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/StackProtector.h" 21 #include "llvm/CodeGen/Passes.h" 22 #include "llvm/IR/DiagnosticInfo.h" 23 #include "llvm/Support/Debug.h" 24 using namespace llvm; 25 26 #define DEBUG_TYPE "reset-machine-function" 27 28 STATISTIC(NumFunctionsReset, "Number of functions reset"); 29 STATISTIC(NumFunctionsVisited, "Number of functions visited"); 30 31 namespace { 32 class ResetMachineFunction : public MachineFunctionPass { 33 /// Tells whether or not this pass should emit a fallback 34 /// diagnostic when it resets a function. 35 bool EmitFallbackDiag; 36 /// Whether we should abort immediately instead of resetting the function. 37 bool AbortOnFailedISel; 38 39 public: 40 static char ID; // Pass identification, replacement for typeid 41 ResetMachineFunction(bool EmitFallbackDiag = false, 42 bool AbortOnFailedISel = false) 43 : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag), 44 AbortOnFailedISel(AbortOnFailedISel) {} 45 46 StringRef getPassName() const override { return "ResetMachineFunction"; } 47 48 void getAnalysisUsage(AnalysisUsage &AU) const override { 49 AU.addPreserved<StackProtector>(); 50 MachineFunctionPass::getAnalysisUsage(AU); 51 } 52 53 bool runOnMachineFunction(MachineFunction &MF) override { 54 ++NumFunctionsVisited; 55 // No matter what happened, whether we successfully selected the function 56 // or not, nothing is going to use the vreg types after us. Make sure they 57 // disappear. 58 auto ClearVRegTypesOnReturn = 59 make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); }); 60 61 if (MF.getProperties().hasProperty( 62 MachineFunctionProperties::Property::FailedISel)) { 63 if (AbortOnFailedISel) 64 report_fatal_error("Instruction selection failed"); 65 LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n'); 66 ++NumFunctionsReset; 67 MF.reset(); 68 if (EmitFallbackDiag) { 69 const Function &F = MF.getFunction(); 70 DiagnosticInfoISelFallback DiagFallback(F); 71 F.getContext().diagnose(DiagFallback); 72 } 73 return true; 74 } 75 return false; 76 } 77 78 }; 79 } // end anonymous namespace 80 81 char ResetMachineFunction::ID = 0; 82 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE, 83 "Reset machine function if ISel failed", false, false) 84 85 MachineFunctionPass * 86 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false, 87 bool AbortOnFailedISel = false) { 88 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel); 89 } 90