1 //===-- ResetMachineFunctionPass.cpp - Reset Machine Function ----*- 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 /// \file 9 /// This file implements a pass that will conditionally reset a machine 10 /// function as if it was just created. This is used to provide a fallback 11 /// mechanism when GlobalISel fails, thus the condition for the reset to 12 /// happen is that the MachineFunction has the FailedISel property. 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/ADT/ScopeExit.h" 16 #include "llvm/ADT/Statistic.h" 17 #include "llvm/CodeGen/MachineFunction.h" 18 #include "llvm/CodeGen/MachineFunctionPass.h" 19 #include "llvm/CodeGen/MachineRegisterInfo.h" 20 #include "llvm/CodeGen/Passes.h" 21 #include "llvm/CodeGen/StackProtector.h" 22 #include "llvm/IR/DiagnosticInfo.h" 23 #include "llvm/InitializePasses.h" 24 #include "llvm/Support/Debug.h" 25 #include "llvm/Target/TargetMachine.h" 26 using namespace llvm; 27 28 #define DEBUG_TYPE "reset-machine-function" 29 30 STATISTIC(NumFunctionsReset, "Number of functions reset"); 31 STATISTIC(NumFunctionsVisited, "Number of functions visited"); 32 33 namespace { 34 class ResetMachineFunction : public MachineFunctionPass { 35 /// Tells whether or not this pass should emit a fallback 36 /// diagnostic when it resets a function. 37 bool EmitFallbackDiag; 38 /// Whether we should abort immediately instead of resetting the function. 39 bool AbortOnFailedISel; 40 41 public: 42 static char ID; // Pass identification, replacement for typeid 43 ResetMachineFunction(bool EmitFallbackDiag = false, 44 bool AbortOnFailedISel = false) 45 : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag), 46 AbortOnFailedISel(AbortOnFailedISel) {} 47 48 StringRef getPassName() const override { return "ResetMachineFunction"; } 49 50 void getAnalysisUsage(AnalysisUsage &AU) const override { 51 AU.addPreserved<StackProtector>(); 52 MachineFunctionPass::getAnalysisUsage(AU); 53 } 54 55 bool runOnMachineFunction(MachineFunction &MF) override { 56 ++NumFunctionsVisited; 57 // No matter what happened, whether we successfully selected the function 58 // or not, nothing is going to use the vreg types after us. Make sure they 59 // disappear. 60 auto ClearVRegTypesOnReturn = 61 make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); }); 62 63 if (MF.getProperties().hasFailedISel()) { 64 if (AbortOnFailedISel) 65 report_fatal_error("Instruction selection failed"); 66 LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n'); 67 ++NumFunctionsReset; 68 MF.reset(); 69 MF.initTargetMachineFunctionInfo(MF.getSubtarget()); 70 71 const TargetMachine &TM = MF.getTarget(); 72 // MRI callback for target specific initializations. 73 TM.registerMachineRegisterInfoCallback(MF); 74 75 if (EmitFallbackDiag) { 76 const Function &F = MF.getFunction(); 77 DiagnosticInfoISelFallback DiagFallback(F); 78 F.getContext().diagnose(DiagFallback); 79 } 80 return true; 81 } 82 return false; 83 } 84 85 }; 86 } // end anonymous namespace 87 88 char ResetMachineFunction::ID = 0; 89 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE, 90 "Reset machine function if ISel failed", false, false) 91 92 MachineFunctionPass * 93 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false, 94 bool AbortOnFailedISel = false) { 95 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel); 96 } 97