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