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     /// Whether we should abort immediately instead of resetting the function.
34     bool AbortOnFailedISel;
35 
36   public:
37     static char ID; // Pass identification, replacement for typeid
38     ResetMachineFunction(bool EmitFallbackDiag = false,
39                          bool AbortOnFailedISel = false)
40         : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag),
41           AbortOnFailedISel(AbortOnFailedISel) {}
42 
43     StringRef getPassName() const override { return "ResetMachineFunction"; }
44 
45     bool runOnMachineFunction(MachineFunction &MF) override {
46       if (MF.getProperties().hasProperty(
47               MachineFunctionProperties::Property::FailedISel)) {
48         if (AbortOnFailedISel)
49           report_fatal_error("Instruction selection failed");
50         DEBUG(dbgs() << "Reseting: " << MF.getName() << '\n');
51         ++NumFunctionsReset;
52         MF.reset();
53         if (EmitFallbackDiag) {
54           const Function &F = *MF.getFunction();
55           DiagnosticInfoISelFallback DiagFallback(F);
56           F.getContext().diagnose(DiagFallback);
57         }
58         return true;
59       }
60       return false;
61     }
62 
63   };
64 } // end anonymous namespace
65 
66 char ResetMachineFunction::ID = 0;
67 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
68                 "reset machine function if ISel failed", false, false)
69 
70 MachineFunctionPass *
71 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
72                                      bool AbortOnFailedISel = false) {
73   return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
74 }
75