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/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
  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 (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
  97 protected:
  98   bool OnlyDebugified;
  99 };
 100 char StripDebugMachineModule::ID = 0;
 101
 102 } // end anonymous namespace
 103
 104 INITIALIZE_PASS_BEGIN(StripDebugMachineModule, DEBUG_TYPE,
 105                       "Machine Strip Debug Module", false, false)
 106 INITIALIZE_PASS_END(StripDebugMachineModule, DEBUG_TYPE,
 107                     "Machine Strip Debug Module", false, false)
 108
 109 ModulePass *llvm::createStripDebugMachineModulePass(bool OnlyDebugified) {
 110   return new StripDebugMachineModule(OnlyDebugified);
 111 }