1 //===-- EHContGuardTargets.cpp - EH continuation target symbols -*- C++ -*-===// 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 /// \file 10 /// This file contains a machine function pass to insert a symbol before each 11 /// valid target where the unwinder in Windows may continue exectution after an 12 /// exception is thrown and store this in the MachineFunction's EHContTargets 13 /// vector. This will be used to emit the table of valid targets used by Windows 14 /// EH Continuation Guard. 15 /// 16 //===----------------------------------------------------------------------===// 17 18 #include "llvm/ADT/Statistic.h" 19 #include "llvm/CodeGen/MachineBasicBlock.h" 20 #include "llvm/CodeGen/MachineFunctionPass.h" 21 #include "llvm/CodeGen/MachineModuleInfo.h" 22 #include "llvm/CodeGen/Passes.h" 23 #include "llvm/IR/Module.h" 24 #include "llvm/InitializePasses.h" 25 26 using namespace llvm; 27 28 #define DEBUG_TYPE "ehcontguard-catchret" 29 30 STATISTIC(EHContGuardTargetsFound, "Number of EHCont Guard targets"); 31 32 namespace { 33 34 /// MachineFunction pass to insert a symbol before each valid catchret target 35 /// and store these in the MachineFunction's CatchRetTargets vector. 36 class EHContGuardTargets : public MachineFunctionPass { 37 public: 38 static char ID; 39 EHContGuardTargets()40 EHContGuardTargets() : MachineFunctionPass(ID) { 41 initializeEHContGuardTargetsPass(*PassRegistry::getPassRegistry()); 42 } 43 getPassName() const44 StringRef getPassName() const override { 45 return "EH Cont Guard catchret targets"; 46 } 47 48 bool runOnMachineFunction(MachineFunction &MF) override; 49 }; 50 51 } // end anonymous namespace 52 53 char EHContGuardTargets::ID = 0; 54 55 INITIALIZE_PASS(EHContGuardTargets, "EHContGuardTargets", 56 "Insert symbols at valid targets for /guard:ehcont", false, 57 false) createEHContGuardTargetsPass()58FunctionPass *llvm::createEHContGuardTargetsPass() { 59 return new EHContGuardTargets(); 60 } 61 runOnMachineFunction(MachineFunction & MF)62bool EHContGuardTargets::runOnMachineFunction(MachineFunction &MF) { 63 64 // Skip modules for which the ehcontguard flag is not set. 65 if (!MF.getFunction().getParent()->getModuleFlag("ehcontguard")) 66 return false; 67 68 // Skip functions that do not have targets 69 if (!MF.hasEHContTarget()) 70 return false; 71 72 bool Result = false; 73 74 for (MachineBasicBlock &MBB : MF) { 75 if (MBB.isEHContTarget()) { 76 MF.addEHContTarget(MBB.getEHContSymbol()); 77 EHContGuardTargetsFound++; 78 Result = true; 79 } 80 } 81 82 return Result; 83 } 84