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().hasProperty( 64 MachineFunctionProperties::Property::FailedISel)) { 65 if (AbortOnFailedISel) 66 report_fatal_error("Instruction selection failed"); 67 LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n'); 68 ++NumFunctionsReset; 69 MF.reset(); 70 MF.initTargetMachineFunctionInfo(MF.getSubtarget()); 71 72 const LLVMTargetMachine &TM = MF.getTarget(); 73 // MRI callback for target specific initializations. 74 TM.registerMachineRegisterInfoCallback(MF); 75 76 if (EmitFallbackDiag) { 77 const Function &F = MF.getFunction(); 78 DiagnosticInfoISelFallback DiagFallback(F); 79 F.getContext().diagnose(DiagFallback); 80 } 81 return true; 82 } 83 return false; 84 } 85 86 }; 87 } // end anonymous namespace 88 89 char ResetMachineFunction::ID = 0; 90 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE, 91 "Reset machine function if ISel failed", false, false) 92 93 MachineFunctionPass * 94 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false, 95 bool AbortOnFailedISel = false) { 96 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel); 97 } 98