llvm/lib/Transforms/Utils/SanitizerStats.cpp

   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(PointerType::getUnqual(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(),
  37                          {PointerType::getUnqual(M->getContext()),
  38                           Type::getInt32Ty(M->getContext()),
  39                           makeModuleStatsArrayTy()});
  40 }
  41
  42 void SanitizerStatReport::create(IRBuilder<> &B, SanitizerStatKind SK) {
  43   Function *F = B.GetInsertBlock()->getParent();
  44   Module *M = F->getParent();
  45   PointerType *PtrTy = B.getPtrTy();
  46   IntegerType *IntPtrTy = B.getIntPtrTy(M->getDataLayout());
  47   ArrayType *StatTy = ArrayType::get(PtrTy, 2);
  48
  49   Inits.push_back(ConstantArray::get(
  50       StatTy,
  51       {Constant::getNullValue(PtrTy),
  52        ConstantExpr::getIntToPtr(
  53            ConstantInt::get(IntPtrTy, uint64_t(SK) << (IntPtrTy->getBitWidth() -
  54                                                        kSanitizerStatKindBits)),
  55            PtrTy)}));
  56
  57   FunctionType *StatReportTy = FunctionType::get(B.getVoidTy(), PtrTy, 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, InitAddr);
  68 }
  69
  70 void SanitizerStatReport::finish() {
  71   if (Inits.empty()) {
  72     ModuleStatsGV->eraseFromParent();
  73     return;
  74   }
  75
  76   PointerType *Int8PtrTy = PointerType::getUnqual(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(NewModuleStatsGV);
  89   ModuleStatsGV->eraseFromParent();
  90
  91   // Create a global constructor to register NewModuleStatsGV.
  92   auto F = Function::Create(FunctionType::get(VoidTy, false),
  93                             GlobalValue::InternalLinkage, "", M);
  94   auto BB = BasicBlock::Create(M->getContext(), "", F);
  95   IRBuilder<> B(BB);
  96
  97   FunctionType *StatInitTy = FunctionType::get(VoidTy, Int8PtrTy, false);
  98   FunctionCallee StatInit =
  99       M->getOrInsertFunction("__sanitizer_stat_init", StatInitTy);
 100
 101   B.CreateCall(StatInit, NewModuleStatsGV);
 102   B.CreateRetVoid();
 103
 104   appendToGlobalCtors(*M, F, 0);
 105 }