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 {
getPassName() const26 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
WebAssemblyNullifyDebugValueLists()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
createWebAssemblyNullifyDebugValueLists()42 FunctionPass *llvm::createWebAssemblyNullifyDebugValueLists() {
43 return new WebAssemblyNullifyDebugValueLists();
44 }
45
runOnMachineFunction(MachineFunction & MF)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