1 //=== WebAssemblyNullifyDebugValueLists.cpp - Nullify DBG_VALUE_LISTs ---===// 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 10 /// Nullify DBG_VALUE_LISTs instructions as a temporary measure before we 11 /// implement DBG_VALUE_LIST handling in WebAssemblyDebugValueManager. 12 /// See https://bugs.llvm.org/show_bug.cgi?id=50361. 13 /// TODO Correctly handle DBG_VALUE_LISTs 14 /// 15 //===----------------------------------------------------------------------===// 16 17 #include "WebAssembly.h" 18 #include "WebAssemblySubtarget.h" 19 using namespace llvm; 20 21 #define DEBUG_TYPE "wasm-nullify-dbg-value-lists" 22 23 namespace { 24 class WebAssemblyNullifyDebugValueLists final : public MachineFunctionPass { 25 StringRef getPassName() const override { 26 return "WebAssembly Nullify DBG_VALUE_LISTs"; 27 } 28 29 bool runOnMachineFunction(MachineFunction &MF) override; 30 31 public: 32 static char ID; // Pass identification, replacement for typeid 33 WebAssemblyNullifyDebugValueLists() : MachineFunctionPass(ID) {} 34 }; 35 } // end anonymous namespace 36 37 char WebAssemblyNullifyDebugValueLists::ID = 0; 38 INITIALIZE_PASS(WebAssemblyNullifyDebugValueLists, DEBUG_TYPE, 39 "WebAssembly Nullify DBG_VALUE_LISTs", false, false) 40 41 FunctionPass *llvm::createWebAssemblyNullifyDebugValueLists() { 42 return new WebAssemblyNullifyDebugValueLists(); 43 } 44 45 bool WebAssemblyNullifyDebugValueLists::runOnMachineFunction( 46 MachineFunction &MF) { 47 LLVM_DEBUG(dbgs() << "********** Nullify DBG_VALUE_LISTs **********\n" 48 "********** Function: " 49 << MF.getName() << '\n'); 50 const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo(); 51 SmallVector<MachineInstr *, 2> DbgValueLists; 52 for (auto &MBB : MF) 53 for (auto &MI : MBB) 54 if (MI.getOpcode() == TargetOpcode::DBG_VALUE_LIST) 55 DbgValueLists.push_back(&MI); 56 57 // Our backend, including WebAssemblyDebugValueManager, currently cannot 58 // handle DBG_VALUE_LISTs correctly. So this converts DBG_VALUE_LISTs to 59 // "DBG_VALUE $noreg", which will appear as "optimized out". 60 for (auto *DVL : DbgValueLists) { 61 BuildMI(*DVL->getParent(), DVL, DVL->getDebugLoc(), 62 TII.get(TargetOpcode::DBG_VALUE), false, Register(), 63 DVL->getOperand(0).getMetadata(), DVL->getOperand(1).getMetadata()); 64 DVL->eraseFromParent(); 65 } 66 67 return !DbgValueLists.empty(); 68 } 69