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