1 //===- SanitizerStats.cpp - Sanitizer statistics gathering ----------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Implements code generation for sanitizer statistics gathering. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/Transforms/Utils/SanitizerStats.h" 14 #include "llvm/IR/Constants.h" 15 #include "llvm/IR/DerivedTypes.h" 16 #include "llvm/IR/GlobalVariable.h" 17 #include "llvm/IR/IRBuilder.h" 18 #include "llvm/IR/Module.h" 19 #include "llvm/Transforms/Utils/ModuleUtils.h" 20 21 using namespace llvm; 22 23 SanitizerStatReport::SanitizerStatReport(Module *M) : M(M) { 24 StatTy = ArrayType::get(Type::getInt8PtrTy(M->getContext()), 2); 25 EmptyModuleStatsTy = makeModuleStatsTy(); 26 27 ModuleStatsGV = new GlobalVariable(*M, EmptyModuleStatsTy, false, 28 GlobalValue::InternalLinkage, nullptr); 29 } 30 31 ArrayType *SanitizerStatReport::makeModuleStatsArrayTy() { 32 return ArrayType::get(StatTy, Inits.size()); 33 } 34 35 StructType *SanitizerStatReport::makeModuleStatsTy() { 36 return StructType::get(M->getContext(), {Type::getInt8PtrTy(M->getContext()), 37 Type::getInt32Ty(M->getContext()), 38 makeModuleStatsArrayTy()}); 39 } 40 41 void SanitizerStatReport::create(IRBuilder<> &B, SanitizerStatKind SK) { 42 Function *F = B.GetInsertBlock()->getParent(); 43 Module *M = F->getParent(); 44 PointerType *Int8PtrTy = B.getInt8PtrTy(); 45 IntegerType *IntPtrTy = B.getIntPtrTy(M->getDataLayout()); 46 ArrayType *StatTy = ArrayType::get(Int8PtrTy, 2); 47 48 Inits.push_back(ConstantArray::get( 49 StatTy, 50 {Constant::getNullValue(Int8PtrTy), 51 ConstantExpr::getIntToPtr( 52 ConstantInt::get(IntPtrTy, uint64_t(SK) << (IntPtrTy->getBitWidth() - 53 kSanitizerStatKindBits)), 54 Int8PtrTy)})); 55 56 FunctionType *StatReportTy = 57 FunctionType::get(B.getVoidTy(), Int8PtrTy, false); 58 FunctionCallee StatReport = 59 M->getOrInsertFunction("__sanitizer_stat_report", StatReportTy); 60 61 auto InitAddr = ConstantExpr::getGetElementPtr( 62 EmptyModuleStatsTy, ModuleStatsGV, 63 ArrayRef<Constant *>{ 64 ConstantInt::get(IntPtrTy, 0), ConstantInt::get(B.getInt32Ty(), 2), 65 ConstantInt::get(IntPtrTy, Inits.size() - 1), 66 }); 67 B.CreateCall(StatReport, ConstantExpr::getBitCast(InitAddr, Int8PtrTy)); 68 } 69 70 void SanitizerStatReport::finish() { 71 if (Inits.empty()) { 72 ModuleStatsGV->eraseFromParent(); 73 return; 74 } 75 76 PointerType *Int8PtrTy = Type::getInt8PtrTy(M->getContext()); 77 IntegerType *Int32Ty = Type::getInt32Ty(M->getContext()); 78 Type *VoidTy = Type::getVoidTy(M->getContext()); 79 80 // Create a new ModuleStatsGV to replace the old one. We can't just set the 81 // old one's initializer because its type is different. 82 auto NewModuleStatsGV = new GlobalVariable( 83 *M, makeModuleStatsTy(), false, GlobalValue::InternalLinkage, 84 ConstantStruct::getAnon( 85 {Constant::getNullValue(Int8PtrTy), 86 ConstantInt::get(Int32Ty, Inits.size()), 87 ConstantArray::get(makeModuleStatsArrayTy(), Inits)})); 88 ModuleStatsGV->replaceAllUsesWith( 89 ConstantExpr::getBitCast(NewModuleStatsGV, ModuleStatsGV->getType())); 90 ModuleStatsGV->eraseFromParent(); 91 92 // Create a global constructor to register NewModuleStatsGV. 93 auto F = Function::Create(FunctionType::get(VoidTy, false), 94 GlobalValue::InternalLinkage, "", M); 95 auto BB = BasicBlock::Create(M->getContext(), "", F); 96 IRBuilder<> B(BB); 97 98 FunctionType *StatInitTy = FunctionType::get(VoidTy, Int8PtrTy, false); 99 FunctionCallee StatInit = 100 M->getOrInsertFunction("__sanitizer_stat_init", StatInitTy); 101 102 B.CreateCall(StatInit, ConstantExpr::getBitCast(NewModuleStatsGV, Int8PtrTy)); 103 B.CreateRetVoid(); 104 105 appendToGlobalCtors(*M, F, 0); 106 } 107