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
ResetMachineFunction(bool EmitFallbackDiag=false,bool AbortOnFailedISel=false)41 ResetMachineFunction(bool EmitFallbackDiag = false,
42 bool AbortOnFailedISel = false)
43 : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag),
44 AbortOnFailedISel(AbortOnFailedISel) {}
45
getPassName() const46 StringRef getPassName() const override { return "ResetMachineFunction"; }
47
getAnalysisUsage(AnalysisUsage & AU) const48 void getAnalysisUsage(AnalysisUsage &AU) const override {
49 AU.addPreserved<StackProtector>();
50 MachineFunctionPass::getAnalysisUsage(AU);
51 }
52
runOnMachineFunction(MachineFunction & MF)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 *
createResetMachineFunctionPass(bool EmitFallbackDiag=false,bool AbortOnFailedISel=false)85 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
86 bool AbortOnFailedISel = false) {
87 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
88 }
89