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/MachineInstr.h"
  21 #include "llvm/CodeGen/MachineModuleInfo.h"
  22 #include "llvm/CodeGen/MachineOperand.h"
  23 #include "llvm/CodeGen/Passes.h"
  24 #include "llvm/InitializePasses.h"
  25
  26 using namespace llvm;
  27
  28 #define DEBUG_TYPE "ehcontguard-catchret"
  29
  30 STATISTIC(EHContGuardCatchretTargets,
  31           "Number of EHCont Guard catchret targets");
  32
  33 namespace {
  34
  35 /// MachineFunction pass to insert a symbol before each valid catchret target
  36 /// and store these in the MachineFunction's CatchRetTargets vector.
  37 class EHContGuardCatchret : public MachineFunctionPass {
  38 public:
  39   static char ID;
  40
  41   EHContGuardCatchret() : MachineFunctionPass(ID) {
  42     initializeEHContGuardCatchretPass(*PassRegistry::getPassRegistry());
  43   }
  44
  45   StringRef getPassName() const override {
  46     return "EH Cont Guard catchret targets";
  47   }
  48
  49   bool runOnMachineFunction(MachineFunction &MF) override;
  50 };
  51
  52 } // end anonymous namespace
  53
  54 char EHContGuardCatchret::ID = 0;
  55
  56 INITIALIZE_PASS(EHContGuardCatchret, "EHContGuardCatchret",
  57                 "Insert symbols at valid catchret targets for /guard:ehcont",
  58                 false, false)
  59 FunctionPass *llvm::createEHContGuardCatchretPass() {
  60   return new EHContGuardCatchret();
  61 }
  62
  63 bool EHContGuardCatchret::runOnMachineFunction(MachineFunction &MF) {
  64
  65   // Skip modules for which the ehcontguard flag is not set.
  66   if (!MF.getMMI().getModule()->getModuleFlag("ehcontguard"))
  67     return false;
  68
  69   // Skip functions that do not have catchret
  70   if (!MF.hasEHCatchret())
  71     return false;
  72
  73   bool Result = false;
  74
  75   for (MachineBasicBlock &MBB : MF) {
  76     if (MBB.isEHCatchretTarget()) {
  77       MF.addCatchretTarget(MBB.getEHCatchretSymbol());
  78       EHContGuardCatchretTargets++;
  79       Result = true;
  80     }
  81   }
  82
  83   return Result;
  84 }