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      1 //===-- FEntryInsertion.cpp - Patchable prologues for LLVM -------------===//
      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 // This file edits function bodies to insert fentry calls.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #include "llvm/CodeGen/MachineFunction.h"
     14 #include "llvm/CodeGen/MachineFunctionPass.h"
     15 #include "llvm/CodeGen/MachineInstrBuilder.h"
     16 #include "llvm/CodeGen/Passes.h"
     17 #include "llvm/CodeGen/TargetFrameLowering.h"
     18 #include "llvm/CodeGen/TargetInstrInfo.h"
     19 #include "llvm/CodeGen/TargetSubtargetInfo.h"
     20 #include "llvm/IR/Function.h"
     21 #include "llvm/IR/Module.h"
     22 #include "llvm/InitializePasses.h"
     23 
     24 using namespace llvm;
     25 
     26 namespace {
     27 struct FEntryInserter : public MachineFunctionPass {
     28   static char ID; // Pass identification, replacement for typeid
     29   FEntryInserter() : MachineFunctionPass(ID) {
     30     initializeFEntryInserterPass(*PassRegistry::getPassRegistry());
     31   }
     32 
     33   bool runOnMachineFunction(MachineFunction &F) override;
     34 };
     35 }
     36 
     37 bool FEntryInserter::runOnMachineFunction(MachineFunction &MF) {
     38   const std::string FEntryName = std::string(
     39       MF.getFunction().getFnAttribute("fentry-call").getValueAsString());
     40   if (FEntryName != "true")
     41     return false;
     42 
     43   auto &FirstMBB = *MF.begin();
     44   auto *TII = MF.getSubtarget().getInstrInfo();
     45   BuildMI(FirstMBB, FirstMBB.begin(), DebugLoc(),
     46           TII->get(TargetOpcode::FENTRY_CALL));
     47   return true;
     48 }
     49 
     50 char FEntryInserter::ID = 0;
     51 char &llvm::FEntryInserterID = FEntryInserter::ID;
     52 INITIALIZE_PASS(FEntryInserter, "fentry-insert", "Insert fentry calls", false,
     53                 false)
     54