1 //===- GCOVProfiling.cpp - Insert edge counters for gcov profiling --------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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"
15 //===----------------------------------------------------------------------===//
17 #define DEBUG_TYPE "insert-gcov-profiling"
19 #include "ProfilingUtils.h"
20 #include "llvm/Transforms/Instrumentation.h"
21 #include "llvm/Analysis/DebugInfo.h"
22 #include "llvm/Module.h"
23 #include "llvm/Pass.h"
24 #include "llvm/Instructions.h"
25 #include "llvm/Support/raw_ostream.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/DebugLoc.h"
28 #include "llvm/Support/InstIterator.h"
29 #include "llvm/Support/IRBuilder.h"
30 #include "llvm/Support/PathV2.h"
31 #include "llvm/ADT/DenseMap.h"
32 #include "llvm/ADT/Statistic.h"
33 #include "llvm/ADT/STLExtras.h"
34 #include "llvm/ADT/StringExtras.h"
35 #include "llvm/ADT/StringMap.h"
36 #include "llvm/ADT/UniqueVector.h"
42 class GCOVProfiler : public ModulePass {
46 : ModulePass(ID), EmitNotes(true), EmitData(true), Use402Format(false) {
47 initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
49 GCOVProfiler(bool EmitNotes, bool EmitData, bool use402Format = false)
50 : ModulePass(ID), EmitNotes(EmitNotes), EmitData(EmitData),
51 Use402Format(use402Format) {
52 assert((EmitNotes || EmitData) && "GCOVProfiler asked to do nothing?");
53 initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
55 virtual const char *getPassName() const {
56 return "GCOV Profiler";
60 bool runOnModule(Module &M);
62 // Create the GCNO files for the Module based on DebugInfo.
65 // Modify the program to track transitions along edges and call into the
66 // profiling runtime to emit .gcda files when run.
67 bool emitProfileArcs();
69 // Get pointers to the functions in the runtime library.
70 Constant *getStartFileFunc();
71 Constant *getIncrementIndirectCounterFunc();
72 Constant *getEmitFunctionFunc();
73 Constant *getEmitArcsFunc();
74 Constant *getEndFileFunc();
76 // Create or retrieve an i32 state value that is used to represent the
77 // pred block number for certain non-trivial edges.
78 GlobalVariable *getEdgeStateValue();
80 // Produce a table of pointers to counters, by predecessor and successor
82 GlobalVariable *buildEdgeLookupTable(Function *F,
83 GlobalVariable *Counter,
84 const UniqueVector<BasicBlock *> &Preds,
85 const UniqueVector<BasicBlock *> &Succs);
87 // Add the function to write out all our counters to the global destructor
89 void insertCounterWriteout(SmallVector<std::pair<GlobalVariable *,
92 std::string mangleName(DICompileUnit CU, std::string NewStem);
103 char GCOVProfiler::ID = 0;
104 INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling",
105 "Insert instrumentation for GCOV profiling", false, false)
107 ModulePass *llvm::createGCOVProfilerPass(bool EmitNotes, bool EmitData,
109 return new GCOVProfiler(EmitNotes, EmitData, Use402Format);
115 static const char *LinesTag;
116 static const char *FunctionTag;
117 static const char *BlockTag;
118 static const char *EdgeTag;
122 void writeBytes(const char *Bytes, int Size) {
123 os->write(Bytes, Size);
126 void write(uint32_t i) {
127 writeBytes(reinterpret_cast<char*>(&i), 4);
130 // Returns the length measured in 4-byte blocks that will be used to
131 // represent this string in a GCOV file
132 unsigned lengthOfGCOVString(StringRef s) {
133 // A GCOV string is a length, followed by a NUL, then between 0 and 3 NULs
134 // padding out to the next 4-byte word. The length is measured in 4-byte
135 // words including padding, not bytes of actual string.
136 return (s.size() / 4) + 1;
139 void writeGCOVString(StringRef s) {
140 uint32_t Len = lengthOfGCOVString(s);
142 writeBytes(s.data(), s.size());
144 // Write 1 to 4 bytes of NUL padding.
145 assert((unsigned)(4 - (s.size() % 4)) > 0);
146 assert((unsigned)(4 - (s.size() % 4)) <= 4);
147 writeBytes("\0\0\0\0", 4 - (s.size() % 4));
152 const char *GCOVRecord::LinesTag = "\0\0\x45\x01";
153 const char *GCOVRecord::FunctionTag = "\0\0\0\1";
154 const char *GCOVRecord::BlockTag = "\0\0\x41\x01";
155 const char *GCOVRecord::EdgeTag = "\0\0\x43\x01";
160 // Constructed only by requesting it from a GCOVBlock, this object stores a
161 // list of line numbers representing lines that belong to the block.
162 class GCOVLines : public GCOVRecord {
164 void addLine(uint32_t Line) {
165 Lines.push_back(Line);
169 // FIXME: ??? What is the significance of 2 here ?
170 return 2 + Lines.size();
174 friend class GCOVBlock;
176 GCOVLines(raw_ostream *os) {
180 SmallVector<uint32_t, 32> Lines;
183 // Represent a basic block in GCOV. Each block has a unique number in the
184 // function, number of lines belonging to each block, and a set of edges to
186 class GCOVBlock : public GCOVRecord {
188 GCOVLines &getFile(StringRef Filename) {
189 GCOVLines *&Lines = LinesByFile[Filename];
191 Lines = new GCOVLines(os);
196 void addEdge(GCOVBlock &Successor) {
197 OutEdges.push_back(&Successor);
202 for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
203 E = LinesByFile.end(); I != E; ++I) {
204 Len = Len + lengthOfGCOVString(I->first()) + I->second->length();
207 writeBytes(LinesTag, 4);
210 for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
211 E = LinesByFile.end(); I != E; ++I) {
213 writeGCOVString(I->first());
214 for (int i = 0, e = I->second->Lines.size(); i != e; ++i) {
215 write(I->second->Lines[i]);
223 DeleteContainerSeconds(LinesByFile);
227 friend class GCOVFunction;
229 GCOVBlock(uint32_t Number, raw_ostream *os)
235 StringMap<GCOVLines *> LinesByFile;
236 SmallVector<GCOVBlock *, 4> OutEdges;
239 // A function has a unique identifier, a checksum (we leave as zero) and a
240 // set of blocks and a map of edges between blocks. This is the only GCOV
241 // object users can construct, the blocks and lines will be rooted here.
242 class GCOVFunction : public GCOVRecord {
244 GCOVFunction(DISubprogram SP, raw_ostream *os, bool Use402Format) {
247 Function *F = SP.getFunction();
249 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
250 Blocks[BB] = new GCOVBlock(i++, os);
252 ReturnBlock = new GCOVBlock(i++, os);
254 writeBytes(FunctionTag, 4);
255 uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(SP.getName()) +
256 1 + lengthOfGCOVString(SP.getFilename()) + 1;
258 ++BlockLen; // For second checksum.
260 uint32_t Ident = reinterpret_cast<intptr_t>((MDNode*)SP);
262 write(0); // checksum #1
264 write(0); // checksum #2
265 writeGCOVString(SP.getName());
266 writeGCOVString(SP.getFilename());
267 write(SP.getLineNumber());
271 DeleteContainerSeconds(Blocks);
275 GCOVBlock &getBlock(BasicBlock *BB) {
279 GCOVBlock &getReturnBlock() {
284 // Emit count of blocks.
285 writeBytes(BlockTag, 4);
286 write(Blocks.size() + 1);
287 for (int i = 0, e = Blocks.size() + 1; i != e; ++i) {
288 write(0); // No flags on our blocks.
291 // Emit edges between blocks.
292 for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = Blocks.begin(),
293 E = Blocks.end(); I != E; ++I) {
294 GCOVBlock &Block = *I->second;
295 if (Block.OutEdges.empty()) continue;
297 writeBytes(EdgeTag, 4);
298 write(Block.OutEdges.size() * 2 + 1);
300 for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
301 write(Block.OutEdges[i]->Number);
302 write(0); // no flags
306 // Emit lines for each block.
307 for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = Blocks.begin(),
308 E = Blocks.end(); I != E; ++I) {
309 I->second->writeOut();
314 DenseMap<BasicBlock *, GCOVBlock *> Blocks;
315 GCOVBlock *ReturnBlock;
319 std::string GCOVProfiler::mangleName(DICompileUnit CU, std::string NewStem) {
320 if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
321 for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
322 MDNode *N = GCov->getOperand(i);
323 if (N->getNumOperands() != 2) continue;
324 MDString *GCovFile = dyn_cast<MDString>(N->getOperand(0));
325 MDNode *CompileUnit = dyn_cast<MDNode>(N->getOperand(1));
326 if (!GCovFile || !CompileUnit) continue;
327 if (CompileUnit == CU) {
328 SmallString<128> Filename = GCovFile->getString();
329 sys::path::replace_extension(Filename, NewStem);
330 return Filename.str();
335 SmallString<128> Filename = CU.getFilename();
336 sys::path::replace_extension(Filename, NewStem);
337 return sys::path::filename(Filename.str());
340 bool GCOVProfiler::runOnModule(Module &M) {
342 Ctx = &M.getContext();
344 if (EmitNotes) emitGCNO();
345 if (EmitData) return emitProfileArcs();
349 void GCOVProfiler::emitGCNO() {
350 DenseMap<const MDNode *, raw_fd_ostream *> GcnoFiles;
351 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
353 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
354 // Each compile unit gets its own .gcno file. This means that whether we run
355 // this pass over the original .o's as they're produced, or run it after
356 // LTO, we'll generate the same .gcno files.
358 DICompileUnit CU(CU_Nodes->getOperand(i));
359 raw_fd_ostream *&out = GcnoFiles[CU];
360 std::string ErrorInfo;
361 out = new raw_fd_ostream(mangleName(CU, "gcno").c_str(), ErrorInfo,
362 raw_fd_ostream::F_Binary);
364 out->write("oncg*404MVLL", 12);
366 out->write("oncg*204MVLL", 12);
368 DIArray SPs = CU.getSubprograms();
369 for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
370 DISubprogram SP(SPs.getElement(i));
371 if (!SP.Verify()) continue;
372 raw_fd_ostream *&os = GcnoFiles[CU];
374 Function *F = SP.getFunction();
376 GCOVFunction Func(SP, os, Use402Format);
378 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
379 GCOVBlock &Block = Func.getBlock(BB);
380 TerminatorInst *TI = BB->getTerminator();
381 if (int successors = TI->getNumSuccessors()) {
382 for (int i = 0; i != successors; ++i) {
383 Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
385 } else if (isa<ReturnInst>(TI)) {
386 Block.addEdge(Func.getReturnBlock());
390 for (BasicBlock::iterator I = BB->begin(), IE = BB->end(); I != IE; ++I) {
391 const DebugLoc &Loc = I->getDebugLoc();
392 if (Loc.isUnknown()) continue;
393 if (Line == Loc.getLine()) continue;
394 Line = Loc.getLine();
395 if (SP != getDISubprogram(Loc.getScope(*Ctx))) continue;
397 GCOVLines &Lines = Block.getFile(SP.getFilename());
398 Lines.addLine(Loc.getLine());
406 for (DenseMap<const MDNode *, raw_fd_ostream *>::iterator
407 I = GcnoFiles.begin(), E = GcnoFiles.end(); I != E; ++I) {
408 raw_fd_ostream *&out = I->second;
409 out->write("\0\0\0\0\0\0\0\0", 8); // EOF
415 bool GCOVProfiler::emitProfileArcs() {
416 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
417 if (!CU_Nodes) return false;
420 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
421 DICompileUnit CU(CU_Nodes->getOperand(i));
422 DIArray SPs = CU.getSubprograms();
423 SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
424 for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
425 DISubprogram SP(SPs.getElement(i));
426 if (!SP.Verify()) continue;
427 Function *F = SP.getFunction();
429 if (!Result) Result = true;
431 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
432 TerminatorInst *TI = BB->getTerminator();
433 if (isa<ReturnInst>(TI))
436 Edges += TI->getNumSuccessors();
439 ArrayType *CounterTy =
440 ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
441 GlobalVariable *Counters =
442 new GlobalVariable(*M, CounterTy, false,
443 GlobalValue::InternalLinkage,
444 Constant::getNullValue(CounterTy),
445 "__llvm_gcov_ctr", 0, false, 0);
446 CountersBySP.push_back(std::make_pair(Counters, (MDNode*)SP));
448 UniqueVector<BasicBlock *> ComplexEdgePreds;
449 UniqueVector<BasicBlock *> ComplexEdgeSuccs;
452 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
453 TerminatorInst *TI = BB->getTerminator();
454 int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
456 IRBuilder<> Builder(TI);
458 if (Successors == 1) {
459 Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
461 Value *Count = Builder.CreateLoad(Counter);
462 Count = Builder.CreateAdd(Count,
463 ConstantInt::get(Type::getInt64Ty(*Ctx),1));
464 Builder.CreateStore(Count, Counter);
465 } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
466 Value *Sel = Builder.CreateSelect(
468 ConstantInt::get(Type::getInt64Ty(*Ctx), Edge),
469 ConstantInt::get(Type::getInt64Ty(*Ctx), Edge + 1));
470 SmallVector<Value *, 2> Idx;
471 Idx.push_back(Constant::getNullValue(Type::getInt64Ty(*Ctx)));
473 Value *Counter = Builder.CreateInBoundsGEP(Counters, Idx);
474 Value *Count = Builder.CreateLoad(Counter);
475 Count = Builder.CreateAdd(Count,
476 ConstantInt::get(Type::getInt64Ty(*Ctx),1));
477 Builder.CreateStore(Count, Counter);
479 ComplexEdgePreds.insert(BB);
480 for (int i = 0; i != Successors; ++i)
481 ComplexEdgeSuccs.insert(TI->getSuccessor(i));
487 if (!ComplexEdgePreds.empty()) {
488 GlobalVariable *EdgeTable =
489 buildEdgeLookupTable(F, Counters,
490 ComplexEdgePreds, ComplexEdgeSuccs);
491 GlobalVariable *EdgeState = getEdgeStateValue();
493 Type *Int32Ty = Type::getInt32Ty(*Ctx);
494 for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
495 IRBuilder<> Builder(ComplexEdgePreds[i+1]->getTerminator());
496 Builder.CreateStore(ConstantInt::get(Int32Ty, i), EdgeState);
498 for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
499 // call runtime to perform increment
500 BasicBlock::iterator InsertPt =
501 ComplexEdgeSuccs[i+1]->getFirstInsertionPt();
502 IRBuilder<> Builder(InsertPt);
503 Value *CounterPtrArray =
504 Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
505 i * ComplexEdgePreds.size());
506 Builder.CreateCall2(getIncrementIndirectCounterFunc(),
507 EdgeState, CounterPtrArray);
508 // clear the predecessor number
509 Builder.CreateStore(ConstantInt::get(Int32Ty, 0xffffffff), EdgeState);
513 insertCounterWriteout(CountersBySP);
518 // All edges with successors that aren't branches are "complex", because it
519 // requires complex logic to pick which counter to update.
520 GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
522 GlobalVariable *Counters,
523 const UniqueVector<BasicBlock *> &Preds,
524 const UniqueVector<BasicBlock *> &Succs) {
525 // TODO: support invoke, threads. We rely on the fact that nothing can modify
526 // the whole-Module pred edge# between the time we set it and the time we next
527 // read it. Threads and invoke make this untrue.
529 // emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
530 Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
531 ArrayType *EdgeTableTy = ArrayType::get(
532 Int64PtrTy, Succs.size() * Preds.size());
534 Constant **EdgeTable = new Constant*[Succs.size() * Preds.size()];
535 Constant *NullValue = Constant::getNullValue(Int64PtrTy);
536 for (int i = 0, ie = Succs.size() * Preds.size(); i != ie; ++i)
537 EdgeTable[i] = NullValue;
540 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
541 TerminatorInst *TI = BB->getTerminator();
542 int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
543 if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
544 for (int i = 0; i != Successors; ++i) {
545 BasicBlock *Succ = TI->getSuccessor(i);
546 IRBuilder<> builder(Succ);
547 Value *Counter = builder.CreateConstInBoundsGEP2_64(Counters, 0,
549 EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
550 (Preds.idFor(BB)-1)] = cast<Constant>(Counter);
556 ArrayRef<Constant*> V(&EdgeTable[0], Succs.size() * Preds.size());
557 GlobalVariable *EdgeTableGV =
559 *M, EdgeTableTy, true, GlobalValue::InternalLinkage,
560 ConstantArray::get(EdgeTableTy, V),
561 "__llvm_gcda_edge_table");
562 EdgeTableGV->setUnnamedAddr(true);
566 Constant *GCOVProfiler::getStartFileFunc() {
567 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
568 Type::getInt8PtrTy(*Ctx), false);
569 return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
572 Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
574 Type::getInt32PtrTy(*Ctx), // uint32_t *predecessor
575 Type::getInt64PtrTy(*Ctx)->getPointerTo(), // uint64_t **state_table_row
577 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
579 return M->getOrInsertFunction("llvm_gcda_increment_indirect_counter", FTy);
582 Constant *GCOVProfiler::getEmitFunctionFunc() {
584 Type::getInt32Ty(*Ctx), // uint32_t ident
585 Type::getInt8PtrTy(*Ctx), // const char *function_name
587 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
589 return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
592 Constant *GCOVProfiler::getEmitArcsFunc() {
594 Type::getInt32Ty(*Ctx), // uint32_t num_counters
595 Type::getInt64PtrTy(*Ctx), // uint64_t *counters
597 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
599 return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
602 Constant *GCOVProfiler::getEndFileFunc() {
603 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
604 return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
607 GlobalVariable *GCOVProfiler::getEdgeStateValue() {
608 GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
610 GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
611 GlobalValue::InternalLinkage,
612 ConstantInt::get(Type::getInt32Ty(*Ctx),
614 "__llvm_gcov_global_state_pred");
615 GV->setUnnamedAddr(true);
620 void GCOVProfiler::insertCounterWriteout(
621 SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> &CountersBySP) {
622 FunctionType *WriteoutFTy =
623 FunctionType::get(Type::getVoidTy(*Ctx), false);
624 Function *WriteoutF = Function::Create(WriteoutFTy,
625 GlobalValue::InternalLinkage,
626 "__llvm_gcov_writeout", M);
627 WriteoutF->setUnnamedAddr(true);
628 BasicBlock *BB = BasicBlock::Create(*Ctx, "", WriteoutF);
629 IRBuilder<> Builder(BB);
631 Constant *StartFile = getStartFileFunc();
632 Constant *EmitFunction = getEmitFunctionFunc();
633 Constant *EmitArcs = getEmitArcsFunc();
634 Constant *EndFile = getEndFileFunc();
636 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
638 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
639 DICompileUnit compile_unit(CU_Nodes->getOperand(i));
640 std::string FilenameGcda = mangleName(compile_unit, "gcda");
641 Builder.CreateCall(StartFile,
642 Builder.CreateGlobalStringPtr(FilenameGcda));
643 for (SmallVector<std::pair<GlobalVariable *, MDNode *>, 8>::iterator
644 I = CountersBySP.begin(), E = CountersBySP.end();
646 DISubprogram SP(I->second);
647 intptr_t ident = reinterpret_cast<intptr_t>(I->second);
648 Builder.CreateCall2(EmitFunction,
649 ConstantInt::get(Type::getInt32Ty(*Ctx), ident),
650 Builder.CreateGlobalStringPtr(SP.getName()));
652 GlobalVariable *GV = I->first;
654 cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
655 Builder.CreateCall2(EmitArcs,
656 ConstantInt::get(Type::getInt32Ty(*Ctx), Arcs),
657 Builder.CreateConstGEP2_64(GV, 0, 0));
659 Builder.CreateCall(EndFile);
662 Builder.CreateRetVoid();
664 InsertProfilingShutdownCall(WriteoutF, M);