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/Statistic.h"
17 #include "llvm/CodeGen/Passes.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineFunctionPass.h"
20 #include "llvm/IR/DiagnosticInfo.h"
21 #include "llvm/Support/Debug.h"
22 using namespace llvm;
23 
24 #define DEBUG_TYPE "reset-machine-function"
25 
26 STATISTIC(NumFunctionsReset, "Number of functions reset");
27 
28 namespace {
29   class ResetMachineFunction : public MachineFunctionPass {
30     /// Tells whether or not this pass should emit a fallback
31     /// diagnostic when it resets a function.
32     bool EmitFallbackDiag;
33 
34   public:
35     static char ID; // Pass identification, replacement for typeid
36     ResetMachineFunction(bool EmitFallbackDiag = false)
37         : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag) {}
38 
39     StringRef getPassName() const override { return "ResetMachineFunction"; }
40 
41     bool runOnMachineFunction(MachineFunction &MF) override {
42       if (MF.getProperties().hasProperty(
43               MachineFunctionProperties::Property::FailedISel)) {
44         DEBUG(dbgs() << "Reseting: " << MF.getName() << '\n');
45         ++NumFunctionsReset;
46         MF.reset();
47         if (EmitFallbackDiag) {
48           const Function &F = *MF.getFunction();
49           DiagnosticInfoISelFallback DiagFallback(F);
50           F.getContext().diagnose(DiagFallback);
51         }
52         return true;
53       }
54       return false;
55     }
56 
57   };
58 } // end anonymous namespace
59 
60 char ResetMachineFunction::ID = 0;
61 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
62                 "reset machine function if ISel failed", false, false)
63 
64 MachineFunctionPass *
65 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false) {
66   return new ResetMachineFunction(EmitFallbackDiag);
67 }
68