (!WriteoutF)
830    WriteoutF = Function::Create(WriteoutFTy, GlobalValue::InternalLinkage,
831                                 "__llvm_gcov_writeout", M);
832  WriteoutF->setUnnamedAddr(true);
833  WriteoutF->addFnAttr(Attribute::NoInline);
834  if (Options.NoRedZone)
835    WriteoutF->addFnAttr(Attribute::NoRedZone);
836
837  BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", WriteoutF);
838  IRBuilder<> Builder(BB);
839
840  Constant *StartFile = getStartFileFunc();
841  Constant *EmitFunction = getEmitFunctionFunc();
842  Constant *EmitArcs = getEmitArcsFunc();
843  Constant *SummaryInfo = getSummaryInfoFunc();
844  Constant *EndFile = getEndFileFunc();
845
846  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
847  if (CU_Nodes) {
848    for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
849      DICompileUnit CU = cast<MDCompileUnit>(CU_Nodes->getOperand(i));
850      std::string FilenameGcda = mangleName(CU, "gcda");
851      uint32_t CfgChecksum = FileChecksums.empty() ? 0 : FileChecksums[i];
852      Builder.CreateCall3(StartFile,
853                          Builder.CreateGlobalStringPtr(FilenameGcda),
854                          Builder.CreateGlobalStringPtr(ReversedVersion),
855                          Builder.getInt32(CfgChecksum));
856      for (unsigned j = 0, e = CountersBySP.size(); j != e; ++j) {
857        auto *SP = cast_or_null<MDSubprogram>(CountersBySP[j].second);
858        uint32_t FuncChecksum = Funcs.empty() ? 0 : Funcs[j]->getFuncChecksum();
859        Builder.CreateCall5(
860            EmitFunction, Builder.getInt32(j),
861            Options.FunctionNamesInData ?
862              Builder.CreateGlobalStringPtr(getFunctionName(SP)) :
863              Constant::getNullValue(Builder.getInt8PtrTy()),
864            Builder.getInt32(FuncChecksum),
865            Builder.getInt8(Options.UseCfgChecksum),
866            Builder.getInt32(CfgChecksum));
867
868        GlobalVariable *GV = CountersBySP[j].first;
869        unsigned Arcs =
870          cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
871        Builder.CreateCall2(EmitArcs,
872                            Builder.getInt32(Arcs),
873                            Builder.CreateConstGEP2_64(GV, 0, 0));
874      }
875      Builder.CreateCall(SummaryInfo);
876      Builder.CreateCall(EndFile);
877    }
878  }
879
880  Builder.CreateRetVoid();
881  return WriteoutF;
882}
883
884void GCOVProfiler::insertIndirectCounterIncrement() {
885  Function *Fn =
886    cast<Function>(GCOVProfiler::getIncrementIndirectCounterFunc());
887  Fn->setUnnamedAddr(true);
888  Fn->setLinkage(GlobalValue::InternalLinkage);
889  Fn->addFnAttr(Attribute::NoInline);
890  if (Options.NoRedZone)
891    Fn->addFnAttr(Attribute::NoRedZone);
892
893  // Create basic blocks for function.
894  BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", Fn);
895  IRBuilder<> Builder(BB);
896
897  BasicBlock *PredNotNegOne = BasicBlock::Create(*Ctx, "", Fn);
898  BasicBlock *CounterEnd = BasicBlock::Create(*Ctx, "", Fn);
899  BasicBlock *Exit = BasicBlock::Create(*Ctx, "exit", Fn);
900
901  // uint32_t pred = *predecessor;
902  // if (pred == 0xffffffff) return;
903  Argument *Arg = Fn->arg_begin();
904  Arg->setName("predecessor");
905  Value *Pred = Builder.CreateLoad(Arg, "pred");
906  Value *Cond = Builder.CreateICmpEQ(Pred, Builder.getInt32(0xffffffff));
907  BranchInst::Create(Exit, PredNotNegOne, Cond, BB);
908
909  Builder.SetInsertPoint(PredNotNegOne);
910
911  // uint64_t *counter = counters[pred];
912  // if (!counter) return;
913  Value *ZExtPred = Builder.CreateZExt(Pred, Builder.getInt64Ty());
914  Arg = std::next(Fn->arg_begin());
915  Arg->setName("counters");
916  Value *GEP = Builder.CreateGEP(Type::getInt64PtrTy(*Ctx), Arg, ZExtPred);
917  Value *Counter = Builder.CreateLoad(GEP, "counter");
918  Cond = Builder.CreateICmpEQ(Counter,
919                              Constant::getNullValue(
920                                  Builder.getInt64Ty()->getPointerTo()));
921  Builder.CreateCondBr(Cond, Exit, CounterEnd);
922
923  // ++*counter;
924  Builder.SetInsertPoint(CounterEnd);
925  Value *Add = Builder.CreateAdd(Builder.CreateLoad(Counter),
926                                 Builder.getInt64(1));
927  Builder.CreateStore(Add, Counter);
928  Builder.CreateBr(Exit);
929
930  // Fill in the exit block.
931  Builder.SetInsertPoint(Exit);
932  Builder.CreateRetVoid();
933}
934
935Function *GCOVProfiler::
936insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> > CountersBySP) {
937  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
938  Function *FlushF = M->getFunction("__llvm_gcov_flush");
939  if (!FlushF)
940    FlushF = Function::Create(FTy, GlobalValue::InternalLinkage,
941                              "__llvm_gcov_flush", M);
942  else
943    FlushF->setLinkage(GlobalValue::InternalLinkage);
944  FlushF->setUnnamedAddr(true);
945  FlushF->addFnAttr(Attribute::NoInline);
946  if (Options.NoRedZone)
947    FlushF->addFnAttr(Attribute::NoRedZone);
948
949  BasicBlock *Entry = BasicBlock::Create(*Ctx, "entry", FlushF);
950
951  // Write out the current counters.
952  Constant *WriteoutF = M->getFunction("__llvm_gcov_writeout");
953  assert(WriteoutF && "Need to create the writeout function first!");
954
955  IRBuilder<> Builder(Entry);
956  Builder.CreateCall(WriteoutF);
957
958  // Zero out the counters.
959  for (ArrayRef<std::pair<GlobalVariable *, MDNode *> >::iterator
960         I = CountersBySP.begin(), E = CountersBySP.end();
961       I != E; ++I) {
962    GlobalVariable *GV = I->first;
963    Constant *Null = Constant::getNullValue(GV->getType()->getElementType());
964    Builder.CreateStore(Null, GV);
965  }
966
967  Type *RetTy = FlushF->getReturnType();
968  if (RetTy == Type::getVoidTy(*Ctx))
969    Builder.CreateRetVoid();
970  else if (RetTy->isIntegerTy())
971    // Used if __llvm_gcov_flush was implicitly declared.
972    Builder.CreateRet(ConstantInt::get(RetTy, 0));
973  else
974    report_fatal_error("invalid return type for __llvm_gcov_flush");
975
976  return FlushF;
977}
978