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 #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 }