lib/CodeGen/ResetMachineFunctionPass.cpp

   1 //===-- ResetMachineFunctionPass.cpp - Reset Machine Function ----*- C++ -*-==//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 /// \file
  10 /// This file implements a pass that will conditionally reset a machine
  11 /// function as if it was just created. This is used to provide a fallback
  12 /// mechanism when GlobalISel fails, thus the condition for the reset to
  13 /// happen is that the MachineFunction has the FailedISel property.
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "llvm/ADT/ScopeExit.h"
  17 #include "llvm/ADT/Statistic.h"
  18 #include "llvm/CodeGen/MachineFunction.h"
  19 #include "llvm/CodeGen/MachineFunctionPass.h"
  20 #include "llvm/CodeGen/MachineRegisterInfo.h"
  21 #include "llvm/CodeGen/StackProtector.h"
  22 #include "llvm/CodeGen/Passes.h"
  23 #include "llvm/IR/DiagnosticInfo.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
  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       // No matter what happened, whether we successfully selected the function
  55       // or not, nothing is going to use the vreg types after us. Make sure they
  56       // disappear.
  57       auto ClearVRegTypesOnReturn =
  58           make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); });
  59
  60       if (MF.getProperties().hasProperty(
  61               MachineFunctionProperties::Property::FailedISel)) {
  62         if (AbortOnFailedISel)
  63           report_fatal_error("Instruction selection failed");
  64         LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n');
  65         ++NumFunctionsReset;
  66         MF.reset();
  67         if (EmitFallbackDiag) {
  68           const Function &F = MF.getFunction();
  69           DiagnosticInfoISelFallback DiagFallback(F);
  70           F.getContext().diagnose(DiagFallback);
  71         }
  72         return true;
  73       }
  74       return false;
  75     }
  76
  77   };
  78 } // end anonymous namespace
  79
  80 char ResetMachineFunction::ID = 0;
  81 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
  82                 "Reset machine function if ISel failed", false, false)
  83
  84 MachineFunctionPass *
  85 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
  86                                      bool AbortOnFailedISel = false) {
  87   return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
  88 }