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);
50
51GCOVOptions GCOVOptions::getDefault() {
52  GCOVOptions Options;
53  Options.EmitNotes = true;
54  Options.EmitData = true;
55  Options.UseCfgChecksum = false;
56  Options.NoRedZone = false;
57  Options.FunctionNamesInData = true;
58
59  if (DefaultGCOVVersion.size() != 4) {
60    llvm::report_fatal_error(std::string("Invalid -default-gcov-version: ") +
61                             DefaultGCOVVersion);
62  }
63  memcpy(Options.Version, DefaultGCOVVersion.c_str(), 4);
64  return Options;
65}
66
67namespace {
68  class GCOVFunction;
69
70  class GCOVProfiler : public ModulePass {
71  public:
72    static char ID;
73    GCOVProfiler() : ModulePass(ID), Options(GCOVOptions::getDefault()) {
74      init();
75    }
76    GCOVProfiler(const GCOVOptions &Options) : ModulePass(ID), Options(Options){
77      assert((Options.EmitNotes || Options.EmitData) &&
78             "GCOVProfiler asked to do nothing?");
79      init();
80    }
81    const char *getPassName() const override {
82      return "GCOV Profiler";
83    }
84
85  private:
86    void init() {
87      ReversedVersion[0] = Options.Version[3];
88      ReversedVersion[1] = Options.Version[2];
89      ReversedVersion[2] = Options.Version[1];
90      ReversedVersion[3] = Options.Version[0];
91      ReversedVersion[4] = '\0';
92      initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
93    }
94    bool runOnModule(Module &M) override;
95
96    // Create the .gcno files for the Module based on DebugInfo.
97    void emitProfileNotes();
98
99    // Modify the program to track transitions along edges and call into the
100    // profiling runtime to emit .gcda files when run.
101    bool emitProfileArcs();
102
103    // Get pointers to the functions in the runtime library.
104    Constant *getStartFileFunc();
105    Constant *getIncrementIndirectCounterFunc();
106    Constant *getEmitFunctionFunc();
107    Constant *getEmitArcsFunc();
108    Constant *getSummaryInfoFunc();
109    Constant *getDeleteWriteoutFunctionListFunc();
110    Constant *getDeleteFlushFunctionListFunc();
111    Constant *getEndFileFunc();
112
113    // Create or retrieve an i32 state value that is used to represent the
114    // pred block number for certain non-trivial edges.
115    GlobalVariable *getEdgeStateValue();
116
117    // Produce a table of pointers to counters, by predecessor and successor
118    // block number.
119    GlobalVariable *buildEdgeLookupTable(Function *F,
120                                         GlobalVariable *Counter,
121                                         const UniqueVector<BasicBlock *>&Preds,
122                                         const UniqueVector<BasicBlock*>&Succs);
123
124    // Add the function to write out all our counters to the global destructor
125    // list.
126    Function *insertCounterWriteout(ArrayRef<std::pair<GlobalVariable*,
127                                                       MDNode*> >);
128    Function *insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> >);
129    void insertIndirectCounterIncrement();
130
131    std::string mangleName(DICompileUnit CU, const char *NewStem);
132
133    GCOVOptions Options;
134
135    // Reversed, NUL-terminated copy of Options.Version.
136    char ReversedVersion[5];
137    // Checksum, produced by hash of EdgeDestinations
138    SmallVector<uint32_t, 4> FileChecksums;
139
140    Module *M;
141    LLVMContext *Ctx;
142    SmallVector<std::unique_ptr<GCOVFunction>, 16> Funcs;
143  };
144}
145
146char GCOVProfiler::ID = 0;
147INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling",
148                "Insert instrumentation for GCOV profiling", false, false)
149
150ModulePass *llvm::createGCOVProfilerPass(const GCOVOptions &Options) {
151  return new GCOVProfiler(Options);
152}
153
154static StringRef getFunctionName(DISubprogram SP) {
155  if (!SP.getLinkageName().empty())
156    return SP.getLinkageName();
157  return SP.getName();
158}
159
160namespace {
161  class GCOVRecord {
162   protected:
163    static const char *const LinesTag;
164    static const char *const FunctionTag;
165    static const char *const BlockTag;
166    static const char *const EdgeTag;
167
168    GCOVRecord() {}
169
170    void writeBytes(const char *Bytes, int Size) {
171      os->write(Bytes, Size);
172    }
173
174    void write(uint32_t i) {
175      writeBytes(reinterpret_cast<char*>(&i), 4);
176    }
177
178    // Returns the length measured in 4-byte blocks that will be used to
179    // represent this string in a GCOV file
180    static unsigned lengthOfGCOVString(StringRef s) {
181      // A GCOV string is a length, followed by a NUL, then between 0 and 3 NULs
182      // padding out to the next 4-byte word. The length is measured in 4-byte
183      // words including padding, not bytes of actual string.
184      return (s.size() / 4) + 1;
185    }
186
187    void writeGCOVString(StringRef s) {
188      uint32_t Len = lengthOfGCOVString(s);
189      write(Len);
190      writeBytes(s.data(), s.size());
191
192      // Write 1 to 4 bytes of NUL padding.
193      assert((unsigned)(4 - (s.size() % 4)) > 0);
194      assert((unsigned)(4 - (s.size() % 4)) <= 4);
195      writeBytes("\0\0\0\0", 4 - (s.size() % 4));
196    }
197
198    raw_ostream *os;
199  };
200  const char *const GCOVRecord::LinesTag = "\0\0\x45\x01";
201  const char *const GCOVRecord::FunctionTag = "\0\0\0\1";
202  const char *const GCOVRecord::BlockTag = "\0\0\x41\x01";
203  const char *const GCOVRecord::EdgeTag = "\0\0\x43\x01";
204
205  class GCOVFunction;
206  class GCOVBlock;
207
208  // Constructed only by requesting it from a GCOVBlock, this object stores a
209  // list of line numbers and a single filename, representing lines that belong
210  // to the block.
211  class GCOVLines : public GCOVRecord {
212   public:
213    void addLine(uint32_t Line) {
214      assert(Line != 0 && "Line zero is not a valid real line number.");
215      Lines.push_back(Line);
216    }
217
218    uint32_t length() const {
219      // Here 2 = 1 for string length + 1 for '0' id#.
220      return lengthOfGCOVString(Filename) + 2 + Lines.size();
221    }
222
223    void writeOut() {
224      write(0);
225      writeGCOVString(Filename);
226      for (int i = 0, e = Lines.size(); i != e; ++i)
227        write(Lines[i]);
228    }
229
230    GCOVLines(StringRef F, raw_ostream *os)
231      : Filename(F) {
232      this->os = os;
233    }
234
235   private:
236    StringRef Filename;
237    SmallVector<uint32_t, 32> Lines;
238  };
239
240
241  // Represent a basic block in GCOV. Each block has a unique number in the
242  // function, number of lines belonging to each block, and a set of edges to
243  // other blocks.
244  class GCOVBlock : public GCOVRecord {
245   public:
246    GCOVLines &getFile(StringRef Filename) {
247      GCOVLines *&Lines = LinesByFile[Filename];
248      if (!Lines) {
249        Lines = new GCOVLines(Filename, os);
250      }
251      return *Lines;
252    }
253
254    void addEdge(GCOVBlock &Successor) {
255      OutEdges.push_back(&Successor);
256    }
257
258    void writeOut() {
259      uint32_t Len = 3;
260      SmallVector<StringMapEntry<GCOVLines *> *, 32> SortedLinesByFile;
261      for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
262               E = LinesByFile.end(); I != E; ++I) {
263        Len += I->second->length();
264        SortedLinesByFile.push_back(&*I);
265      }
266
267      writeBytes(LinesTag, 4);
268      write(Len);
269      write(Number);
270
271      std::sort(SortedLinesByFile.begin(), SortedLinesByFile.end(),
272                [](StringMapEntry<GCOVLines *> *LHS,
273                   StringMapEntry<GCOVLines *> *RHS) {
274        return LHS->getKey() < RHS->getKey();
275      });
276      for (SmallVectorImpl<StringMapEntry<GCOVLines *> *>::iterator
277               I = SortedLinesByFile.begin(), E = SortedLinesByFile.end();
278           I != E; ++I)
279        (*I)->getValue()->writeOut();
280      write(0);
281      write(0);
282    }
283
284    ~GCOVBlock() {
285      DeleteContainerSeconds(LinesByFile);
286    }
287
288   private:
289    friend class GCOVFunction;
290
291    GCOVBlock(uint32_t Number, raw_ostream *os)
292        : Number(Number) {
293      this->os = os;
294    }
295
296    uint32_t Number;
297    StringMap<GCOVLines *> LinesByFile;
298    SmallVector<GCOVBlock *, 4> OutEdges;
299  };
300
301  // A function has a unique identifier, a checksum (we leave as zero) and a
302  // set of blocks and a map of edges between blocks. This is the only GCOV
303  // object users can construct, the blocks and lines will be rooted here.
304  class GCOVFunction : public GCOVRecord {
305   public:
306    GCOVFunction(DISubprogram SP, raw_ostream *os, uint32_t Ident,
307                 bool UseCfgChecksum) :
308        SP(SP), Ident(Ident), UseCfgChecksum(UseCfgChecksum), CfgChecksum(0) {
309      this->os = os;
310
311      Function *F = SP.getFunction();
312      DEBUG(dbgs() << "Function: " << getFunctionName(SP) << "\n");
313      uint32_t i = 0;
314      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
315        Blocks[BB] = new GCOVBlock(i++, os);
316      }
317      ReturnBlock = new GCOVBlock(i++, os);
318
319      std::string FunctionNameAndLine;
320      raw_string_ostream FNLOS(FunctionNameAndLine);
321      FNLOS << getFunctionName(SP) << SP.getLineNumber();
322      FNLOS.flush();
323      FuncChecksum = hash_value(FunctionNameAndLine);
324    }
325
326    ~GCOVFunction() {
327      DeleteContainerSeconds(Blocks);
328      delete ReturnBlock;
329    }
330
331    GCOVBlock &getBlock(BasicBlock *BB) {
332      return *Blocks[BB];
333    }
334
335    GCOVBlock &getReturnBlock() {
336      return *ReturnBlock;
337    }
338
339    std::string getEdgeDestinations() {
340      std::string EdgeDestinations;
341      raw_string_ostream EDOS(EdgeDestinations);
342      Function *F = Blocks.begin()->first->getParent();
343      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
344        GCOVBlock &Block = *Blocks[I];
345        for (int i = 0, e = Block.OutEdges.size(); i != e; ++i)
346          EDOS << Block.OutEdges[i]->Number;
347      }
348      return EdgeDestinations;
349    }
350
351    uint32_t getFuncChecksum() {
352      return FuncChecksum;
353    }
354
355    void setCfgChecksum(uint32_t Checksum) {
356      CfgChecksum = Checksum;
357    }
358
359    void writeOut() {
360      writeBytes(FunctionTag, 4);
361      uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
362          1 + lengthOfGCOVString(SP.getFilename()) + 1;
363      if (UseCfgChecksum)
364        ++BlockLen;
365      write(BlockLen);
366      write(Ident);
367      write(FuncChecksum);
368      if (UseCfgChecksum)
369        write(CfgChecksum);
370      writeGCOVString(getFunctionName(SP));
371      writeGCOVString(SP.getFilename());
372      write(SP.getLineNumber());
373
374      // Emit count of blocks.
375      writeBytes(BlockTag, 4);
376      write(Blocks.size() + 1);
377      for (int i = 0, e = Blocks.size() + 1; i != e; ++i) {
378        write(0);  // No flags on our blocks.
379      }
380      DEBUG(dbgs() << Blocks.size() << " blocks.\n");
381
382      // Emit edges between blocks.
383      if (Blocks.empty()) return;
384      Function *F = Blocks.begin()->first->getParent();
385      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
386        GCOVBlock &Block = *Blocks[I];
387        if (Block.OutEdges.empty()) continue;
388
389        writeBytes(EdgeTag, 4);
390        write(Block.OutEdges.size() * 2 + 1);
391        write(Block.Number);
392        for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
393          DEBUG(dbgs() << Block.Number << " -> " << Block.OutEdges[i]->Number
394                       << "\n");
395          write(Block.OutEdges[i]->Number);
396          write(0);  // no flags
397        }
398      }
399
400      // Emit lines for each block.
401      for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
402        Blocks[I]->writeOut();
403      }
404    }
405
406   private:
407    DISubprogram SP;
408    uint32_t Ident;
409    uint32_t FuncChecksum;
410    bool UseCfgChecksum;
411    uint32_t CfgChecksum;
412    DenseMap<BasicBlock *, GCOVBlock *> Blocks;
413    GCOVBlock *ReturnBlock;
414  };
415}
416
417std::string GCOVProfiler::mangleName(DICompileUnit CU, const char *NewStem) {
418  if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
419    for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
420      MDNode *N = GCov->getOperand(i);
421      if (N->getNumOperands() != 2) continue;
422      MDString *GCovFile = dyn_cast<MDString>(N->getOperand(0));
423      MDNode *CompileUnit = dyn_cast<MDNode>(N->getOperand(1));
424      if (!GCovFile || !CompileUnit) continue;
425      if (CompileUnit == CU) {
426        SmallString<128> Filename = GCovFile->getString();
427        sys::path::replace_extension(Filename, NewStem);
428        return Filename.str();
429      }
430    }
431  }
432
433  SmallString<128> Filename = CU.getFilename();
434  sys::path::replace_extension(Filename, NewStem);
435  StringRef FName = sys::path::filename(Filename);
436  SmallString<128> CurPath;
437  if (sys::fs::current_path(CurPath)) return FName;
438  sys::path::append(CurPath, FName.str());
439  return CurPath.str();
440}
441
442bool GCOVProfiler::runOnModule(Module &M) {
443  this->M = &M;
444  Ctx = &M.getContext();
445
446  if (Options.EmitNotes) emitProfileNotes();
447  if (Options.EmitData) return emitProfileArcs();
448  return false;
449}
450
451static bool functionHasLines(Function *F) {
452  // Check whether this function actually has any source lines. Not only
453  // do these waste space, they also can crash gcov.
454  for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
455    for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
456         I != IE; ++I) {
457      // Debug intrinsic locations correspond to the location of the
458      // declaration, not necessarily any statements or expressions.
459      if (isa<DbgInfoIntrinsic>(I)) continue;
460
461      const DebugLoc &Loc = I->getDebugLoc();
462      if (Loc.isUnknown()) continue;
463
464      // Artificial lines such as calls to the global constructors.
465      if (Loc.getLine() == 0) continue;
466
467      return true;
468    }
469  }
470  return false;
471}
472
473void GCOVProfiler::emitProfileNotes() {
474  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
475  if (!CU_Nodes) return;
476
477  for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
478    // Each compile unit gets its own .gcno file. This means that whether we run
479    // this pass over the original .o's as they're produced, or run it after
480    // LTO, we'll generate the same .gcno files.
481
482    DICompileUnit CU(CU_Nodes->getOperand(i));
483    std::string ErrorInfo;
484    raw_fd_ostream out(mangleName(CU, "gcno").c_str(), ErrorInfo,
485                       sys::fs::F_None);
486    std::string EdgeDestinations;
487
488    DIArray SPs = CU.getSubprograms();
489    for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
490      DISubprogram SP(SPs.getElement(i));
491      assert((!SP || SP.isSubprogram()) &&
492        "A MDNode in subprograms of a CU should be null or a DISubprogram.");
493      if (!SP)
494        continue;
495
496      Function *F = SP.getFunction();
497      if (!F) continue;
498      if (!functionHasLines(F)) continue;
499
500      // gcov expects every function to start with an entry block that has a
501      // single successor, so split the entry block to make sure of that.
502      BasicBlock &EntryBlock = F->getEntryBlock();
503      BasicBlock::iterator It = EntryBlock.begin();
504      while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
505        ++It;
506      EntryBlock.splitBasicBlock(It);
507
508      Funcs.push_back(
509          make_unique<GCOVFunction>(SP, &out, i, Options.UseCfgChecksum));
510      GCOVFunction &Func = *Funcs.back();
511
512      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
513        GCOVBlock &Block = Func.getBlock(BB);
514        TerminatorInst *TI = BB->getTerminator();
515        if (int successors = TI->getNumSuccessors()) {
516          for (int i = 0; i != successors; ++i) {
517            Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
518          }
519        } else if (isa<ReturnInst>(TI)) {
520          Block.addEdge(Func.getReturnBlock());
521        }
522
523        uint32_t Line = 0;
524        for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
525             I != IE; ++I) {
526          // Debug intrinsic locations correspond to the location of the
527          // declaration, not necessarily any statements or expressions.
528          if (isa<DbgInfoIntrinsic>(I)) continue;
529
530          const DebugLoc &Loc = I->getDebugLoc();
531          if (Loc.isUnknown()) continue;
532
533          // Artificial lines such as calls to the global constructors.
534          if (Loc.getLine() == 0) continue;
535
536          if (Line == Loc.getLine()) continue;
537          Line = Loc.getLine();
538          if (SP != getDISubprogram(Loc.getScope(*Ctx))) continue;
539
540          GCOVLines &Lines = Block.getFile(SP.getFilename());
541          Lines.addLine(Loc.getLine());
542        }
543      }
544      EdgeDestinations += Func.getEdgeDestinations();
545    }
546
547    FileChecksums.push_back(hash_value(EdgeDestinations));
548    out.write("oncg", 4);
549    out.write(ReversedVersion, 4);
550    out.write(reinterpret_cast<char*>(&FileChecksums.back()), 4);
551
552    for (auto &Func : Funcs) {
553      Func->setCfgChecksum(FileChecksums.back());
554      Func->writeOut();
555    }
556
557    out.write("\0\0\0\0\0\0\0\0", 8);  // EOF
558    out.close();
559  }
560}
561
562bool GCOVProfiler::emitProfileArcs() {
563  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
564  if (!CU_Nodes) return false;
565
566  bool Result = false;
567  bool InsertIndCounterIncrCode = false;
568  for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
569    DICompileUnit CU(CU_Nodes->getOperand(i));
570    DIArray SPs = CU.getSubprograms();
571    SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
572    for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
573      DISubprogram SP(SPs.getElement(i));
574      assert((!SP || SP.isSubprogram()) &&
575        "A MDNode in subprograms of a CU should be null or a DISubprogram.");
576      if (!SP)
577        continue;
578      Function *F = SP.getFunction();
579      if (!F) continue;
580      if (!functionHasLines(F)) continue;
581      if (!Result) Result = true;
582      unsigned Edges = 0;
583      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
584        TerminatorInst *TI = BB->getTerminator();
585        if (isa<ReturnInst>(TI))
586          ++Edges;
587        else
588          Edges += TI->getNumSuccessors();
589      }
590
591      ArrayType *CounterTy =
592        ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
593      GlobalVariable *Counters =
594        new GlobalVariable(*M, CounterTy, false,
595                           GlobalValue::InternalLinkage,
596                           Constant::getNullValue(CounterTy),
597                           "__llvm_gcov_ctr");
598      CountersBySP.push_back(std::make_pair(Counters, (MDNode*)SP));
599
600      UniqueVector<BasicBlock *> ComplexEdgePreds;
601      UniqueVector<BasicBlock *> ComplexEdgeSuccs;
602
603      unsigned Edge = 0;
604      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
605        TerminatorInst *TI = BB->getTerminator();
606        int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
607        if (Successors) {
608          if (Successors == 1) {
609            IRBuilder<> Builder(BB->getFirstInsertionPt());
610            Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
611                                                                Edge);
612            Value *Count = Builder.CreateLoad(Counter);
613            Count = Builder.CreateAdd(Count, Builder.getInt64(1));
614            Builder.CreateStore(Count, Counter);
615          } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
616            IRBuilder<> Builder(BI);
617            Value *Sel = Builder.CreateSelect(BI->getCondition(),
618                                              Builder.getInt64(Edge),
619                                              Builder.getInt64(Edge + 1));
620            SmallVector<Value *, 2> Idx;
621            Idx.push_back(Builder.getInt64(0));
622            Idx.push_back(Sel);
623            Value *Counter = Builder.CreateInBoundsGEP(Counters, Idx);
624            Value *Count = Builder.CreateLoad(Counter);
625            Count = Builder.CreateAdd(Count, Builder.getInt64(1));
626            Builder.CreateStore(Count, Counter);
627          } else {
628            ComplexEdgePreds.insert(BB);
629            for (int i = 0; i != Successors; ++i)
630              ComplexEdgeSuccs.insert(TI->getSuccessor(i));
631          }
632
633          Edge += Successors;
634        }
635      }
636
637      if (!ComplexEdgePreds.empty()) {
638        GlobalVariable *EdgeTable =
639          buildEdgeLookupTable(F, Counters,
640                               ComplexEdgePreds, ComplexEdgeSuccs);
641        GlobalVariable *EdgeState = getEdgeStateValue();
642
643        for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
644          IRBuilder<> Builder(ComplexEdgePreds[i + 1]->getFirstInsertionPt());
645          Builder.CreateStore(Builder.getInt32(i), EdgeState);
646        }
647
648        for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
649          // Call runtime to perform increment.
650          IRBuilder<> Builder(ComplexEdgeSuccs[i+1]->getFirstInsertionPt());
651          Value *CounterPtrArray =
652            Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
653                                               i * ComplexEdgePreds.size());
654
655          // Build code to increment the counter.
656          InsertIndCounterIncrCode = true;
657          Builder.CreateCall2(getIncrementIndirectCounterFunc(),
658                              EdgeState, CounterPtrArray);
659        }
660      }
661    }
662
663    Function *WriteoutF = insertCounterWriteout(CountersBySP);
664    Function *FlushF = insertFlush(CountersBySP);
665
666    // Create a small bit of code that registers the "__llvm_gcov_writeout" to
667    // be executed at exit and the "__llvm_gcov_flush" function to be executed
668    // when "__gcov_flush" is called.
669    FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
670    Function *F = Function::Create(FTy, GlobalValue::InternalLinkage,
671                                   "__llvm_gcov_init", M);
672    F->setUnnamedAddr(true);
673    F->setLinkage(GlobalValue::InternalLinkage);
674    F->addFnAttr(Attribute::NoInline);
675    if (Options.NoRedZone)
676      F->addFnAttr(Attribute::NoRedZone);
677
678    BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
679    IRBuilder<> Builder(BB);
680
681    FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
682    Type *Params[] = {
683      PointerType::get(FTy, 0),
684      PointerType::get(FTy, 0)
685    };
686    FTy = FunctionType::get(Builder.getVoidTy(), Params, false);
687
688    // Initialize the environment and register the local writeout and flush
689    // functions.
690    Constant *GCOVInit = M->getOrInsertFunction("llvm_gcov_init", FTy);
691    Builder.CreateCall2(GCOVInit, WriteoutF, FlushF);
692    Builder.CreateRetVoid();
693
694    appendToGlobalCtors(*M, F, 0);
695  }
696
697  if (InsertIndCounterIncrCode)
698    insertIndirectCounterIncrement();
699
700  return Result;
701}
702
703// All edges with successors that aren't branches are "complex", because it
704// requires complex logic to pick which counter to update.
705GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
706    Function *F,
707    GlobalVariable *Counters,
708    const UniqueVector<BasicBlock *> &Preds,
709    const UniqueVector<BasicBlock *> &Succs) {
710  // TODO: support invoke, threads. We rely on the fact that nothing can modify
711  // the whole-Module pred edge# between the time we set it and the time we next
712  // read it. Threads and invoke make this untrue.
713
714  // emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
715  size_t TableSize = Succs.size() * Preds.size();
716  Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
717  ArrayType *EdgeTableTy = ArrayType::get(Int64PtrTy, TableSize);
718
719  std::unique_ptr<Constant * []> EdgeTable(new Constant *[TableSize]);
720  Constant *NullValue = Constant::getNullValue(Int64PtrTy);
721  for (size_t i = 0; i != TableSize; ++i)
722    EdgeTable[i] = NullValue;
723
724  unsigned Edge = 0;
725  for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
726    TerminatorInst *TI = BB->getTerminator();
727    int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
728    if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
729      for (int i = 0; i != Successors; ++i) {
730        BasicBlock *Succ = TI->getSuccessor(i);
731        IRBuilder<> Builder(Succ);
732        Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
733                                                            Edge + i);
734        EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
735                  (Preds.idFor(BB)-1)] = cast<Constant>(Counter);
736      }
737    }
738    Edge += Successors;
739  }
740
741  ArrayRef<Constant*> V(&EdgeTable[0], TableSize);
742  GlobalVariable *EdgeTableGV =
743      new GlobalVariable(
744          *M, EdgeTableTy, true, GlobalValue::InternalLinkage,
745          ConstantArray::get(EdgeTableTy, V),
746          "__llvm_gcda_edge_table");
747  EdgeTableGV->setUnnamedAddr(true);
748  return EdgeTableGV;
749}
750
751Constant *GCOVProfiler::getStartFileFunc() {
752  Type *Args[] = {
753    Type::getInt8PtrTy(*Ctx),  // const char *orig_filename
754    Type::getInt8PtrTy(*Ctx),  // const char version[4]
755    Type::getInt32Ty(*Ctx),    // uint32_t checksum
756  };
757  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
758  return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
759}
760
761Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
762  Type *Int32Ty = Type::getInt32Ty(*Ctx);
763  Type *Int64Ty = Type::getInt64Ty(*Ctx);
764  Type *Args[] = {
765    Int32Ty->getPointerTo(),                // uint32_t *predecessor
766    Int64Ty->getPointerTo()->getPointerTo() // uint64_t **counters
767  };
768  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
769  return M->getOrInsertFunction("__llvm_gcov_indirect_counter_increment", FTy);
770}
771
772Constant *GCOVProfiler::getEmitFunctionFunc() {
773  Type *Args[] = {
774    Type::getInt32Ty(*Ctx),    // uint32_t ident
775    Type::getInt8PtrTy(*Ctx),  // const char *function_name
776    Type::getInt32Ty(*Ctx),    // uint32_t func_checksum
777    Type::getInt8Ty(*Ctx),     // uint8_t use_extra_checksum
778    Type::getInt32Ty(*Ctx),    // uint32_t cfg_checksum
779  };
780  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
781  return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
782}
783
784Constant *GCOVProfiler::getEmitArcsFunc() {
785  Type *Args[] = {
786    Type::getInt32Ty(*Ctx),     // uint32_t num_counters
787    Type::getInt64PtrTy(*Ctx),  // uint64_t *counters
788  };
789  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
790  return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
791}
792
793Constant *GCOVProfiler::getSummaryInfoFunc() {
794  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
795  return M->getOrInsertFunction("llvm_gcda_summary_info", FTy);
796}
797
798Constant *GCOVProfiler::getDeleteWriteoutFunctionListFunc() {
799  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
800  return M->getOrInsertFunction("llvm_delete_writeout_function_list", FTy);
801}
802
803Constant *GCOVProfiler::getDeleteFlushFunctionListFunc() {
804  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
805  return M->getOrInsertFunction("llvm_delete_flush_function_list", FTy);
806}
807
808Constant *GCOVProfiler::getEndFileFunc() {
809  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
810  return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
811}
812
813GlobalVariable *GCOVProfiler::getEdgeStateValue() {
814  GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
815  if (!GV) {
816    GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
817                            GlobalValue::InternalLinkage,
818                            ConstantInt::get(Type::getInt32Ty(*Ctx),
819                                             0xffffffff),
820                            "__llvm_gcov_global_state_pred");
821    GV->setUnnamedAddr(true);
822  }
823  return GV;
824}
825
826Function *GCOVProfiler::insertCounterWriteout(
827    ArrayRef<std::pair<GlobalVariable *, MDNode *> > CountersBySP) {
828  FunctionType *WriteoutFTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
829  Function *WriteoutF = M->getFunction("__llvm_gcov_writeout");
830  if (!WriteoutF)
831    WriteoutF = Function::Create(WriteoutFTy, GlobalValue::InternalLinkage,
832                                 "__llvm_gcov_writeout", M);
833  WriteoutF->setUnnamedAddr(true);
834  WriteoutF->addFnAttr(Attribute::NoInline);
835  if (Options.NoRedZone)
836    WriteoutF->addFnAttr(Attribute::NoRedZone);
837
838  BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", WriteoutF);
839  IRBuilder<> Builder(BB);
840
841  Constant *StartFile = getStartFileFunc();
842  Constant *EmitFunction = getEmitFunctionFunc();
843  Constant *EmitArcs = getEmitArcsFunc();
844  Constant *SummaryInfo = getSummaryInfoFunc();
845  Constant *EndFile = getEndFileFunc();
846
847  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
848  if (CU_Nodes) {
849    for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
850      DICompileUnit CU(CU_Nodes->getOperand(i));
851      std::string FilenameGcda = mangleName(CU, "gcda");
852      uint32_t CfgChecksum = FileChecksums.empty() ? 0 : FileChecksums[i];
853      Builder.CreateCall3(StartFile,
854                          Builder.CreateGlobalStringPtr(FilenameGcda),
855                          Builder.CreateGlobalStringPtr(ReversedVersion),
856                          Builder.getInt32(CfgChecksum));
857      for (unsigned j = 0, e = CountersBySP.size(); j != e; ++j) {
858        DISubprogram SP(CountersBySP[j].second);
859        uint32_t FuncChecksum = Funcs.empty() ? 0 : Funcs[j]->getFuncChecksum();
860        Builder.CreateCall5(
861            EmitFunction, Builder.getInt32(j),
862            Options.FunctionNamesInData ?
863              Builder.CreateGlobalStringPtr(getFunctionName(SP)) :
864              Constant::getNullValue(Builder.getInt8PtrTy()),
865            Builder.getInt32(FuncChecksum),
866            Builder.getInt8(Options.UseCfgChecksum),
867            Builder.getInt32(CfgChecksum));
868
869        GlobalVariable *GV = CountersBySP[j].first;
870        unsigned Arcs =
871          cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
872        Builder.CreateCall2(EmitArcs,
873                            Builder.getInt32(Arcs),
874                            Builder.CreateConstGEP2_64(GV, 0, 0));
875      }
876      Builder.CreateCall(SummaryInfo);
877      Builder.CreateCall(EndFile);
878    }
879  }
880
881  Builder.CreateRetVoid();
882  return WriteoutF;
883}
884
885void GCOVProfiler::insertIndirectCounterIncrement() {
886  Function *Fn =
887    cast<Function>(GCOVProfiler::getIncrementIndirectCounterFunc());
888  Fn->setUnnamedAddr(true);
889  Fn->setLinkage(GlobalValue::InternalLinkage);
890  Fn->addFnAttr(Attribute::NoInline);
891  if (Options.NoRedZone)
892    Fn->addFnAttr(Attribute::NoRedZone);
893
894  // Create basic blocks for function.
895  BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", Fn);
896  IRBuilder<> Builder(BB);
897
898  BasicBlock *PredNotNegOne = BasicBlock::Create(*Ctx, "", Fn);
899  BasicBlock *CounterEnd = BasicBlock::Create(*Ctx, "", Fn);
900  BasicBlock *Exit = BasicBlock::Create(*Ctx, "exit", Fn);
901
902  // uint32_t pred = *predecessor;
903  // if (pred == 0xffffffff) return;
904  Argument *Arg = Fn->arg_begin();
905  Arg->setName("predecessor");
906  Value *Pred = Builder.CreateLoad(Arg, "pred");
907  Value *Cond = Builder.CreateICmpEQ(Pred, Builder.getInt32(0xffffffff));
908  BranchInst::Create(Exit, PredNotNegOne, Cond, BB);
909
910  Builder.SetInsertPoint(PredNotNegOne);
911
912  // uint64_t *counter = counters[pred];
913  // if (!counter) return;
914  Value *ZExtPred = Builder.CreateZExt(Pred, Builder.getInt64Ty());
915  Arg = std::next(Fn->arg_begin());
916  Arg->setName("counters");
917  Value *GEP = Builder.CreateGEP(Arg, ZExtPred);
918  Value *Counter = Builder.CreateLoad(GEP, "counter");
919  Cond = Builder.CreateICmpEQ(Counter,
920                              Constant::getNullValue(
921                                  Builder.getInt64Ty()->getPointerTo()));
922  Builder.CreateCondBr(Cond, Exit, CounterEnd);
923
924  // ++*counter;
925  Builder.SetInsertPoint(CounterEnd);
926  Value *Add = Builder.CreateAdd(Builder.CreateLoad(Counter),
927                                 Builder.getInt64(1));
928  Builder.CreateStore(Add, Counter);
929  Builder.CreateBr(Exit);
930
931  // Fill in the exit block.
932  Builder.SetInsertPoint(Exit);
933  Builder.CreateRetVoid();
934}
935
936Function *GCOVProfiler::
937insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> > CountersBySP) {
938  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
939  Function *FlushF = M->getFunction("__llvm_gcov_flush");
940  if (!FlushF)
941    FlushF = Function::Create(FTy, GlobalValue::InternalLinkage,
942                              "__llvm_gcov_flush", M);
943  else
944    FlushF->setLinkage(GlobalValue::InternalLinkage);
945  FlushF->setUnnamedAddr(true);
946  FlushF->addFnAttr(Attribute::NoInline);
947  if (Options.NoRedZone)
948    FlushF->addFnAttr(Attribute::NoRedZone);
949
950  BasicBlock *Entry = BasicBlock::Create(*Ctx, "entry", FlushF);
951
952  // Write out the current counters.
953  Constant *WriteoutF = M->getFunction("__llvm_gcov_writeout");
954  assert(WriteoutF && "Need to create the writeout function first!");
955
956  IRBuilder<> Builder(Entry);
957  Builder.CreateCall(WriteoutF);
958
959  // Zero out the counters.
960  for (ArrayRef<std::pair<GlobalVariable *, MDNode *> >::iterator
961         I = CountersBySP.begin(), E = CountersBySP.end();
962       I != E; ++I) {
963    GlobalVariable *GV = I->first;
964    Constant *Null = Constant::getNullValue(GV->getType()->getElementType());
965    Builder.CreateStore(Null, GV);
966  }
967
968  Type *RetTy = FlushF->getReturnType();
969  if (RetTy == Type::getVoidTy(*Ctx))
970    Builder.CreateRetVoid();
971  else if (RetTy->isIntegerTy())
972    // Used if __llvm_gcov_flush was implicitly declared.
973    Builder.CreateRet(ConstantInt::get(RetTy, 0));
974  else
975    report_fatal_error("invalid return type for __llvm_gcov_flush");
976
977  return FlushF;
978}
979