Line data    Source code

       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         199 :         : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag),
      44         199 :           AbortOnFailedISel(AbortOnFailedISel) {}
      45             : 
      46         159 :     StringRef getPassName() const override { return "ResetMachineFunction"; }
      47             : 
      48         152 :     void getAnalysisUsage(AnalysisUsage &AU) const override {
      49             :       AU.addPreserved<StackProtector>();
      50         152 :       MachineFunctionPass::getAnalysisUsage(AU);
      51         152 :     }
      52             : 
      53         823 :     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         823 :           make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); });
      59             : 
      60         823 :       if (MF.getProperties().hasProperty(
      61             :               MachineFunctionProperties::Property::FailedISel)) {
      62         125 :         if (AbortOnFailedISel)
      63           0 :           report_fatal_error("Instruction selection failed");
      64             :         LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n');
      65             :         ++NumFunctionsReset;
      66             :         MF.reset();
      67         125 :         if (EmitFallbackDiag) {
      68         101 :           const Function &F = MF.getFunction();
      69             :           DiagnosticInfoISelFallback DiagFallback(F);
      70         101 :           F.getContext().diagnose(DiagFallback);
      71             :         }
      72         125 :         return true;
      73             :       }
      74             :       return false;
      75             :     }
      76             : 
      77             :   };
      78             : } // end anonymous namespace
      79             : 
      80             : char ResetMachineFunction::ID = 0;
      81           0 : INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
      82             :                 "Reset machine function if ISel failed", false, false)
      83             : 
      84             : MachineFunctionPass *
      85         199 : llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
      86             :                                      bool AbortOnFailedISel = false) {
      87         199 :   return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
      88             : }