llvm/lib/CodeGen/EHContGuardCatchret.cpp

   1 //===-- EHContGuardCatchret.cpp - Catchret 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 catchret target and store this in the MachineFunction's
  12 /// CatchRetTargets vector. This will be used to emit the table of valid targets
  13 /// used by EHCont Guard.
  14 ///
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/ADT/Statistic.h"
  18 #include "llvm/CodeGen/MachineBasicBlock.h"
  19 #include "llvm/CodeGen/MachineFunctionPass.h"
  20 #include "llvm/CodeGen/MachineModuleInfo.h"
  21 #include "llvm/CodeGen/Passes.h"
  22 #include "llvm/IR/Module.h"
  23 #include "llvm/InitializePasses.h"
  24
  25 using namespace llvm;
  26
  27 #define DEBUG_TYPE "ehcontguard-catchret"
  28
  29 STATISTIC(EHContGuardCatchretTargets,
  30           "Number of EHCont Guard catchret 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 EHContGuardCatchret : public MachineFunctionPass {
  37 public:
  38   static char ID;
  39
  40   EHContGuardCatchret() : MachineFunctionPass(ID) {
  41     initializeEHContGuardCatchretPass(*PassRegistry::getPassRegistry());
  42   }
  43
  44   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 EHContGuardCatchret::ID = 0;
  54
  55 INITIALIZE_PASS(EHContGuardCatchret, "EHContGuardCatchret",
  56                 "Insert symbols at valid catchret targets for /guard:ehcont",
  57                 false, false)
  58 FunctionPass *llvm::createEHContGuardCatchretPass() {
  59   return new EHContGuardCatchret();
  60 }
  61
  62 bool EHContGuardCatchret::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 catchret
  69   if (!MF.hasEHCatchret())
  70     return false;
  71
  72   bool Result = false;
  73
  74   for (MachineBasicBlock &MBB : MF) {
  75     if (MBB.isEHCatchretTarget()) {
  76       MF.addCatchretTarget(MBB.getEHCatchretSymbol());
  77       EHContGuardCatchretTargets++;
  78       Result = true;
  79     }
  80   }
  81
  82   return Result;
  83 }