llvm/lib/Target/WebAssembly/WebAssemblyNullifyDebugValueLists.cpp

   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://github.com/llvm/llvm-project/issues/49705.
  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   bool Changed = false;
  52   // Our backend, including WebAssemblyDebugValueManager, currently cannot
  53   // handle DBG_VALUE_LISTs correctly. So this makes them undefined, which will
  54   // appear as "optimized out".
  55   for (auto &MBB : MF) {
  56     for (auto &MI : MBB) {
  57       if (MI.getOpcode() == TargetOpcode::DBG_VALUE_LIST) {
  58         MI.setDebugValueUndef();
  59         Changed = true;
  60       }
  61     }
  62   }
  63   return Changed;
  64 }