1//===- MachineStripDebug.cpp - Strip debug info ---------------------------===//
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///
9/// \file This removes debug info from everything. It can be used to ensure
10/// tests can be debugified without affecting the output MIR.
11//===----------------------------------------------------------------------===//
12
13#include "llvm/CodeGen/MachineFunctionPass.h"
14#include "llvm/CodeGen/MachineModuleInfo.h"
15#include "llvm/CodeGen/Passes.h"
16#include "llvm/IR/DebugInfo.h"
17#include "llvm/InitializePasses.h"
18#include "llvm/Support/CommandLine.h"
19#include "llvm/Transforms/Utils/Debugify.h"
20
21#define DEBUG_TYPE "mir-strip-debug"
22
23using namespace llvm;
24
25namespace {
26cl::opt<bool>
27    OnlyDebugifiedDefault("mir-strip-debugify-only",
28                          cl::desc("Should mir-strip-debug only strip debug "
29                                   "info from debugified modules by default"),
30                          cl::init(true));
31
32struct StripDebugMachineModule : public ModulePass {
33  bool runOnModule(Module &M) override {
34    if (OnlyDebugified) {
35      NamedMDNode *DebugifyMD = M.getNamedMetadata("llvm.debugify");
36      if (!DebugifyMD) {
37        LLVM_DEBUG(dbgs() << "Not stripping debug info"
38                             " (debugify metadata not found)?\n");
39        return false;
40      }
41    }
42
43    MachineModuleInfo &MMI =
44        getAnalysis<MachineModuleInfoWrapperPass>().getMMI();
45
46    bool Changed = false;
47    for (Function &F : M.functions()) {
48      MachineFunction *MaybeMF = MMI.getMachineFunction(F);
49      if (!MaybeMF)
50        continue;
51      MachineFunction &MF = *MaybeMF;
52      for (MachineBasicBlock &MBB : MF) {
53        for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
54             I != E;) {
55          if (I->isDebugInstr()) {
56            // FIXME: We should remove all of them. However, AArch64 emits an
57            //        invalid `DBG_VALUE $lr` with only one operand instead of
58            //        the usual three and has a test that depends on it's
59            //        preservation. Preserve it for now.
60            if (I->getNumOperands() > 1) {
61              LLVM_DEBUG(dbgs() << "Removing debug instruction " << *I);
62              I = MBB.erase(I);
63              Changed |= true;
64              continue;
65            }
66          }
67          if (I->getDebugLoc()) {
68            LLVM_DEBUG(dbgs() << "Removing location " << *I);
69            I->setDebugLoc(DebugLoc());
70            Changed |= true;
71            ++I;
72            continue;
73          }
74          LLVM_DEBUG(dbgs() << "Keeping " << *I);
75          ++I;
76        }
77      }
78    }
79
80    Changed |= stripDebugifyMetadata(M);
81
82    return Changed;
83  }
84
85  StripDebugMachineModule() : StripDebugMachineModule(OnlyDebugifiedDefault) {}
86  StripDebugMachineModule(bool OnlyDebugified)
87      : ModulePass(ID), OnlyDebugified(OnlyDebugified) {}
88
89  void getAnalysisUsage(AnalysisUsage &AU) const override {
90    AU.addRequired<MachineModuleInfoWrapperPass>();
91    AU.addPreserved<MachineModuleInfoWrapperPass>();
92    AU.setPreservesCFG();
93  }
94
95  static char ID; // Pass identification.
96
97protected:
98  bool OnlyDebugified;
99};
100char StripDebugMachineModule::ID = 0;
101
102} // end anonymous namespace
103
104INITIALIZE_PASS_BEGIN(StripDebugMachineModule, DEBUG_TYPE,
105                      "Machine Strip Debug Module", false, false)
106INITIALIZE_PASS_END(StripDebugMachineModule, DEBUG_TYPE,
107                    "Machine Strip Debug Module", false, false)
108
109ModulePass *llvm::createStripDebugMachineModulePass(bool OnlyDebugified) {
110  return new StripDebugMachineModule(OnlyDebugified);
111}
112