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 #include "llvm/CodeGen/MachineFunctionPass.h" 20 using namespace llvm; 21 22 #define DEBUG_TYPE "wasm-nullify-dbg-value-lists" 23 24 namespace { 25 class WebAssemblyNullifyDebugValueLists final : public MachineFunctionPass { 26 StringRef getPassName() const override { 27 return "WebAssembly Nullify DBG_VALUE_LISTs"; 28 } 29 30 bool runOnMachineFunction(MachineFunction &MF) override; 31 32 public: 33 static char ID; // Pass identification, replacement for typeid 34 WebAssemblyNullifyDebugValueLists() : MachineFunctionPass(ID) {} 35 }; 36 } // end anonymous namespace 37 38 char WebAssemblyNullifyDebugValueLists::ID = 0; 39 INITIALIZE_PASS(WebAssemblyNullifyDebugValueLists, DEBUG_TYPE, 40 "WebAssembly Nullify DBG_VALUE_LISTs", false, false) 41 42 FunctionPass *llvm::createWebAssemblyNullifyDebugValueLists() { 43 return new WebAssemblyNullifyDebugValueLists(); 44 } 45 46 bool WebAssemblyNullifyDebugValueLists::runOnMachineFunction( 47 MachineFunction &MF) { 48 LLVM_DEBUG(dbgs() << "********** Nullify DBG_VALUE_LISTs **********\n" 49 "********** Function: " 50 << MF.getName() << '\n'); 51 const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo(); 52 SmallVector<MachineInstr *, 2> DbgValueLists; 53 for (auto &MBB : MF) 54 for (auto &MI : MBB) 55 if (MI.getOpcode() == TargetOpcode::DBG_VALUE_LIST) 56 DbgValueLists.push_back(&MI); 57 58 // Our backend, including WebAssemblyDebugValueManager, currently cannot 59 // handle DBG_VALUE_LISTs correctly. So this converts DBG_VALUE_LISTs to 60 // "DBG_VALUE $noreg", which will appear as "optimized out". 61 for (auto *DVL : DbgValueLists) { 62 BuildMI(*DVL->getParent(), DVL, DVL->getDebugLoc(), 63 TII.get(TargetOpcode::DBG_VALUE), false, Register(), 64 DVL->getOperand(0).getMetadata(), DVL->getOperand(1).getMetadata()); 65 DVL->eraseFromParent(); 66 } 67 68 return !DbgValueLists.empty(); 69 } 70