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 #include "llvm/Transforms/Instrumentation.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/Hashing.h"
20 #include "llvm/ADT/STLExtras.h"
21 #include "llvm/ADT/Statistic.h"
22 #include "llvm/ADT/StringExtras.h"
23 #include "llvm/ADT/StringMap.h"
24 #include "llvm/ADT/UniqueVector.h"
25 #include "llvm/IR/DebugInfo.h"
26 #include "llvm/IR/DebugLoc.h"
27 #include "llvm/IR/IRBuilder.h"
28 #include "llvm/IR/InstIterator.h"
29 #include "llvm/IR/Instructions.h"
30 #include "llvm/IR/IntrinsicInst.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/Pass.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/Debug.h"
35 #include "llvm/Support/FileSystem.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 <memory>
41 #include <string>
42 #include <utility>
43 using namespace llvm;
44
45 #define DEBUG_TYPE "insert-gcov-profiling"
46
47 static cl::opt<std::string>
48 DefaultGCOVVersion("default-gcov-version", cl::init("402*"), cl::Hidden,
49 cl::ValueRequired);
50 static cl::opt<bool> DefaultExitBlockBeforeBody("gcov-exit-block-before-body",
51 cl::init(false), cl::Hidden);
52
getDefault()53 GCOVOptions GCOVOptions::getDefault() {
54 GCOVOptions Options;
55 Options.EmitNotes = true;
56 Options.EmitData = true;
57 Options.UseCfgChecksum = false;
58 Options.NoRedZone = false;
59 Options.FunctionNamesInData = true;
60 Options.ExitBlockBeforeBody = DefaultExitBlockBeforeBody;
61
62 if (DefaultGCOVVersion.size() != 4) {
63 llvm::report_fatal_error(std::string("Invalid -default-gcov-version: ") +
64 DefaultGCOVVersion);
65 }
66 memcpy(Options.Version, DefaultGCOVVersion.c_str(), 4);
67 return Options;
68 }
69
70 namespace {
71 class GCOVFunction;
72
73 class GCOVProfiler : public ModulePass {
74 public:
75 static char ID;
GCOVProfiler()76 GCOVProfiler() : GCOVProfiler(GCOVOptions::getDefault()) {}
GCOVProfiler(const GCOVOptions & Opts)77 GCOVProfiler(const GCOVOptions &Opts) : ModulePass(ID), Options(Opts) {
78 assert((Options.EmitNotes || Options.EmitData) &&
79 "GCOVProfiler asked to do nothing?");
80 ReversedVersion[0] = Options.Version[3];
81 ReversedVersion[1] = Options.Version[2];
82 ReversedVersion[2] = Options.Version[1];
83 ReversedVersion[3] = Options.Version[0];
84 ReversedVersion[4] = '\0';
85 initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
86 }
getPassName() const87 const char *getPassName() const override {
88 return "GCOV Profiler";
89 }
90
91 private:
92 bool runOnModule(Module &M) override;
93
94 // Create the .gcno files for the Module based on DebugInfo.
95 void emitProfileNotes();
96
97 // Modify the program to track transitions along edges and call into the
98 // profiling runtime to emit .gcda files when run.
99 bool emitProfileArcs();
100
101 // Get pointers to the functions in the runtime library.
102 Constant *getStartFileFunc();
103 Constant *getIncrementIndirectCounterFunc();
104 Constant *getEmitFunctionFunc();
105 Constant *getEmitArcsFunc();
106 Constant *getSummaryInfoFunc();
107 Constant *getDeleteWriteoutFunctionListFunc();
108 Constant *getDeleteFlushFunctionListFunc();
109 Constant *getEndFileFunc();
110
111 // Create or retrieve an i32 state value that is used to represent the
112 // pred block number for certain non-trivial edges.
113 GlobalVariable *getEdgeStateValue();
114
115 // Produce a table of pointers to counters, by predecessor and successor
116 // block number.
117 GlobalVariable *buildEdgeLookupTable(Function *F,
118 GlobalVariable *Counter,
119 const UniqueVector<BasicBlock *>&Preds,
120 const UniqueVector<BasicBlock*>&Succs);
121
122 // Add the function to write out all our counters to the global destructor
123 // list.
124 Function *insertCounterWriteout(ArrayRef<std::pair<GlobalVariable*,
125 MDNode*> >);
126 Function *insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> >);
127 void insertIndirectCounterIncrement();
128
129 std::string mangleName(const DICompileUnit *CU, const char *NewStem);
130
131 GCOVOptions Options;
132
133 // Reversed, NUL-terminated copy of Options.Version.
134 char ReversedVersion[5];
135 // Checksum, produced by hash of EdgeDestinations
136 SmallVector<uint32_t, 4> FileChecksums;
137
138 Module *M;
139 LLVMContext *Ctx;
140 SmallVector<std::unique_ptr<GCOVFunction>, 16> Funcs;
141 };
142 }
143
144 char GCOVProfiler::ID = 0;
145 INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling",
146 "Insert instrumentation for GCOV profiling", false, false)
147
createGCOVProfilerPass(const GCOVOptions & Options)148 ModulePass *llvm::createGCOVProfilerPass(const GCOVOptions &Options) {
149 return new GCOVProfiler(Options);
150 }
151
getFunctionName(const DISubprogram * SP)152 static StringRef getFunctionName(const DISubprogram *SP) {
153 if (!SP->getLinkageName().empty())
154 return SP->getLinkageName();
155 return SP->getName();
156 }
157
158 namespace {
159 class GCOVRecord {
160 protected:
161 static const char *const LinesTag;
162 static const char *const FunctionTag;
163 static const char *const BlockTag;
164 static const char *const EdgeTag;
165
166 GCOVRecord() = default;
167
writeBytes(const char * Bytes,int Size)168 void writeBytes(const char *Bytes, int Size) {
169 os->write(Bytes, Size);
170 }
171
write(uint32_t i)172 void write(uint32_t i) {
173 writeBytes(reinterpret_cast<char*>(&i), 4);
174 }
175
176 // Returns the length measured in 4-byte blocks that will be used to
177 // represent this string in a GCOV file
lengthOfGCOVString(StringRef s)178 static unsigned lengthOfGCOVString(StringRef s) {
179 // A GCOV string is a length, followed by a NUL, then between 0 and 3 NULs
180 // padding out to the next 4-byte word. The length is measured in 4-byte
181 // words including padding, not bytes of actual string.
182 return (s.size() / 4) + 1;
183 }
184
writeGCOVString(StringRef s)185 void writeGCOVString(StringRef s) {
186 uint32_t Len = lengthOfGCOVString(s);
187 write(Len);
188 writeBytes(s.data(), s.size());
189
190 // Write 1 to 4 bytes of NUL padding.
191 assert((unsigned)(4 - (s.size() % 4)) > 0);
192 assert((unsigned)(4 - (s.size() % 4)) <= 4);
193 writeBytes("\0\0\0\0", 4 - (s.size() % 4));
194 }
195
196 raw_ostream *os;
197 };
198 const char *const GCOVRecord::LinesTag = "\0\0\x45\x01";
199 const char *const GCOVRecord::FunctionTag = "\0\0\0\1";
200 const char *const GCOVRecord::BlockTag = "\0\0\x41\x01";
201 const char *const GCOVRecord::EdgeTag = "\0\0\x43\x01";
202
203 class GCOVFunction;
204 class GCOVBlock;
205
206 // Constructed only by requesting it from a GCOVBlock, this object stores a
207 // list of line numbers and a single filename, representing lines that belong
208 // to the block.
209 class GCOVLines : public GCOVRecord {
210 public:
addLine(uint32_t Line)211 void addLine(uint32_t Line) {
212 assert(Line != 0 && "Line zero is not a valid real line number.");
213 Lines.push_back(Line);
214 }
215
length() const216 uint32_t length() const {
217 // Here 2 = 1 for string length + 1 for '0' id#.
218 return lengthOfGCOVString(Filename) + 2 + Lines.size();
219 }
220
writeOut()221 void writeOut() {
222 write(0);
223 writeGCOVString(Filename);
224 for (int i = 0, e = Lines.size(); i != e; ++i)
225 write(Lines[i]);
226 }
227
GCOVLines(StringRef F,raw_ostream * os)228 GCOVLines(StringRef F, raw_ostream *os)
229 : Filename(F) {
230 this->os = os;
231 }
232
233 private:
234 StringRef Filename;
235 SmallVector<uint32_t, 32> Lines;
236 };
237
238
239 // Represent a basic block in GCOV. Each block has a unique number in the
240 // function, number of lines belonging to each block, and a set of edges to
241 // other blocks.
242 class GCOVBlock : public GCOVRecord {
243 public:
getFile(StringRef Filename)244 GCOVLines &getFile(StringRef Filename) {
245 GCOVLines *&Lines = LinesByFile[Filename];
246 if (!Lines) {
247 Lines = new GCOVLines(Filename, os);
248 }
249 return *Lines;
250 }
251
addEdge(GCOVBlock & Successor)252 void addEdge(GCOVBlock &Successor) {
253 OutEdges.push_back(&Successor);
254 }
255
writeOut()256 void writeOut() {
257 uint32_t Len = 3;
258 SmallVector<StringMapEntry<GCOVLines *> *, 32> SortedLinesByFile;
259 for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
260 E = LinesByFile.end(); I != E; ++I) {
261 Len += I->second->length();
262 SortedLinesByFile.push_back(&*I);
263 }
264
265 writeBytes(LinesTag, 4);
266 write(Len);
267 write(Number);
268
269 std::sort(SortedLinesByFile.begin(), SortedLinesByFile.end(),
270 [](StringMapEntry<GCOVLines *> *LHS,
271 StringMapEntry<GCOVLines *> *RHS) {
272 return LHS->getKey() < RHS->getKey();
273 });
274 for (SmallVectorImpl<StringMapEntry<GCOVLines *> *>::iterator
275 I = SortedLinesByFile.begin(), E = SortedLinesByFile.end();
276 I != E; ++I)
277 (*I)->getValue()->writeOut();
278 write(0);
279 write(0);
280 }
281
~GCOVBlock()282 ~GCOVBlock() {
283 DeleteContainerSeconds(LinesByFile);
284 }
285
GCOVBlock(const GCOVBlock & RHS)286 GCOVBlock(const GCOVBlock &RHS) : GCOVRecord(RHS), Number(RHS.Number) {
287 // Only allow copy before edges and lines have been added. After that,
288 // there are inter-block pointers (eg: edges) that won't take kindly to
289 // blocks being copied or moved around.
290 assert(LinesByFile.empty());
291 assert(OutEdges.empty());
292 }
293
294 private:
295 friend class GCOVFunction;
296
GCOVBlock(uint32_t Number,raw_ostream * os)297 GCOVBlock(uint32_t Number, raw_ostream *os)
298 : Number(Number) {
299 this->os = os;
300 }
301
302 uint32_t Number;
303 StringMap<GCOVLines *> LinesByFile;
304 SmallVector<GCOVBlock *, 4> OutEdges;
305 };
306
307 // A function has a unique identifier, a checksum (we leave as zero) and a
308 // set of blocks and a map of edges between blocks. This is the only GCOV
309 // object users can construct, the blocks and lines will be rooted here.
310 class GCOVFunction : public GCOVRecord {
311 public:
GCOVFunction(const DISubprogram * SP,raw_ostream * os,uint32_t Ident,bool UseCfgChecksum,bool ExitBlockBeforeBody)312 GCOVFunction(const DISubprogram *SP, raw_ostream *os, uint32_t Ident,
313 bool UseCfgChecksum, bool ExitBlockBeforeBody)
314 : SP(SP), Ident(Ident), UseCfgChecksum(UseCfgChecksum), CfgChecksum(0),
315 ReturnBlock(1, os) {
316 this->os = os;
317
318 Function *F = SP->getFunction();
319 DEBUG(dbgs() << "Function: " << getFunctionName(SP) << "\n");
320
321 uint32_t i = 0;
322 for (auto &BB : *F) {
323 // Skip index 1 if it's assigned to the ReturnBlock.
324 if (i == 1 && ExitBlockBeforeBody)
325 ++i;
326 Blocks.insert(std::make_pair(&BB, GCOVBlock(i++, os)));
327 }
328 if (!ExitBlockBeforeBody)
329 ReturnBlock.Number = i;
330
331 std::string FunctionNameAndLine;
332 raw_string_ostream FNLOS(FunctionNameAndLine);
333 FNLOS << getFunctionName(SP) << SP->getLine();
334 FNLOS.flush();
335 FuncChecksum = hash_value(FunctionNameAndLine);
336 }
337
getBlock(BasicBlock * BB)338 GCOVBlock &getBlock(BasicBlock *BB) {
339 return Blocks.find(BB)->second;
340 }
341
getReturnBlock()342 GCOVBlock &getReturnBlock() {
343 return ReturnBlock;
344 }
345
getEdgeDestinations()346 std::string getEdgeDestinations() {
347 std::string EdgeDestinations;
348 raw_string_ostream EDOS(EdgeDestinations);
349 Function *F = Blocks.begin()->first->getParent();
350 for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
351 GCOVBlock &Block = getBlock(I);
352 for (int i = 0, e = Block.OutEdges.size(); i != e; ++i)
353 EDOS << Block.OutEdges[i]->Number;
354 }
355 return EdgeDestinations;
356 }
357
getFuncChecksum()358 uint32_t getFuncChecksum() {
359 return FuncChecksum;
360 }
361
setCfgChecksum(uint32_t Checksum)362 void setCfgChecksum(uint32_t Checksum) {
363 CfgChecksum = Checksum;
364 }
365
writeOut()366 void writeOut() {
367 writeBytes(FunctionTag, 4);
368 uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
369 1 + lengthOfGCOVString(SP->getFilename()) + 1;
370 if (UseCfgChecksum)
371 ++BlockLen;
372 write(BlockLen);
373 write(Ident);
374 write(FuncChecksum);
375 if (UseCfgChecksum)
376 write(CfgChecksum);
377 writeGCOVString(getFunctionName(SP));
378 writeGCOVString(SP->getFilename());
379 write(SP->getLine());
380
381 // Emit count of blocks.
382 writeBytes(BlockTag, 4);
383 write(Blocks.size() + 1);
384 for (int i = 0, e = Blocks.size() + 1; i != e; ++i) {
385 write(0); // No flags on our blocks.
386 }
387 DEBUG(dbgs() << Blocks.size() << " blocks.\n");
388
389 // Emit edges between blocks.
390 if (Blocks.empty()) return;
391 Function *F = Blocks.begin()->first->getParent();
392 for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
393 GCOVBlock &Block = getBlock(I);
394 if (Block.OutEdges.empty()) continue;
395
396 writeBytes(EdgeTag, 4);
397 write(Block.OutEdges.size() * 2 + 1);
398 write(Block.Number);
399 for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
400 DEBUG(dbgs() << Block.Number << " -> " << Block.OutEdges[i]->Number
401 << "\n");
402 write(Block.OutEdges[i]->Number);
403 write(0); // no flags
404 }
405 }
406
407 // Emit lines for each block.
408 for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
409 getBlock(I).writeOut();
410 }
411 }
412
413 private:
414 const DISubprogram *SP;
415 uint32_t Ident;
416 uint32_t FuncChecksum;
417 bool UseCfgChecksum;
418 uint32_t CfgChecksum;
419 DenseMap<BasicBlock *, GCOVBlock> Blocks;
420 GCOVBlock ReturnBlock;
421 };
422 }
423
mangleName(const DICompileUnit * CU,const char * NewStem)424 std::string GCOVProfiler::mangleName(const DICompileUnit *CU,
425 const char *NewStem) {
426 if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
427 for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
428 MDNode *N = GCov->getOperand(i);
429 if (N->getNumOperands() != 2) continue;
430 MDString *GCovFile = dyn_cast<MDString>(N->getOperand(0));
431 MDNode *CompileUnit = dyn_cast<MDNode>(N->getOperand(1));
432 if (!GCovFile || !CompileUnit) continue;
433 if (CompileUnit == CU) {
434 SmallString<128> Filename = GCovFile->getString();
435 sys::path::replace_extension(Filename, NewStem);
436 return Filename.str();
437 }
438 }
439 }
440
441 SmallString<128> Filename = CU->getFilename();
442 sys::path::replace_extension(Filename, NewStem);
443 StringRef FName = sys::path::filename(Filename);
444 SmallString<128> CurPath;
445 if (sys::fs::current_path(CurPath)) return FName;
446 sys::path::append(CurPath, FName);
447 return CurPath.str();
448 }
449
runOnModule(Module & M)450 bool GCOVProfiler::runOnModule(Module &M) {
451 this->M = &M;
452 Ctx = &M.getContext();
453
454 if (Options.EmitNotes) emitProfileNotes();
455 if (Options.EmitData) return emitProfileArcs();
456 return false;
457 }
458
functionHasLines(Function * F)459 static bool functionHasLines(Function *F) {
460 // Check whether this function actually has any source lines. Not only
461 // do these waste space, they also can crash gcov.
462 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
463 for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
464 I != IE; ++I) {
465 // Debug intrinsic locations correspond to the location of the
466 // declaration, not necessarily any statements or expressions.
467 if (isa<DbgInfoIntrinsic>(I)) continue;
468
469 const DebugLoc &Loc = I->getDebugLoc();
470 if (!Loc)
471 continue;
472
473 // Artificial lines such as calls to the global constructors.
474 if (Loc.getLine() == 0) continue;
475
476 return true;
477 }
478 }
479 return false;
480 }
481
emitProfileNotes()482 void GCOVProfiler::emitProfileNotes() {
483 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
484 if (!CU_Nodes) return;
485
486 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
487 // Each compile unit gets its own .gcno file. This means that whether we run
488 // this pass over the original .o's as they're produced, or run it after
489 // LTO, we'll generate the same .gcno files.
490
491 auto *CU = cast<DICompileUnit>(CU_Nodes->getOperand(i));
492 std::error_code EC;
493 raw_fd_ostream out(mangleName(CU, "gcno"), EC, sys::fs::F_None);
494 std::string EdgeDestinations;
495
496 unsigned FunctionIdent = 0;
497 for (auto *SP : CU->getSubprograms()) {
498 Function *F = SP->getFunction();
499 if (!F) continue;
500 if (!functionHasLines(F)) continue;
501
502 // gcov expects every function to start with an entry block that has a
503 // single successor, so split the entry block to make sure of that.
504 BasicBlock &EntryBlock = F->getEntryBlock();
505 BasicBlock::iterator It = EntryBlock.begin();
506 while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
507 ++It;
508 EntryBlock.splitBasicBlock(It);
509
510 Funcs.push_back(make_unique<GCOVFunction>(SP, &out, FunctionIdent++,
511 Options.UseCfgChecksum,
512 Options.ExitBlockBeforeBody));
513 GCOVFunction &Func = *Funcs.back();
514
515 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
516 GCOVBlock &Block = Func.getBlock(BB);
517 TerminatorInst *TI = BB->getTerminator();
518 if (int successors = TI->getNumSuccessors()) {
519 for (int i = 0; i != successors; ++i) {
520 Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
521 }
522 } else if (isa<ReturnInst>(TI)) {
523 Block.addEdge(Func.getReturnBlock());
524 }
525
526 uint32_t Line = 0;
527 for (BasicBlock::iterator I = BB->begin(), IE = BB->end();
528 I != IE; ++I) {
529 // Debug intrinsic locations correspond to the location of the
530 // declaration, not necessarily any statements or expressions.
531 if (isa<DbgInfoIntrinsic>(I)) continue;
532
533 const DebugLoc &Loc = I->getDebugLoc();
534 if (!Loc)
535 continue;
536
537 // Artificial lines such as calls to the global constructors.
538 if (Loc.getLine() == 0) continue;
539
540 if (Line == Loc.getLine()) continue;
541 Line = Loc.getLine();
542 if (SP != getDISubprogram(Loc.getScope()))
543 continue;
544
545 GCOVLines &Lines = Block.getFile(SP->getFilename());
546 Lines.addLine(Loc.getLine());
547 }
548 }
549 EdgeDestinations += Func.getEdgeDestinations();
550 }
551
552 FileChecksums.push_back(hash_value(EdgeDestinations));
553 out.write("oncg", 4);
554 out.write(ReversedVersion, 4);
555 out.write(reinterpret_cast<char*>(&FileChecksums.back()), 4);
556
557 for (auto &Func : Funcs) {
558 Func->setCfgChecksum(FileChecksums.back());
559 Func->writeOut();
560 }
561
562 out.write("\0\0\0\0\0\0\0\0", 8); // EOF
563 out.close();
564 }
565 }
566
emitProfileArcs()567 bool GCOVProfiler::emitProfileArcs() {
568 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
569 if (!CU_Nodes) return false;
570
571 bool Result = false;
572 bool InsertIndCounterIncrCode = false;
573 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
574 auto *CU = cast<DICompileUnit>(CU_Nodes->getOperand(i));
575 SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
576 for (auto *SP : CU->getSubprograms()) {
577 Function *F = SP->getFunction();
578 if (!F) continue;
579 if (!functionHasLines(F)) continue;
580 if (!Result) Result = true;
581 unsigned Edges = 0;
582 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
583 TerminatorInst *TI = BB->getTerminator();
584 if (isa<ReturnInst>(TI))
585 ++Edges;
586 else
587 Edges += TI->getNumSuccessors();
588 }
589
590 ArrayType *CounterTy =
591 ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
592 GlobalVariable *Counters =
593 new GlobalVariable(*M, CounterTy, false,
594 GlobalValue::InternalLinkage,
595 Constant::getNullValue(CounterTy),
596 "__llvm_gcov_ctr");
597 CountersBySP.push_back(std::make_pair(Counters, SP));
598
599 UniqueVector<BasicBlock *> ComplexEdgePreds;
600 UniqueVector<BasicBlock *> ComplexEdgeSuccs;
601
602 unsigned Edge = 0;
603 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
604 TerminatorInst *TI = BB->getTerminator();
605 int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
606 if (Successors) {
607 if (Successors == 1) {
608 IRBuilder<> Builder(BB->getFirstInsertionPt());
609 Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
610 Edge);
611 Value *Count = Builder.CreateLoad(Counter);
612 Count = Builder.CreateAdd(Count, Builder.getInt64(1));
613 Builder.CreateStore(Count, Counter);
614 } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
615 IRBuilder<> Builder(BI);
616 Value *Sel = Builder.CreateSelect(BI->getCondition(),
617 Builder.getInt64(Edge),
618 Builder.getInt64(Edge + 1));
619 SmallVector<Value *, 2> Idx;
620 Idx.push_back(Builder.getInt64(0));
621 Idx.push_back(Sel);
622 Value *Counter = Builder.CreateInBoundsGEP(Counters->getValueType(),
623 Counters, Idx);
624 Value *Count = Builder.CreateLoad(Counter);
625 Count = Builder.CreateAdd(Count, Builder.getInt64(1));
626 Builder.CreateStore(Count, Counter);
627 } else {
628 ComplexEdgePreds.insert(BB);
629 for (int i = 0; i != Successors; ++i)
630 ComplexEdgeSuccs.insert(TI->getSuccessor(i));
631 }
632
633 Edge += Successors;
634 }
635 }
636
637 if (!ComplexEdgePreds.empty()) {
638 GlobalVariable *EdgeTable =
639 buildEdgeLookupTable(F, Counters,
640 ComplexEdgePreds, ComplexEdgeSuccs);
641 GlobalVariable *EdgeState = getEdgeStateValue();
642
643 for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
644 IRBuilder<> Builder(ComplexEdgePreds[i + 1]->getFirstInsertionPt());
645 Builder.CreateStore(Builder.getInt32(i), EdgeState);
646 }
647
648 for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
649 // Call runtime to perform increment.
650 IRBuilder<> Builder(ComplexEdgeSuccs[i+1]->getFirstInsertionPt());
651 Value *CounterPtrArray =
652 Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
653 i * ComplexEdgePreds.size());
654
655 // Build code to increment the counter.
656 InsertIndCounterIncrCode = true;
657 Builder.CreateCall(getIncrementIndirectCounterFunc(),
658 {EdgeState, CounterPtrArray});
659 }
660 }
661 }
662
663 Function *WriteoutF = insertCounterWriteout(CountersBySP);
664 Function *FlushF = insertFlush(CountersBySP);
665
666 // Create a small bit of code that registers the "__llvm_gcov_writeout" to
667 // be executed at exit and the "__llvm_gcov_flush" function to be executed
668 // when "__gcov_flush" is called.
669 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
670 Function *F = Function::Create(FTy, GlobalValue::InternalLinkage,
671 "__llvm_gcov_init", M);
672 F->setUnnamedAddr(true);
673 F->setLinkage(GlobalValue::InternalLinkage);
674 F->addFnAttr(Attribute::NoInline);
675 if (Options.NoRedZone)
676 F->addFnAttr(Attribute::NoRedZone);
677
678 BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
679 IRBuilder<> Builder(BB);
680
681 FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
682 Type *Params[] = {
683 PointerType::get(FTy, 0),
684 PointerType::get(FTy, 0)
685 };
686 FTy = FunctionType::get(Builder.getVoidTy(), Params, false);
687
688 // Initialize the environment and register the local writeout and flush
689 // functions.
690 Constant *GCOVInit = M->getOrInsertFunction("llvm_gcov_init", FTy);
691 Builder.CreateCall(GCOVInit, {WriteoutF, FlushF});
692 Builder.CreateRetVoid();
693
694 appendToGlobalCtors(*M, F, 0);
695 }
696
697 if (InsertIndCounterIncrCode)
698 insertIndirectCounterIncrement();
699
700 return Result;
701 }
702
703 // All edges with successors that aren't branches are "complex", because it
704 // requires complex logic to pick which counter to update.
buildEdgeLookupTable(Function * F,GlobalVariable * Counters,const UniqueVector<BasicBlock * > & Preds,const UniqueVector<BasicBlock * > & Succs)705 GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
706 Function *F,
707 GlobalVariable *Counters,
708 const UniqueVector<BasicBlock *> &Preds,
709 const UniqueVector<BasicBlock *> &Succs) {
710 // TODO: support invoke, threads. We rely on the fact that nothing can modify
711 // the whole-Module pred edge# between the time we set it and the time we next
712 // read it. Threads and invoke make this untrue.
713
714 // emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
715 size_t TableSize = Succs.size() * Preds.size();
716 Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
717 ArrayType *EdgeTableTy = ArrayType::get(Int64PtrTy, TableSize);
718
719 std::unique_ptr<Constant * []> EdgeTable(new Constant *[TableSize]);
720 Constant *NullValue = Constant::getNullValue(Int64PtrTy);
721 for (size_t i = 0; i != TableSize; ++i)
722 EdgeTable[i] = NullValue;
723
724 unsigned Edge = 0;
725 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
726 TerminatorInst *TI = BB->getTerminator();
727 int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
728 if (Successors > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
729 for (int i = 0; i != Successors; ++i) {
730 BasicBlock *Succ = TI->getSuccessor(i);
731 IRBuilder<> Builder(Succ);
732 Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
733 Edge + i);
734 EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
735 (Preds.idFor(BB)-1)] = cast<Constant>(Counter);
736 }
737 }
738 Edge += Successors;
739 }
740
741 GlobalVariable *EdgeTableGV =
742 new GlobalVariable(
743 *M, EdgeTableTy, true, GlobalValue::InternalLinkage,
744 ConstantArray::get(EdgeTableTy,
745 makeArrayRef(&EdgeTable[0],TableSize)),
746 "__llvm_gcda_edge_table");
747 EdgeTableGV->setUnnamedAddr(true);
748 return EdgeTableGV;
749 }
750
getStartFileFunc()751 Constant *GCOVProfiler::getStartFileFunc() {
752 Type *Args[] = {
753 Type::getInt8PtrTy(*Ctx), // const char *orig_filename
754 Type::getInt8PtrTy(*Ctx), // const char version[4]
755 Type::getInt32Ty(*Ctx), // uint32_t checksum
756 };
757 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
758 return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
759 }
760
getIncrementIndirectCounterFunc()761 Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
762 Type *Int32Ty = Type::getInt32Ty(*Ctx);
763 Type *Int64Ty = Type::getInt64Ty(*Ctx);
764 Type *Args[] = {
765 Int32Ty->getPointerTo(), // uint32_t *predecessor
766 Int64Ty->getPointerTo()->getPointerTo() // uint64_t **counters
767 };
768 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
769 return M->getOrInsertFunction("__llvm_gcov_indirect_counter_increment", FTy);
770 }
771
getEmitFunctionFunc()772 Constant *GCOVProfiler::getEmitFunctionFunc() {
773 Type *Args[] = {
774 Type::getInt32Ty(*Ctx), // uint32_t ident
775 Type::getInt8PtrTy(*Ctx), // const char *function_name
776 Type::getInt32Ty(*Ctx), // uint32_t func_checksum
777 Type::getInt8Ty(*Ctx), // uint8_t use_extra_checksum
778 Type::getInt32Ty(*Ctx), // uint32_t cfg_checksum
779 };
780 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
781 return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
782 }
783
getEmitArcsFunc()784 Constant *GCOVProfiler::getEmitArcsFunc() {
785 Type *Args[] = {
786 Type::getInt32Ty(*Ctx), // uint32_t num_counters
787 Type::getInt64PtrTy(*Ctx), // uint64_t *counters
788 };
789 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
790 return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
791 }
792
getSummaryInfoFunc()793 Constant *GCOVProfiler::getSummaryInfoFunc() {
794 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
795 return M->getOrInsertFunction("llvm_gcda_summary_info", FTy);
796 }
797
getDeleteWriteoutFunctionListFunc()798 Constant *GCOVProfiler::getDeleteWriteoutFunctionListFunc() {
799 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
800 return M->getOrInsertFunction("llvm_delete_writeout_function_list", FTy);
801 }
802
getDeleteFlushFunctionListFunc()803 Constant *GCOVProfiler::getDeleteFlushFunctionListFunc() {
804 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
805 return M->getOrInsertFunction("llvm_delete_flush_function_list", FTy);
806 }
807
getEndFileFunc()808 Constant *GCOVProfiler::getEndFileFunc() {
809 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
810 return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
811 }
812
getEdgeStateValue()813 GlobalVariable *GCOVProfiler::getEdgeStateValue() {
814 GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
815 if (!GV) {
816 GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
817 GlobalValue::InternalLinkage,
818 ConstantInt::get(Type::getInt32Ty(*Ctx),
819 0xffffffff),
820 "__llvm_gcov_global_state_pred");
821 GV->setUnnamedAddr(true);
822 }
823 return GV;
824 }
825
insertCounterWriteout(ArrayRef<std::pair<GlobalVariable *,MDNode * >> CountersBySP)826 Function *GCOVProfiler::insertCounterWriteout(
827 ArrayRef<std::pair<GlobalVariable *, MDNode *> > CountersBySP) {
828 FunctionType *WriteoutFTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
829 Function *WriteoutF = M->getFunction("__llvm_gcov_writeout");
830 if (!WriteoutF)
831 WriteoutF = Function::Create(WriteoutFTy, GlobalValue::InternalLinkage,
832 "__llvm_gcov_writeout", M);
833 WriteoutF->setUnnamedAddr(true);
834 WriteoutF->addFnAttr(Attribute::NoInline);
835 if (Options.NoRedZone)
836 WriteoutF->addFnAttr(Attribute::NoRedZone);
837
838 BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", WriteoutF);
839 IRBuilder<> Builder(BB);
840
841 Constant *StartFile = getStartFileFunc();
842 Constant *EmitFunction = getEmitFunctionFunc();
843 Constant *EmitArcs = getEmitArcsFunc();
844 Constant *SummaryInfo = getSummaryInfoFunc();
845 Constant *EndFile = getEndFileFunc();
846
847 NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
848 if (CU_Nodes) {
849 for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
850 auto *CU = cast<DICompileUnit>(CU_Nodes->getOperand(i));
851 std::string FilenameGcda = mangleName(CU, "gcda");
852 uint32_t CfgChecksum = FileChecksums.empty() ? 0 : FileChecksums[i];
853 Builder.CreateCall(StartFile,
854 {Builder.CreateGlobalStringPtr(FilenameGcda),
855 Builder.CreateGlobalStringPtr(ReversedVersion),
856 Builder.getInt32(CfgChecksum)});
857 for (unsigned j = 0, e = CountersBySP.size(); j != e; ++j) {
858 auto *SP = cast_or_null<DISubprogram>(CountersBySP[j].second);
859 uint32_t FuncChecksum = Funcs.empty() ? 0 : Funcs[j]->getFuncChecksum();
860 Builder.CreateCall(
861 EmitFunction,
862 {Builder.getInt32(j),
863 Options.FunctionNamesInData
864 ? Builder.CreateGlobalStringPtr(getFunctionName(SP))
865 : Constant::getNullValue(Builder.getInt8PtrTy()),
866 Builder.getInt32(FuncChecksum),
867 Builder.getInt8(Options.UseCfgChecksum),
868 Builder.getInt32(CfgChecksum)});
869
870 GlobalVariable *GV = CountersBySP[j].first;
871 unsigned Arcs =
872 cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
873 Builder.CreateCall(EmitArcs, {Builder.getInt32(Arcs),
874 Builder.CreateConstGEP2_64(GV, 0, 0)});
875 }
876 Builder.CreateCall(SummaryInfo, {});
877 Builder.CreateCall(EndFile, {});
878 }
879 }
880
881 Builder.CreateRetVoid();
882 return WriteoutF;
883 }
884
insertIndirectCounterIncrement()885 void GCOVProfiler::insertIndirectCounterIncrement() {
886 Function *Fn =
887 cast<Function>(GCOVProfiler::getIncrementIndirectCounterFunc());
888 Fn->setUnnamedAddr(true);
889 Fn->setLinkage(GlobalValue::InternalLinkage);
890 Fn->addFnAttr(Attribute::NoInline);
891 if (Options.NoRedZone)
892 Fn->addFnAttr(Attribute::NoRedZone);
893
894 // Create basic blocks for function.
895 BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", Fn);
896 IRBuilder<> Builder(BB);
897
898 BasicBlock *PredNotNegOne = BasicBlock::Create(*Ctx, "", Fn);
899 BasicBlock *CounterEnd = BasicBlock::Create(*Ctx, "", Fn);
900 BasicBlock *Exit = BasicBlock::Create(*Ctx, "exit", Fn);
901
902 // uint32_t pred = *predecessor;
903 // if (pred == 0xffffffff) return;
904 Argument *Arg = Fn->arg_begin();
905 Arg->setName("predecessor");
906 Value *Pred = Builder.CreateLoad(Arg, "pred");
907 Value *Cond = Builder.CreateICmpEQ(Pred, Builder.getInt32(0xffffffff));
908 BranchInst::Create(Exit, PredNotNegOne, Cond, BB);
909
910 Builder.SetInsertPoint(PredNotNegOne);
911
912 // uint64_t *counter = counters[pred];
913 // if (!counter) return;
914 Value *ZExtPred = Builder.CreateZExt(Pred, Builder.getInt64Ty());
915 Arg = std::next(Fn->arg_begin());
916 Arg->setName("counters");
917 Value *GEP = Builder.CreateGEP(Type::getInt64PtrTy(*Ctx), Arg, ZExtPred);
918 Value *Counter = Builder.CreateLoad(GEP, "counter");
919 Cond = Builder.CreateICmpEQ(Counter,
920 Constant::getNullValue(
921 Builder.getInt64Ty()->getPointerTo()));
922 Builder.CreateCondBr(Cond, Exit, CounterEnd);
923
924 // ++*counter;
925 Builder.SetInsertPoint(CounterEnd);
926 Value *Add = Builder.CreateAdd(Builder.CreateLoad(Counter),
927 Builder.getInt64(1));
928 Builder.CreateStore(Add, Counter);
929 Builder.CreateBr(Exit);
930
931 // Fill in the exit block.
932 Builder.SetInsertPoint(Exit);
933 Builder.CreateRetVoid();
934 }
935
936 Function *GCOVProfiler::
insertFlush(ArrayRef<std::pair<GlobalVariable *,MDNode * >> CountersBySP)937 insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> > CountersBySP) {
938 FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
939 Function *FlushF = M->getFunction("__llvm_gcov_flush");
940 if (!FlushF)
941 FlushF = Function::Create(FTy, GlobalValue::InternalLinkage,
942 "__llvm_gcov_flush", M);
943 else
944 FlushF->setLinkage(GlobalValue::InternalLinkage);
945 FlushF->setUnnamedAddr(true);
946 FlushF->addFnAttr(Attribute::NoInline);
947 if (Options.NoRedZone)
948 FlushF->addFnAttr(Attribute::NoRedZone);
949
950 BasicBlock *Entry = BasicBlock::Create(*Ctx, "entry", FlushF);
951
952 // Write out the current counters.
953 Constant *WriteoutF = M->getFunction("__llvm_gcov_writeout");
954 assert(WriteoutF && "Need to create the writeout function first!");
955
956 IRBuilder<> Builder(Entry);
957 Builder.CreateCall(WriteoutF, {});
958
959 // Zero out the counters.
960 for (ArrayRef<std::pair<GlobalVariable *, MDNode *> >::iterator
961 I = CountersBySP.begin(), E = CountersBySP.end();
962 I != E; ++I) {
963 GlobalVariable *GV = I->first;
964 Constant *Null = Constant::getNullValue(GV->getType()->getElementType());
965 Builder.CreateStore(Null, GV);
966 }
967
968 Type *RetTy = FlushF->getReturnType();
969 if (RetTy == Type::getVoidTy(*Ctx))
970 Builder.CreateRetVoid();
971 else if (RetTy->isIntegerTy())
972 // Used if __llvm_gcov_flush was implicitly declared.
973 Builder.CreateRet(ConstantInt::get(RetTy, 0));
974 else
975 report_fatal_error("invalid return type for __llvm_gcov_flush");
976
977 return FlushF;
978 }
979