llvm/lib/CodeGen/MachineStripDebug.cpp

   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/MachineBasicBlock.h"
  14 #include "llvm/CodeGen/MachineFunction.h"
  15 #include "llvm/CodeGen/MachineModuleInfo.h"
  16 #include "llvm/CodeGen/Passes.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
  23 using namespace llvm;
  24
  25 namespace {
  26 cl::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
  32 struct 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 (MachineInstr &MI : llvm::make_early_inc_range(MBB)) {
  54           if (MI.isDebugInstr()) {
  55             // FIXME: We should remove all of them. However, AArch64 emits an
  56             //        invalid `DBG_VALUE $lr` with only one operand instead of
  57             //        the usual three and has a test that depends on it's
  58             //        preservation. Preserve it for now.
  59             if (MI.getNumOperands() > 1) {
  60               LLVM_DEBUG(dbgs() << "Removing debug instruction " << MI);
  61               MBB.erase(&MI);
  62               Changed |= true;
  63               continue;
  64             }
  65           }
  66           if (MI.getDebugLoc()) {
  67             LLVM_DEBUG(dbgs() << "Removing location " << MI);
  68             MI.setDebugLoc(DebugLoc());
  69             Changed |= true;
  70             continue;
  71           }
  72           LLVM_DEBUG(dbgs() << "Keeping " << MI);
  73         }
  74       }
  75     }
  76
  77     Changed |= stripDebugifyMetadata(M);
  78
  79     return Changed;
  80   }
  81
  82   StripDebugMachineModule() : StripDebugMachineModule(OnlyDebugifiedDefault) {}
  83   StripDebugMachineModule(bool OnlyDebugified)
  84       : ModulePass(ID), OnlyDebugified(OnlyDebugified) {}
  85
  86   void getAnalysisUsage(AnalysisUsage &AU) const override {
  87     AU.addRequired<MachineModuleInfoWrapperPass>();
  88     AU.addPreserved<MachineModuleInfoWrapperPass>();
  89     AU.setPreservesCFG();
  90   }
  91
  92   static char ID; // Pass identification.
  93
  94 protected:
  95   bool OnlyDebugified;
  96 };
  97 char StripDebugMachineModule::ID = 0;
  98
  99 } // end anonymous namespace
 100
 101 INITIALIZE_PASS_BEGIN(StripDebugMachineModule, DEBUG_TYPE,
 102                       "Machine Strip Debug Module", false, false)
 103 INITIALIZE_PASS_END(StripDebugMachineModule, DEBUG_TYPE,
 104                     "Machine Strip Debug Module", false, false)
 105
 106 ModulePass *llvm::createStripDebugMachineModulePass(bool OnlyDebugified) {
 107   return new StripDebugMachineModule(OnlyDebugified);
 108 }