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