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