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/InitializePasses.h"
  23
  24 using namespace llvm;
  25
  26 #define DEBUG_TYPE "ehcontguard-catchret"
  27
  28 STATISTIC(EHContGuardCatchretTargets,
  29           "Number of EHCont Guard catchret targets");
  30
  31 namespace {
  32
  33 /// MachineFunction pass to insert a symbol before each valid catchret target
  34 /// and store these in the MachineFunction's CatchRetTargets vector.
  35 class EHContGuardCatchret : public MachineFunctionPass {
  36 public:
  37   static char ID;
  38
  39   EHContGuardCatchret() : MachineFunctionPass(ID) {
  40     initializeEHContGuardCatchretPass(*PassRegistry::getPassRegistry());
  41   }
  42
  43   StringRef getPassName() const override {
  44     return "EH Cont Guard catchret targets";
  45   }
  46
  47   bool runOnMachineFunction(MachineFunction &MF) override;
  48 };
  49
  50 } // end anonymous namespace
  51
  52 char EHContGuardCatchret::ID = 0;
  53
  54 INITIALIZE_PASS(EHContGuardCatchret, "EHContGuardCatchret",
  55                 "Insert symbols at valid catchret targets for /guard:ehcont",
  56                 false, false)
  57 FunctionPass *llvm::createEHContGuardCatchretPass() {
  58   return new EHContGuardCatchret();
  59 }
  60
  61 bool EHContGuardCatchret::runOnMachineFunction(MachineFunction &MF) {
  62
  63   // Skip modules for which the ehcontguard flag is not set.
  64   if (!MF.getMMI().getModule()->getModuleFlag("ehcontguard"))
  65     return false;
  66
  67   // Skip functions that do not have catchret
  68   if (!MF.hasEHCatchret())
  69     return false;
  70
  71   bool Result = false;
  72
  73   for (MachineBasicBlock &MBB : MF) {
  74     if (MBB.isEHCatchretTarget()) {
  75       MF.addCatchretTarget(MBB.getEHCatchretSymbol());
  76       EHContGuardCatchretTargets++;
  77       Result = true;
  78     }
  79   }
  80
  81   return Result;
  82 }