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 and a single filename, representing lines that belong
163 class GCOVLines : public GCOVRecord {
165 void addLine(uint32_t Line) {
166 Lines.push_back(Line);
170 // Here 2 = 1 for string lenght + 1 for '0' id#.
171 return lengthOfGCOVString(Filename) + 2 + Lines.size();
176 writeGCOVString(Filename);
177 for (int i = 0, e = Lines.size(); i != e; ++i)
181 friend class GCOVBlock;
183 GCOVLines(StringRef F, raw_ostream *os)
189 SmallVector<uint32_t, 32> Lines;
192 // Represent a basic block in GCOV. Each block has a unique number in the
193 // function, number of lines belonging to each block, and a set of edges to
195 class GCOVBlock : public GCOVRecord {
197 GCOVLines &getFile(StringRef Filename) {
198 GCOVLines *&Lines = LinesByFile[Filename];
200 Lines = new GCOVLines(Filename, os);
205 void addEdge(GCOVBlock &Successor) {
206 OutEdges.push_back(&Successor);
211 for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
212 E = LinesByFile.end(); I != E; ++I) {
213 Len += I->second->length();
216 writeBytes(LinesTag, 4);
219 for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
220 E = LinesByFile.end(); I != E; ++I)
221 I->second->writeOut();
227 DeleteContainerSeconds(LinesByFile);
231 friend class GCOVFunction;
233 GCOVBlock(uint32_t Number, raw_ostream *os)
239 StringMap<GCOVLines *> LinesByFile;
240 SmallVector<GCOVBlock *, 4> OutEdges;
243 // A function has a unique identifier, a checksum (we leave as zero) and a
244 // set of blocks and a map of edges between blocks. This is the only GCOV
245 // object users can construct, the blocks and lines will be rooted here.
246 class GCOVFunction : public GCOVRecord {
248 GCOVFunction(DISubprogram SP, raw_ostream *os, bool Use402Format) {
251 Function *F = SP.getFunction();
253 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
254 Blocks[BB] = new GCOVBlock(i++, os);
256 ReturnBlock = new GCOVBlock(i++, os);
258 writeBytes(FunctionTag, 4);
259 uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(SP.getName()) +
260 1 + lengthOfGCOVString(SP.getFilename()) + 1;
262 ++BlockLen; // For second checksum.
264 uint32_t Ident = reinterpret_cast<intptr_t>((MDNode*)SP);
266 write(0); // checksum #1
268 write(0); // checksum #2
269 writeGCOVString(SP.getName());
270 writeGCOVString(SP.getFilename());
271 write(SP.getLineNumber());
275 DeleteContainerSeconds(Blocks);
279 GCOVBlock &getBlock(BasicBlock *BB) {
283 GCOVBlock &getReturnBlock() {
288 // Emit count of blocks.
289 writeBytes(BlockTag, 4);
290 write(Blocks.size() + 1);
291 for (int i = 0, e = Blocks.size() + 1; i != e; ++i) {
292 write(0); // No flags on our blocks.
295 // Emit edges between blocks.
296 for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = Blocks.begin(),
297 E = Blocks.end(); I != E; ++I) {
298 GCOVBlock &Block = *I->second;
299 if (Block.OutEdges.empty()) continue;
301 writeBytes(EdgeTag, 4);
302 write(Block.OutEdges.size() * 2 + 1);
304 for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
305 write(Block.OutEdges[i]->Number);
306 write(0); // no flags
310 // Emit lines for each block.
311 for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = Blocks.begin(),
312 E = Blocks.end(); I != E; ++I) {
313 I->second->writeOut();
318 DenseMap<BasicBlock *, GCOVBlock *> Blocks;
319 GCOVBlock *ReturnBlock;
323 std::string GCOVProfiler::mangleName(DICompileUnit CU, std::string NewStem) {
324 if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
325 for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
326 MDNode *N = GCov->getOperand(i);
327 if (N->getNumOperands() != 2) continue;
328 MDString *GCovFile = dyn_cast<MDString>(N->getOperand(0));
329 MDNode *CompileUnit = dyn_cast<MDNode>(N->getOperand(1));
330 if (!GCovFile || !CompileUnit) continue;
331 if (CompileUnit == CU) {
332 SmallString<128> Filename = GCovFile->getString();
333 sys::path::replace_extension(Filename, NewStem);
334 return Filename.str();
339 SmallString<128> Filename = CU.getFilename();
340 sys::path::replace_extension(Filename, NewStem);
341 return sys::path::filename(Filename.str());
344 bool GCOVProfiler::runOnModule(Module &M) {
346 Ctx = &M.getContext();
348 if (EmitNotes) emitGCNO();
349 if (EmitData) return emitProfileArcs();
353 void GCOVProfiler::emitGCNO() {
354 DenseMap<const MDNode *, raw_fd_ostream *> GcnoFiles;
355 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
357 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
358 // Each compile unit gets its own .gcno file. This means that whether we run
359 // this pass over the original .o's as they're produced, or run it after
360 // LTO, we'll generate the same .gcno files.
362 DICompileUnit CU(CU_Nodes->getOperand(i));
363 raw_fd_ostream *&out = GcnoFiles[CU];
364 std::string ErrorInfo;
365 out = new raw_fd_ostream(mangleName(CU, "gcno").c_str(), ErrorInfo,
366 raw_fd_ostream::F_Binary);
368 out->write("oncg*404MVLL", 12);
370 out->write("oncg*204MVLL", 12);
372 DIArray SPs = CU.getSubprograms();
373 for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
374 DISubprogram SP(SPs.getElement(i));
375 if (!SP.Verify()) continue;
376 raw_fd_ostream *&os = GcnoFiles[CU];
378 Function *F = SP.getFunction();
380 GCOVFunction Func(SP, os, Use402Format);
382 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
383 GCOVBlock &Block = Func.getBlock(BB);
384 TerminatorInst *TI = BB->getTerminator();
385 if (int successors = TI->getNumSuccessors()) {
386 for (int i = 0; i != successors; ++i) {
387 Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
389 } else if (isa<ReturnInst>(TI)) {
390 Block.addEdge(Func.getReturnBlock());
394 for (BasicBlock::iterator I = BB->begin(), IE = BB->end(); I != IE; ++I) {
395 const DebugLoc &Loc = I->getDebugLoc();
396 if (Loc.isUnknown()) continue;
397 if (Line == Loc.getLine()) continue;
398 Line = Loc.getLine();
399 if (SP != getDISubprogram(Loc.getScope(*Ctx))) continue;
401 GCOVLines &Lines = Block.getFile(SP.getFilename());
402 Lines.addLine(Loc.getLine());
410 for (DenseMap<const MDNode *, raw_fd_ostream *>::iterator
411 I = GcnoFiles.begin(), E = GcnoFiles.end(); I != E; ++I) {
412 raw_fd_ostream *&out = I->second;
413 out->write("\0\0\0\0\0\0\0\0", 8); // EOF
419 bool GCOVProfiler::emitProfileArcs() {
420 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
421 if (!CU_Nodes) return false;
424 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
425 DICompileUnit CU(CU_Nodes->getOperand(i));
426 DIArray SPs = CU.getSubprograms();
427 SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
428 for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
429 DISubprogram SP(SPs.getElement(i));
430 if (!SP.Verify()) continue;
431 Function *F = SP.getFunction();
433 if (!Result) Result = true;
435 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
436 TerminatorInst *TI = BB->getTerminator();
437 if (isa<ReturnInst>(TI))
440 Edges += TI->getNumSuccessors();
443 ArrayType *CounterTy =
444 ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
445 GlobalVariable *Counters =
446 new GlobalVariable(*M, CounterTy, false,
447 GlobalValue::InternalLinkage,
448 Constant::getNullValue(CounterTy),
449 "__llvm_gcov_ctr", 0, false, 0);
450 CountersBySP.push_back(std::make_pair(Counters, (MDNode*)SP));
452 UniqueVector<BasicBlock *> ComplexEdgePreds;
453 UniqueVector<BasicBlock *> ComplexEdgeSuccs;
456 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
457 TerminatorInst *TI = BB->getTerminator();
458 int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
460 IRBuilder<> Builder(TI);
462 if (Successors == 1) {
463 Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
465 Value *Count = Builder.CreateLoad(Counter);
466 Count = Builder.CreateAdd(Count,
467 ConstantInt::get(Type::getInt64Ty(*Ctx),1));
468 Builder.CreateStore(Count, Counter);
469 } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
470 Value *Sel = Builder.CreateSelect(
472 ConstantInt::get(Type::getInt64Ty(*Ctx), Edge),
473 ConstantInt::get(Type::getInt64Ty(*Ctx), Edge + 1));
474 SmallVector<Value *, 2> Idx;
475 Idx.push_back(Constant::getNullValue(Type::getInt64Ty(*Ctx)));
477 Value *Counter = Builder.CreateInBoundsGEP(Counters, Idx);
478 Value *Count = Builder.CreateLoad(Counter);
479 Count = Builder.CreateAdd(Count,
480 ConstantInt::get(Type::getInt64Ty(*Ctx),1));
481 Builder.CreateStore(Count, Counter);
483 ComplexEdgePreds.insert(BB);
484 for (int i = 0; i != Successors; ++i)
485 ComplexEdgeSuccs.insert(TI->getSuccessor(i));
491 if (!ComplexEdgePreds.empty()) {
492 GlobalVariable *EdgeTable =
493 buildEdgeLookupTable(F, Counters,
494 ComplexEdgePreds, ComplexEdgeSuccs);
495 GlobalVariable *EdgeState = getEdgeStateValue();
497 Type *Int32Ty = Type::getInt32Ty(*Ctx);
498 for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
499 IRBuilder<> Builder(ComplexEdgePreds[i+1]->getTerminator());
500 Builder.CreateStore(ConstantInt::get(Int32Ty, i), EdgeState);
502 for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
503 // call runtime to perform increment
504 BasicBlock::iterator InsertPt =
505 ComplexEdgeSuccs[i+1]->getFirstInsertionPt();
506 IRBuilder<> Builder(InsertPt);
507 Value *CounterPtrArray =
508 Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
509 i * ComplexEdgePreds.size());
510 Builder.CreateCall2(getIncrementIndirectCounterFunc(),
511 EdgeState, CounterPtrArray);
512 // clear the predecessor number
513 Builder.CreateStore(ConstantInt::get(Int32Ty, 0xffffffff), EdgeState);
517 insertCounterWriteout(CountersBySP);
522 // All edges with successors that aren't branches are "complex", because it
523 // requires complex logic to pick which counter to update.
524 GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
526 GlobalVariable *Counters,
527 const UniqueVector<BasicBlock *> &Preds,
528 const UniqueVector<BasicBlock *> &Succs) {
529 // TODO: support invoke, threads. We rely on the fact that nothing can modify
530 // the whole-Module pred edge# between the time we set it and the time we next
531 // read it. Threads and invoke make this untrue.
533 // emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
534 Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
535 ArrayType *EdgeTableTy = ArrayType::get(
536 Int64PtrTy, Succs.size() * Preds.size());
538 Constant **EdgeTable = new Constant*[Succs.size() * Preds.size()];
539 Constant *NullValue = Constant::getNullValue(Int64PtrTy);
540 for (int i = 0, ie = Succs.size() * Preds.size(); i != ie; ++i)
541 EdgeTable[i] = NullValue;
544 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
545 TerminatorInst *TI = BB->getTerminator();
546 int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
547 if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
548 for (int i = 0; i != Successors; ++i) {
549 BasicBlock *Succ = TI->getSuccessor(i);
550 IRBuilder<> builder(Succ);
551 Value *Counter = builder.CreateConstInBoundsGEP2_64(Counters, 0,
553 EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
554 (Preds.idFor(BB)-1)] = cast<Constant>(Counter);
560 ArrayRef<Constant*> V(&EdgeTable[0], Succs.size() * Preds.size());
561 GlobalVariable *EdgeTableGV =
563 *M, EdgeTableTy, true, GlobalValue::InternalLinkage,
564 ConstantArray::get(EdgeTableTy, V),
565 "__llvm_gcda_edge_table");
566 EdgeTableGV->setUnnamedAddr(true);
570 Constant *GCOVProfiler::getStartFileFunc() {
571 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
572 Type::getInt8PtrTy(*Ctx), false);
573 return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
576 Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
578 Type::getInt32PtrTy(*Ctx), // uint32_t *predecessor
579 Type::getInt64PtrTy(*Ctx)->getPointerTo(), // uint64_t **state_table_row
581 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
583 return M->getOrInsertFunction("llvm_gcda_increment_indirect_counter", FTy);
586 Constant *GCOVProfiler::getEmitFunctionFunc() {
588 Type::getInt32Ty(*Ctx), // uint32_t ident
589 Type::getInt8PtrTy(*Ctx), // const char *function_name
591 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
593 return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
596 Constant *GCOVProfiler::getEmitArcsFunc() {
598 Type::getInt32Ty(*Ctx), // uint32_t num_counters
599 Type::getInt64PtrTy(*Ctx), // uint64_t *counters
601 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
603 return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
606 Constant *GCOVProfiler::getEndFileFunc() {
607 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
608 return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
611 GlobalVariable *GCOVProfiler::getEdgeStateValue() {
612 GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
614 GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
615 GlobalValue::InternalLinkage,
616 ConstantInt::get(Type::getInt32Ty(*Ctx),
618 "__llvm_gcov_global_state_pred");
619 GV->setUnnamedAddr(true);
624 void GCOVProfiler::insertCounterWriteout(
625 SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> &CountersBySP) {
626 FunctionType *WriteoutFTy =
627 FunctionType::get(Type::getVoidTy(*Ctx), false);
628 Function *WriteoutF = Function::Create(WriteoutFTy,
629 GlobalValue::InternalLinkage,
630 "__llvm_gcov_writeout", M);
631 WriteoutF->setUnnamedAddr(true);
632 BasicBlock *BB = BasicBlock::Create(*Ctx, "", WriteoutF);
633 IRBuilder<> Builder(BB);
635 Constant *StartFile = getStartFileFunc();
636 Constant *EmitFunction = getEmitFunctionFunc();
637 Constant *EmitArcs = getEmitArcsFunc();
638 Constant *EndFile = getEndFileFunc();
640 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
642 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
643 DICompileUnit compile_unit(CU_Nodes->getOperand(i));
644 std::string FilenameGcda = mangleName(compile_unit, "gcda");
645 Builder.CreateCall(StartFile,
646 Builder.CreateGlobalStringPtr(FilenameGcda));
647 for (SmallVector<std::pair<GlobalVariable *, MDNode *>, 8>::iterator
648 I = CountersBySP.begin(), E = CountersBySP.end();
650 DISubprogram SP(I->second);
651 intptr_t ident = reinterpret_cast<intptr_t>(I->second);
652 Builder.CreateCall2(EmitFunction,
653 ConstantInt::get(Type::getInt32Ty(*Ctx), ident),
654 Builder.CreateGlobalStringPtr(SP.getName()));
656 GlobalVariable *GV = I->first;
658 cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
659 Builder.CreateCall2(EmitArcs,
660 ConstantInt::get(Type::getInt32Ty(*Ctx), Arcs),
661 Builder.CreateConstGEP2_64(GV, 0, 0));
663 Builder.CreateCall(EndFile);
666 Builder.CreateRetVoid();
668 InsertProfilingShutdownCall(WriteoutF, M);