lib/Transforms/Instrumentation/GCOVProfiling.cpp

   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 #define DEBUG_TYPE "insert-gcov-profiling"
  18
  19 #include "ProfilingUtils.h"
  20 #include "llvm/Transforms/Instrumentation.h"
  21 #include "llvm/Analysis/DebugInfo.h"
  22 #include "llvm/Module.h"
  23 #include "llvm/Pass.h"
  24 #include "llvm/Instructions.h"
  25 #include "llvm/Support/raw_ostream.h"
  26 #include "llvm/Support/Debug.h"
  27 #include "llvm/Support/DebugLoc.h"
  28 #include "llvm/Support/InstIterator.h"
  29 #include "llvm/Support/IRBuilder.h"
  30 #include "llvm/Support/PathV2.h"
  31 #include "llvm/ADT/DenseMap.h"
  32 #include "llvm/ADT/Statistic.h"
  33 #include "llvm/ADT/STLExtras.h"
  34 #include "llvm/ADT/StringExtras.h"
  35 #include "llvm/ADT/StringMap.h"
  36 #include "llvm/ADT/UniqueVector.h"
  37 #include <string>
  38 #include <utility>
  39 using namespace llvm;
  40
  41 namespace {
  42   class GCOVProfiler : public ModulePass {
  43     bool runOnModule(Module &M);
  44   public:
  45     static char ID;
  46     GCOVProfiler()
  47         : ModulePass(ID), EmitNotes(true), EmitData(true) {
  48       initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
  49     }
  50     GCOVProfiler(bool EmitNotes, bool EmitData)
  51         : ModulePass(ID), EmitNotes(EmitNotes), EmitData(EmitData) {
  52       assert((EmitNotes || EmitData) && "GCOVProfiler asked to do nothing?");
  53       initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
  54     }
  55     virtual const char *getPassName() const {
  56       return "GCOV Profiler";
  57     }
  58
  59   private:
  60     // Create the GCNO files for the Module based on DebugInfo.
  61     void emitGCNO(DebugInfoFinder &DIF);
  62
  63     // Modify the program to track transitions along edges and call into the
  64     // profiling runtime to emit .gcda files when run.
  65     bool emitProfileArcs(DebugInfoFinder &DIF);
  66
  67     // Get pointers to the functions in the runtime library.
  68     Constant *getStartFileFunc();
  69     Constant *getIncrementIndirectCounterFunc();
  70     Constant *getEmitFunctionFunc();
  71     Constant *getEmitArcsFunc();
  72     Constant *getEndFileFunc();
  73
  74     // Create or retrieve an i32 state value that is used to represent the
  75     // pred block number for certain non-trivial edges.
  76     GlobalVariable *getEdgeStateValue();
  77
  78     // Produce a table of pointers to counters, by predecessor and successor
  79     // block number.
  80     GlobalVariable *buildEdgeLookupTable(Function *F,
  81                                          GlobalVariable *Counter,
  82                                          const UniqueVector<BasicBlock *> &Preds,
  83                                          const UniqueVector<BasicBlock *> &Succs);
  84
  85     // Add the function to write out all our counters to the global destructor
  86     // list.
  87     void insertCounterWriteout(DebugInfoFinder &,
  88                                SmallVector<std::pair<GlobalVariable *,
  89                                                      uint32_t>, 8> &);
  90
  91     bool EmitNotes;
  92     bool EmitData;
  93
  94     Module *M;
  95     LLVMContext *Ctx;
  96   };
  97 }
  98
  99 char GCOVProfiler::ID = 0;
 100 INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling",
 101                 "Insert instrumentation for GCOV profiling", false, false)
 102
 103 ModulePass *llvm::createGCOVProfilerPass(bool EmitNotes, bool EmitData) {
 104   return new GCOVProfiler(EmitNotes, EmitData);
 105 }
 106
 107 static DISubprogram findSubprogram(DIScope Scope) {
 108   while (!Scope.isSubprogram()) {
 109     assert(Scope.isLexicalBlock() &&
 110            "Debug location not lexical block or subprogram");
 111     Scope = DILexicalBlock(Scope).getContext();
 112   }
 113   return DISubprogram(Scope);
 114 }
 115
 116 namespace {
 117   class GCOVRecord {
 118    protected:
 119     static const char *LinesTag;
 120     static const char *FunctionTag;
 121     static const char *BlockTag;
 122     static const char *EdgeTag;
 123
 124     GCOVRecord() {}
 125
 126     void writeBytes(const char *Bytes, int Size) {
 127       os->write(Bytes, Size);
 128     }
 129
 130     void write(uint32_t i) {
 131       writeBytes(reinterpret_cast<char*>(&i), 4);
 132     }
 133
 134     // Returns the length measured in 4-byte blocks that will be used to
 135     // represent this string in a GCOV file
 136     unsigned lengthOfGCOVString(StringRef s) {
 137       // A GCOV string is a length, followed by a NUL, then between 0 and 3 NULs
 138       // padding out to the next 4-byte word. The length is measured in 4-byte
 139       // words including padding, not bytes of actual string.
 140       return (s.size() + 5) / 4;
 141     }
 142
 143     void writeGCOVString(StringRef s) {
 144       uint32_t Len = lengthOfGCOVString(s);
 145       write(Len);
 146       writeBytes(s.data(), s.size());
 147
 148       // Write 1 to 4 bytes of NUL padding.
 149       assert((unsigned)(4 - (s.size() % 4)) > 0);
 150       assert((unsigned)(4 - (s.size() % 4)) <= 4);
 151       writeBytes("\0\0\0\0", 4 - (s.size() % 4));
 152     }
 153
 154     raw_ostream *os;
 155   };
 156   const char *GCOVRecord::LinesTag = "\0\0\x45\x01";
 157   const char *GCOVRecord::FunctionTag = "\0\0\0\1";
 158   const char *GCOVRecord::BlockTag = "\0\0\x41\x01";
 159   const char *GCOVRecord::EdgeTag = "\0\0\x43\x01";
 160
 161   class GCOVFunction;
 162   class GCOVBlock;
 163
 164   // Constructed only by requesting it from a GCOVBlock, this object stores a
 165   // list of line numbers and a single filename, representing lines that belong
 166   // to the block.
 167   class GCOVLines : public GCOVRecord {
 168    public:
 169     void addLine(uint32_t Line) {
 170       Lines.push_back(Line);
 171     }
 172
 173     uint32_t length() {
 174       return lengthOfGCOVString(Filename) + 2 + Lines.size();
 175     }
 176
 177    private:
 178     friend class GCOVBlock;
 179
 180     GCOVLines(std::string Filename, raw_ostream *os)
 181         : Filename(Filename) {
 182       this->os = os;
 183     }
 184
 185     std::string Filename;
 186     SmallVector<uint32_t, 32> Lines;
 187   };
 188
 189   // Represent a basic block in GCOV. Each block has a unique number in the
 190   // function, number of lines belonging to each block, and a set of edges to
 191   // other blocks.
 192   class GCOVBlock : public GCOVRecord {
 193    public:
 194     GCOVLines &getFile(std::string Filename) {
 195       GCOVLines *&Lines = LinesByFile[Filename];
 196       if (!Lines) {
 197         Lines = new GCOVLines(Filename, os);
 198       }
 199       return *Lines;
 200     }
 201
 202     void addEdge(GCOVBlock &Successor) {
 203       OutEdges.push_back(&Successor);
 204     }
 205
 206     void writeOut() {
 207       uint32_t Len = 3;
 208       for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
 209                E = LinesByFile.end(); I != E; ++I) {
 210         Len += I->second->length();
 211       }
 212
 213       writeBytes(LinesTag, 4);
 214       write(Len);
 215       write(Number);
 216       for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
 217                E = LinesByFile.end(); I != E; ++I) {
 218         write(0);
 219         writeGCOVString(I->second->Filename);
 220         for (int i = 0, e = I->second->Lines.size(); i != e; ++i) {
 221           write(I->second->Lines[i]);
 222         }
 223       }
 224       write(0);
 225       write(0);
 226     }
 227
 228     ~GCOVBlock() {
 229       DeleteContainerSeconds(LinesByFile);
 230     }
 231
 232    private:
 233     friend class GCOVFunction;
 234
 235     GCOVBlock(uint32_t Number, raw_ostream *os)
 236         : Number(Number) {
 237       this->os = os;
 238     }
 239
 240     uint32_t Number;
 241     StringMap<GCOVLines *> LinesByFile;
 242     SmallVector<GCOVBlock *, 4> OutEdges;
 243   };
 244
 245   // A function has a unique identifier, a checksum (we leave as zero) and a
 246   // set of blocks and a map of edges between blocks. This is the only GCOV
 247   // object users can construct, the blocks and lines will be rooted here.
 248   class GCOVFunction : public GCOVRecord {
 249    public:
 250     GCOVFunction(DISubprogram SP, raw_ostream *os) {
 251       this->os = os;
 252
 253       Function *F = SP.getFunction();
 254       uint32_t i = 0;
 255       for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
 256         Blocks[BB] = new GCOVBlock(i++, os);
 257       }
 258       ReturnBlock = new GCOVBlock(i++, os);
 259
 260       writeBytes(FunctionTag, 4);
 261       uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(SP.getName()) +
 262           1 + lengthOfGCOVString(SP.getFilename()) + 1;
 263       write(BlockLen);
 264       uint32_t Ident = reinterpret_cast<intptr_t>((MDNode*)SP);
 265       write(Ident);
 266       write(0);  // checksum
 267       writeGCOVString(SP.getName());
 268       writeGCOVString(SP.getFilename());
 269       write(SP.getLineNumber());
 270     }
 271
 272     ~GCOVFunction() {
 273       DeleteContainerSeconds(Blocks);
 274       delete ReturnBlock;
 275     }
 276
 277     GCOVBlock &getBlock(BasicBlock *BB) {
 278       return *Blocks[BB];
 279     }
 280
 281     GCOVBlock &getReturnBlock() {
 282       return *ReturnBlock;
 283     }
 284
 285     void writeOut() {
 286       // Emit count of blocks.
 287       writeBytes(BlockTag, 4);
 288       write(Blocks.size() + 1);
 289       for (int i = 0, e = Blocks.size() + 1; i != e; ++i) {
 290         write(0);  // No flags on our blocks.
 291       }
 292
 293       // Emit edges between blocks.
 294       for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = Blocks.begin(),
 295                E = Blocks.end(); I != E; ++I) {
 296         GCOVBlock &Block = *I->second;
 297         if (Block.OutEdges.empty()) continue;
 298
 299         writeBytes(EdgeTag, 4);
 300         write(Block.OutEdges.size() * 2 + 1);
 301         write(Block.Number);
 302         for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
 303           write(Block.OutEdges[i]->Number);
 304           write(0);  // no flags
 305         }
 306       }
 307
 308       // Emit lines for each block.
 309       for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = Blocks.begin(),
 310                E = Blocks.end(); I != E; ++I) {
 311         I->second->writeOut();
 312       }
 313     }
 314
 315    private:
 316     DenseMap<BasicBlock *, GCOVBlock *> Blocks;
 317     GCOVBlock *ReturnBlock;
 318   };
 319 }
 320
 321 // Replace the stem of a file, or add one if missing.
 322 static std::string replaceStem(std::string OrigFilename, std::string NewStem) {
 323   return (sys::path::stem(OrigFilename) + "." + NewStem).str();
 324 }
 325
 326 bool GCOVProfiler::runOnModule(Module &M) {
 327   this->M = &M;
 328   Ctx = &M.getContext();
 329
 330   DebugInfoFinder DIF;
 331   DIF.processModule(M);
 332
 333   if (EmitNotes) emitGCNO(DIF);
 334   if (EmitData) return emitProfileArcs(DIF);
 335   return false;
 336 }
 337
 338 void GCOVProfiler::emitGCNO(DebugInfoFinder &DIF) {
 339   DenseMap<const MDNode *, raw_fd_ostream *> GcnoFiles;
 340   for (DebugInfoFinder::iterator I = DIF.compile_unit_begin(),
 341            E = DIF.compile_unit_end(); I != E; ++I) {
 342     // Each compile unit gets its own .gcno file. This means that whether we run
 343     // this pass over the original .o's as they're produced, or run it after
 344     // LTO, we'll generate the same .gcno files.
 345
 346     DICompileUnit CU(*I);
 347     raw_fd_ostream *&out = GcnoFiles[CU];
 348     std::string ErrorInfo;
 349     out = new raw_fd_ostream(replaceStem(CU.getFilename(), "gcno").c_str(),
 350                              ErrorInfo, raw_fd_ostream::F_Binary);
 351     out->write("oncg*404MVLL", 12);
 352   }
 353
 354   for (DebugInfoFinder::iterator SPI = DIF.subprogram_begin(),
 355            SPE = DIF.subprogram_end(); SPI != SPE; ++SPI) {
 356     DISubprogram SP(*SPI);
 357     raw_fd_ostream *&os = GcnoFiles[SP.getCompileUnit()];
 358
 359     Function *F = SP.getFunction();
 360     if (!F) continue;
 361     GCOVFunction Func(SP, os);
 362
 363     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
 364       GCOVBlock &Block = Func.getBlock(BB);
 365       TerminatorInst *TI = BB->getTerminator();
 366       if (int successors = TI->getNumSuccessors()) {
 367         for (int i = 0; i != successors; ++i) {
 368           Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
 369         }
 370       } else if (isa<ReturnInst>(TI)) {
 371         Block.addEdge(Func.getReturnBlock());
 372       }
 373
 374       uint32_t Line = 0;
 375       for (BasicBlock::iterator I = BB->begin(), IE = BB->end(); I != IE; ++I) {
 376         const DebugLoc &Loc = I->getDebugLoc();
 377         if (Loc.isUnknown()) continue;
 378         if (Line == Loc.getLine()) continue;
 379         Line = Loc.getLine();
 380         if (SP != findSubprogram(DIScope(Loc.getScope(*Ctx)))) continue;
 381
 382         GCOVLines &Lines = Block.getFile(SP.getFilename());
 383         Lines.addLine(Loc.getLine());
 384       }
 385     }
 386     Func.writeOut();
 387   }
 388
 389   for (DenseMap<const MDNode *, raw_fd_ostream *>::iterator
 390            I = GcnoFiles.begin(), E = GcnoFiles.end(); I != E; ++I) {
 391     raw_fd_ostream *&out = I->second;
 392     out->write("\0\0\0\0\0\0\0\0", 8);  // EOF
 393     out->close();
 394     delete out;
 395   }
 396 }
 397
 398 bool GCOVProfiler::emitProfileArcs(DebugInfoFinder &DIF) {
 399   if (DIF.subprogram_begin() == DIF.subprogram_end())
 400     return false;
 401
 402   SmallVector<std::pair<GlobalVariable *, uint32_t>, 8> CountersByIdent;
 403   for (DebugInfoFinder::iterator SPI = DIF.subprogram_begin(),
 404            SPE = DIF.subprogram_end(); SPI != SPE; ++SPI) {
 405     DISubprogram SP(*SPI);
 406     Function *F = SP.getFunction();
 407     if (!F) continue;
 408
 409     unsigned Edges = 0;
 410     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
 411       TerminatorInst *TI = BB->getTerminator();
 412       if (isa<ReturnInst>(TI))
 413         ++Edges;
 414       else
 415         Edges += TI->getNumSuccessors();
 416     }
 417
 418     const ArrayType *CounterTy =
 419         ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
 420     GlobalVariable *Counters =
 421         new GlobalVariable(*M, CounterTy, false,
 422                            GlobalValue::InternalLinkage,
 423                            Constant::getNullValue(CounterTy),
 424                            "__llvm_gcov_ctr", 0, false, 0);
 425     CountersByIdent.push_back(
 426         std::make_pair(Counters, reinterpret_cast<intptr_t>((MDNode*)SP)));
 427
 428     UniqueVector<BasicBlock *> ComplexEdgePreds;
 429     UniqueVector<BasicBlock *> ComplexEdgeSuccs;
 430
 431     unsigned Edge = 0;
 432     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
 433       TerminatorInst *TI = BB->getTerminator();
 434       int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
 435       if (Successors) {
 436         IRBuilder<> Builder(TI);
 437
 438         if (Successors == 1) {
 439           Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
 440                                                               Edge);
 441           Value *Count = Builder.CreateLoad(Counter);
 442           Count = Builder.CreateAdd(Count,
 443                                     ConstantInt::get(Type::getInt64Ty(*Ctx),1));
 444           Builder.CreateStore(Count, Counter);
 445         } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
 446           Value *Sel = Builder.CreateSelect(
 447               BI->getCondition(),
 448               ConstantInt::get(Type::getInt64Ty(*Ctx), Edge),
 449               ConstantInt::get(Type::getInt64Ty(*Ctx), Edge + 1));
 450           SmallVector<Value *, 2> Idx;
 451           Idx.push_back(Constant::getNullValue(Type::getInt64Ty(*Ctx)));
 452           Idx.push_back(Sel);
 453           Value *Counter = Builder.CreateInBoundsGEP(Counters,
 454                                                      Idx.begin(), Idx.end());
 455           Value *Count = Builder.CreateLoad(Counter);
 456           Count = Builder.CreateAdd(Count,
 457                                     ConstantInt::get(Type::getInt64Ty(*Ctx),1));
 458           Builder.CreateStore(Count, Counter);
 459         } else {
 460           ComplexEdgePreds.insert(BB);
 461           for (int i = 0; i != Successors; ++i)
 462             ComplexEdgeSuccs.insert(TI->getSuccessor(i));
 463         }
 464         Edge += Successors;
 465       }
 466     }
 467
 468     if (!ComplexEdgePreds.empty()) {
 469       GlobalVariable *EdgeTable =
 470           buildEdgeLookupTable(F, Counters,
 471                                ComplexEdgePreds, ComplexEdgeSuccs);
 472       GlobalVariable *EdgeState = getEdgeStateValue();
 473
 474       const Type *Int32Ty = Type::getInt32Ty(*Ctx);
 475       for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
 476         IRBuilder<> Builder(ComplexEdgePreds[i+1]->getTerminator());
 477         Builder.CreateStore(ConstantInt::get(Int32Ty, i), EdgeState);
 478       }
 479       for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
 480         // call runtime to perform increment
 481         IRBuilder<> Builder(ComplexEdgeSuccs[i+1]->getFirstNonPHI());
 482         Value *CounterPtrArray =
 483             Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
 484                                                i * ComplexEdgePreds.size());
 485         Builder.CreateCall2(getIncrementIndirectCounterFunc(),
 486                             EdgeState, CounterPtrArray);
 487         // clear the predecessor number
 488         Builder.CreateStore(ConstantInt::get(Int32Ty, 0xffffffff), EdgeState);
 489       }
 490     }
 491   }
 492
 493   insertCounterWriteout(DIF, CountersByIdent);
 494
 495   return true;
 496 }
 497
 498 // All edges with successors that aren't branches are "complex", because it
 499 // requires complex logic to pick which counter to update.
 500 GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
 501     Function *F,
 502     GlobalVariable *Counters,
 503     const UniqueVector<BasicBlock *> &Preds,
 504     const UniqueVector<BasicBlock *> &Succs) {
 505   // TODO: support invoke, threads. We rely on the fact that nothing can modify
 506   // the whole-Module pred edge# between the time we set it and the time we next
 507   // read it. Threads and invoke make this untrue.
 508
 509   // emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
 510   const Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
 511   const ArrayType *EdgeTableTy = ArrayType::get(
 512       Int64PtrTy, Succs.size() * Preds.size());
 513
 514   Constant **EdgeTable = new Constant*[Succs.size() * Preds.size()];
 515   Constant *NullValue = Constant::getNullValue(Int64PtrTy);
 516   for (int i = 0, ie = Succs.size() * Preds.size(); i != ie; ++i)
 517     EdgeTable[i] = NullValue;
 518
 519   unsigned Edge = 0;
 520   for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
 521     TerminatorInst *TI = BB->getTerminator();
 522     int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
 523     if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
 524       for (int i = 0; i != Successors; ++i) {
 525         BasicBlock *Succ = TI->getSuccessor(i);
 526         IRBuilder<> builder(Succ);
 527         Value *Counter = builder.CreateConstInBoundsGEP2_64(Counters, 0,
 528                                                             Edge + i);
 529         EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
 530                   (Preds.idFor(BB)-1)] = cast<Constant>(Counter);
 531       }
 532     }
 533     Edge += Successors;
 534   }
 535
 536   GlobalVariable *EdgeTableGV =
 537       new GlobalVariable(
 538           *M, EdgeTableTy, true, GlobalValue::InternalLinkage,
 539           ConstantArray::get(EdgeTableTy,
 540                              &EdgeTable[0], Succs.size() * Preds.size()),
 541           "__llvm_gcda_edge_table");
 542   EdgeTableGV->setUnnamedAddr(true);
 543   return EdgeTableGV;
 544 }
 545
 546 Constant *GCOVProfiler::getStartFileFunc() {
 547   const Type *Args[] = { Type::getInt8PtrTy(*Ctx) };
 548   const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
 549                                               Args, false);
 550   return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
 551 }
 552
 553 Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
 554   const Type *Args[] = {
 555     Type::getInt32PtrTy(*Ctx),                  // uint32_t *predecessor
 556     Type::getInt64PtrTy(*Ctx)->getPointerTo(),  // uint64_t **state_table_row
 557   };
 558   const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
 559                                               Args, false);
 560   return M->getOrInsertFunction("llvm_gcda_increment_indirect_counter", FTy);
 561 }
 562
 563 Constant *GCOVProfiler::getEmitFunctionFunc() {
 564   const Type *Args[] = { Type::getInt32Ty(*Ctx) };
 565   const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
 566                                               Args, false);
 567   return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
 568 }
 569
 570 Constant *GCOVProfiler::getEmitArcsFunc() {
 571   const Type *Args[] = {
 572     Type::getInt32Ty(*Ctx),     // uint32_t num_counters
 573     Type::getInt64PtrTy(*Ctx),  // uint64_t *counters
 574   };
 575   const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
 576                                               Args, false);
 577   return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
 578 }
 579
 580 Constant *GCOVProfiler::getEndFileFunc() {
 581   const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
 582   return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
 583 }
 584
 585 GlobalVariable *GCOVProfiler::getEdgeStateValue() {
 586   GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
 587   if (!GV) {
 588     GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
 589                             GlobalValue::InternalLinkage,
 590                             ConstantInt::get(Type::getInt32Ty(*Ctx),
 591                                              0xffffffff),
 592                             "__llvm_gcov_global_state_pred");
 593     GV->setUnnamedAddr(true);
 594   }
 595   return GV;
 596 }
 597
 598 void GCOVProfiler::insertCounterWriteout(
 599     DebugInfoFinder &DIF,
 600     SmallVector<std::pair<GlobalVariable *, uint32_t>, 8> &CountersByIdent) {
 601   const FunctionType *WriteoutFTy =
 602       FunctionType::get(Type::getVoidTy(*Ctx), false);
 603   Function *WriteoutF = Function::Create(WriteoutFTy,
 604                                          GlobalValue::InternalLinkage,
 605                                          "__llvm_gcov_writeout", M);
 606   WriteoutF->setUnnamedAddr(true);
 607   BasicBlock *BB = BasicBlock::Create(*Ctx, "", WriteoutF);
 608   IRBuilder<> Builder(BB);
 609
 610   Constant *StartFile = getStartFileFunc();
 611   Constant *EmitFunction = getEmitFunctionFunc();
 612   Constant *EmitArcs = getEmitArcsFunc();
 613   Constant *EndFile = getEndFileFunc();
 614
 615   for (DebugInfoFinder::iterator CUI = DIF.compile_unit_begin(),
 616            CUE = DIF.compile_unit_end(); CUI != CUE; ++CUI) {
 617     DICompileUnit compile_unit(*CUI);
 618     std::string FilenameGcda = replaceStem(compile_unit.getFilename(), "gcda");
 619     Builder.CreateCall(StartFile,
 620                        Builder.CreateGlobalStringPtr(FilenameGcda));
 621     for (SmallVector<std::pair<GlobalVariable *, uint32_t>, 8>::iterator
 622              I = CountersByIdent.begin(), E = CountersByIdent.end();
 623          I != E; ++I) {
 624       Builder.CreateCall(EmitFunction, ConstantInt::get(Type::getInt32Ty(*Ctx),
 625                                                         I->second));
 626       GlobalVariable *GV = I->first;
 627       unsigned Arcs =
 628           cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
 629       Builder.CreateCall2(EmitArcs,
 630                           ConstantInt::get(Type::getInt32Ty(*Ctx), Arcs),
 631                           Builder.CreateConstGEP2_64(GV, 0, 0));
 632     }
 633     Builder.CreateCall(EndFile);
 634   }
 635   Builder.CreateRetVoid();
 636
 637   InsertProfilingShutdownCall(WriteoutF, M);
 638 }