1 //===-- InstrProfiling.cpp - Frontend instrumentation based 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 lowers instrprof_increment intrinsics emitted by a frontend for
11 // profiling. It also builds the data structures and initialization code needed
12 // for updating execution counts and emitting the profile at runtime.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Instrumentation.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/IR/IRBuilder.h"
20 #include "llvm/IR/IntrinsicInst.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Transforms/Utils/ModuleUtils.h"
26 #define DEBUG_TYPE "instrprof"
30 class InstrProfiling : public ModulePass {
34 InstrProfiling() : ModulePass(ID) {}
36 InstrProfiling(const InstrProfOptions &Options)
37 : ModulePass(ID), Options(Options) {}
39 const char *getPassName() const override {
40 return "Frontend instrumentation-based coverage lowering";
43 bool runOnModule(Module &M) override;
45 void getAnalysisUsage(AnalysisUsage &AU) const override {
50 InstrProfOptions Options;
52 DenseMap<GlobalVariable *, GlobalVariable *> RegionCounters;
53 std::vector<Value *> UsedVars;
55 bool isMachO() const {
56 return Triple(M->getTargetTriple()).isOSBinFormatMachO();
59 /// Get the section name for the counter variables.
60 StringRef getCountersSection() const {
61 return isMachO() ? "__DATA,__llvm_prf_cnts" : "__llvm_prf_cnts";
64 /// Get the section name for the name variables.
65 StringRef getNameSection() const {
66 return isMachO() ? "__DATA,__llvm_prf_names" : "__llvm_prf_names";
69 /// Get the section name for the profile data variables.
70 StringRef getDataSection() const {
71 return isMachO() ? "__DATA,__llvm_prf_data" : "__llvm_prf_data";
74 /// Get the section name for the coverage mapping data.
75 StringRef getCoverageSection() const {
76 return isMachO() ? "__DATA,__llvm_covmap" : "__llvm_covmap";
79 /// Replace instrprof_increment with an increment of the appropriate value.
80 void lowerIncrement(InstrProfIncrementInst *Inc);
82 /// Set up the section and uses for coverage data and its references.
83 void lowerCoverageData(GlobalVariable *CoverageData);
85 /// Get the region counters for an increment, creating them if necessary.
87 /// If the counter array doesn't yet exist, the profile data variables
88 /// referring to them will also be created.
89 GlobalVariable *getOrCreateRegionCounters(InstrProfIncrementInst *Inc);
91 /// Emit runtime registration functions for each profile data variable.
92 void emitRegistration();
94 /// Emit the necessary plumbing to pull in the runtime initialization.
95 void emitRuntimeHook();
97 /// Add uses of our data variables and runtime hook.
100 /// Create a static initializer for our data, on platforms that need it,
101 /// and for any profile output file that was specified.
102 void emitInitialization();
105 } // anonymous namespace
107 char InstrProfiling::ID = 0;
108 INITIALIZE_PASS(InstrProfiling, "instrprof",
109 "Frontend instrumentation-based coverage lowering.", false,
112 ModulePass *llvm::createInstrProfilingPass(const InstrProfOptions &Options) {
113 return new InstrProfiling(Options);
116 bool InstrProfiling::runOnModule(Module &M) {
117 bool MadeChange = false;
120 RegionCounters.clear();
123 for (Function &F : M)
124 for (BasicBlock &BB : F)
125 for (auto I = BB.begin(), E = BB.end(); I != E;)
126 if (auto *Inc = dyn_cast<InstrProfIncrementInst>(I++)) {
130 if (GlobalVariable *Coverage = M.getNamedGlobal("__llvm_coverage_mapping")) {
131 lowerCoverageData(Coverage);
140 emitInitialization();
144 void InstrProfiling::lowerIncrement(InstrProfIncrementInst *Inc) {
145 GlobalVariable *Counters = getOrCreateRegionCounters(Inc);
147 IRBuilder<> Builder(Inc->getParent(), *Inc);
148 uint64_t Index = Inc->getIndex()->getZExtValue();
149 Value *Addr = Builder.CreateConstInBoundsGEP2_64(Counters, 0, Index);
150 Value *Count = Builder.CreateLoad(Addr, "pgocount");
151 Count = Builder.CreateAdd(Count, Builder.getInt64(1));
152 Inc->replaceAllUsesWith(Builder.CreateStore(Count, Addr));
153 Inc->eraseFromParent();
156 void InstrProfiling::lowerCoverageData(GlobalVariable *CoverageData) {
157 CoverageData->setSection(getCoverageSection());
158 CoverageData->setAlignment(8);
160 Constant *Init = CoverageData->getInitializer();
161 // We're expecting { i32, i32, i32, i32, [n x { i8*, i32, i32 }], [m x i8] }
162 // for some C. If not, the frontend's given us something broken.
163 assert(Init->getNumOperands() == 6 && "bad number of fields in coverage map");
164 assert(isa<ConstantArray>(Init->getAggregateElement(4)) &&
165 "invalid function list in coverage map");
166 ConstantArray *Records = cast<ConstantArray>(Init->getAggregateElement(4));
167 for (unsigned I = 0, E = Records->getNumOperands(); I < E; ++I) {
168 Constant *Record = Records->getOperand(I);
169 Value *V = const_cast<Value *>(Record->getOperand(0))->stripPointerCasts();
171 assert(isa<GlobalVariable>(V) && "Missing reference to function name");
172 GlobalVariable *Name = cast<GlobalVariable>(V);
174 // If we have region counters for this name, we've already handled it.
175 auto It = RegionCounters.find(Name);
176 if (It != RegionCounters.end())
179 // Move the name variable to the right section.
180 Name->setSection(getNameSection());
181 Name->setAlignment(1);
185 /// Get the name of a profiling variable for a particular function.
186 static std::string getVarName(InstrProfIncrementInst *Inc, StringRef VarName) {
187 auto *Arr = cast<ConstantDataArray>(Inc->getName()->getInitializer());
188 StringRef Name = Arr->isCString() ? Arr->getAsCString() : Arr->getAsString();
189 return ("__llvm_profile_" + VarName + "_" + Name).str();
193 InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
194 GlobalVariable *Name = Inc->getName();
195 auto It = RegionCounters.find(Name);
196 if (It != RegionCounters.end())
199 // Move the name variable to the right section. Make sure it is placed in the
200 // same comdat as its associated function. Otherwise, we may get multiple
201 // counters for the same function in certain cases.
202 Function *Fn = Inc->getParent()->getParent();
203 Name->setSection(getNameSection());
204 Name->setAlignment(1);
205 Name->setComdat(Fn->getComdat());
207 uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
208 LLVMContext &Ctx = M->getContext();
209 ArrayType *CounterTy = ArrayType::get(Type::getInt64Ty(Ctx), NumCounters);
211 // Create the counters variable.
212 auto *Counters = new GlobalVariable(*M, CounterTy, false, Name->getLinkage(),
213 Constant::getNullValue(CounterTy),
214 getVarName(Inc, "counters"));
215 Counters->setVisibility(Name->getVisibility());
216 Counters->setSection(getCountersSection());
217 Counters->setAlignment(8);
218 Counters->setComdat(Fn->getComdat());
220 RegionCounters[Inc->getName()] = Counters;
222 // Create data variable.
223 auto *NameArrayTy = Name->getType()->getPointerElementType();
224 auto *Int32Ty = Type::getInt32Ty(Ctx);
225 auto *Int64Ty = Type::getInt64Ty(Ctx);
226 auto *Int8PtrTy = Type::getInt8PtrTy(Ctx);
227 auto *Int64PtrTy = Type::getInt64PtrTy(Ctx);
229 Type *DataTypes[] = {Int32Ty, Int32Ty, Int64Ty, Int8PtrTy, Int64PtrTy};
230 auto *DataTy = StructType::get(Ctx, makeArrayRef(DataTypes));
231 Constant *DataVals[] = {
232 ConstantInt::get(Int32Ty, NameArrayTy->getArrayNumElements()),
233 ConstantInt::get(Int32Ty, NumCounters),
234 ConstantInt::get(Int64Ty, Inc->getHash()->getZExtValue()),
235 ConstantExpr::getBitCast(Name, Int8PtrTy),
236 ConstantExpr::getBitCast(Counters, Int64PtrTy)};
237 auto *Data = new GlobalVariable(*M, DataTy, true, Name->getLinkage(),
238 ConstantStruct::get(DataTy, DataVals),
239 getVarName(Inc, "data"));
240 Data->setVisibility(Name->getVisibility());
241 Data->setSection(getDataSection());
242 Data->setAlignment(8);
243 Data->setComdat(Fn->getComdat());
245 // Mark the data variable as used so that it isn't stripped out.
246 UsedVars.push_back(Data);
251 void InstrProfiling::emitRegistration() {
252 // Don't do this for Darwin. compiler-rt uses linker magic.
253 if (Triple(M->getTargetTriple()).isOSDarwin())
256 // Construct the function.
257 auto *VoidTy = Type::getVoidTy(M->getContext());
258 auto *VoidPtrTy = Type::getInt8PtrTy(M->getContext());
259 auto *RegisterFTy = FunctionType::get(VoidTy, false);
260 auto *RegisterF = Function::Create(RegisterFTy, GlobalValue::InternalLinkage,
261 "__llvm_profile_register_functions", M);
262 RegisterF->setUnnamedAddr(true);
263 if (Options.NoRedZone)
264 RegisterF->addFnAttr(Attribute::NoRedZone);
266 auto *RuntimeRegisterTy = FunctionType::get(VoidTy, VoidPtrTy, false);
267 auto *RuntimeRegisterF =
268 Function::Create(RuntimeRegisterTy, GlobalVariable::ExternalLinkage,
269 "__llvm_profile_register_function", M);
271 IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", RegisterF));
272 for (Value *Data : UsedVars)
273 IRB.CreateCall(RuntimeRegisterF, IRB.CreateBitCast(Data, VoidPtrTy));
277 void InstrProfiling::emitRuntimeHook() {
278 const char *const RuntimeVarName = "__llvm_profile_runtime";
279 const char *const RuntimeUserName = "__llvm_profile_runtime_user";
281 // If the module's provided its own runtime, we don't need to do anything.
282 if (M->getGlobalVariable(RuntimeVarName))
285 // Declare an external variable that will pull in the runtime initialization.
286 auto *Int32Ty = Type::getInt32Ty(M->getContext());
288 new GlobalVariable(*M, Int32Ty, false, GlobalValue::ExternalLinkage,
289 nullptr, RuntimeVarName);
291 // Make a function that uses it.
293 Function::Create(FunctionType::get(Int32Ty, false),
294 GlobalValue::LinkOnceODRLinkage, RuntimeUserName, M);
295 User->addFnAttr(Attribute::NoInline);
296 if (Options.NoRedZone)
297 User->addFnAttr(Attribute::NoRedZone);
298 User->setVisibility(GlobalValue::HiddenVisibility);
300 IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", User));
301 auto *Load = IRB.CreateLoad(Var);
304 // Mark the user variable as used so that it isn't stripped out.
305 UsedVars.push_back(User);
308 void InstrProfiling::emitUses() {
309 if (UsedVars.empty())
312 GlobalVariable *LLVMUsed = M->getGlobalVariable("llvm.used");
313 std::vector<Constant *> MergedVars;
315 // Collect the existing members of llvm.used.
316 ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
317 for (unsigned I = 0, E = Inits->getNumOperands(); I != E; ++I)
318 MergedVars.push_back(Inits->getOperand(I));
319 LLVMUsed->eraseFromParent();
322 Type *i8PTy = Type::getInt8PtrTy(M->getContext());
323 // Add uses for our data.
324 for (auto *Value : UsedVars)
325 MergedVars.push_back(
326 ConstantExpr::getBitCast(cast<Constant>(Value), i8PTy));
328 // Recreate llvm.used.
329 ArrayType *ATy = ArrayType::get(i8PTy, MergedVars.size());
331 new GlobalVariable(*M, ATy, false, GlobalValue::AppendingLinkage,
332 ConstantArray::get(ATy, MergedVars), "llvm.used");
334 LLVMUsed->setSection("llvm.metadata");
337 void InstrProfiling::emitInitialization() {
338 std::string InstrProfileOutput = Options.InstrProfileOutput;
340 Constant *RegisterF = M->getFunction("__llvm_profile_register_functions");
341 if (!RegisterF && InstrProfileOutput.empty())
344 // Create the initialization function.
345 auto *VoidTy = Type::getVoidTy(M->getContext());
347 Function::Create(FunctionType::get(VoidTy, false),
348 GlobalValue::InternalLinkage, "__llvm_profile_init", M);
349 F->setUnnamedAddr(true);
350 F->addFnAttr(Attribute::NoInline);
351 if (Options.NoRedZone)
352 F->addFnAttr(Attribute::NoRedZone);
354 // Add the basic block and the necessary calls.
355 IRBuilder<> IRB(BasicBlock::Create(M->getContext(), "", F));
357 IRB.CreateCall(RegisterF, {});
358 if (!InstrProfileOutput.empty()) {
359 auto *Int8PtrTy = Type::getInt8PtrTy(M->getContext());
360 auto *SetNameTy = FunctionType::get(VoidTy, Int8PtrTy, false);
362 Function::Create(SetNameTy, GlobalValue::ExternalLinkage,
363 "__llvm_profile_override_default_filename", M);
365 // Create variable for profile name.
366 Constant *ProfileNameConst =
367 ConstantDataArray::getString(M->getContext(), InstrProfileOutput, true);
368 GlobalVariable *ProfileName =
369 new GlobalVariable(*M, ProfileNameConst->getType(), true,
370 GlobalValue::PrivateLinkage, ProfileNameConst);
372 IRB.CreateCall(SetNameF, IRB.CreatePointerCast(ProfileName, Int8PtrTy));
376 appendToGlobalCtors(*M, F, 0);