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#include "llvm/Target/TargetMachine.h"
26using namespace llvm;
27
28#define DEBUG_TYPE "reset-machine-function"
29
30STATISTIC(NumFunctionsReset, "Number of functions reset");
31STATISTIC(NumFunctionsVisited, "Number of functions visited");
32
33namespace {
34 class ResetMachineFunction : public MachineFunctionPass {
35 /// Tells whether or not this pass should emit a fallback
36 /// diagnostic when it resets a function.
37 bool EmitFallbackDiag;
38 /// Whether we should abort immediately instead of resetting the function.
39 bool AbortOnFailedISel;
40
41 public:
42 static char ID; // Pass identification, replacement for typeid
43 ResetMachineFunction(bool EmitFallbackDiag = false,
44 bool AbortOnFailedISel = false)
45 : MachineFunctionPass(ID), EmitFallbackDiag(EmitFallbackDiag),
46 AbortOnFailedISel(AbortOnFailedISel) {}
47
48 StringRef getPassName() const override { return "ResetMachineFunction"; }
49
50 void getAnalysisUsage(AnalysisUsage &AU) const override {
51 AU.addPreserved<StackProtector>();
52 MachineFunctionPass::getAnalysisUsage(AU);
53 }
54
55 bool runOnMachineFunction(MachineFunction &MF) override {
56 ++NumFunctionsVisited;
57 // No matter what happened, whether we successfully selected the function
58 // or not, nothing is going to use the vreg types after us. Make sure they
59 // disappear.
60 auto ClearVRegTypesOnReturn =
61 make_scope_exit(F: [&MF]() { MF.getRegInfo().clearVirtRegTypes(); });
62
63 if (MF.getProperties().hasFailedISel()) {
64 if (AbortOnFailedISel)
65 report_fatal_error(reason: "Instruction selection failed");
66 LLVM_DEBUG(dbgs() << "Resetting: " << MF.getName() << '\n');
67 ++NumFunctionsReset;
68 MF.reset();
69 MF.initTargetMachineFunctionInfo(STI: MF.getSubtarget());
70
71 const TargetMachine &TM = MF.getTarget();
72 // MRI callback for target specific initializations.
73 TM.registerMachineRegisterInfoCallback(MF);
74
75 if (EmitFallbackDiag) {
76 const Function &F = MF.getFunction();
77 DiagnosticInfoISelFallback DiagFallback(F);
78 F.getContext().diagnose(DI: DiagFallback);
79 }
80 return true;
81 }
82 return false;
83 }
84
85 };
86} // end anonymous namespace
87
88char ResetMachineFunction::ID = 0;
89INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
90 "Reset machine function if ISel failed", false, false)
91
92MachineFunctionPass *
93llvm::createResetMachineFunctionPass(bool EmitFallbackDiag = false,
94 bool AbortOnFailedISel = false) {
95 return new ResetMachineFunction(EmitFallbackDiag, AbortOnFailedISel);
96}
97