1 //===-- ResetMachineFunctionPass.cpp - Reset Machine Function ----*- C++ -*-==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 /// \file
9 /// This file implements a pass that will conditionally reset a machine
10 /// function as if it was just created. This is used to provide a fallback
11 /// mechanism when GlobalISel fails, thus the condition for the reset to
12 /// happen is that the MachineFunction has the FailedISel property.
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/ADT/ScopeExit.h"
16 #include "llvm/ADT/Statistic.h"
17 #include "llvm/CodeGen/MachineFunction.h"
18 #include "llvm/CodeGen/MachineFunctionPass.h"
19 #include "llvm/CodeGen/MachineRegisterInfo.h"
20 #include "llvm/CodeGen/Passes.h"
21 #include "llvm/CodeGen/StackProtector.h"
22 #include "llvm/IR/DiagnosticInfo.h"
23 #include "llvm/InitializePasses.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 STATISTIC(NumFunctionsVisited, "Number of functions visited");
31
32 namespace {
33 class ResetMachineFunction : public MachineFunctionPass {
34 /// Tells whether or not this pass should emit a fallback
35 /// diagnostic when it resets a function.
36 bool EmitFallbackDiag;
37 /// Whether we should abort immediately instead of resetting the function.
38 bool AbortOnFailedISel;
39
40 public:
41 static char ID; // Pass identification, replacement for typeid
ResetMachineFunction(bool EmitFallbackDiag=false,bool AbortOnFailedISel=false)42 ResetMachineFunction(bool EmitFallbackDiag = false,
43 bool AbortOnFailedISel = false)
44 : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag),
45 AbortOnFailedISel(AbortOnFailedISel) {}
46
getPassName() const47 StringRef getPassName() const override { return "ResetMachineFunction"; }
48
getAnalysisUsage(AnalysisUsage & AU) const49 void getAnalysisUsage(AnalysisUsage &AU) const override {
50 AU.addPreserved<StackProtector>();
51 MachineFunctionPass::getAnalysisUsage(AU);
52 }
53
runOnMachineFunction(MachineFunction & MF)54 bool runOnMachineFunction(MachineFunction &MF) override {
55 ++NumFunctionsVisited;
56 // No matter what happened, whether we successfully selected the function
57 // or not, nothing is going to use the vreg types after us. Make sure they
58 // disappear.
59 auto ClearVRegTypesOnReturn =
60 make_scope_exit([&MF]() { MF.getRegInfo().clearVirtRegTypes(); });
61
62 if (MF.getProperties().hasProperty(
63 MachineFunctionProperties::Property::FailedISel)) {
64 if (AbortOnFailedISel)
65 report_fatal_error("Instruction selection failed");
66 LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n');
67 ++NumFunctionsReset;
68 MF.reset();
69 if (EmitFallbackDiag) {
70 const Function &F = MF.getFunction();
71 DiagnosticInfoISelFallback DiagFallback(F);
72 F.getContext().diagnose(DiagFallback);
73 }
74 return true;
75 }
76 return false;
77 }
78
79 };
80 } // end anonymous namespace
81
82 char ResetMachineFunction::ID = 0;
83 INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
84 "Reset machine function if ISel failed", false, false)
85
86 MachineFunctionPass *
createResetMachineFunctionPass(bool EmitFallbackDiag=false,bool AbortOnFailedISel=false)87 llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
88 bool AbortOnFailedISel = false) {
89 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
90 }
91