lib/CodeGen/ResetMachineFunctionPass.cpp

   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 }